ARRT Computed Tomography (CT) Certification Examination — Questions and Answers

Question 1: Which of the following best explains why ARRT periodically revises its CT examination content specifications?

To match content used by competing certification bodies
To satisfy JRCERT annual audit requirements
To align the examination with evolving clinical practice identified through practice analysis (Correct answer)
To increase examination difficulty and reduce pass rates

Correct answer: To align the examination with evolving clinical practice identified through practice analysis

ARRT updates content specifications based on practice analysis data to ensure examinations reflect what entry-level technologists actually need to know in current clinical settings.

Question 2: What is the mechanism of an anaphylactoid (allergic-like) reaction to iodinated contrast media?

Cytotoxic T-cell destruction of endothelial cells
Non-IgE-mediated direct mast cell and basophil activation independent of prior sensitization (Correct answer)
Complement activation by iodine forming immune complexes
IgE-mediated mast cell degranulation identical to classic allergy

Correct answer: Non-IgE-mediated direct mast cell and basophil activation independent of prior sensitization

Anaphylactoid reactions to contrast are non-IgE-mediated; contrast directly activates mast cells and basophils, releasing histamine and other mediators without requiring prior sensitization.

Question 3: Which of the following correctly defines 'effective dose' (E) in radiation protection?

The absorbed dose to a single organ multiplied by the quality factor
The dose measured at the surface of a standard phantom
The weighted sum of equivalent doses to all irradiated tissues, reflecting overall stochastic risk (Correct answer)
The total energy deposited in the patient during a CT scan

Correct answer: The weighted sum of equivalent doses to all irradiated tissues, reflecting overall stochastic risk

Effective dose uses tissue weighting factors to sum equivalent doses across organs, yielding a single value (in mSv) that represents whole-body stochastic risk.

Question 4: A technologist is scanning a patient with metal hip implants. To reduce dose while managing metal artifact, which approach is MOST appropriate?

Skip the hip region entirely regardless of clinical indication
Double the mAs in the hip region to overpower artifacts
Switch to a lower kVp to increase contrast resolution
Use metal artifact reduction (MAR) software at standard dose rather than routinely increasing mAs (Correct answer)

Correct answer: Use metal artifact reduction (MAR) software at standard dose rather than routinely increasing mAs

Metal artifact reduction software effectively manages implant artifacts at standard dose; routinely increasing mAs adds unnecessary patient dose without eliminating artifacts.

Question 5: What is the primary radiation hazard associated with CT compared to conventional radiography?

Higher peak kilovoltage
Use of radioactive isotopes as contrast agents
Significantly greater patient dose due to multiple rotational acquisitions and extended scan volumes (Correct answer)
Greater secondary radiation reaching personnel in adjacent rooms

Correct answer: Significantly greater patient dose due to multiple rotational acquisitions and extended scan volumes

CT delivers substantially higher patient doses than conventional radiography because it involves multiple rotational X-ray acquisitions covering large anatomical volumes.

Question 6: Which entity must sponsor a continuing education activity for it to count toward ARRT CT recertification?

The technologist's employing hospital
The American College of Radiology only
An ARRT-approved CE sponsor (Correct answer)
Any national radiology organization

Correct answer: An ARRT-approved CE sponsor

ARRT only accepts Category A CE credits from activities provided by ARRT-approved sponsors, ensuring quality and relevance.

Question 7: What is the role of the ARRT Board of Trustees in the accreditation and credentialing process?

They govern ARRT policy, including eligibility requirements and ethical standards (Correct answer)
They perform on-site inspections of clinical training sites
They issue state radiologic technology licenses
They directly score individual certification examinations

Correct answer: They govern ARRT policy, including eligibility requirements and ethical standards

The ARRT Board of Trustees is the governing body responsible for setting policy, eligibility criteria, and ethical standards for the organization.

Question 8: On axial CT of the chest, the right and left main bronchi are best distinguished because:

The left main bronchus is shorter and more vertical than the right
The right main bronchus is shorter and more vertical, making aspiration more likely (Correct answer)
The left main bronchus has a larger caliber than the right
The right main bronchus is longer and more horizontal than the left

Correct answer: The right main bronchus is shorter and more vertical, making aspiration more likely

The right main bronchus is shorter, wider, and more vertical, which is why aspirated foreign bodies most commonly lodge on the right side.

Question 9: What is homeostasis?

A type of cell division
A disease state
The body's ability to maintain stable internal conditions (Correct answer)
An organ system

Correct answer: The body's ability to maintain stable internal conditions

Homeostasis is the body's dynamic process of maintaining stable internal conditions (temperature, pH, blood sugar) despite external changes.

Question 10: On axial brain CT, the internal capsule is bounded medially by which structure?

Caudate nucleus (Correct answer)
Globus pallidus
Putamen
Thalamus

Correct answer: Caudate nucleus

The anterior limb of the internal capsule is bounded medially by the head of the caudate nucleus.

Question 11: A patient receiving oxygen via nasal cannula at 2 L/min needs a portable chest X-ray. The technologist should:

Discontinue oxygen as it interferes with imaging
Switch the patient to a face mask before imaging
Remove the oxygen cannula during the exposure
Leave the oxygen in place and proceed with the exam (Correct answer)

Correct answer: Leave the oxygen in place and proceed with the exam

Supplemental oxygen should not be interrupted; nasal cannulas do not significantly affect image quality and the patient's oxygenation status must be maintained.

Question 12: On axial CT of the abdomen, the superior mesenteric artery (SMA) is typically located:

Within the hepatoduodenal ligament
Posterior to the splenic vein
Directly anterior to the abdominal aorta, surrounded by fat (Correct answer)
Lateral to the inferior vena cava

Correct answer: Directly anterior to the abdominal aorta, surrounded by fat

The SMA arises from the anterior aorta and is typically seen as a vessel surrounded by a halo of mesenteric fat on axial CT.

Question 13: Which of the following is an example of a breach of patient confidentiality?

Documenting contrast administration in the patient's chart
Confirming a patient's identity before beginning a procedure
Sharing patient imaging results with the ordering physician
Discussing a patient's case with a family member without patient consent (Correct answer)

Correct answer: Discussing a patient's case with a family member without patient consent

Under HIPAA, patient health information may not be shared with family members without the patient's explicit consent, except in specific circumstances.

Question 14: When creating coronal MPR images from a helical chest CT, image quality is best when the original acquisition used:

Thin slices (≤1 mm) reconstructed at overlapping intervals (0.5–0.7 mm) (Correct answer)
High pitch with standard soft tissue kernel only
Large FOV and minimal overlap
Thick slices (5–10 mm) reconstructed at 5 mm intervals

Correct answer: Thin slices (≤1 mm) reconstructed at overlapping intervals (0.5–0.7 mm)

Thin, overlapping reconstructions produce near-isotropic voxels that allow high-quality coronal and sagittal reformations without visible stair-step artifacts.

Question 15: What is the first priority in any emergency situation?

Save equipment
Contact the media
Write a report
Ensure the safety of all personnel (Correct answer)

Correct answer: Ensure the safety of all personnel

In any emergency, the first priority is always the safety and well-being of all personnel. Equipment and materials can be replaced; lives cannot.

Question 16: Which CT post-processing technique displays only voxels above a selected threshold, making it useful for 3D visualization of bones and vascular structures?

Maximum intensity projection (MIP) (Correct answer)
Volume rendering (VR)
Surface shaded display (SSD)
Multiplanar reformation (MPR)

Correct answer: Maximum intensity projection (MIP)

Maximum intensity projection (MIP) selects and displays the highest attenuation voxel along each ray through the dataset, ideal for visualizing contrast-enhanced vessels or calcifications.

Question 17: On axial brain CT, the sylvian fissure (lateral sulcus) separates which lobes?

Parietal lobe from occipital lobe
Frontal and parietal lobes from the temporal lobe (Correct answer)
Frontal lobe from occipital lobe
Frontal lobe from the parietal lobe only

Correct answer: Frontal and parietal lobes from the temporal lobe

The sylvian (lateral) fissure separates the frontal and parietal lobes superiorly from the temporal lobe inferiorly.

Question 18: Which reconstruction kernel (filter) should be chosen to minimize noise when imaging soft tissue structures in the abdomen?

Ultra-high resolution kernel
Smooth or standard soft tissue kernel (Correct answer)
Bone or edge-enhancing kernel
Lung kernel

Correct answer: Smooth or standard soft tissue kernel

Soft tissue kernels apply low-pass filtering that smooths the image and reduces noise, which is appropriate for abdominal soft tissue evaluation.

Question 19: What are the principles of mission command?

Rank, authority, obedience
Technology, firepower, logistics
Speed, power, aggression
Competence, mutual trust, shared understanding, commander's intent (Correct answer)

Correct answer: Competence, mutual trust, shared understanding, commander's intent

Mission command empowers subordinates through trust, shared understanding of the commander's intent, and disciplined initiative.

Question 20: Which of the following is a non-financial benefit of ARRT CT certification that directly impacts a technologist's daily work?

Increased confidence and clinical decision-making ability in CT protocols (Correct answer)
Automatic scheduling priority for day shifts
Exemption from hospital-wide mandatory training
Reduced number of CT scans assigned per shift

Correct answer: Increased confidence and clinical decision-making ability in CT protocols

Preparing for and passing the CT exam deepens protocol knowledge, which enhances the technologist's confidence and quality of clinical decisions.

Question 21: A CT technologist holds both Radiography (R) and CT credentials. How many CE credits are required biennially?

24 total, shared across all credentials (Correct answer)
12 per credential for a total of 24
48 total (24 per credential)
24 R-specific + 12 CT-specific = 36

Correct answer: 24 total, shared across all credentials

ARRT allows CE credits to be shared across all held credentials, so 24 credits per 2-year cycle satisfies requirements for multiple credentials.

Question 22: A hospital's Imaging Director wants to ensure staff are competent in CT protocols. Which credential most directly validates CT-specific competency?

OSHA safety training certificate
ARRT CT post-primary certification (Correct answer)
ACR accreditation badge
Basic Life Support (BLS) certification

Correct answer: ARRT CT post-primary certification

ARRT CT post-primary certification specifically validates a technologist's advanced knowledge and skills in computed tomography.

Question 23: CT calcium scoring of the coronary arteries uses which post-processing method to quantify calcification?

MIP projection over the cardiac cycle
Subtraction of non-contrast from contrast images
Agatston scoring based on lesion area and peak Hounsfield unit density (Correct answer)
Volume rendering with opacity mapping

Correct answer: Agatston scoring based on lesion area and peak Hounsfield unit density

Agatston scoring multiplies the area of each calcified lesion by a density factor based on peak HU (1–4 scale), then sums all lesions to yield the total calcium score.

Question 24: On CT spine, which finding is most consistent with a herniated nucleus pulposus at L4-L5 causing left leg radiculopathy?

Central disc bulge at L3-L4
Right paracentral disc protrusion compressing the L4 nerve root in the lateral recess
Left paracentral disc extrusion compressing the left L5 nerve root (Correct answer)
Left foraminal stenosis at L3-L4

Correct answer: Left paracentral disc extrusion compressing the left L5 nerve root

A left paracentral extrusion at L4-L5 compresses the traversing L5 nerve root in the lateral recess, causing ipsilateral radiculopathy.

Question 25: A ring or band artifact centered on the image is most likely caused by a malfunction of which CT component?

Gantry motor
X-ray tube
Collimator
A single detector element (Correct answer)

Correct answer: A single detector element

Ring artifacts result from a miscalibrated or malfunctioning detector element producing a circular artifact at a fixed radius from the isocenter.

Question 26: For a CT-guided biopsy protocol, which parameter is typically reduced to minimize patient dose during the procedure?

Tube current (mA) (Correct answer)
Gantry rotation speed
Tube voltage (kVp)
Slice thickness

Correct answer: Tube current (mA)

Fluoroscopic CT guidance uses low-mA (fluoroCT) settings to reduce cumulative dose while maintaining adequate image quality for needle visualization.

Question 27: What type of artifact appears as bright or dark streaks radiating from high-density objects like metal implants in CT images?

Ring artifact
Partial volume artifact
Beam hardening artifact (Correct answer)
Motion artifact

Correct answer: Beam hardening artifact

Beam hardening artifacts appear as streaks or dark bands radiating from dense metallic objects because lower-energy photons are preferentially absorbed.

Question 28: For a CT scan of the spine performed to evaluate for disk herniation, which reconstruction kernel is preferred?

Lung (high-frequency) kernel
Bone (high-frequency) kernel
Ultra-high-resolution kernel
Standard soft tissue kernel (Correct answer)

Correct answer: Standard soft tissue kernel

A standard or intermediate soft tissue kernel is preferred for disk and neural structure evaluation, reducing noise while preserving relevant detail.

Question 29: To troubleshoot a CT image showing significant noise (grainy appearance), the technologist should first consider adjusting which parameter?

Reducing matrix size
Increasing pitch
Decreasing kVp
Increasing mAs (Correct answer)

Correct answer: Increasing mAs

Increasing mAs raises the number of X-ray photons, directly reducing quantum noise and improving signal-to-noise ratio.

Question 30: What is the ALARA principle in radiation safety?

As Low As Reasonably Achievable — minimize radiation exposure (Correct answer)
Always Lock And Restrict Access
All Labs And Rooms Assessed
Automated Limiting Adjustment for Radiation Applications

Correct answer: As Low As Reasonably Achievable — minimize radiation exposure

ALARA means keeping radiation doses as low as reasonably achievable while still obtaining diagnostic-quality images, balancing benefit against risk.

Question 31: The 'cupping artifact' in CT, where the center of a uniform object appears less dense than its periphery, is a manifestation of which phenomenon?

Aliasing
Partial volume averaging
Quantum noise
Beam hardening (Correct answer)

Correct answer: Beam hardening

Cupping artifact is a form of beam hardening where the edges of the object appear brighter because the beam hardens less traveling a shorter path length.

Question 32: A 'ring artifact' in CT is most commonly caused by:

Too high a pitch value
Incorrect window/level settings
Patient motion during scanning
A malfunctioning or miscalibrated detector element (Correct answer)

Correct answer: A malfunctioning or miscalibrated detector element

Ring artifacts form concentric circles centered on the scanner's isocenter when one or more detector channels give consistently incorrect readings.

Question 33: Which of the following best describes the purpose of the ARRT pre-application ethics review?

To assess continuing education compliance only
To evaluate past violations before a candidate invests in examination preparation (Correct answer)
To waive clinical competency requirements for candidates with clean records
To replace the formal application process

Correct answer: To evaluate past violations before a candidate invests in examination preparation

The pre-application ethics review allows candidates with potential concerns to learn their eligibility status before paying fees and preparing for the exam.

Question 34: On a CT system, what does the term 'isocenter' refer to?

The precise center of gantry rotation where the X-ray beam and detector array intersect (Correct answer)
The center of the X-ray beam at the detector plane
The center of the patient table surface
The midpoint of the scan field of view display

Correct answer: The precise center of gantry rotation where the X-ray beam and detector array intersect

The isocenter is the exact point at the center of gantry rotation where the X-ray beam is focused, and proper patient centering at this point optimizes image quality and dose.

Question 35: Which of the following correctly describes 'isotropic voxels' in CT?

Voxels that contain only one tissue type
Voxels with equal x, y, and z dimensions (Correct answer)
Voxels calibrated to HU = 0
Voxels with a z-dimension larger than x and y

Correct answer: Voxels with equal x, y, and z dimensions

Isotropic voxels have equal dimensions in all three planes, enabling high-quality multiplanar reformations without resolution loss.

Question 36: Which ACR-recommended CT quality control test should be performed if visual image artifacts are noted during clinical scanning?

Reduce the scan FOV and repeat without QC evaluation
Immediately repeat the patient scan at higher mAs
Switch to a different reconstruction kernel and continue scanning
Perform artifact analysis using an appropriate phantom and document findings before continuing clinical use (Correct answer)

Correct answer: Perform artifact analysis using an appropriate phantom and document findings before continuing clinical use

When clinical artifacts are observed, ACR guidelines require phantom-based artifact analysis and documentation before continuing patient scanning to ensure diagnostic image quality.

Question 37: What prerequisite must a radiologic technologist fulfill before sitting for the ARRT CT certification examination?

Holding a current ARRT primary certification and meeting CT clinical experience requirements (Correct answer)
Passing the American Board of Radiology oral examination
Obtaining approval from the state radiologic technology board
Completing a two-year CT fellowship program

Correct answer: Holding a current ARRT primary certification and meeting CT clinical experience requirements

Candidates must hold a current ARRT primary certification and document the required number of CT clinical procedures before applying for the CT post-primary exam.

Question 38: 3D volume rendering of CT data allows the display of internal structures through which technique?

Selecting only the highest attenuation voxel per projection ray
Assigning opacity values to voxels based on their Hounsfield units (Correct answer)
Subtracting bone from the dataset
Applying a smooth kernel to the raw data

Correct answer: Assigning opacity values to voxels based on their Hounsfield units

Volume rendering assigns transfer functions that map each HU value to a color and opacity, allowing semi-transparent visualization of multiple tissue types simultaneously.

Question 39: In CT, the filtered back projection (FBP) reconstruction algorithm applies a mathematical filter primarily to:

Remove quantum noise before reconstruction
Align misregistered projection data
Segment soft tissue from bone
Correct for star artifacts inherent in simple back projection (Correct answer)

Correct answer: Correct for star artifacts inherent in simple back projection

FBP applies a ramp or other convolution filter to projection data before back-projecting to eliminate the blurring ('star artifact') produced by simple back projection.

Question 40: Which of the following is the correct order of the surgical hand-scrub process?

Remove jewelry, scrub hands and forearms with antiseptic, rinse from fingers to elbows, dry, don gloves (Correct answer)
Rinse, apply antiseptic, scrub hands, don gloves while wet
Wash with soap, apply sterile gloves, perform exam
Don gloves, scrub hands, rinse, dry

Correct answer: Remove jewelry, scrub hands and forearms with antiseptic, rinse from fingers to elbows, dry, don gloves

Proper surgical scrub progresses from fingers to elbows, rinsing in the same direction to move microbes away from the hands rather than toward them.

Question 41: Minimum intensity projection (MinIP) post-processing is particularly useful for displaying which anatomical structures?

Contrast-enhanced blood vessels
Dense bone and calcifications
Solid abdominal organs
Air-filled airways and lung parenchyma (Correct answer)

Correct answer: Air-filled airways and lung parenchyma

MinIP projects the lowest attenuation voxel along each ray, making it ideal for displaying air-containing structures like the tracheobronchial tree or emphysematous lung.

Question 42: What does the term 'detector efficiency' refer to in CT scanner performance?

The number of detector rows in the system
The FOV coverage per rotation
The speed at which the gantry rotates
The ability of detectors to capture and convert X-ray photons into usable signal (Correct answer)

Correct answer: The ability of detectors to capture and convert X-ray photons into usable signal

Detector efficiency describes how effectively CT detectors absorb incident X-ray photons and convert them into electrical signal, directly affecting image quality and dose.

Question 43: Which patient condition is an absolute contraindication to intravascular iodinated contrast media administration?

Age over 70 years
Serum creatinine of 1.2 mg/dL
Previous severe anaphylactic reaction to iodinated contrast without premedication (Correct answer)
History of mild contrast allergy treated with antihistamines

Correct answer: Previous severe anaphylactic reaction to iodinated contrast without premedication

A prior severe anaphylactic contrast reaction is a contraindication unless the patient is premedicated and the benefit outweighs the risk; the radiologist must be involved.

Question 44: For a CT abdomen/pelvis with IV contrast, what is the typical scan delay after contrast injection to capture the nephrographic phase of the kidneys?

3–5 minutes
25–35 seconds
80–120 seconds (Correct answer)
10–15 seconds

Correct answer: 80–120 seconds

The nephrographic phase occurs approximately 80–120 seconds post-injection, when the renal cortex and medulla enhance uniformly, optimizing detection of renal masses.

Question 45: A horizontal band of decreased attenuation passing through the posterior fossa on a head CT is a classic example of which artifact?

Beam hardening between the petrous bones (Correct answer)
Ring artifact
Partial volume artifact
Motion artifact from cardiac pulsation

Correct answer: Beam hardening between the petrous bones

The dense petrous temporal bones cause preferential absorption of lower-energy photons, producing a dark band across the posterior fossa known as a beam hardening artifact.

Question 46: When negotiating a salary increase, a CT technologist cites their ARRT CT certification. Which argument is most compelling to the employer?

The certification cost the technologist money to obtain
Certified technologists reduce department liability by demonstrating validated competency (Correct answer)
The credential was easy to earn and required minimal study
The technologist now qualifies to perform radiologist duties

Correct answer: Certified technologists reduce department liability by demonstrating validated competency

Employers value that certified technologists have met a national standard, which reduces risk of errors, supports accreditation, and reflects positively on department quality.

Question 47: CT of the abdomen shows a 'target sign' (layered bowel wall with alternating attenuation) in the small bowel. This is most consistent with:

Intussusception or inflammatory bowel disease with submucosal edema (Correct answer)
Malignant bowel obstruction
Bowel infarction
Bowel perforation

Correct answer: Intussusception or inflammatory bowel disease with submucosal edema

The CT target sign reflects bowel wall stratification due to submucosal edema or fat, seen in intussusception, Crohn's disease, or ischemia.

Question 48: When performing a venipuncture for contrast administration, the needle bevel should be oriented:

Facing down toward the vein wall
Parallel to the skin surface, bevel sideways
At a 90-degree angle to the skin
Facing up (bevel up) (Correct answer)

Correct answer: Facing up (bevel up)

The bevel-up orientation allows the needle to enter the vein smoothly and reduces the risk of piercing the posterior vein wall.

Question 49: In CT, the term 'pitch' for single-slice CT is calculated as:

Table feed per rotation / slice thickness (Correct answer)
Table speed / gantry rotation time
kVp / mAs
Detector width / field of view

Correct answer: Table feed per rotation / slice thickness

Pitch = table feed per 360° rotation divided by the nominal slice thickness; a pitch >1 means gaps exist between consecutive slices.

Question 50: On a coronal CT reconstruction, the right hemidiaphragm is typically higher than the left because:

The right crus of the diaphragm is thicker than the left
The right lung is larger and displaces the diaphragm inferiorly
The liver occupies the right upper quadrant and elevates the right hemidiaphragm (Correct answer)
The spleen is positioned more inferiorly than the liver

Correct answer: The liver occupies the right upper quadrant and elevates the right hemidiaphragm

The mass of the liver beneath the right hemidiaphragm elevates it approximately half a rib space higher than the left.

Question 51: Which reconstruction kernel (filter) should be selected to best visualize lung parenchyma and fine pulmonary detail?

High-resolution (sharp/edge-enhancing) kernel (Correct answer)
Liver kernel
Brain kernel
Soft tissue (smoothing) kernel

Correct answer: High-resolution (sharp/edge-enhancing) kernel

A high-resolution or edge-enhancing kernel accentuates fine structural detail needed for lung parenchyma evaluation, at the cost of increased noise.

Question 52: On axial CT of the head at the level of the fourth ventricle, which structure is immediately posterior to the fourth ventricle?

Medulla oblongata
Cerebellum (vermis) (Correct answer)
Pons
Choroid plexus

Correct answer: Cerebellum (vermis)

The cerebellar vermis forms the posterior wall of the fourth ventricle on axial CT images.

Question 53: What is the window level and window width on CT images?

Patient positioning parameters
Physical measurements of the CT scanner
Scan speed controls
Settings that control the brightness and contrast of displayed images (Correct answer)

Correct answer: Settings that control the brightness and contrast of displayed images

Window level sets the center brightness (what HU appears as middle gray) and window width controls contrast range (how many HUs span from black to white).

Question 54: CT perfusion imaging requires specialized post-processing to generate which type of parametric maps?

Standardized uptake value (SUV) maps
Hounsfield unit histograms
Cerebral blood flow, cerebral blood volume, and mean transit time maps (Correct answer)
Bone mineral density scores

Correct answer: Cerebral blood flow, cerebral blood volume, and mean transit time maps

CT perfusion post-processing applies deconvolution or maximum slope models to time-attenuation curves to produce quantitative maps of CBF, CBV, and MTT.

Question 55: The windmill artifact in multislice CT helical acquisitions is MOST pronounced when:

High kVp is used with thin collimation
High pitch values are combined with thick slice reconstruction (Correct answer)
Low mAs is used with a smooth kernel
Small FOV is selected with fine matrix

Correct answer: High pitch values are combined with thick slice reconstruction

Windmill artifact stems from undersampling in the z-direction; it is most visible with high pitch (sparse data) and thick reconstructions that exaggerate interpolation errors.

Question 56: The inverse square law states that radiation intensity is related to distance by which relationship?

Intensity decreases linearly with distance
Intensity is directly proportional to distance
Intensity is inversely proportional to the cube of the distance
Intensity is inversely proportional to the square of the distance (Correct answer)

Correct answer: Intensity is inversely proportional to the square of the distance

The inverse square law: I ∝ 1/d², meaning doubling the distance from the source reduces intensity to one-quarter of its original value.

Question 57: Which type of CT detector material is most commonly used in modern multi-detector CT (MDCT) systems due to its high conversion efficiency and fast decay time?

Sodium iodide (NaI) crystal detectors
Gadolinium oxysulfide (GOS) solid-state scintillators (Correct answer)
Bismuth germanate (BGO) crystals
Xenon gas ionization chambers

Correct answer: Gadolinium oxysulfide (GOS) solid-state scintillators

Modern MDCT scanners predominantly use solid-state scintillator detectors such as gadolinium oxysulfide because of their high X-ray absorption efficiency and rapid afterglow decay.

Question 58: What documentation does an ARRT candidate typically need to submit to verify clinical competency in CT?

Employer payroll records
Competency verification signed by a supervising radiologist or qualified technologist (Correct answer)
A letter from the state radiology board
ACR accreditation certificate of the facility

Correct answer: Competency verification signed by a supervising radiologist or qualified technologist

Clinical competency must be verified by a supervising qualified professional who can attest that the candidate performed required procedures.

Question 59: Which of the following is the primary reason for using a low-osmolar, non-ionic iodinated contrast agent for intravenous CT contrast?

It significantly reduces the risk of adverse reactions compared to ionic agents (Correct answer)
It is less expensive than ionic contrast
It requires a lower injection rate
It provides higher iodine concentration per mL

Correct answer: It significantly reduces the risk of adverse reactions compared to ionic agents

Non-ionic, low-osmolar contrast agents have a much lower rate of adverse reactions (including severe reactions) compared to older high-osmolar ionic agents.

Question 60: What is homeostasis?

An organ system
A disease state
A type of cell division
The body's ability to maintain stable internal conditions (Correct answer)

Correct answer: The body's ability to maintain stable internal conditions

Homeostasis is the body's dynamic process of maintaining stable internal conditions (temperature, pH, blood sugar) despite external changes.

Question 61: What does a noise index (NI) setting in automatic tube current modulation (ATCM) control?

The target image noise level that drives mA adjustments (Correct answer)
The maximum allowed kVp during the scan
The number of reconstruction iterations applied
The amount of bowtie filter attenuation

Correct answer: The target image noise level that drives mA adjustments

The noise index defines the target standard deviation of image noise; ATCM raises or lowers mA to achieve this noise target based on patient attenuation.

Question 62: When performing a CT colonography, the technologist selects a 0.625 mm detector row width versus 5 mm. This change PRIMARILY improves:

Temporal resolution for cardiac gating
Patient dose efficiency
Longitudinal (z-axis) spatial resolution enabling multiplanar reformats (Correct answer)
Contrast resolution for soft tissue differentiation

Correct answer: Longitudinal (z-axis) spatial resolution enabling multiplanar reformats

Thinner detector rows provide finer z-axis sampling, enabling isotropic voxels and high-quality multiplanar reformats for polyp detection.

Question 63: How does ARRT CT certification affect a technologist’s earning potential?

It may result in a pay cut, depending on the region
It provides a one-time bonus but no long-term salary benefits
Certified technologists typically earn higher salaries compared to non-certified ones (Correct answer)
It does not affect salary in any way

Correct answer: Certified technologists typically earn higher salaries compared to non-certified ones

ARRT CT certification signifies a higher level of specialized training and expertise, which is often reflected in compensation. Employers recognize the value of certified professionals, leading to certified technologists typically commanding higher salaries and better benefits compared to their non-certified counterparts.

Question 64: Which window setting is most appropriate for evaluating pulmonary nodules in the lung parenchyma?

Window width ~400 HU, window level ~40 HU
Window width ~1500 HU, window level ~-600 HU (Correct answer)
Window width ~200 HU, window level ~80 HU
Window width ~3000 HU, window level ~300 HU

Correct answer: Window width ~1500 HU, window level ~-600 HU

Lung windows use a wide width (~1500 HU) and negative level (~-600 HU) to display the full range of lung attenuation from air to soft tissue.

Question 65: What is the most effective way to prevent healthcare-associated infections?

Proper hand hygiene (Correct answer)
Cleaning the floor
Wearing gloves at all times
Taking antibiotics

Correct answer: Proper hand hygiene

Hand hygiene (washing with soap and water or using alcohol-based hand rub) is the single most effective measure for preventing the spread of infections in healthcare settings.

Question 66: A patient has a Foley catheter in place. When transferring this patient, the urinary drainage bag should be positioned:

Below the level of the bladder to prevent backflow (Correct answer)
Clamped during all transfers to avoid spillage
Above the level of the bladder to maintain drainage
Disconnected temporarily during the move

Correct answer: Below the level of the bladder to prevent backflow

The drainage bag must remain below bladder level at all times to use gravity for urine drainage and prevent backflow that could cause infection.

Question 67: On CT urography, a urothelial carcinoma of the ureter would most likely appear as:

Smooth fusiform dilation of the ureter
Intraluminal filling defect with upstream hydronephrosis (Correct answer)
Ureteral wall calcification
Periureteral fat stranding only

Correct answer: Intraluminal filling defect with upstream hydronephrosis

Urothelial carcinoma typically presents as an intraluminal filling defect causing partial or complete obstruction with upstream hydronephrosis.

Question 68: If the ARRT discovers that a candidate provided false information on their CT application, the consequence may include:

A warning letter with no other action
Permanent revocation of eligibility and any existing ARRT credentials (Correct answer)
Mandatory retaking of the primary examination
A 30-day suspension of testing privileges

Correct answer: Permanent revocation of eligibility and any existing ARRT credentials

Providing false information is an ethics violation that can result in permanent loss of eligibility and revocation of all ARRT credentials.

Question 69: Which of the following is the correct documentation entry after administering IV contrast?

Contrast given — no issues noted
Contrast given per radiologist order
Patient tolerated procedure well
Type of contrast, lot number, dose, route, rate, patient response, and technologist's signature (Correct answer)

Correct answer: Type of contrast, lot number, dose, route, rate, patient response, and technologist's signature

Complete contrast documentation must include the agent name, lot number, dose, route, rate of administration, patient response, and the administering technologist's identification.

Question 70: Which phenomenon explains why CT numbers for bone may appear elevated at the center of a thick bony structure compared to peripheral bone?

Ring artifact
Partial volume effect
Beam hardening cupping artifact (Correct answer)
Undersampling artifact

Correct answer: Beam hardening cupping artifact

Beam hardening causes preferential absorption of lower-energy photons; more hardening occurs centrally, leading to erroneously high CT numbers at bone edges and low values centrally (cupping).

Question 71: A technologist working in a trauma center wants to advance to a CT lead position. Which prerequisite is most commonly required by employers?

Five years of emergency department experience only
ARRT CT post-primary certification (Correct answer)
A master's degree in radiologic science
Completion of a vendor-specific scanner training course

Correct answer: ARRT CT post-primary certification

ARRT CT certification is the most universally recognized and commonly required credential for CT lead or supervisory positions.

Question 72: On CT of the head, lenticular (biconvex) hyperdensity is identified adjacent to the temporal bone. What is the most likely cause?

Hypertensive hemorrhage
Middle meningeal artery rupture causing epidural hematoma (Correct answer)
Berry aneurysm rupture
Bridging vein rupture causing subdural hematoma

Correct answer: Middle meningeal artery rupture causing epidural hematoma

Epidural hematomas result from middle meningeal artery injury and form a biconvex hyperdense collection limited by dural attachments at sutures.

Question 73: Increasing the x-ray tube voltage (kVp) in CT primarily results in:

Lower mean photon energy and higher subject contrast
Unchanged image quality but increased scan time
Higher image noise and lower contrast
Higher mean photon energy and reduced photoelectric interactions (Correct answer)

Correct answer: Higher mean photon energy and reduced photoelectric interactions

Higher kVp produces a higher mean photon energy beam with greater penetrating power; Compton scatter dominates over photoelectric effect, reducing subject contrast.

Question 74: When evaluating a CT image for streak artifacts emanating from a hip prosthesis, the BEST corrective technique is:

Widening the reconstruction FOV
Decreasing the mAs by 50%
Increasing the kVp to 140
Metal artifact reduction (MAR) reconstruction algorithm (Correct answer)

Correct answer: Metal artifact reduction (MAR) reconstruction algorithm

Metal artifact reduction algorithms use iterative or sinogram-based techniques to model and subtract metal-induced streaks from the image.

Question 75: The Hounsfield unit (HU) value of pure water is:

+100
0 (Correct answer)
+1000
-1000

Correct answer: 0

By definition, pure water is assigned an HU value of 0 on the Hounsfield scale used in CT imaging.

Question 76: What is the window level and window width on CT images?

Physical measurements of the CT scanner
Scan speed controls
Settings that control the brightness and contrast of displayed images (Correct answer)
Patient positioning parameters

Correct answer: Settings that control the brightness and contrast of displayed images

Window level sets the center brightness (what HU appears as middle gray) and window width controls contrast range (how many HUs span from black to white).

Question 77: A patient states, 'I am Jehovah's Witness and refuse any blood transfusion.' The radiologic technologist should:

Contact the patient's family to override the decision
Proceed with the procedure and allow physicians to decide later
Document the statement and notify the supervising clinician immediately (Correct answer)
Disregard the statement as the patient may not understand their condition

Correct answer: Document the statement and notify the supervising clinician immediately

A competent adult patient has the right to refuse treatment; the technologist must document this and notify the care team to ensure informed refusal is properly handled.

Question 78: What physiologic mechanism underlies contrast-induced nephropathy (CIN)?

Renal medullary ischemia and direct tubular cell toxicity from contrast (Correct answer)
Obstructive uropathy from contrast precipitation in the collecting ducts
Immune-mediated glomerulonephritis triggered by iodine
Systemic vasodilation leading to prerenal azotemia

Correct answer: Renal medullary ischemia and direct tubular cell toxicity from contrast

CIN results from renal medullary vasoconstriction causing ischemia combined with direct cytotoxic effects of contrast on tubular epithelial cells.

Question 79: The windmill artifact seen in helical CT is most commonly associated with which acquisition parameter?

Small reconstruction FOV
High pitch values (Correct answer)
Large detector collimation
Low kVp

Correct answer: High pitch values

Windmill artifacts appear as alternating dark and bright streaks rotating around structures and are caused by the under-sampling that occurs at high pitch values.

Question 80: Which of the following best describes the purpose of ARRT's Standards of Ethics in the accreditation context?

They outline equipment quality standards
They define conduct requirements candidates must meet to obtain and maintain credentials (Correct answer)
They establish imaging protocols
They set radiation dose limits

Correct answer: They define conduct requirements candidates must meet to obtain and maintain credentials

The ARRT Standards of Ethics outline the professional conduct requirements that candidates and credential holders must satisfy.

Question 81: A CT technologist completes a 3-credit online module from an ARRT-approved sponsor. How should this be recorded?

Only if the module includes a hands-on component
As 3 Category A CE credits (Correct answer)
As Category B self-study credit
It counts only if completed before the renewal year begins

Correct answer: As 3 Category A CE credits

Online modules from ARRT-approved sponsors qualify as Category A CE credits and count toward the 24-credit renewal requirement.

Question 82: Which eGFR threshold does the ACR use to define increased risk for contrast-induced acute kidney injury when administering IV iodinated contrast?

eGFR < 30 mL/min/1.73m² (Correct answer)
eGFR < 45 mL/min/1.73m²
eGFR < 90 mL/min/1.73m²
eGFR < 60 mL/min/1.73m²

Correct answer: eGFR < 30 mL/min/1.73m²

The ACR Manual on Contrast Media identifies eGFR < 30 mL/min/1.73m² as the threshold for significantly increased risk of contrast-induced acute kidney injury.

Question 83: Multiplanar reformation (MPR) in CT refers to:

Generating 3D surface models from volumetric data
Reconstructing axial images into coronal, sagittal, or oblique planes (Correct answer)
Applying color to CT images based on Hounsfield units
Subtracting pre-contrast from post-contrast images

Correct answer: Reconstructing axial images into coronal, sagittal, or oblique planes

MPR uses the volumetric CT dataset to create reformatted images in any anatomical plane without additional radiation exposure to the patient.

Question 84: What is the primary purpose of the bow-tie filter in a CT scanner?

Calibrate the detector array
Remove scatter radiation from the detector
Compensate for the cylindrical shape of patients to reduce peripheral dose (Correct answer)
Increase tube current

Correct answer: Compensate for the cylindrical shape of patients to reduce peripheral dose

The bow-tie (wedge) filter shapes the beam so less radiation hits the thinner periphery of the patient, reducing dose and preventing detector saturation.

Question 85: Under the ARRT ethics requirement, which of the following past offenses is MOST likely to result in denial of CT certification eligibility?

A civil lawsuit unrelated to healthcare
Felony conviction related to the practice of radiologic technology (Correct answer)
Unpaid parking tickets
Minor traffic violation

Correct answer: Felony conviction related to the practice of radiologic technology

Felony convictions, especially those related to healthcare practice, are subject to ARRT ethics review and can result in denial.

Question 86: Quantum (photon) noise in CT images is most visible under which conditions?

Fast pitch and narrow FOV
High mAs and thin slices
High kVp and wide window
Low mAs or large patient size (Correct answer)

Correct answer: Low mAs or large patient size

Quantum noise increases when fewer photons reach the detectors, which occurs with low mAs settings or when X-rays are attenuated by a large patient.

Question 87: Which organization is primarily responsible for accrediting radiologic technology programs in the United States?

ACR
ACR-AAPM
JRCERT (Correct answer)
ARRT

Correct answer: JRCERT

The Joint Review Committee on Education in Radiologic Technology (JRCERT) is the primary accrediting body for radiologic technology programs.

Question 88: An ARRT credential holder moves to a state that requires separate state licensure. Which of the following is correct?

JRCERT issues the state license upon request
The technologist must retake the ARRT exam for state purposes
State licensure is separate from ARRT certification and must be obtained independently (Correct answer)
ARRT certification automatically fulfills state licensure requirements in all states

Correct answer: State licensure is separate from ARRT certification and must be obtained independently

ARRT certification and state licensure are distinct; technologists must comply with individual state requirements separately.

Question 89: At the level of the aortic arch on axial CT, which vessel arises first (most rightward/anterior) from the arch?

Left common carotid artery
Brachiocephalic (innominate) artery (Correct answer)
Right subclavian artery
Left subclavian artery

Correct answer: Brachiocephalic (innominate) artery

The brachiocephalic artery is the first and most rightward branch of the aortic arch, followed by the left common carotid and left subclavian.

Question 90: How does ARRT CT certification impact patient care?

It guarantees faster patient turnaround times in CT imaging
It reduces the cost of CT procedures for patients
It improves patient care by ensuring that technologists are properly trained in CT safety and imaging protocols (Correct answer)
It has no significant impact on patient care

Correct answer: It improves patient care by ensuring that technologists are properly trained in CT safety and imaging protocols

ARRT CT certification directly impacts patient care by guaranteeing that technologists have met rigorous standards for education, clinical competency, and ethical conduct. This ensures they are proficient in CT safety, proper imaging protocols, and patient interaction, leading to accurate diagnoses and safer procedures for patients.

Question 91: Which professional organization co-sponsors ARRT's Standards of Ethics alongside the Society of Radiologic Technologists?

Joint Commission on Allied Health Personnel in Ophthalmology
American Medical Association
American Society of Radiologic Technologists (ASRT) (Correct answer)
American College of Radiology

Correct answer: American Society of Radiologic Technologists (ASRT)

ARRT developed its Standards of Ethics in collaboration with the American Society of Radiologic Technologists (ASRT), the primary professional association for RT professionals.

Question 92: Which of the following best describes a 'Category A' CE credit in the ARRT system?

Structured educational activity provided by an ARRT-approved sponsor (Correct answer)
Clinical hours logged during overtime shifts
Any learning activity self-reported by the technologist
Peer-reviewed article reading logged in a journal

Correct answer: Structured educational activity provided by an ARRT-approved sponsor

Category A credits are earned through formal, structured educational activities provided by sponsors recognized and approved by ARRT.

Question 93: A 'blooming artifact' in CT most commonly results from:

Incorrect HU calibration of the scanner
Patient motion during acquisition
Undersampling of high-frequency data
High-density metallic objects causing overestimation of structure size (Correct answer)

Correct answer: High-density metallic objects causing overestimation of structure size

Blooming occurs when high-attenuation objects like metals or calcifications appear larger than their true size due to beam hardening and partial volume effects.

Question 94: Which window setting is most appropriate for evaluating acute intracranial hemorrhage on a non-contrast head CT?

Soft tissue window (WW 400, WL 50)
Bone window (WW 2000, WL 300)
Brain window (WW 80, WL 35) (Correct answer)
Lung window (WW 1500, WL -500)

Correct answer: Brain window (WW 80, WL 35)

The brain window (narrow width ~80 HU, level ~35 HU) provides optimal contrast between hyperdense blood and surrounding brain tissue.

Question 95: What is the largest organ in the human body?

Brain
Liver
Skin (Correct answer)
Heart

Correct answer: Skin

The skin is the largest organ, covering approximately 20 square feet in adults and weighing about 8 pounds. It serves as the primary barrier against the environment.

Question 96: Which factor does NOT directly influence the CTDI_vol value displayed on the CT console?

Reconstruction kernel (filter) (Correct answer)
kVp
Tube current (mAs)
Pitch

Correct answer: Reconstruction kernel (filter)

Reconstruction kernel is a post-processing parameter applied after data acquisition and does not change the radiation output; CTDI_vol reflects acquisition parameters only.

Question 97: A radiologic technologist holds R.T.(R)(CT) credentials. What do the letters in parentheses each represent?

(R) = residency completed; (CT) = computed tomography board
(R) = primary ARRT registration in Radiography; (CT) = post-primary CT certification (Correct answer)
(R) = state registration; (CT) = federal CT permit
(R) = Radiology degree; (CT) = computed tomography license

Correct answer: (R) = primary ARRT registration in Radiography; (CT) = post-primary CT certification

R.T.(R) denotes primary ARRT registration in Radiography, and (CT) denotes the additional post-primary CT certification earned.

Question 98: A technologist holds ARRT primary certification in Radiography and a post-primary in CT. How many total CE credits are required per cycle?

24 total, with at least 6 specific to CT
48 total — 24 for each credential separately
36 total — 24 for primary plus 12 for post-primary
24 total, shared across both credentials (Correct answer)

Correct answer: 24 total, shared across both credentials

ARRT allows the same 24 Category A CE credits to satisfy renewal requirements for both the primary and post-primary certifications simultaneously.

Question 99: Which technique is most commonly used to reduce metal artifact in CT imaging of patients with hip prostheses?

Metal artifact reduction (MAR) software (Correct answer)
Increasing slice thickness
Decreasing kVp
Using a smaller FOV

Correct answer: Metal artifact reduction (MAR) software

Metal artifact reduction (MAR) algorithms replace corrupted projection data near metal with interpolated data, significantly reducing streaking artifacts.

Question 100: What is the purpose of contrast media in CT scans?

To enhance the visibility of specific structures and pathology (Correct answer)
To speed up the scan
To make the patient comfortable
To reduce radiation dose

Correct answer: To enhance the visibility of specific structures and pathology

Contrast media (dye) enhances the visibility of blood vessels, organs, and abnormalities by changing how X-rays interact with specific tissues.

Question 101: The Hounsfield unit (HU) value of pure water is defined as:

0 HU (Correct answer)
-1000 HU
+500 HU
+1000 HU

Correct answer: 0 HU

The CT number scale defines water as 0 HU and air as −1000 HU, with other tissues placed relative to these references.

Question 102: On axial CT at the level of L4-L5, which structure is found anterior to the vertebral body?

Celiac axis
Abdominal aortic bifurcation (Correct answer)
Inferior mesenteric artery origin
Superior mesenteric artery origin

Correct answer: Abdominal aortic bifurcation

The abdominal aorta bifurcates into the common iliac arteries at approximately the L4 vertebral level.

Question 103: Which of the following scenarios would make a technologist INELIGIBLE to apply for ARRT CT certification?

Working in a facility that performs fewer than 50 CT scans per month
Holding an ARRT credential that is currently suspended (Correct answer)
Having graduated from a JRCERT-accredited program more than 3 years ago
Holding both R and RT credentials simultaneously

Correct answer: Holding an ARRT credential that is currently suspended

A suspended credential is not considered active and unrestricted, which is a prerequisite for CT post-primary eligibility.

Question 104: Which of the following activities can count toward the continuing education credits for ARRT CT certification?

Attending an industry conference
All of the above (Correct answer)
Completing a patient care workshop
Publishing a research article in a professional journal

Correct answer: All of the above

ARRT accepts a wide range of activities for continuing education (CE) credits, provided they are relevant to the radiologic sciences. This includes attending industry conferences, participating in patient care workshops, and even publishing research articles in professional journals. The goal is to encourage diverse learning that enhances professional practice.

Question 105: Iodinated contrast media produces vascular enhancement in CT primarily because iodine:

Increases the paramagnetic properties of blood
Has a high atomic number that strongly attenuates X-rays (Correct answer)
Reduces blood viscosity, increasing flow speed
Emits positrons that scatter X-rays

Correct answer: Has a high atomic number that strongly attenuates X-rays

Iodine (atomic number 53) has a high atomic number that dramatically increases X-ray attenuation in blood vessels and tissues, creating contrast enhancement on CT.

Question 106: How many total attempts does ARRT allow a candidate to take the CT certification examination?

Unlimited attempts
2 attempts
5 attempts
3 attempts (Correct answer)

Correct answer: 3 attempts

ARRT limits candidates to 3 total attempts to pass each post-primary examination, including CT.

Question 107: Under ARRT's ethics requirements, a technologist who is convicted of a felony must do which of the following?

Self-report the conviction to ARRT (Correct answer)
Request a voluntary suspension of registration
Notify their state licensing board only
Immediately surrender their certificate

Correct answer: Self-report the conviction to ARRT

ARRT's Standards of Ethics require technologists to self-report criminal convictions, including felonies, to the ARRT within 30 days.

Question 108: ARRT's recertification policy allows CE credits earned through which type of structured journal activity?

Informal article reading without assessment
Department-based journal clubs without an approved sponsor
ARRT-approved self-assessment modules or journal-based CE with post-tests (Correct answer)
Any peer-reviewed radiology journal subscription

Correct answer: ARRT-approved self-assessment modules or journal-based CE with post-tests

Journal-based CE activities qualify only when they include a post-test and are offered through an ARRT-approved sponsor, not casual reading alone.

Question 109: Which body administers the ARRT CT certification examination at testing centers?

ARRT staff at ARRT headquarters
Prometric (Correct answer)
ACR regional offices
JRCERT-affiliated schools

Correct answer: Prometric

ARRT partners with Prometric to deliver its certification examinations at testing centers nationwide.

Question 110: Which ARRT primary pathway requires holding an unrestricted radiography certification before applying for CT?

Nuclear Medicine (N)
Radiography (R) (Correct answer)
Sonography (S)
Radiation Therapy (T)

Correct answer: Radiography (R)

The primary CT pathway most commonly used requires holding an active, unrestricted ARRT Radiography (R) credential.

Question 111: Which section of the ARRT application requires disclosure of prior criminal history and ethics violations?

Structured education section
Reference section
Ethics section (Correct answer)
Clinical competency section

Correct answer: Ethics section

The ethics section of the ARRT application requires applicants to disclose criminal history, professional disciplinary actions, and other relevant ethical matters.

Question 112: Which structure separates the anterior and middle cranial fossae on axial CT?

Clinoid processes only
Petrous ridge of the temporal bone
Crista galli of the ethmoid bone
Lesser wing of the sphenoid bone (Correct answer)

Correct answer: Lesser wing of the sphenoid bone

The lesser wing of the sphenoid bone forms the posterior boundary of the anterior cranial fossa, separating it from the middle cranial fossa.

Question 113: Which statement BEST describes the relationship between CT noise and mAs?

Noise is proportional to 1/√mAs (Correct answer)
Noise is inversely proportional to mAs
Noise is unaffected by mAs changes
Noise is directly proportional to mAs

Correct answer: Noise is proportional to 1/√mAs

CT noise follows Poisson statistics; doubling mAs quadruples photons but only reduces noise by a factor of √2, making noise proportional to 1/√mAs.

Question 114: What is the effect of decreasing detector collimation (thinner slices) on image noise, assuming all other factors remain constant?

Noise increases (Correct answer)
Noise decreases
Noise is unaffected
Noise is eliminated

Correct answer: Noise increases

Thinner collimation means fewer photons contribute to each voxel, increasing statistical noise in the image.

Question 115: Which CT quality control phantom is most commonly used to evaluate CT number accuracy, noise, uniformity, and spatial resolution?

AAPM CT performance phantom (Correct answer)
MOSFET dosimetry phantom
Leeds TOR phantom
Alderson Rando phantom

Correct answer: AAPM CT performance phantom

The AAPM CT performance phantom contains inserts for testing multiple image quality parameters including HU accuracy, noise, and spatial resolution.

Question 116: Which pitch factor would result in the longest scan time for a given scan range?

1.0
1.5
0.5 (Correct answer)
2.0

Correct answer: 0.5

A lower pitch means the table moves more slowly relative to rotation speed, resulting in more overlap and a longer scan time.

Question 117: What does the term 'half-scan reconstruction' refer to in CT?

Reconstructing only half the detector channels
Using 180° + fan angle of data instead of a full 360° to reduce motion artifact (Correct answer)
Reducing matrix size by half to speed processing
Acquiring data with only half normal mAs

Correct answer: Using 180° + fan angle of data instead of a full 360° to reduce motion artifact

Half-scan reconstruction uses approximately 180° + fan beam angle of data, which can reduce cardiac or other motion artifacts by shortening effective scan time.

Question 118: A CT image shows ring artifacts. The MOST likely cause is:

A malfunctioning or miscalibrated detector element (Correct answer)
Too low an mAs setting
Incorrect kVp selection
Patient motion during scanning

Correct answer: A malfunctioning or miscalibrated detector element

Ring artifacts appear as circular bands centered on the isocenter and are caused by a single detector element producing consistently incorrect readings.

Question 119: Which scan parameter adjustment would best reduce streak artifact from dental fillings on a head/neck CT?

Decrease tube voltage
Decrease rotation time
Increase tube current (mA)
Use gantry tilt to avoid the plane of the fillings (Correct answer)

Correct answer: Use gantry tilt to avoid the plane of the fillings

Tilting the gantry angles the scan plane away from dense dental hardware, reducing the metal streak artifact through structures of interest.

Question 120: What is the first step in the ARRT CT certification process?

Complete the required clinical competencies
Obtain a recommendation letter from an employer
Submit an online application through the ARRT portal (Correct answer)
Schedule the CT certification exam

Correct answer: Submit an online application through the ARRT portal

The initial step in the ARRT CT certification process, after meeting all prerequisites, is to formally apply. This is done by submitting an online application through the official ARRT website portal. This application initiates the eligibility review and allows candidates to proceed with scheduling their exam.

Question 121: A candidate fails the ARRT CT examination. What is the minimum waiting period before their first retake?

1 year
6 months
3 months (Correct answer)
2 weeks

Correct answer: 3 months

ARRT requires a 3-month waiting period between examination attempts to allow candidates time for remediation.

Question 122: What is the main clinical use of dual-energy CT (DECT)?

Eliminating the need for contrast agents entirely
Material decomposition to differentiate tissue composition (e.g., iodine vs. calcium) (Correct answer)
Increasing patient dose efficiency
Reducing scan time by half

Correct answer: Material decomposition to differentiate tissue composition (e.g., iodine vs. calcium)

DECT acquires data at two different kVp levels; the difference in attenuation at each energy allows material decomposition to characterize tissue composition.

Question 123: How often must ARRT-certified technologists complete continuing education to maintain their credentials?

Every 2 years (Correct answer)
Every 3 years
Every 5 years
Every year

Correct answer: Every 2 years

ARRT requires 24 continuing education credits every 2 years to maintain certification.

Question 124: Respiratory motion artifacts on chest CT can best be minimized by:

Using breath-hold technique during acquisition (Correct answer)
Increasing kVp
Widening the display window
Increasing slice thickness

Correct answer: Using breath-hold technique during acquisition

Instructing the patient to suspend respiration during CT acquisition eliminates breathing motion, preventing blurring and step artifacts in the chest.

Question 125: A CT technologist completes 30 Category A credits in one renewal cycle. How many, if any, credits can be carried over to the next cycle?

6 credits can be carried over
0 credits — no carryover is allowed (Correct answer)
All excess credits carry over automatically
12 credits can be carried over

Correct answer: 0 credits — no carryover is allowed

ARRT does not allow Category A CE credits to be carried over from one renewal cycle to the next.

Question 126: Which of the following best describes the CT appearance of the caudate lobe of the liver?

A small segment located between the IVC and the fissure for the ligamentum venosum (Correct answer)
Located posterior to the inferior vena cava and anterior to the portal vein
Located between the gallbladder fossa and the fissure for the ligamentum teres
The largest segment of the left hepatic lobe

Correct answer: A small segment located between the IVC and the fissure for the ligamentum venosum

The caudate lobe (segment I) lies between the IVC posteriorly and the fissure for the ligamentum venosum anteriorly.

Question 127: A patient is on hemodialysis and requires a contrast-enhanced CT. Which statement regarding iodinated contrast in dialysis patients is correct?

Contrast can be given; iodinated agents are removed by dialysis and residual renal function is already negligible (Correct answer)
Emergent dialysis must be performed within 1 hour of contrast to prevent harm
Only half the standard contrast dose may be given regardless of clinical indication
Contrast is absolutely contraindicated in dialysis patients

Correct answer: Contrast can be given; iodinated agents are removed by dialysis and residual renal function is already negligible

Dialysis-dependent patients have no significant residual renal function to protect; contrast can be given when clinically indicated, as dialysis will remove the agent.

Question 128: What is the correct order for donning PPE?

Gown, mask, eye protection, gloves (Correct answer)
Mask, gloves, gown, eye protection
Gloves, gown, mask, eye protection
Any order is acceptable

Correct answer: Gown, mask, eye protection, gloves

The correct donning sequence is gown first, then mask/respirator, eye protection/face shield, and gloves last. This prevents contamination during application.

Question 129: The ARRT Standards of Ethics is incorporated into the CT certification process primarily to:

Confirm candidates' insurance coverage
Assess candidates' academic GPA
Verify candidates' financial standing
Ensure candidates demonstrate professional integrity and moral character (Correct answer)

Correct answer: Ensure candidates demonstrate professional integrity and moral character

The Standards of Ethics screening ensures that only individuals with demonstrated professional integrity are certified.

Question 130: Which of the following describes the location of the zona incerta on axial CT brain images?

A thin band of gray matter between the lenticular fasciculus and the thalamic fasciculus in the subthalamus (Correct answer)
A sulcus separating the caudate from the putamen
A white matter tract connecting the thalamus to the frontal lobe
Gray matter located in the posterior limb of the internal capsule

Correct answer: A thin band of gray matter between the lenticular fasciculus and the thalamic fasciculus in the subthalamus

The zona incerta is a subthalamic gray matter band situated between the lenticular and thalamic fasciculi.

Question 131: In CT, contrast-to-noise ratio (CNR) is BEST described as:

The difference in HU between two structures divided by image noise (Correct answer)
The ratio of signal to detector dark current
The number of line pairs per centimeter resolved
The ability to detect objects of varying sizes

Correct answer: The difference in HU between two structures divided by image noise

CNR = (HU_structure − HU_background) ÷ noise standard deviation, quantifying how well a structure stands out against background noise.

Question 132: The pitch value in helical CT is defined as:

Gantry rotation speed divided by table speed
Slice thickness divided by detector row width
Table travel per rotation divided by total beam collimation width (Correct answer)
kVp divided by mA

Correct answer: Table travel per rotation divided by total beam collimation width

Pitch = table distance traveled per 360° rotation ÷ total collimated beam width, and values >1 indicate gaps in data coverage.

Question 133: To meet ARRT’s ethics requirements, which of the following is necessary?

Take a separate ethics exam during the certification process
Submit a personal statement of professional ethics
Agree to follow the ARRT Standards of Ethics and report any potential violations (Correct answer)
Pass a background check and provide character references

Correct answer: Agree to follow the ARRT Standards of Ethics and report any potential violations

The ARRT places a strong emphasis on ethical conduct within the radiologic technology profession. To meet their ethics requirements, candidates must formally agree to adhere to the ARRT Standards of Ethics, which outline professional responsibilities and conduct. This commitment includes reporting any potential violations, upholding the integrity of the profession.

Question 134: Which oral contrast agent is most commonly used in CT of the abdomen and pelvis to opacify the bowel?

Manganese chloride solution
Air alone as a negative contrast agent
Barium sulfate suspension or dilute water-soluble iodinated contrast (Correct answer)
Gadolinium-based oral agent

Correct answer: Barium sulfate suspension or dilute water-soluble iodinated contrast

Barium sulfate or dilute iodinated contrast (e.g., dilute Gastrografin) are the standard oral agents used to opacify the GI tract in abdominal/pelvic CT.

Question 135: CT colonoscopy (virtual colonoscopy) relies on which post-processing technique to create a simulated fly-through view of the colon lumen?

Minimum intensity projection
Subtraction imaging
Volume rendering with endoluminal navigation (Correct answer)
Maximum intensity projection

Correct answer: Volume rendering with endoluminal navigation

Volume rendering with endoluminal navigation uses the air-distended colon as a flight path, generating a simulated colonoscopic perspective of the mucosal surface.

Question 136: Which of the following is the correct action if a detector ring artifact is identified during a quality control check of the CT scanner?

Decrease the FOV
Continue scanning and note in the patient report
Recalibrate the detector and notify the medical physicist (Correct answer)
Increase mAs to compensate

Correct answer: Recalibrate the detector and notify the medical physicist

A ring artifact indicates a detector calibration issue that must be corrected by recalibration or service; the medical physicist should be notified per QC protocols.

Question 137: On a CT KUB (kidneys, ureters, bladder), which stone type appears LEAST dense (lowest Hounsfield units)?

Cystine
Calcium oxalate monohydrate
Uric acid (Correct answer)
Struvite

Correct answer: Uric acid

Uric acid stones are the least dense urinary calculi on CT (100–400 HU), compared to calcium-based stones which exceed 800 HU.

Question 138: Which daily CT quality control test verifies that CT numbers (Hounsfield Units) remain accurate and consistent?

Slice thickness verification
Noise index measurement
CT number accuracy/linearity test (Correct answer)
High-contrast spatial resolution test

Correct answer: CT number accuracy/linearity test

The CT number accuracy/linearity test confirms that scanned materials produce the expected HU values, ensuring diagnostic consistency.

Question 139: ARRT certification in CT is best described as which type of credential?

Post-primary specialty certification (Correct answer)
Academic degree credential
State-issued license
Entry-level primary certification

Correct answer: Post-primary specialty certification

CT certification is a post-primary specialty credential, meaning it is layered on top of a primary ARRT certification in a related discipline.

Question 140: Which CT feature differentiates an acute from a chronic subdural hematoma?

Crescent shape
Hypodense (low attenuation) appearance of the collection (Correct answer)
Location over the convexity
Mass effect on the brain

Correct answer: Hypodense (low attenuation) appearance of the collection

Chronic subdural hematomas become hypodense (isodense to CSF) over weeks as hemoglobin degrades, unlike acute hyperdense collections.

Question 141: The 'noise' measured in a CT image is quantified as:

The mean CT number in a region of interest
The difference between maximum and minimum CT numbers in the image
The number of image artifacts present
The standard deviation of CT numbers in a uniform region of interest (Correct answer)

Correct answer: The standard deviation of CT numbers in a uniform region of interest

Image noise in CT is quantified as the standard deviation of HU values within a uniform phantom region; higher standard deviation indicates greater noise.

Question 142: Which radiation weighting factor (wR) applies to X-rays used in CT imaging?

1 (Correct answer)
20
2
5

Correct answer: 1

X-rays and gamma rays have a radiation weighting factor of 1, meaning 1 Gy equals 1 Sv.

Question 143: A candidate applies for CT certification under the structured education pathway. Which type of program must they have completed?

Any radiology-related online course
A self-designed independent study program
A hospital orientation program
A CT-specific structured education program accredited by a recognized body (Correct answer)

Correct answer: A CT-specific structured education program accredited by a recognized body

The structured education pathway requires completion of a CT program accredited by a body recognized by ARRT, such as JRCERT.

Question 144: How many continuing education (CE) credits are required for recertification in ARRT CT?

12 CE credits
40 CE credits
24 CE credits (Correct answer)
20 CE credits

Correct answer: 24 CE credits

To maintain ARRT CT certification, technologists must complete a specific number of continuing education (CE) credits within each two-year renewal period. The requirement is 24 CE credits, which helps ensure that certified professionals stay updated with advancements and best practices in the field of computed tomography.

Question 145: Which of the following is a potential benefit of obtaining ARRT CT certification?

Increased job security and advancement opportunities (Correct answer)
Exemption from state licensure requirements
A significant reduction in the required continuing education hours
Eligibility for an automatic salary increase

Correct answer: Increased job security and advancement opportunities

Obtaining ARRT CT certification demonstrates a specialized skill set and commitment to professional standards, which is highly valued by employers. This often translates into increased job security, as certified professionals are preferred, and opens doors to advancement opportunities within the medical imaging field.

Question 146: A CT technologist notices the dose reference level (DRL) for a routine chest CT is being routinely exceeded. The BEST first step is to:

Continue scanning since DRLs are not legally binding limits
Report the finding only to the radiologist and take no further action
Immediately halve the mAs for all chest CT exams
Review and optimize the scan protocol to determine if dose can be reduced without compromising diagnostic quality (Correct answer)

Correct answer: Review and optimize the scan protocol to determine if dose can be reduced without compromising diagnostic quality

DRLs serve as benchmarks; exceeding them triggers a protocol review to identify optimization opportunities while preserving diagnostic image quality.

Question 147: Which artifact appears as a dark band between two high-density objects on a CT image and is caused by beam hardening?

Moiré artifact
Windmill artifact
Shadowing or 'dark band' artifact (Correct answer)
Ring artifact

Correct answer: Shadowing or 'dark band' artifact

Dark bands (also called 'shadowing' or 'cupping' between dense objects) arise from extreme beam hardening where few low-energy photons survive to reach the detector between two dense structures.

Question 148: Which of the following is NOT a requirement for ARRT CT post-primary certification eligibility?

Completing required structured education in CT
Meeting clinical experience requirements in CT procedures
Holding a current, unrestricted ARRT credential in a qualifying discipline
Graduating from a JRCERT-accredited CT-specific degree program (Correct answer)

Correct answer: Graduating from a JRCERT-accredited CT-specific degree program

CT certification does not require graduation from a JRCERT-accredited CT degree program; structured education and clinical experience through other approved pathways are accepted.

Question 149: On axial CT of the knee, the iliotibial band is best identified at which location?

Posterior to the lateral collateral ligament at the fibular head
Posterolateral aspect of the knee, inserting on the femoral condyle
Lateral aspect of the knee, inserting on Gerdy's tubercle of the tibia (Correct answer)
Anteromedial compartment between the patellar tendon and medial collateral ligament

Correct answer: Lateral aspect of the knee, inserting on Gerdy's tubercle of the tibia

The iliotibial band runs along the lateral thigh and inserts on Gerdy's tubercle on the anterolateral tibia.

Question 150: In CT dose reporting, CTDI_vol represents:

Dose only at the center of the phantom
Volume-averaged radiation dose within the scan volume (Correct answer)
Dose at a single point in the patient
Total energy deposited in the room

Correct answer: Volume-averaged radiation dose within the scan volume

CTDI_vol is the volume CT dose index, representing average dose within the irradiated volume; it accounts for pitch in helical scanning.

Question 151: In CT, the term 'isotropic voxel' means:

The voxel's HU value is calibrated to water
The voxel represents a single tissue type
The voxel has no noise contribution
The voxel dimensions are equal in all three axes (x, y, z) (Correct answer)

Correct answer: The voxel dimensions are equal in all three axes (x, y, z)

An isotropic voxel has equal dimensions in x, y, and z directions, enabling multiplanar reformats of equal quality in any plane.

Question 152: How long is the ARRT CT post-primary certification credential valid before renewal is required?

5 years
2 years (biennium) (Correct answer)
Lifetime with no renewal
1 year

Correct answer: 2 years (biennium)

Like all ARRT credentials, CT post-primary certification must be renewed every two years through the biennial renewal process.

Question 153: Cardiac motion artifacts on coronary CT angiography are primarily reduced by which technique?

ECG gating to synchronize data acquisition with the cardiac cycle (Correct answer)
Administering iodinated contrast slowly
High-pitch helical scanning only
Using maximum mAs

Correct answer: ECG gating to synchronize data acquisition with the cardiac cycle

ECG gating synchronizes CT data acquisition to the relatively motion-free phases of the cardiac cycle (typically mid-diastole), reducing coronary motion artifact.

Question 154: A CT technologist who allows their ARRT registration to lapse must do which of the following to reinstate it?

Retake the primary certification exam
Apply through JRCERT for re-entry
Complete a reinstatement application and pay the reinstatement fee (Correct answer)
Repeat clinical training

Correct answer: Complete a reinstatement application and pay the reinstatement fee

Lapsed registrants must submit a reinstatement application with the appropriate fee and may need to fulfill CE requirements.

Question 155: In CT quality control, 'low-contrast detectability' refers to the system's ability to:

Distinguish objects with small differences in attenuation from background (Correct answer)
Resolve fine structural detail in bone
Determine the maximum scan field of view
Measure exact CT numbers for each tissue type

Correct answer: Distinguish objects with small differences in attenuation from background

Low-contrast detectability measures the scanner's ability to visualize objects with subtle attenuation differences, which is critical for soft-tissue diagnosis.

Question 156: A CT head without contrast shows a hyperdense crescent-shaped collection along the inner table of the skull. This is most consistent with:

Subarachnoid hemorrhage
Acute subdural hematoma (Correct answer)
Epidural hematoma
Intraparenchymal hematoma

Correct answer: Acute subdural hematoma

Acute subdural hematomas appear as hyperdense crescent-shaped collections that conform to the brain surface and cross suture lines.

Question 157: Which artifact appears as bright or dark bands radiating from high-density structures like metal implants?

Streak artifact (Correct answer)
Beam hardening artifact
Partial volume artifact
Ring artifact

Correct answer: Streak artifact

Streak artifacts arise from highly attenuating objects (metal, dense bone) causing inconsistent projections that reconstruct as linear streaks.

Question 158: During a CT angiography of the neck (CTA neck), the scan direction is typically:

Caudal to cranial (Correct answer)
Bidirectional simultaneously
Cranial to caudal
Axial only without table movement

Correct answer: Caudal to cranial

CTA of the neck scans caudal to cranial to follow the contrast bolus as it travels superiorly through the carotid and vertebral arteries.

Question 159: Which artifact is caused by patient movement during CT data acquisition and appears as blurring or ghosting on the reconstructed image?

Cupping artifact
Motion artifact (Correct answer)
Partial volume artifact
Aliasing artifact

Correct answer: Motion artifact

Motion artifacts result from patient movement during scanning, causing inconsistent data at each projection angle and manifesting as blurring or streaking.

Question 160: Under ARRT's Continuing Qualifications Requirements (CQR), what must credential holders demonstrate?

Completion of a new clinical rotation every 10 years
A passing score on a repeat certification exam every 10 years
Employer attestation of satisfactory job performance
Ongoing competency through self-assessment and structured activities related to their discipline (Correct answer)

Correct answer: Ongoing competency through self-assessment and structured activities related to their discipline

CQR requires credential holders to complete self-assessment and structured CE activities demonstrating continued competency in their specialty.

Question 161: An ARRT-certified CT technologist moves to a state that also requires state licensure for CT practice. Which statement is true?

ARRT certification replaces all state licensing requirements
State licensure and ARRT certification are separate and both may be required (Correct answer)
State licensure CE requirements always mirror ARRT requirements exactly
ARRT automatically notifies the state upon renewal

Correct answer: State licensure and ARRT certification are separate and both may be required

ARRT certification and state licensure are independent processes; meeting ARRT standards does not automatically satisfy state licensing requirements.

Question 162: How does ARRT CT certification influence a technologist's ability to work at facilities affiliated with academic medical centers?

Academic medical centers often require specialty certifications for positions involving advanced imaging modalities (Correct answer)
It only matters for technologists who also teach radiology students
It is disqualifying because academic centers prefer non-certified staff
It is irrelevant because academic centers set their own competency standards independently of ARRT

Correct answer: Academic medical centers often require specialty certifications for positions involving advanced imaging modalities

Academic medical centers frequently list specialty ARRT certifications as required or preferred qualifications for CT positions due to their high-acuity patient populations.

Question 163: Partial volume averaging artifact in CT is BEST minimized by:

Using a smoother reconstruction kernel
Decreasing the tube current
Increasing the reconstruction matrix
Using thinner slice collimation (Correct answer)

Correct answer: Using thinner slice collimation

Thinner slices reduce the z-axis extent of each voxel, decreasing the chance that multiple tissue types are averaged into a single voxel.

Question 164: A radiologic technologist notices that CT images of the liver appear uniformly noisy despite using standard mAs. The MOST appropriate first corrective action is:

Double the mAs for the repeat scan immediately
Verify that the correct reconstruction kernel and algorithm are applied (Correct answer)
Switch to a narrower window width for display
Reduce the reconstruction FOV by 50%

Correct answer: Verify that the correct reconstruction kernel and algorithm are applied

Verifying protocol settings (kernel, algorithm, slice thickness) first ensures the source of apparent noise is identified before unnecessarily increasing dose.

Question 165: Which reconstruction kernel (filter) choice produces the HIGHEST spatial resolution but MOST noise in CT?

Soft/smooth kernel
Sharp/edge-enhancing kernel (Correct answer)
Lung kernel
Standard kernel

Correct answer: Sharp/edge-enhancing kernel

Sharp or bone kernels enhance high-frequency data to improve edge detail but amplify noise, making them high-resolution but noisy.

Question 166: What are the four basic tissue types in the human body?

Skin, bone, blood, and fat
Smooth, rough, dense, and loose
Epithelial, connective, muscle, and nervous (Correct answer)
Brain, heart, lung, and liver

Correct answer: Epithelial, connective, muscle, and nervous

The four fundamental tissue types are epithelial (covering/lining), connective (support/connection), muscle (movement), and nervous (communication/control).

Question 167: In a CT perfusion study of the brain, which parameter measures the volume of blood in a given unit of brain tissue?

Cerebral blood volume (CBV) (Correct answer)
Mean transit time (MTT)
Cerebral blood flow (CBF)
Time to peak (TTP)

Correct answer: Cerebral blood volume (CBV)

Cerebral blood volume (CBV) represents the total volume of blood within a defined brain tissue volume, measured in mL/100g.

Question 168: The window level (WL) in CT display refers to:

The center Hounsfield unit value of the displayed grayscale range (Correct answer)
The reconstruction matrix size
The total range of Hounsfield units shown
The minimum threshold for bone segmentation

Correct answer: The center Hounsfield unit value of the displayed grayscale range

Window level sets the midpoint of the HU range being displayed, determining which tissue densities appear as medium gray on the monitor.

Question 169: Which statement about the ARRT CT examination content specifications is accurate?

They are developed and periodically updated by ARRT based on practice analysis surveys (Correct answer)
They are set by individual state radiation control programs
They mirror the ACR practice parameters exactly
They have not changed since 2000

Correct answer: They are developed and periodically updated by ARRT based on practice analysis surveys

ARRT periodically conducts practice analysis surveys of working technologists to keep examination content relevant to current clinical practice.

Question 170: What is the primary purpose of ARRT's structured competency-based renewal requirements for CT certification?

To align with Medicare billing requirements
To limit the number of active CT technologists
To ensure technologists maintain current knowledge and skills (Correct answer)
To increase revenue for the ARRT organization

Correct answer: To ensure technologists maintain current knowledge and skills

ARRT's renewal structure is designed to ensure that certified professionals stay current with evolving technology, safety standards, and clinical practice.

Question 171: Aliasing artifacts in CT, which appear as fine streaks or Moiré patterns, are caused by which factor?

Insufficient detector sampling (Correct answer)
Excessive patient size
Incorrect table speed
High kVp settings

Correct answer: Insufficient detector sampling

Aliasing artifacts occur when the object being imaged contains spatial frequencies higher than the detector sampling rate can capture, per the Nyquist theorem.

Question 172: Which of the following patient populations has the HIGHEST radiosensitivity?

Elderly patients over 75
Pregnant women in the third trimester
Adult males aged 40-60
Fetuses and children under 5 years of age (Correct answer)

Correct answer: Fetuses and children under 5 years of age

Fetuses and young children are most radiosensitive due to rapidly dividing cells and longer life expectancy over which stochastic effects can manifest.

Question 173: Which approach is used in a split-bolus IV contrast protocol for CT of the abdomen?

A single rapid bolus followed by immediate scanning
Saline flush only with no contrast
Two separate injections given at different time points before scanning (Correct answer)
Contrast injected into the portal vein directly

Correct answer: Two separate injections given at different time points before scanning

The split-bolus technique delivers two injections at different time intervals so a single scan pass captures both nephrographic and excretory phases simultaneously.

Question 174: CT window width (WW) setting controls which aspect of image display?

The overall brightness of the image
The spatial resolution of the image
The range of Hounsfield units displayed as the full gray scale from black to white (Correct answer)
The center Hounsfield unit of the gray scale

Correct answer: The range of Hounsfield units displayed as the full gray scale from black to white

Window width determines the range of CT numbers (HU) mapped to the grayscale; a narrow window increases contrast but limits the HU range displayed.

Question 175: A technologist reconstructs axial CT images with 5 mm thickness then reforms sagittal images showing 'staircase' appearance. The BEST solution is:

Use a sharper reconstruction kernel
Increase mAs for the next scan
Increase the reconstruction FOV
Reconstruct using thinner overlapping slices before reformatting (Correct answer)

Correct answer: Reconstruct using thinner overlapping slices before reformatting

Staircase artifact on reformats results from thick axial slices; reconstructing thinner overlapping slices provides finer z-axis sampling and smoother multiplanar reformats.

Question 176: What is the correct technique for removing contaminated gloves to prevent self-contamination?

Snap gloves off at the wrist and discard immediately
Wash gloves with soap and water before removal
Pull both gloves off by the fingertips simultaneously
Peel one glove inside-out from the wrist, then use bare fingers inside the second glove's wrist to remove it (Correct answer)

Correct answer: Peel one glove inside-out from the wrist, then use bare fingers inside the second glove's wrist to remove it

The proper technique keeps contaminated outer surfaces folded inside during removal so bare skin never contacts the contaminated exterior.

Question 177: What is the recommended frequency for performing a full CT equipment performance evaluation by a qualified medical physicist?

Every five years
Daily
Annually (Correct answer)
Weekly

Correct answer: Annually

ACR and AAPM guidelines recommend a comprehensive CT performance evaluation by a qualified medical physicist at least annually.

Question 178: What is the function of epithelial tissue?

To store fat
To contract and produce movement
To transmit electrical signals
To cover body surfaces, line cavities, and form glands (Correct answer)

Correct answer: To cover body surfaces, line cavities, and form glands

Epithelial tissue covers all body surfaces, lines body cavities and organs, and forms glands. It provides protection, absorption, secretion, and sensation.

Question 179: Iterative reconstruction (IR) techniques in CT offer which primary advantage over filtered back projection?

Reduced image noise at the same or lower radiation dose (Correct answer)
Higher spatial resolution
Faster reconstruction speed
Elimination of all artifacts

Correct answer: Reduced image noise at the same or lower radiation dose

IR algorithms use repeated mathematical modeling of the imaging process to suppress noise, allowing diagnostic image quality to be maintained at reduced mAs and dose.

Question 180: What is the primary purpose of the CT dose index (CTDI)?

To calculate the effective dose to the technologist
To determine scatter radiation levels in the control room
To characterize radiation output of a CT scanner independent of patient size (Correct answer)
To measure patient absorbed dose in a single organ

Correct answer: To characterize radiation output of a CT scanner independent of patient size

CTDI characterizes the radiation output of a CT scanner and allows standardized comparison between scanners and protocols.

Question 181: Increasing the reconstruction field of view (FOV) while keeping matrix size constant will:

Increase pixel size and decrease spatial resolution (Correct answer)
Have no effect on spatial resolution
Increase noise while improving contrast
Decrease pixel size and increase spatial resolution

Correct answer: Increase pixel size and decrease spatial resolution

Larger FOV with the same matrix means each pixel covers more area, increasing pixel size and reducing spatial resolution.

Question 182: An automatic exposure control (AEC) system in CT adjusts which parameter in real time?

Detector row width
Tube current (mA) based on patient attenuation (Correct answer)
Gantry rotation speed
Reconstruction kernel

Correct answer: Tube current (mA) based on patient attenuation

CT AEC (tube current modulation) automatically adjusts mA based on patient size and attenuation to maintain consistent image quality at optimal dose.

Question 183: What does CT stand for in medical imaging?

Central Treatment
Computed Tomography (Correct answer)
Cardiac Testing
Clinical Therapy

Correct answer: Computed Tomography

CT (Computed Tomography) uses X-ray technology and computer processing to create detailed cross-sectional images of the body.

Question 184: A patient with a cardiac pacemaker presents for chest CT. Which artifact should the technologist anticipate?

Ring artifact
Metallic streak artifact from the pacemaker leads and generator (Correct answer)
Cupping artifact
Windmill artifact

Correct answer: Metallic streak artifact from the pacemaker leads and generator

Pacemaker generators and leads are highly attenuating metallic objects that produce characteristic beam hardening streak artifacts on chest CT.

Question 185: What is the purpose of a risk assessment?

To track inventory levels
To calculate financial budgets
To identify potential hazards and determine mitigation measures (Correct answer)
To assign work shifts

Correct answer: To identify potential hazards and determine mitigation measures

Risk assessments identify potential hazards, evaluate the likelihood and severity of harm, and determine appropriate controls to minimize risk.

Question 186: What is the application window for the ARRT CT post-primary examination after a candidate is deemed eligible?

30 days from approval to test
Six months from approval to test
One year from approval to test (Correct answer)
Two years from approval to test

Correct answer: One year from approval to test

Once approved, ARRT candidates have one year to schedule and sit for the post-primary CT examination.

Question 187: A CT scan for appendicitis in a young female patient of childbearing age should be preceded by:

Administration of glucagon
Double dose of IV contrast
Evaluation for pregnancy and consideration of alternative imaging (Correct answer)
Lung window reconstruction

Correct answer: Evaluation for pregnancy and consideration of alternative imaging

Radiation dose to a fetus is a critical concern; pregnancy should be assessed and ultrasound or MRI considered as alternatives before CT in reproductive-age females.

Question 188: Which of these statements is true about eligibility for ARRT CT certification?

Clinical competencies must be completed after passing the CT exam.
Applicants must hold an existing ARRT certification in an eligible primary pathway discipline. (Correct answer)
Holding a state radiography license is enough to apply for certification.
Only professionals with a master's degree can apply for CT certification.

Correct answer: Applicants must hold an existing ARRT certification in an eligible primary pathway discipline.

ARRT CT certification is considered a post-primary certification, meaning it builds upon a foundational credential. Therefore, a prerequisite for applying is holding an active ARRT certification in a primary pathway discipline such as radiography, nuclear medicine technology, or radiation therapy. This ensures applicants have a core understanding of medical imaging principles.

Question 189: In CT, the modulation transfer function (MTF) is used to characterize:

Contrast resolution at different tissue densities
Detector quantum efficiency
Patient dose efficiency
Spatial frequency response and limiting spatial resolution (Correct answer)

Correct answer: Spatial frequency response and limiting spatial resolution

The MTF describes how well the CT system transfers spatial frequencies from object to image, defining the system's spatial resolution capability.

Question 190: Which of the following is a valid reason ARRT may revoke or suspend a technologist's CT certification?

Transferring employment to a different imaging facility
Completing CE credits after the renewal deadline
Failure to update a home address in the ARRT database
Violation of the ARRT Standards of Ethics (Correct answer)

Correct answer: Violation of the ARRT Standards of Ethics

ARRT can revoke or suspend certification for violations of its Standards of Ethics, which govern professional and personal conduct.

Question 191: Which post-processing technique is most appropriate for evaluating luminal stenosis of the carotid arteries on a CT angiogram?

Minimum intensity projection (MinIP)
Standard axial images only
Multiplanar reformation combined with MIP (Correct answer)
Volume rendering alone

Correct answer: Multiplanar reformation combined with MIP

Combining MPR (which shows vessel walls and plaques in cross-section) with MIP (which shows the lumen in projection) gives the most complete assessment of carotid stenosis.

Question 192: Which CT parameter most directly controls the amount of radiation dose delivered to the patient?

Reconstruction kernel
Pitch
mAs (Correct answer)
kVp

Correct answer: mAs

mAs (milliampere-seconds) directly determines the number of X-ray photons produced and is the primary controller of patient dose.

Question 193: Which reconstruction field of view (FOV) is most appropriate when performing targeted high-resolution CT of the temporal bone?

25 cm (medium FOV)
10–15 cm (small targeted FOV) (Correct answer)
40 cm (large FOV)
50 cm (full body FOV)

Correct answer: 10–15 cm (small targeted FOV)

A 10–15 cm reconstruction FOV over the temporal bone maximizes pixel density within the small region of interest, yielding the highest possible spatial resolution.

Question 194: Which type of iodinated contrast media is considered safest for patients at risk for contrast-induced nephropathy?

Low-osmolar ionic contrast
High-osmolar ionic contrast
Iso-osmolar nonionic contrast (Correct answer)
High-osmolar nonionic contrast

Correct answer: Iso-osmolar nonionic contrast

Iso-osmolar nonionic contrast (e.g., iodixanol) has the lowest nephrotoxic potential and is preferred for high-risk patients.

ARRT Computed Tomography (CT) Certification Examination

The ARRT CT certification exam assesses entry-level knowledge and cognitive skills required for computed tomography practice, covering patient care, radiation safety, image production, and CT imaging procedures across all major anatomical regions.

Questions

35 min

Time Limit

75%

To Pass

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