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

Question 1: Which ACR-recommended CT quality control test should be performed if visual image artifacts are noted during clinical scanning?

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

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

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

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

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

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

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

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

Soft/smooth kernel
Lung kernel
Sharp/edge-enhancing kernel (Correct answer)
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 6: 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 7: Which CT finding helps differentiate a retroperitoneal hematoma from a retroperitoneal abscess?

Presence of gas bubbles within the collection
Location posterior to the peritoneum
Displacement of adjacent organs
Hyperdense content on non-contrast CT (Correct answer)

Correct answer: Hyperdense content on non-contrast CT

Acute hematomas appear hyperdense (50–70 HU) on non-contrast CT due to clotted blood, distinguishing them from fluid collections.

Question 8: A CT technologist who allows their ARRT registration to lapse must do which of the following to reinstate it?

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

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 9: What is the primary purpose of performing a daily air calibration (warm-up scan) on a CT scanner?

To measure patient dose output
To test the table weight limit
To verify gantry tilt accuracy
To calibrate detector channels and normalize dark current (Correct answer)

Correct answer: To calibrate detector channels and normalize dark current

The daily air calibration normalizes detector channel responses and corrects for dark current drift, maintaining uniform image quality.

Question 10: Which of the following best describes 'overranging' (z-overscanning) in helical CT?

Extra rotations acquired beyond the requested scan range to complete helical reconstruction (Correct answer)
Applying too wide a display window
Using a higher kVp than needed
Scanning beyond the prescribed FOV diameter

Correct answer: Extra rotations acquired beyond the requested scan range to complete helical reconstruction

Overranging refers to the additional tube rotations at the start and end of a helical scan needed to reconstruct the first and last requested slices, increasing dose.

Question 11: Within how many years of completing structured education must a candidate apply for ARRT CT post-primary certification under the structured education pathway?

10 years
5 years (Correct answer)
2 years
1 year

Correct answer: 5 years

Candidates pursuing the structured education pathway must apply within 5 years of completing the qualifying program.

Question 12: A patient states, 'I am Jehovah's Witness and refuse any blood transfusion.' The radiologic technologist should:

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

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

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

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 14: A CT abdomen in a trauma patient shows high-density fluid in the hepatorenal space (Morison's pouch). What does this indicate?

Biliary leak
Hemoperitoneum (Correct answer)
Lymphocele
Physiologic peritoneal fluid

Correct answer: Hemoperitoneum

High-attenuation free fluid (>30 HU) in Morison's pouch following trauma indicates hemoperitoneum from solid organ or vascular injury.

Question 15: A Radiation Therapy (T) credential holder who wishes to obtain CT certification must complete which category of clinical competencies?

No clinical competencies — written exam only
CT-specific competencies as outlined in the ARRT CT content specifications (Correct answer)
MRI competencies as a prerequisite
Radiography general competencies only

Correct answer: CT-specific competencies as outlined in the ARRT CT content specifications

All CT candidates, regardless of their primary pathway, must satisfy CT-specific clinical competency requirements.

Question 16: When a CT abdomen protocol specifies 'nephrographic phase,' scanning typically occurs at what delay after IV contrast injection?

15–25 seconds
30–45 seconds
80–120 seconds (Correct answer)
5–10 minutes

Correct answer: 80–120 seconds

The nephrographic phase occurs at approximately 80–120 seconds post-injection when both cortex and medulla enhance uniformly, optimizing renal parenchymal visualization.

Question 17: The pitch value in helical CT is defined as:

Table travel per rotation divided by total beam collimation width (Correct answer)
Gantry rotation speed divided by table speed
Slice thickness divided by detector row width
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 18: Which CT post-processing technique displays only voxels above a selected threshold, making it useful for 3D visualization of bones and vascular structures?

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

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 19: On a non-contrast CT of the abdomen, a renal calculus most likely to be missed is composed of which material?

Uric acid
Calcium oxalate
Indinavir (drug-related) (Correct answer)
Struvite

Correct answer: Indinavir (drug-related)

Indinavir stones are radiolucent and have very low Hounsfield units, making them nearly invisible on non-contrast CT.

Question 20: For a CT scan of the spine performed to evaluate for disk herniation, which reconstruction kernel is preferred?

Ultra-high-resolution kernel
Lung (high-frequency) kernel
Bone (high-frequency) 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 21: Which regulatory body sets the annual occupational effective dose limit of 50 mSv in the United States?

ARRT
FDA
CDC
NRC and Agreement States (Correct answer)

Correct answer: NRC and Agreement States

The Nuclear Regulatory Commission (NRC) and Agreement State regulations set the 50 mSv/year occupational effective dose limit (10 CFR 20).

Question 22: What is the role of the bowtie (beam-shaping) filter in CT equipment operation?

To equalize X-ray flux across the fan beam, reducing dose at the periphery and minimizing detector saturation (Correct answer)
To increase photon energy for improved tissue penetration
To harden the beam and remove low-energy photons uniformly across the beam
To collimate the beam to the prescribed slice thickness

Correct answer: To equalize X-ray flux across the fan beam, reducing dose at the periphery and minimizing detector saturation

The bowtie filter is thicker at the edges and thinner at the center, compensating for the cylindrical shape of patients to equalize detector flux and reduce peripheral skin dose.

Question 23: Within what timeframe must newly certified CT technologists complete their first renewal cycle?

When their primary registration expires (Correct answer)
Two years from certification date
Three years from certification date
One year from certification date

Correct answer: When their primary registration expires

Post-primary certification renewal is typically aligned with the technologist's primary registration renewal date, not a separate independent cycle.

Question 24: Which of the following best summarizes the overall career impact of achieving ARRT CT certification?

Its benefits are limited to the first five years after passing the exam
It limits career options to CT-only positions permanently
It expands earning potential, job mobility, leadership opportunities, and professional credibility in CT imaging (Correct answer)
It replaces the need for any additional professional development

Correct answer: It expands earning potential, job mobility, leadership opportunities, and professional credibility in CT imaging

ARRT CT certification broadly enhances a technologist's career by improving compensation, widening employment options, enabling leadership roles, and establishing professional credibility.

Question 25: On axial CT of the head at the level of the fourth ventricle, which structure is immediately posterior to the fourth ventricle?

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

Correct answer: Cerebellum (vermis)

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

Question 26: Which of the following BEST describes noise power spectrum (NPS) in CT?

The standard deviation of HU values in a uniform phantom
A test of detector linearity across HU ranges
The ratio of signal to total detector noise
A measure of how noise is distributed across spatial frequencies in an image (Correct answer)

Correct answer: A measure of how noise is distributed across spatial frequencies in an image

NPS characterizes the frequency content of image noise, showing whether noise is more granular (high-frequency) or blotchy (low-frequency) depending on reconstruction parameters.

Question 27: A standard high-resolution CT (HRCT) chest protocol uses which reconstruction approach to evaluate interstitial lung disease?

Thin slices with soft tissue kernel
Thick slices with bone kernel
Thin slices with high-frequency (sharp) kernel (Correct answer)
Thick slices with soft tissue kernel

Correct answer: Thin slices with high-frequency (sharp) kernel

HRCT uses thin slices (≤1.5 mm) with a high-spatial-frequency kernel to maximize edge detail of lung parenchyma and airways.

Question 28: 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
Maximum intensity projection
Volume rendering with endoluminal navigation (Correct answer)

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 29: 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 Category B self-study credit
As 3 Category A CE credits (Correct answer)
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 30: When preparing a sterile field for an interventional procedure, which action would contaminate the field?

Opening sterile packages by peeling back corners and dropping contents onto the field
Placing sterile items within the 1-inch border of the sterile drape
Wearing sterile gloves throughout the procedure
Reaching across the sterile field with a non-sterile sleeve (Correct answer)

Correct answer: Reaching across the sterile field with a non-sterile sleeve

Reaching a non-sterile sleeve or arm over the sterile field contaminates it because anything below the waist or any non-sterile surface passing over the field breaks sterility.

Question 31: What type of artifact appears as bright or dark streaks radiating from high-density objects like metal implants in CT images?

Motion artifact
Partial volume artifact
Beam hardening artifact (Correct answer)
Ring 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 32: What is the significance of ARRT accreditation reciprocity with respect to international technologists seeking U.S. credentials?

ARRT has formal reciprocity agreements with all countries
Foreign credentials are automatically accepted as equivalent to ARRT certification
Foreign technologists are exempt from the ethics review
ARRT does not grant reciprocity; international candidates must meet all ARRT eligibility requirements independently (Correct answer)

Correct answer: ARRT does not grant reciprocity; international candidates must meet all ARRT eligibility requirements independently

ARRT does not have reciprocity agreements with foreign credentialing bodies; all candidates must independently meet ARRT's eligibility and examination requirements.

Question 33: Which reconstruction field of view (FOV) is most appropriate when performing targeted high-resolution CT of the temporal bone?

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

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 34: Which of the following activities qualifies as a Category A continuing education credit for ARRT recertification?

Reviewing patient charts for quality assurance
Reading a radiology textbook independently
Attending an ARRT-approved educational seminar (Correct answer)
Performing additional clinical shifts

Correct answer: Attending an ARRT-approved educational seminar

Category A credits require structured learning through ARRT-approved providers such as accredited seminars, courses, or self-assessment activities.

Question 35: What is the recommended frequency for performing a full CT equipment performance evaluation by a qualified medical physicist?

Weekly
Annually (Correct answer)
Every five years
Daily

Correct answer: Annually

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

Question 36: On axial CT of the pelvis, the obturator internus muscle is best identified by its location:

Lining the lateral wall of the true pelvis adjacent to the obturator foramen (Correct answer)
Between the iliacus and psoas muscles in the iliac fossa
Anterior to the pubic symphysis forming the pelvic floor
Posterior to the sacrum in the gluteal region

Correct answer: Lining the lateral wall of the true pelvis adjacent to the obturator foramen

The obturator internus lines the lateral wall of the true pelvis, arising from the inner surface of the obturator foramen.

Question 37: A CT myelography protocol requires which patient preparation step unique to this exam?

Fasting for 6 hours prior
IV injection of gadolinium contrast
Oral bowel prep the night before
Intrathecal injection of iodinated contrast (Correct answer)

Correct answer: Intrathecal injection of iodinated contrast

CT myelography requires intrathecal (subarachnoid) injection of water-soluble iodinated contrast to opacify the spinal canal.

Question 38: A pediatric patient is uncooperative and crying during a radiographic exam. Which approach is most appropriate?

Physically restrain the child immediately to complete the exam quickly
Administer sedation without physician order to calm the child
Reschedule the exam for another day without attempting to proceed
Speak calmly, involve the parent or guardian, and use age-appropriate distraction techniques before attempting immobilization (Correct answer)

Correct answer: Speak calmly, involve the parent or guardian, and use age-appropriate distraction techniques before attempting immobilization

A calm approach with parental involvement and distraction is the least traumatic first step and often allows successful completion of the exam without restraint.

Question 39: In a CT perfusion study of the brain, which parameter measures the volume of blood in a given unit of brain tissue?

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

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

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

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

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

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 42: Partial volume averaging artifact in CT is BEST minimized by:

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

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

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

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

Quantum noise
Aliasing
Partial volume averaging
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 45: CT perfusion imaging requires specialized post-processing to generate which type of parametric maps?

Cerebral blood flow, cerebral blood volume, and mean transit time maps (Correct answer)
Standardized uptake value (SUV) maps
Hounsfield unit histograms
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 46: How often must ARRT CT technologists renew their registration?

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

Correct answer: Every 2 years

ARRT registration is renewed on a biennial (every 2 years) basis, coinciding with the CE credit cycle.

Question 47: Under NRC regulations, which of the following events involving a CT scanner MUST be reported as a medical event?

Delivery of a dose differing from the prescribed dose by more than 50 mSv effective dose or 500 mSv to an organ when not due to patient condition (Correct answer)
Using a slightly higher mAs than the standard protocol
A scan performed 2 cm longer than prescribed due to patient movement
Scanning without verbal confirmation of the patient's name

Correct answer: Delivery of a dose differing from the prescribed dose by more than 50 mSv effective dose or 500 mSv to an organ when not due to patient condition

A medical event under 10 CFR 35.3045 requires reporting when the wrong patient receives a dose, or dose differs from the prescribed dose by >50 mSv effective dose or >500 mSv to any organ.

Question 48: A ring or band artifact centered on the image is most likely caused by a malfunction of which CT component?

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

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 49: Stochastic effects of radiation are characterized by which of the following?

Severity increasing proportionally with dose above the threshold
No dose threshold; probability of occurrence increases with dose (Correct answer)
A threshold dose below which the effect cannot occur
Occurring only in radiosensitive tissues such as bone marrow

Correct answer: No dose threshold; probability of occurrence increases with dose

Stochastic effects (e.g., radiation-induced cancer) are assumed to have no threshold; their probability, not severity, increases with dose.

Question 50: What is the effect of decreasing detector collimation (thinner slices) on image noise, assuming all other factors remain constant?

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

Correct answer: Noise increases

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

Question 51: A technologist reconstructs axial CT images with 5 mm thickness then reforms sagittal images showing 'staircase' appearance. The BEST solution is:

Increase the reconstruction FOV
Increase mAs for the next scan
Use a sharper reconstruction kernel
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 52: What is the minimum passing score for the ARRT CT certification exam?

70
65
80
75 (Correct answer)

Correct answer: 75

To successfully pass the ARRT CT certification exam, candidates must achieve a scaled score of 75 or higher. This score represents the minimum level of competency required by the ARRT to demonstrate proficiency in computed tomography. Scores are scaled to ensure fairness across different exam forms.

Question 53: When comparing filtered back projection (FBP) to model-based iterative reconstruction (MBIR) at matched noise levels, MBIR typically demonstrates:

Equivalent resolution but increased beam hardening artifacts
Higher spatial resolution with fewer artifacts at lower dose (Correct answer)
Longer reconstruction times with no image quality advantage
Lower spatial resolution but equivalent noise

Correct answer: Higher spatial resolution with fewer artifacts at lower dose

MBIR models the entire imaging chain including optics and statistics, achieving better resolution and artifact suppression at lower dose than FBP.

Question 54: 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
Ongoing competency through self-assessment and structured activities related to their discipline (Correct answer)
Employer attestation of satisfactory job performance

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 55: A technologist holds both ARRT Radiography (R) and MRI (MR) credentials. To add CT certification, which credential serves as the qualifying primary pathway?

Only MRI (MR) qualifies
Either R or MR can serve as the qualifying primary credential (Correct answer)
Only Radiography (R) qualifies
Both credentials must be listed; neither alone qualifies

Correct answer: Either R or MR can serve as the qualifying primary credential

ARRT allows multiple qualifying primary pathways for CT, so either an active R or MR credential can serve as the qualifying base.

Question 56: What is the function of red blood cells?

To transport oxygen from lungs to tissues and CO2 back (Correct answer)
To produce hormones
To clot blood
To fight infection

Correct answer: To transport oxygen from lungs to tissues and CO2 back

Red blood cells (erythrocytes) contain hemoglobin that binds oxygen in the lungs and delivers it to tissues, then carries carbon dioxide back for exhalation.

Question 57: On axial brain CT, the sylvian fissure (lateral sulcus) separates which lobes?

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

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

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

Correct answer: 3 attempts

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

Question 59: What does 'afterglow' (or 'ghosting') in CT solid-state detectors cause?

Ring artifacts from a single failed detector channel
Residual signal carried over from prior projections, causing streak artifacts (Correct answer)
Increased image noise due to photon starvation
Reduced spatial resolution due to detector cross-talk

Correct answer: Residual signal carried over from prior projections, causing streak artifacts

Afterglow occurs when scintillator crystals continue to emit light after X-ray exposure ends, carrying residual signal into subsequent projections and causing streak or shading artifacts.

Question 60: Which statement best describes an isotropic voxel in CT imaging?

A voxel reconstructed using iterative algorithms
A voxel with equal dimensions in x, y, and z axes (Correct answer)
A voxel that contains only one tissue type
A voxel with maximum attenuation value

Correct answer: A voxel with equal dimensions in x, y, and z axes

Isotropic voxels have equal measurements in all three spatial dimensions, enabling high-quality MPR and 3D reconstructions in any plane without stair-step degradation.

Question 61: 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 spleen is positioned more inferiorly than the liver
The liver occupies the right upper quadrant and elevates the right hemidiaphragm (Correct answer)
The right lung is larger and displaces the diaphragm inferiorly

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 62: A CT enterography protocol differs from a standard abdominal CT primarily in which way?

Use of oral contrast to distend the small bowel (Correct answer)
Intravenous contrast is not used
Scanning only the large intestine
Higher tube current for better resolution

Correct answer: Use of oral contrast to distend the small bowel

CT enterography uses large volumes of neutral oral contrast (e.g., VoLumen) to distend and visualize the small bowel mucosa.

Question 63: The purpose of a body mechanics principle such as 'keeping the load close to the body' when lifting a patient is to:

Maintain proper sterile field distance
Protect the patient from falling
Increase the speed of the transfer
Reduce strain on the lumbar spine by minimizing torque (Correct answer)

Correct answer: Reduce strain on the lumbar spine by minimizing torque

Keeping a load close to the body reduces the moment arm and therefore the torque placed on the lumbar vertebrae, preventing injury.

Question 64: 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 provides higher iodine concentration per mL
It requires a lower injection rate

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

Within the hepatoduodenal ligament
Directly anterior to the abdominal aorta, surrounded by fat (Correct answer)
Posterior to the splenic vein
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 66: When noise in a CT image is described as 'quantum mottle,' it most directly reflects:

Software processing errors
Electronic noise in the detector
Mechanical vibration of the gantry
Statistical variation in the number of photons detected (Correct answer)

Correct answer: Statistical variation in the number of photons detected

Quantum mottle (quantum noise) results from statistical variations in photon fluence reaching the detector, following Poisson statistics.

Question 67: How is the ARRT Computed Tomography (CT) certification exam administered?

During an in-person workshop or seminar
At a Pearson VUE testing center (Correct answer)
Through online remote proctoring
In-person at a hospital or clinic

Correct answer: At a Pearson VUE testing center

The ARRT Computed Tomography (CT) certification exam is administered through a professional testing service. Candidates are required to schedule and take their exam at an authorized Pearson VUE testing center. These centers provide a standardized, secure, and proctored environment for examinations.

Question 68: CT of the neck in a patient with a palpable mass shows a cystic lesion at the angle of the mandible deep to the sternocleidomastoid muscle. This is most consistent with:

Dermoid cyst
Branchial cleft cyst (Correct answer)
Thyroglossal duct cyst
Lymphatic malformation

Correct answer: Branchial cleft cyst

Branchial cleft cysts characteristically appear as unilocular cystic masses at the angle of the mandible adjacent to the sternocleidomastoid muscle.

Question 69: At the level of the aortic arch on axial CT, which vessel arises first (most rightward/anterior) from the arch?

Left common carotid artery
Right subclavian artery
Brachiocephalic (innominate) artery (Correct answer)
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 70: Which of the following is required as proof of identity when a candidate checks in for the ARRT CT examination?

Employer-issued badge
Social Security card
ARRT membership card only
Government-issued photo ID with signature (Correct answer)

Correct answer: Government-issued photo ID with signature

Pearson VUE and ARRT require a valid, unexpired government-issued photo ID with a matching signature at check-in.

Question 71: What is the minimum number of Category A CE credits that must be completed in the final year of a 2-year ARRT renewal cycle?

12 credits minimum in the second year
0 — credits can all be earned in one year (Correct answer)
All 24 credits must be earned evenly each year
6 credits minimum per year are required

Correct answer: 0 — credits can all be earned in one year

ARRT does not require credits to be distributed evenly across both years; all 24 Category A credits can technically be earned at any point during the 2-year cycle.

Question 72: Which career pathway is most directly opened by holding ARRT CT certification?

Lead CT technologist or CT supervisor (Correct answer)
Radiology billing and coding specialist
Radiation oncology physician assistant
Nuclear medicine physician

Correct answer: Lead CT technologist or CT supervisor

CT certification establishes the specialized credential often required for leadership roles such as lead CT tech or CT department supervisor.

Question 73: For a pancreatic protocol CT, which phase is most critical for detecting hypervascular pancreatic neuroendocrine tumors?

Unenhanced phase
Delayed phase at 5 minutes
Portal venous phase at 70 seconds
Late arterial (pancreatic parenchymal) phase at 40–50 seconds (Correct answer)

Correct answer: Late arterial (pancreatic parenchymal) phase at 40–50 seconds

Pancreatic neuroendocrine tumors are hypervascular and enhance most conspicuously during the pancreatic parenchymal phase (approximately 40–50 seconds), when the pancreas peaks in enhancement.

Question 74: Adaptive statistical iterative reconstruction (ASIR) improves CT image quality primarily by:

Increasing spatial resolution beyond filtered back projection
Eliminating beam hardening artifacts
Improving temporal resolution
Reducing image noise while maintaining resolution (Correct answer)

Correct answer: Reducing image noise while maintaining resolution

ASIR uses statistical modeling to reduce noise, allowing diagnostic images at lower dose without proportional loss of spatial resolution.

Question 75: What are the principles of mission command?

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

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 76: A patient's blood pressure reads 88/52 mmHg after contrast injection and they appear pale and diaphoretic. The technologist should suspect:

Dehydration unrelated to contrast
Hypotensive contrast reaction requiring immediate intervention (Correct answer)
Hypertensive crisis
Normal post-procedure response

Correct answer: Hypotensive contrast reaction requiring immediate intervention

Hypotension (BP <90/60), pallor, and diaphoresis following contrast injection indicate a vasomotor or anaphylactoid reaction requiring immediate emergency response.

Question 77: 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
A 30-day suspension of testing privileges
Mandatory retaking of the primary examination
Permanent revocation of eligibility and any existing ARRT credentials (Correct answer)

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 78: What is the difference between arteries and veins?

Arteries are only in the lungs
They carry the same blood in the same direction
Veins are thicker than arteries
Arteries carry blood away from the heart; veins carry blood toward the heart (Correct answer)

Correct answer: Arteries carry blood away from the heart; veins carry blood toward the heart

Arteries carry blood away from the heart (usually oxygenated) while veins carry blood toward the heart (usually deoxygenated). Arteries have thicker walls to handle higher pressure.

Question 79: What is a Hounsfield unit?

A quantitative measurement of tissue density on CT images (Correct answer)
A measure of scan speed
A unit of radiation dose
A unit of image resolution

Correct answer: A quantitative measurement of tissue density on CT images

Hounsfield units (HU) measure tissue density on CT, with water at 0 HU, air at -1000 HU, and dense bone at +1000 HU or higher.

Question 80: 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
Undersampling artifact
Partial volume effect
Beam hardening cupping artifact (Correct answer)

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 81: In CT colonography (virtual colonoscopy), which type of contrast material is used to 'tag' residual stool and fluid?

CO2 gas instilled into the colon
IV iodinated contrast to enhance the colonic mucosa
Rectal gadolinium solution
Oral barium and/or dilute iodinated contrast ingested before the exam (Correct answer)

Correct answer: Oral barium and/or dilute iodinated contrast ingested before the exam

Fecal tagging uses oral barium and/or iodinated contrast ingested in the days before CTC to label residual stool and fluid, allowing software subtraction.

Question 82: Which artifact appears as a dark band between two high-density objects on a CT image and is caused by beam hardening?

Moiré artifact
Shadowing or 'dark band' artifact (Correct answer)
Ring artifact
Windmill 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 83: A technologist passes the ARRT CT exam on their first attempt. Which professional document should they update immediately to reflect this achievement?

Their state driver's license
Their malpractice insurance policy
Their facility's CT scanner service contract
Their professional resume and credential listings (Correct answer)

Correct answer: Their professional resume and credential listings

Updating a resume with the new ARRT(CT) credential ensures prospective employers and current supervisors are aware of the technologist's new qualification.

Question 84: Which vital sign finding in an adult patient should be reported to the supervising clinician before proceeding with a routine radiographic exam?

Temperature of 98.6°F (37°C)
Respiratory rate of 10 breaths per minute (Correct answer)
Blood pressure of 118/76 mmHg
Pulse of 72 beats per minute

Correct answer: Respiratory rate of 10 breaths per minute

A respiratory rate of 10 breaths per minute is below the normal range (12-20) and indicates bradypnea, which warrants clinical notification.

Question 85: A patient presents with acute vision loss. CT brain shows hyperdensity in the basilar artery. What does this finding represent?

Acute thrombosis of the basilar artery (Correct answer)
Atherosclerotic calcification
Basilar artery aneurysm
Normal flow-related artifact

Correct answer: Acute thrombosis of the basilar artery

The 'dense basilar artery sign' on non-contrast CT indicates acute thromboembolism and is a CT marker of posterior circulation stroke.

Question 86: Which artifact appears as bright or dark bands radiating from high-density structures like metal implants?

Beam hardening artifact
Streak artifact (Correct answer)
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 87: Which injection technique is used to maintain steady arterial opacification during a lengthy CT acquisition such as a runoff study of the lower extremities?

Multiple sequential hand injections
Biphasic injection with an initial rapid bolus followed by a slower maintenance rate (Correct answer)
Slow continuous drip infusion at 0.5 mL/sec only
Single rapid bolus at 5 mL/sec

Correct answer: Biphasic injection with an initial rapid bolus followed by a slower maintenance rate

A biphasic injection protocol delivers an initial high-rate bolus for peak enhancement followed by a lower-rate phase to sustain opacification during the longer acquisition time.

Question 88: How often must an ARRT CT certification be renewed?

Every 5 years
Every 3 years
Every 2 years (Correct answer)
Every 10 years

Correct answer: Every 2 years

ARRT CT certification, like most ARRT credentials, requires regular renewal to ensure technologists maintain current knowledge and skills. Certified professionals must renew their certification every two years. This biennial renewal process typically involves meeting continuing education requirements.

Question 89: How many continuing education (CE) credits must ARRT-certified technologists earn in each biennium to maintain eligibility for CT certification renewal?

36 credits
12 credits
24 credits (Correct answer)
48 credits

Correct answer: 24 credits

ARRT requires 24 CE credits per two-year renewal cycle to maintain an active, unrestricted credential.

Question 90: 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)
24 R-specific + 12 CT-specific = 36
48 total (24 per credential)
12 per credential for a total of 24

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 91: Which CT quality control parameter is most directly affected by X-ray tube focal spot size?

CT number uniformity
High-contrast spatial resolution (Correct answer)
Image noise
Low-contrast detectability

Correct answer: High-contrast spatial resolution

A smaller focal spot produces sharper images with improved high-contrast spatial resolution because the geometric unsharpness is reduced.

Question 92: A patient receiving IV contrast media suddenly develops stridor and facial edema 5 minutes after injection. These findings are most consistent with:

Anaphylactoid reaction (Correct answer)
Phlebitis at the injection site
Vasovagal reaction
Contrast nephropathy

Correct answer: Anaphylactoid reaction

Stridor (upper airway obstruction) and facial edema are hallmark signs of anaphylactoid reaction, requiring immediate epinephrine and airway management.

Question 93: What is the primary purpose of selecting a small reconstruction FOV (field of view) during CT image reconstruction?

To decrease image noise
To increase the pixel size for better soft tissue contrast
To reduce patient dose
To improve spatial resolution by sampling more detail per pixel (Correct answer)

Correct answer: To improve spatial resolution by sampling more detail per pixel

A smaller reconstruction FOV divides the imaged area into the same matrix of pixels, resulting in smaller pixel size and therefore higher spatial resolution of the region of interest.

Question 94: What is the primary advantage of CT over conventional X-ray?

CT uses no radiation
CT is cheaper
CT takes less time
CT provides cross-sectional images with superior soft tissue contrast (Correct answer)

Correct answer: CT provides cross-sectional images with superior soft tissue contrast

CT provides detailed cross-sectional images with much better soft tissue contrast resolution than conventional X-rays, allowing visualization of subtle differences between tissues.

Question 95: Under ARRT policy, which of the following best describes the purpose of mandatory continuing education for CT technologists?

To standardize CT protocols across all imaging facilities
To reduce malpractice insurance premiums for employers
To generate revenue for accreditation bodies
To protect patients by ensuring technologists stay current in their field (Correct answer)

Correct answer: To protect patients by ensuring technologists stay current in their field

The fundamental purpose of mandatory CE is patient protection — ensuring technologists maintain the knowledge and skills needed for safe, effective practice.

Question 96: Which CT finding most reliably indicates complicated acute pancreatitis?

Pancreatic necrosis (non-enhancing parenchyma) (Correct answer)
Peripancreatic fat stranding
Peripancreatic fluid collections
Pancreatic enlargement

Correct answer: Pancreatic necrosis (non-enhancing parenchyma)

Pancreatic necrosis, identified as non-enhancing parenchyma after IV contrast, is the defining feature of necrotizing pancreatitis.

Question 97: CT window width (WW) setting controls which aspect of image display?

The overall brightness of the image
The range of Hounsfield units displayed as the full gray scale from black to white (Correct answer)
The spatial resolution of the image
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 98: What is the main clinical use of dual-energy CT (DECT)?

Eliminating the need for contrast agents entirely
Increasing patient dose efficiency
Material decomposition to differentiate tissue composition (e.g., iodine vs. calcium) (Correct answer)
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 99: Increasing the CT reconstruction matrix from 512×512 to 1024×1024 while keeping FOV constant will:

Reduce scan time
Decrease pixel size and potentially improve spatial resolution (Correct answer)
Decrease image noise
Increase pixel size and reduce spatial resolution

Correct answer: Decrease pixel size and potentially improve spatial resolution

Doubling the matrix halves the pixel size (FOV/matrix), which can improve displayed spatial resolution but also increases image noise and data storage requirements.

Question 100: 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 101: Which post-processing technique is most appropriate for evaluating luminal stenosis of the carotid arteries on a CT angiogram?

Multiplanar reformation combined with MIP (Correct answer)
Standard axial images only
Minimum intensity projection (MinIP)
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 102: 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
Intraparenchymal hematoma
Epidural hematoma
Acute subdural hematoma (Correct answer)

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 103: The spatial frequency at which the MTF falls to 10% is commonly used to define:

The limiting spatial resolution of the CT system (Correct answer)
The noise power spectrum peak
The optimal reconstruction FOV
The detective quantum efficiency (DQE)

Correct answer: The limiting spatial resolution of the CT system

MTF10% represents the highest spatial frequency the system can transfer with 10% modulation, effectively defining the limiting resolution.

Question 104: Partial volume averaging artifacts in CT are best reduced by which acquisition parameter adjustment?

Increasing mAs
Using a thinner slice thickness (Correct answer)
Widening the display window
Increasing kVp

Correct answer: Using a thinner slice thickness

Thinner slices reduce partial volume averaging by ensuring each voxel contains tissue from a smaller volume, improving accuracy of CT numbers.

Question 105: On axial CT at the level of L4-L5, which structure is found anterior to the vertebral body?

Celiac axis
Inferior mesenteric artery origin
Abdominal aortic bifurcation (Correct answer)
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 106: Which of the following best describes the purpose of the ARRT pre-application ethics review?

To replace the formal application process
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

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 107: A patient undergoing a radiographic exam becomes unresponsive and pulseless. The technologist should FIRST:

Activate the emergency response system (call code)
Administer oxygen via nasal cannula
Begin chest compressions immediately while calling for help (Correct answer)
Place the patient in recovery position and observe

Correct answer: Begin chest compressions immediately while calling for help

According to current AHA guidelines, high-quality chest compressions should begin immediately while simultaneously calling for emergency help.

Question 108: Which of the following best describes the purpose of ARRT's Standards of Ethics in the accreditation context?

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

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

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

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

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

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

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

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 112: Quantum mottle in CT images is primarily caused by:

An insufficient number of detected photons (Correct answer)
High kVp beam hardening
Excessive table speed
Detector calibration errors

Correct answer: An insufficient number of detected photons

Quantum mottle (noise) occurs when too few photons reach the detector, causing statistical fluctuations that appear as grainy image texture.

Question 113: What is the chain of command?

A type of equipment
A combat formation
A supply system
The hierarchical structure of authority in a military organization (Correct answer)

Correct answer: The hierarchical structure of authority in a military organization

The chain of command is the line of authority along which orders pass from the highest rank to the lowest.

Question 114: Which CT finding is most characteristic of acute mesenteric ischemia due to superior mesenteric artery occlusion?

Retroperitoneal hematoma
Bowel wall thickening with hyperenhancement
Pneumatosis intestinalis (Correct answer)
Ascites alone

Correct answer: Pneumatosis intestinalis

Pneumatosis intestinalis (gas within the bowel wall) indicates bowel infarction and is a hallmark of severe mesenteric ischemia.

Question 115: What is the primary advantage of CT over conventional X-ray?

CT takes less time
CT is cheaper
CT provides cross-sectional images with superior soft tissue contrast (Correct answer)
CT uses no radiation

Correct answer: CT provides cross-sectional images with superior soft tissue contrast

CT provides detailed cross-sectional images with much better soft tissue contrast resolution than conventional X-rays, allowing visualization of subtle differences between tissues.

Question 116: A patient is on hemodialysis and requires a contrast-enhanced CT. Which statement regarding iodinated contrast in dialysis patients is correct?

Only half the standard contrast dose may be given regardless of clinical indication
Emergent dialysis must be performed within 1 hour of contrast to prevent harm
Contrast can be given; iodinated agents are removed by dialysis and residual renal function is already negligible (Correct answer)
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 117: The annual occupational dose limit for the lens of the eye, as updated by NCRP Report No. 172, is:

20 mSv (Correct answer)
50 mSv
150 mSv
5 mSv

Correct answer: 20 mSv

NCRP Report No. 172 (2016) lowered the recommended annual occupational lens dose limit to 20 mSv/year averaged over 5 years, consistent with ICRP 103.

Question 118: What is a SITREP?

An intelligence brief
A training exercise
A situation report providing current status to command (Correct answer)
A supply request

Correct answer: A situation report providing current status to command

SITREP (Situation Report) provides commanders with timely information about the current operational situation.

Question 119: What does the term 'detector efficiency' refer to in CT scanner performance?

The number of detector rows in the system
The speed at which the gantry rotates
The FOV coverage per rotation
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 120: What is a nosocomial infection?

A childhood disease
A genetic condition
A respiratory infection
An infection acquired in a healthcare facility (Correct answer)

Correct answer: An infection acquired in a healthcare facility

Nosocomial (healthcare-associated) infections are acquired during the course of receiving medical treatment in a healthcare facility, not present at admission.

Question 121: When performing a CT pulmonary angiography (CTPA), which scan direction is preferred?

Cranial to caudal
Either direction equally
Caudal to cranial (Correct answer)
Bidirectional

Correct answer: Caudal to cranial

Caudal-to-cranial scanning in CTPA ensures the densest contrast bolus reaches the pulmonary arteries during image acquisition.

Question 122: On CT of the head, lenticular (biconvex) hyperdensity is identified adjacent to the temporal bone. What is the most likely cause?

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

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 123: During a CT-guided biopsy procedure, which measure BEST reduces radiation exposure to the interventional CT technologist?

Reducing tube current to zero between acquisitions
Wearing a lead apron only when the patient is being positioned
Using fluoroscopy-like CT intermittently and stepping back during exposures (Correct answer)
Standing at the gantry opening throughout the procedure

Correct answer: Using fluoroscopy-like CT intermittently and stepping back during exposures

Intermittent CT fluoroscopy combined with stepping away from the gantry during exposures significantly reduces occupational dose during interventional procedures.

Question 124: In a renal stone protocol CT, intravenous contrast is typically:

Administered before scanning only
Not administered (Correct answer)
Administered in a split-bolus technique
Administered after scanning only

Correct answer: Not administered

Non-contrast CT is the gold standard for detecting urolithiasis because stones are visible without IV contrast and contrast can obscure small calculi.

Question 125: Which of the following best describes the purpose of a test bolus or bolus tracking technique in CT angiography?

To improve bone subtraction
To reduce overall contrast volume needed
To eliminate venous contamination
To determine the optimal scan delay for peak arterial enhancement (Correct answer)

Correct answer: To determine the optimal scan delay for peak arterial enhancement

Test bolus or bolus-tracking (SmartPrep/SureStar) determines when contrast peaks in the target vessel so scanning begins at the optimal moment.

Question 126: The Hounsfield unit (HU) value of pure water is:

+100
+1000
0 (Correct answer)
-1000

Correct answer: 0

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

Question 127: Which structure forms the posterior boundary of the adrenal glands on axial CT images?

Psoas major muscle
Perirenal fat
Diaphragmatic crura (Correct answer)
Quadratus lumborum muscle

Correct answer: Diaphragmatic crura

The diaphragmatic crura form the posterior border of the adrenal glands, which lie in the perirenal space.

Question 128: In CT, 'DLP' (dose-length product) is calculated as:

SSDE × patient weight
CTDIvol × scan length (Correct answer)
CTDIw × pitch
mAs × kVp × scan length

Correct answer: CTDIvol × scan length

DLP = CTDIvol × scan length (cm); it estimates the total energy deposited in the patient and is used to calculate effective dose.

Question 129: Which CT image quality parameter is measured using a modulation transfer function (MTF)?

Temporal resolution
Noise power spectrum
Spatial resolution (Correct answer)
Contrast resolution

Correct answer: Spatial resolution

The MTF quantifies spatial resolution by describing how faithfully the CT system reproduces objects of varying spatial frequencies.

Question 130: Which radiation weighting factor (wR) applies to X-rays used in CT imaging?

2
1 (Correct answer)
5
20

Correct answer: 1

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

Question 131: Curved planar reformation (CPR) in CT is most useful for:

Straightening and displaying tortuous structures such as vessels or the spine along their entire length (Correct answer)
Creating color-coded perfusion maps
Generating endoscopic views of hollow organs
Subtracting bone from CT angiography images

Correct answer: Straightening and displaying tortuous structures such as vessels or the spine along their entire length

CPR follows a user-defined curved path through the volume dataset to display a tortuous structure in a single unfolded plane, useful for coronary arteries or the aorta.

Question 132: A traveling radiologic technologist wants to maximize placement opportunities across the country. Which credential most broadly enhances CT assignment eligibility?

A local hospital's internal CT competency checklist
ARRT CT post-primary certification recognized by travel staffing agencies nationwide (Correct answer)
A vendor training certificate from a single CT manufacturer
State-specific CT operator permit from one state only

Correct answer: ARRT CT post-primary certification recognized by travel staffing agencies nationwide

Travel staffing agencies and their client facilities consistently recognize ARRT CT certification as the standard credential for CT assignment eligibility across the US.

Question 133: An applicant discloses a misdemeanor conviction on the ARRT ethics pre-application. What is the likely next step?

The application is automatically denied
The applicant is approved with a probationary credential
The misdemeanor is ignored if more than 5 years old
ARRT conducts an ethics review before granting or denying eligibility (Correct answer)

Correct answer: ARRT conducts an ethics review before granting or denying eligibility

Any disclosed violation triggers an ARRT ethics review, which evaluates the nature and context of the offense before deciding eligibility.

Question 134: What is the primary radiation hazard associated with CT compared to conventional radiography?

Use of radioactive isotopes as contrast agents
Higher peak kilovoltage
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 135: Which window setting is most appropriate for evaluating pulmonary nodules in the lung parenchyma?

Window width ~400 HU, window level ~40 HU
Window width ~3000 HU, window level ~300 HU
Window width ~1500 HU, window level ~-600 HU (Correct answer)
Window width ~200 HU, window level ~80 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 136: How does ARRT CT certification benefit patients receiving CT imaging services?

It ensures patients pay lower co-pays for CT exams
It signals that the performing technologist has met a validated standard of CT knowledge and skill (Correct answer)
It eliminates the possibility of radiation dose errors
It guarantees the exam will be read by a board-certified radiologist

Correct answer: It signals that the performing technologist has met a validated standard of CT knowledge and skill

ARRT CT certification assures patients and referring physicians that the technologist has demonstrated competency through a rigorous standardized examination.

Question 137: A technologist working in a trauma center wants to advance to a CT lead position. Which prerequisite is most commonly required by employers?

ARRT CT post-primary certification (Correct answer)
A master's degree in radiologic science
Five years of emergency department experience only
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 138: The primary advantage of iterative reconstruction over filtered back projection (FBP) in CT is:

Reduced image noise at equivalent or lower dose (Correct answer)
Faster image processing time
Elimination of all beam hardening artifacts
Larger field of view capability

Correct answer: Reduced image noise at equivalent or lower dose

Iterative reconstruction algorithms reduce noise by modeling the imaging system and iteratively comparing projection data, allowing lower-dose acquisitions.

Question 139: A starburst pattern of streaks emanating from the edge of the patient's shoulders during a neck CT is most likely caused by:

Gantry tilt error
Detector malfunction
Beam hardening from bone and soft tissue interfaces (Correct answer)
Incorrect windowing

Correct answer: Beam hardening from bone and soft tissue interfaces

Dense cortical bone at the shoulder causes beam hardening, producing characteristic streak artifacts that radiate into adjacent soft tissues.

Question 140: During a CT angiography of the neck (CTA neck), the scan direction is typically:

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

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 141: Multiplanar reformation (MPR) in CT refers to:

Reconstructing axial images into coronal, sagittal, or oblique planes (Correct answer)
Applying color to CT images based on Hounsfield units
Generating 3D surface models from volumetric data
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 142: What is the window level and window width on CT images?

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

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

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

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 144: What is the Continuing Qualifications Requirements (CQR) process for ARRT CT certification?

A recertification application process every 5 years
A review of clinical competencies performed every year
A self-assessment and continuing education program every 10 years (Correct answer)
A mandatory exam that must be passed every 5 years

Correct answer: A self-assessment and continuing education program every 10 years

The Continuing Qualifications Requirements (CQR) is a distinct process from the biennial CE requirements. For ARRT CT certification, CQR involves a self-assessment and targeted continuing education program that must be completed every 10 years. This ensures long-term competency and addresses any identified knowledge gaps.

Question 145: Which statement BEST describes the relationship between CT noise and mAs?

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

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

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

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

Putamen
Globus pallidus
Caudate nucleus (Correct answer)
Thalamus

Correct answer: Caudate nucleus

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

Question 148: What does a noise index (NI) setting in automatic tube current modulation (ATCM) control?

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

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 149: For a pediatric CT head scan, compared to an adult protocol, the technologist should generally:

Reduce mAs significantly because children are more radiosensitive and smaller (Correct answer)
Increase kVp to 140 kV to penetrate the skull
Use the same mAs to ensure adequate image quality
Extend scan length to cover the entire neuraxis

Correct answer: Reduce mAs significantly because children are more radiosensitive and smaller

Children have greater radiosensitivity and smaller body dimensions, so pediatric CT protocols use substantially lower mAs than adult protocols.

Question 150: Which of the following scan parameters most directly affects the z-axis (longitudinal) spatial resolution in CT?

Matrix size
Field of view (FOV)
Window width
Slice thickness (Correct answer)

Correct answer: Slice thickness

Slice thickness determines the size of the voxel in the z-direction and therefore directly controls longitudinal (through-plane) spatial resolution.

Question 151: The right coronary artery is most reliably identified on axial CT in which anatomical groove?

Left atrioventricular groove
Anterior interventricular groove
Posterior interventricular groove
Right atrioventricular (coronary) groove (Correct answer)

Correct answer: Right atrioventricular (coronary) groove

The right coronary artery runs within the right atrioventricular groove between the right atrium and right ventricle.

Question 152: What is the recommended gonadal shielding practice for most routine CT examinations of the abdomen and pelvis?

Always shield gonads with bismuth shields placed directly on the skin
Use shadow shielding on all patients regardless of scan region
Place lead gonadal shields inside the bore before every scan
Gonadal shielding is not routinely recommended because it can degrade image quality and obscure anatomy (Correct answer)

Correct answer: Gonadal shielding is not routinely recommended because it can degrade image quality and obscure anatomy

Current ACR and AAPM guidance (2019) recommends against routine gonadal shielding in CT because it degrades image quality, increases dose, and gonads are rarely in the primary beam.

Question 153: Iterative reconstruction (IR) techniques in CT offer which primary advantage over filtered back projection?

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

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 154: What is the ALARA principle in radiation safety?

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

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

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

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 156: Which statement best describes the ARRT's reciprocity or equivalency policy for CT candidates credentialed by a foreign radiologic technology body?

Foreign credentials are fully accepted without additional review
Foreign credentials qualify candidates for an expedited review process
Foreign-credentialed technologists are exempt from the CT examination
Foreign credentials are not automatically accepted; candidates must meet ARRT eligibility requirements independently (Correct answer)

Correct answer: Foreign credentials are not automatically accepted; candidates must meet ARRT eligibility requirements independently

ARRT does not grant automatic reciprocity for foreign credentials; each candidate must independently satisfy ARRT eligibility criteria.

Question 157: Which professional organization administers the ARRT CT certification examination?

American College of Radiology
American Registry of Radiologic Technologists (Correct answer)
American Society of Radiologic Technologists
Society of Computed Tomography

Correct answer: American Registry of Radiologic Technologists

The ARRT is the credentialing body that administers the CT certification exam for radiologic technologists.

Question 158: What is the difference between arteries and veins?

Arteries carry blood away from the heart; veins carry blood toward the heart (Correct answer)
Arteries are only in the lungs
Veins are thicker than arteries
They carry the same blood in the same direction

Correct answer: Arteries carry blood away from the heart; veins carry blood toward the heart

Arteries carry blood away from the heart (usually oxygenated) while veins carry blood toward the heart (usually deoxygenated). Arteries have thicker walls to handle higher pressure.

Question 159: A CT scan protocol using 'prospective ECG gating' for cardiac imaging acquires data only during which part of the cardiac cycle?

During both systole and diastole equally
Only during a pre-selected phase of diastole (Correct answer)
Throughout the entire R-R interval
Only during systole

Correct answer: Only during a pre-selected phase of diastole

Prospective ECG gating triggers X-ray exposure only during a selected quiescent diastolic window, substantially reducing radiation dose compared to retrospective gating.

Question 160: What is HIPAA?

A hospital ranking system
A medical diagnosis code
A type of insurance plan
Health Insurance Portability and Accountability Act — protects patient privacy (Correct answer)

Correct answer: Health Insurance Portability and Accountability Act — protects patient privacy

HIPAA establishes national standards for protecting patient health information, ensuring privacy and security of medical records.

Question 161: A patient with a cardiac pacemaker presents for chest CT. Which artifact should the technologist anticipate?

Windmill artifact
Metallic streak artifact from the pacemaker leads and generator (Correct answer)
Cupping artifact
Ring 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 162: What is the first priority in any emergency situation?

Contact the media
Save equipment
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 163: 3D volume rendering of CT data allows the display of internal structures through which technique?

Applying a smooth kernel to the raw data
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

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 164: What does CT stand for in medical imaging?

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

Correct answer: Computed Tomography

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

Question 165: Which statement about self-referral in the ARRT CE system is accurate?

Reading ARRT-published newsletters counts as Category A credit
Technologists can create their own CE modules and claim credit
Technologists may self-report any learning activity for Category A credit
Only activities from ARRT-approved sponsors qualify for Category A (Correct answer)

Correct answer: Only activities from ARRT-approved sponsors qualify for Category A

Category A credits require the activity to be organized and offered through an ARRT-approved CE sponsor — self-reported or self-created activities do not qualify.

Question 166: In CT quality control documentation, what is the purpose of establishing 'action limits' for QC measurements?

To determine the minimum number of QC tests per week
To establish the contrast media injection rate limits
To define the maximum patient dose per study
To set thresholds that, when exceeded, require investigation and corrective action before clinical use (Correct answer)

Correct answer: To set thresholds that, when exceeded, require investigation and corrective action before clinical use

Action limits define tolerance thresholds for QC parameters; if a measurement falls outside these limits, the scanner must be taken out of service for investigation and repair.

Question 167: A CT image shows ring artifacts. The MOST likely cause is:

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

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 168: What is preventive maintenance?

Cleaning only
Replacing all equipment annually
Fixing equipment after it breaks
Regular scheduled maintenance to prevent equipment failure (Correct answer)

Correct answer: Regular scheduled maintenance to prevent equipment failure

Preventive maintenance involves regular, scheduled inspections and servicing to prevent unexpected breakdowns and extend equipment life.

Question 169: To troubleshoot a CT image showing significant noise (grainy appearance), the technologist should first consider adjusting which parameter?

Decreasing kVp
Increasing pitch
Reducing matrix size
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 170: Respiratory motion artifacts on chest CT can best be minimized by:

Widening the display window
Using breath-hold technique during acquisition (Correct answer)
Increasing kVp
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 171: Under the ARRT ethics requirement, which of the following past offenses is MOST likely to result in denial of CT certification eligibility?

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

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

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

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 173: What is the minimum passing score on the ARRT CT certification examination?

70 (percent correct)
65 (scaled score)
80 (percent correct)
75 (scaled score) (Correct answer)

Correct answer: 75 (scaled score)

ARRT uses a scaled scoring system and sets the minimum passing scaled score at 75.

Question 174: Which category of ARRT continuing education credit requires direct patient care activities or case-based learning?

Category C
Category A (Correct answer)
Category D
Category B

Correct answer: Category A

ARRT Category A credits are structured learning activities, often directly tied to clinical or patient-care-relevant content.

Question 175: Which of the following is an example of a breach of patient confidentiality?

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

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 176: Which of the following best describes an out-of-field artifact in CT?

Blurring from respiratory motion
Ring caused by detector failure
Streaking caused by anatomy extending beyond the scan FOV (Correct answer)
Noise from low mAs

Correct answer: Streaking caused by anatomy extending beyond the scan FOV

Out-of-field artifacts occur when part of the patient's anatomy lies outside the calibrated scan FOV, causing truncation of projection data and bright peripheral streaks.

Question 177: For a CT coronary angiography (CCTA) protocol, which heart rate range is generally ideal to minimize motion artifact?

65–80 bpm
<65 bpm (Correct answer)
80–100 bpm
>100 bpm

Correct answer: <65 bpm

Heart rates below 65 bpm allow longer diastolic rest periods, reducing cardiac motion artifact during CCTA acquisition.

Question 178: In CT, the term 'isotropic voxel' means:

The voxel has no noise contribution
The voxel's HU value is calibrated to water
The voxel represents a single tissue type
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 179: How long is the ARRT CT post-primary certification credential valid before renewal is required?

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

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 180: On axial CT of the neck, the hypopharynx is best visualized at which vertebral level?

C7-T1
C4-C6 (Correct answer)
C1-C2
C3-C4

Correct answer: C4-C6

The hypopharynx extends from the level of the hyoid bone (C3) to the cricopharyngeus muscle (C6), and is best visualized on CT at C4-C6.

Question 181: A contrast CT of the abdomen shows a 'whirl sign' in the mesentery. What condition does this indicate?

Appendicitis
Closed-loop small bowel obstruction with volvulus (Correct answer)
Bowel perforation
Mesenteric adenitis

Correct answer: Closed-loop small bowel obstruction with volvulus

The whirl sign on CT represents twisting of mesenteric vessels and bowel loops, indicating volvulus typically causing closed-loop obstruction.

Question 182: In CT, the filtered back projection (FBP) reconstruction algorithm applies a mathematical filter primarily to:

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

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 183: Which of the following correctly identifies the position of the common bile duct on axial CT?

Posterior and to the left of the portal vein in the hepatoduodenal ligament
Medial to the hepatic artery within the liver parenchyma
Anterior and to the right of the portal vein in the hepatoduodenal ligament (Correct answer)
Within the fissure for the ligamentum teres

Correct answer: Anterior and to the right of the portal vein in the hepatoduodenal ligament

In the hepatoduodenal ligament, the common bile duct lies anteriorly and to the right of the portal vein, with the hepatic artery to the left.

Question 184: Under ARRT rules, how long does a candidate have to complete the examination after their application is approved?

1 year (Correct answer)
3 years
90 days
30 days

Correct answer: 1 year

Once approved, candidates generally have a 1-year eligibility window during which they must schedule and complete the examination.

Question 185: A diabetic patient scheduled for a barium enema reports they skipped breakfast and have not eaten since last night. The technologist should be alert for signs of:

Hyperglycemia
Dehydration only
Hypoglycemia (Correct answer)
Hypervolemia

Correct answer: Hypoglycemia

An NPO diabetic patient is at high risk for hypoglycemia; the technologist should assess for dizziness, diaphoresis, confusion, and notify clinical staff.

Question 186: Cupping artifact on a CT image of a large cylindrical phantom most likely indicates:

Patient motion during scanning
Incorrect detector gain calibration
Beam hardening due to preferential absorption of lower-energy photons (Correct answer)
Excessive pitch value

Correct answer: Beam hardening due to preferential absorption of lower-energy photons

Cupping artifact occurs because low-energy photons are preferentially absorbed by the periphery, hardening the beam and making the center appear falsely darker.

Question 187: What is a key requirement related to clinical experience for ARRT CT certification eligibility?

Work in a CT department for a minimum of one year
Perform at least 10 supervised CT scans
Attend a CT-specific conference or seminar
Document and complete a set of clinical competencies in CT imaging (Correct answer)

Correct answer: Document and complete a set of clinical competencies in CT imaging

A crucial requirement for ARRT CT certification is demonstrating practical proficiency through documented clinical experience. Candidates must complete a specified set of clinical competencies, which involve performing and documenting various CT procedures under supervision. This ensures they have hands-on experience and can safely and effectively operate CT equipment.

Question 188: Which premedication regimen is most commonly recommended for elective contrast administration in patients with a prior mild allergic-like contrast reaction?

No premedication is needed for mild prior reactions
IV epinephrine 30 minutes before contrast
Oral prednisone 50 mg at 13, 7, and 1 hour before contrast plus diphenhydramine 50 mg 1 hour before (Correct answer)
IV methylprednisolone only, given 1 minute before injection

Correct answer: Oral prednisone 50 mg at 13, 7, and 1 hour before contrast plus diphenhydramine 50 mg 1 hour before

The ACR-recommended premedication protocol for non-emergent cases includes oral prednisone at 13, 7, and 1 hour before contrast plus diphenhydramine 50 mg 1 hour before.

Question 189: Which window setting is most appropriate for evaluating acute intracranial hemorrhage on a non-contrast head CT?

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

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

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

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 191: Which factor primarily determines the z-axis (longitudinal) resolution in a multislice CT scanner?

Gantry rotation speed
kVp setting
Reconstruction matrix size
Detector row width (Correct answer)

Correct answer: Detector row width

Z-axis resolution is primarily determined by detector row width (collimation), which defines slice thickness in the longitudinal direction.

Question 192: If a CT technologist allows their ARRT registration to lapse, what is required before they can reinstate it?

Complete the required CE credits and pay applicable fees (Correct answer)
Submit a written appeal to the ARRT board
Pay a late fee only
Retake the full certification examination

Correct answer: Complete the required CE credits and pay applicable fees

Reinstatement of a lapsed ARRT registration requires fulfilling outstanding CE requirements and paying any applicable reinstatement fees.

Question 193: 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 194: 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.

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.

195

Questions

180 min

Time Limit

75%

To Pass

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