Question 1: What principle does an ultrasound imaging system use to create images of internal body structures?

• Ionizing radiation absorption
• Piezoelectric transducer emitting and receiving high-frequency sound waves (Correct answer)
• Magnetic resonance of hydrogen atoms
• Infrared thermal detection

Correct answer: Piezoelectric transducer emitting and receiving high-frequency sound waves

Ultrasound uses piezoelectric transducers to emit high-frequency sound waves and detect reflected echoes to create real-time images.

Piezoelectric crystals convert electrical signals to mechanical vibrations at 2-18 MHz. Echo amplitude determines pixel brightness (B-mode imaging). Biomedical technicians test image quality with phantoms.

Question 2: In a mechanical ventilator, what is the function of the PEEP (Positive End-Expiratory Pressure) valve?

• To regulate oxygen concentration
• To maintain positive pressure in the airways at the end of exhalation, preventing alveolar collapse (Correct answer)
• To measure tidal volume
• To trigger the next breath cycle

Correct answer: To maintain positive pressure in the airways at the end of exhalation, preventing alveolar collapse

The PEEP valve maintains positive pressure at end-exhalation, preventing alveoli from collapsing and improving oxygenation.

Biomedical technicians must verify PEEP accuracy during PM using a calibrated manometer. Testing includes verifying PEEP at multiple settings and ensuring no PEEP is present when set to zero.

Question 3: What type of pump mechanism do most volumetric IV infusion pumps use to deliver fluids?

• Centrifugal pump
• Peristaltic pump mechanism that sequentially compresses IV tubing (Correct answer)
• Gear pump
• Diaphragm pump

Correct answer: Peristaltic pump mechanism that sequentially compresses IV tubing

Most volumetric IV infusion pumps use a peristaltic mechanism that sequentially compresses the tubing to push fluid forward.

Only manufacturer-specified tubing sets should be used as tubing compliance affects accuracy. PM testing includes flow rate accuracy, occlusion alarm testing, air-in-line detector sensitivity, and free-flow protection verification.

Question 4: How does a pulse oximeter differentiate between oxygenated and deoxygenated hemoglobin?

• By measuring blood pressure changes
• By comparing absorption of red (660nm) and infrared (940nm) light wavelengths through tissue (Correct answer)
• By analyzing exhaled carbon dioxide
• By measuring skin temperature changes

Correct answer: By comparing absorption of red (660nm) and infrared (940nm) light wavelengths through tissue

Pulse oximeters use two wavelengths because oxyhemoglobin and deoxyhemoglobin absorb them differently.

Limitations include poor perfusion, motion artifact, ambient light interference, carboxyhemoglobin (reads falsely high), and methemoglobin (reads approximately 85%).

Question 5: What is the primary function of a defibrillator's capacitor?

• To regulate the charging voltage
• To store electrical energy that is rapidly discharged through the patient's chest to restore normal heart rhythm (Correct answer)
• To filter the incoming AC power
• To power the display screen

Correct answer: To store electrical energy that is rapidly discharged through the patient's chest to restore normal heart rhythm

The defibrillator's main capacitor stores electrical energy that is rapidly discharged to depolarize the heart.

Long-idle capacitors need periodic charging to maintain dielectric integrity (capacitor reformation). Biomedical technicians verify energy delivery accuracy, charge time, and internal discharge function during PM.

Question 6: What safety feature prevents a patient from receiving an uncontrolled free flow of IV fluid if the tubing is removed from an infusion pump?

• The drip chamber
• Anti-free-flow clamp mechanism built into the pump door or tubing set (Correct answer)
• The roller clamp
• The filter in the tubing

Correct answer: Anti-free-flow clamp mechanism built into the pump door or tubing set

The anti-free-flow mechanism automatically occludes the tubing when removed from the pump, preventing uncontrolled fluid delivery.

A failed anti-free-flow mechanism is a critical safety failure requiring immediate removal from service. Verify during every PM by opening the door and confirming zero flow.

Question 7: What does an automated external defibrillator (AED) analyze before advising a shock?

• The patient's blood pressure
• The patient's ECG rhythm to determine if it is a shockable rhythm (VF or pulseless VT) (Correct answer)
• The patient's blood oxygen level
• The patient's body temperature

Correct answer: The patient's ECG rhythm to determine if it is a shockable rhythm (VF or pulseless VT)

An AED analyzes the ECG rhythm to determine if it is ventricular fibrillation or pulseless ventricular tachycardia.

AED algorithms have sensitivity >90% and specificity >95% for shockable rhythms. Biomedical technicians verify algorithm performance using AED test simulators that generate known rhythms.

Question 8: In a CT scanner, what is the function of the slip ring?

• To hold the patient in position
• To provide continuous electrical connection between the rotating gantry and the stationary frame, enabling helical scanning (Correct answer)
• To adjust the X-ray tube voltage
• To filter the X-ray beam

Correct answer: To provide continuous electrical connection between the rotating gantry and the stationary frame, enabling helical scanning

Slip rings provide continuous electrical connection allowing unlimited rotation for helical/spiral scanning.

Modern slip rings transmit high voltage, low voltage, and high-bandwidth data signals. Biomedical technicians inspect slip ring brushes for wear and monitor for signal noise indicating degrading contacts.

Question 9: What is the purpose of the beam hardening filter in an X-ray tube assembly?

• To focus the X-ray beam
• To remove low-energy X-ray photons that would only increase patient skin dose without contributing to image formation (Correct answer)
• To reduce the beam intensity evenly
• To convert X-rays to visible light

Correct answer: To remove low-energy X-ray photons that would only increase patient skin dose without contributing to image formation

Beam hardening filters absorb low-energy photons that would be absorbed by superficial tissue, reducing patient dose.

Biomedical technicians verify filtration by measuring the half-value layer (HVL). Insufficient filtration is a serious safety issue requiring immediate correction.

Question 10: How does a biphasic defibrillation waveform differ from a monophasic waveform, and why is it preferred?

• Biphasic uses higher energy levels
• Biphasic delivers current in two directions, requiring less energy for effective defibrillation (Correct answer)
• Biphasic charges faster
• Biphasic uses DC instead of AC

Correct answer: Biphasic delivers current in two directions, requiring less energy for effective defibrillation

Biphasic waveforms achieve higher first-shock success rates at lower energies (120-200J vs 360J monophasic), reducing myocardial damage.

Modern biphasic designs include impedance-compensating features. Biomedical technicians testing biphasic defibrillators must use analyzers that can display and measure biphasic waveforms.

Question 11: What is the role of the collimator in an X-ray system?

• To generate X-ray photons
• To restrict the X-ray beam to the area of clinical interest, reducing patient dose and improving image quality (Correct answer)
• To detect the X-ray beam after passing through the patient
• To cool the X-ray tube

Correct answer: To restrict the X-ray beam to the area of clinical interest, reducing patient dose and improving image quality

The collimator uses adjustable lead shutters to restrict the beam to the area of interest.

Biomedical technicians must verify light field to X-ray field alignment (within 2% of SID), beam perpendicularity, and PBL function. Misaligned collimation is a common finding.

Question 12: What does the term 'duty cycle' refer to in the context of an electrosurgical unit?

• The percentage of time the device is powered on per day
• The ratio of active current delivery time to total cycle time, which differentiates cutting from coagulation modes (Correct answer)
• The number of procedures before maintenance
• The percentage of power output relative to maximum

Correct answer: The ratio of active current delivery time to total cycle time, which differentiates cutting from coagulation modes

CUT mode uses continuous waveform (100% duty cycle) for tissue vaporization; COAGULATION uses intermittent waveform (6% duty cycle) for protein denaturation.

BLEND modes offer intermediate duty cycles (25-75%). Biomedical technicians verify output power accuracy, waveform characteristics, and peak voltage levels during testing.

Question 13: In a pulse oximeter, which physiological principle is used to differentiate oxygenated from deoxygenated hemoglobin?

• Differential light absorption at two wavelengths (660 nm and 940 nm) (Correct answer)
• Measurement of blood pressure waveform morphology
• Detection of CO2 partial pressure via infrared spectroscopy
• Impedance plethysmography across the finger

Correct answer: Differential light absorption at two wavelengths (660 nm and 940 nm)

Pulse oximeters exploit the fact that oxyhemoglobin and deoxyhemoglobin absorb red (660 nm) and infrared (940 nm) light at different ratios.

Question 14: A patient-controlled analgesia (PCA) pump must include which safety feature to prevent accidental overdose?

• A lockout interval that disables bolus delivery for a set time after each dose (Correct answer)
• A variable drip rate adjusted by nursing staff every hour
• An automatic increase in dose when the patient presses the button repeatedly
• A pressure sensor that detects IV line occlusion only

Correct answer: A lockout interval that disables bolus delivery for a set time after each dose

The lockout interval enforces a mandatory waiting period between boluses, preventing the patient from receiving dangerous cumulative doses.

Question 15: What is the primary function of the inspiratory-to-expiratory (I:E) ratio setting on a mechanical ventilator?

• It controls the proportion of time spent in inhalation versus exhalation during each breath cycle (Correct answer)
• It sets the tidal volume delivered with each breath
• It determines the oxygen concentration in delivered gas
• It adjusts the peak airway pressure alarm threshold

Correct answer: It controls the proportion of time spent in inhalation versus exhalation during each breath cycle

The I:E ratio defines how the breath cycle is divided, affecting gas distribution and hemodynamic impact; normal is approximately 1:2.

Question 16: In electrosurgical units (ESU), the return electrode (dispersive pad) functions by:

• Distributing current over a large surface area to minimize current density at the patient return site (Correct answer)
• Increasing the frequency of current to improve cutting precision
• Grounding the patient to earth to prevent shock
• Concentrating current to coagulate tissue at the return site

Correct answer: Distributing current over a large surface area to minimize current density at the patient return site

The large area of the dispersive pad spreads current so densely is too low to heat tissue, preventing burns at the return site.

Question 17: A phototherapy unit used for neonatal jaundice delivers light primarily in which spectral range?

• Blue-green light (420–500 nm) (Correct answer)
• Red light (620–700 nm)
• Ultraviolet-C (200–280 nm)
• Near-infrared (750–900 nm)

Correct answer: Blue-green light (420–500 nm)

Blue-green light in the 420–500 nm range is absorbed by bilirubin, converting it to water-soluble isomers that can be excreted.

Question 18: Which mechanism allows a double-lumen endobronchial tube to facilitate one-lung ventilation during thoracic surgery?

• Separate lumens allow one lung to be isolated and collapsed while the other is ventilated (Correct answer)
• It delivers 100% oxygen to both lungs simultaneously at high flow
• A balloon in the trachea seals off the airway above the carina
• It uses CPAP on one side and PEEP on the other to equalize pressures

Correct answer: Separate lumens allow one lung to be isolated and collapsed while the other is ventilated

Each lumen opens to one bronchus; clamping one lumen collapses that lung for surgical access while the other continues ventilation.

Question 19: In a hemodialysis machine, the dialysate flow direction relative to blood flow is typically:

• Countercurrent, to maximize the concentration gradient for diffusion across the dialyzer membrane (Correct answer)
• Co-current, to prevent pressure differentials across the membrane
• Perpendicular, to promote ultrafiltration only
• Intermittent, alternating direction every five minutes

Correct answer: Countercurrent, to maximize the concentration gradient for diffusion across the dialyzer membrane

Countercurrent flow maintains a favorable concentration gradient along the entire length of the dialyzer, maximizing solute clearance.