100+ Free CRES Practice Questions

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Question 1

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Which structure within an X-ray tube is responsible for producing electrons via thermionic emission?

The tungsten filament at the cathode

The rotating anode disc

The glass or metal vacuum envelope

The copper stem of the anode assembly

to track

2026 Statistics

Key Facts: CRES Exam

165

Total Questions

ACI CRES exam page

3 hrs

Exam Time

ACI candidate handbook

$410+

Exam Fee

ACI 2026 fee schedule

25%

HIT Domain

Updated June 2025 outline

2x/yr

Testing Windows

May and November

3 yrs

Recertification Cycle

30 CEUs required

The ACI CRES exam uses 165 multiple-choice questions with a 3-hour time limit and $410-$460 fee. Content: Healthcare Technology (25%), Problem Solving (25%), Healthcare IT/PACS/DICOM (25%), Electronics (10%), Safety (8%), Anatomy (7%). Administered twice yearly (May/November) at testing centers. Requires BMET credential + 2-4 years experience with 25-40% in radiology. Updated June 2025 content outline.

Sample CRES Practice Questions

Try these sample questions to test your CRES exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which structure within an X-ray tube is responsible for producing electrons via thermionic emission?

A.The tungsten filament at the cathode

B.The rotating anode disc

C.The glass or metal vacuum envelope

D.The copper stem of the anode assembly

Explanation: The cathode filament, typically made of tungsten, is heated by a low-voltage current until it emits electrons through thermionic emission. These electrons are then accelerated toward the anode by the applied tube voltage (kVp). The anode is the target that produces X-rays when struck by electrons, not the electron source. The vacuum envelope maintains the vacuum but does not generate electrons.

2In diagnostic radiography, what does increasing the kVp setting primarily affect?

A.The quantity of X-ray photons produced

B.The quality (penetrating ability) of the X-ray beam

C.The focal spot size on the anode

D.The exposure time duration

Explanation: Kilovoltage peak (kVp) controls the maximum energy of the X-ray photons and therefore the beam quality or penetrating ability. Higher kVp produces higher-energy photons that can penetrate denser tissues. While increasing kVp also slightly increases photon quantity, its primary effect is on beam quality. The mA setting controls photon quantity, and focal spot size is determined by filament selection.

3Which imaging modality relies on the piezoelectric effect to generate and receive sound waves?

A.Computed tomography (CT)

B.Magnetic resonance imaging (MRI)

C.Diagnostic ultrasound

D.Digital radiography (DR)

Explanation: Diagnostic ultrasound transducers use piezoelectric crystals (such as lead zirconate titanate, PZT) that vibrate when an electrical signal is applied, producing sound waves. The same crystals convert returning echoes back into electrical signals. CT and DR use X-ray photons, while MRI uses radiofrequency pulses and magnetic fields.

4Iodinated contrast media used in CT examinations primarily enhance image contrast by which mechanism?

A.Emitting fluorescent light when struck by X-rays

B.Increasing the atomic number of tissues, thereby increasing X-ray attenuation

C.Reducing patient motion artifacts during scanning

D.Increasing the signal-to-noise ratio of the detector

Explanation: Iodine has a high atomic number (Z=53), which significantly increases X-ray attenuation in the tissues where the contrast agent accumulates. This differential attenuation improves the visibility of blood vessels, organs, and pathology on CT images. The contrast agent does not emit light, reduce motion, or directly improve detector performance.

5In MRI, the Larmor frequency of hydrogen protons is directly proportional to which factor?

A.The radiofrequency coil diameter

B.The main magnetic field strength (B0)

C.The patient's body mass index

D.The gradient coil slew rate

Explanation: The Larmor equation states that the precession frequency of hydrogen protons is equal to the gyromagnetic ratio multiplied by the magnetic field strength (f = γ × B0). At 1.5T, hydrogen protons precess at approximately 63.86 MHz, and at 3T they precess at approximately 127.73 MHz. The RF coil diameter, patient size, and gradient slew rate do not determine the Larmor frequency.

6A chest X-ray shows the heart shadow occupying more than 50% of the thoracic diameter. Which anatomical condition does this most likely indicate?

A.Pneumothorax

B.Cardiomegaly

C.Pleural effusion

D.Pulmonary embolism

Explanation: A cardiothoracic ratio greater than 0.5 (heart shadow exceeding 50% of the thoracic diameter) on a PA chest radiograph is the classic radiographic indicator of cardiomegaly. This measurement is a standard assessment performed during equipment quality checks when evaluating image quality on chest phantoms. Pneumothorax shows absent lung markings, pleural effusion shows fluid levels, and pulmonary embolism is not typically visible on plain radiographs.

7Which physiological effect is of greatest concern when a patient with a ferromagnetic implant enters the MRI scan room?

A.Thermal burns from radiofrequency heating

B.Projectile effect and implant displacement from the static magnetic field

C.Peripheral nerve stimulation from gradient switching

D.Acoustic noise-induced hearing damage

Explanation: The greatest immediate danger is the projectile (missile) effect, where the strong static magnetic field exerts a powerful translational force on ferromagnetic objects, potentially displacing implants within the body and causing life-threatening injury. While RF heating, peripheral nerve stimulation, and acoustic noise are all valid MRI safety concerns, the projectile effect with ferromagnetic implants poses the most acute and catastrophic risk.

8What is the maximum permissible whole-body occupational radiation dose limit per year for a radiation worker in the United States?

A.1 mSv (100 mrem)

B.5 mSv (500 mrem)

C.50 mSv (5,000 mrem)

D.100 mSv (10,000 mrem)

Explanation: Per NRC regulations (10 CFR 20.1201), the annual occupational whole-body effective dose limit for radiation workers is 50 mSv (5 rem or 5,000 mrem). The 1 mSv limit applies to the general public, not occupational workers. 5 mSv is the occupational limit for minors or declared pregnant workers. 100 mSv has no regulatory basis as an annual limit.

9Which type of personal radiation monitoring device provides an immediate, real-time dose reading?

A.Film badge dosimeter

B.Optically stimulated luminescence (OSL) dosimeter

C.Electronic personal dosimeter (EPD)

D.Thermoluminescent dosimeter (TLD)

Explanation: Electronic personal dosimeters (EPDs) provide immediate, real-time digital readouts of accumulated radiation dose and dose rate, with audible and visual alarms when preset thresholds are exceeded. Film badges, TLDs, and OSL dosimeters all require processing after a wear period (monthly or quarterly) and cannot provide instantaneous readings.

10According to NFPA 99, what is the maximum allowable leakage current from a patient-applied medical device?

A.10 microamperes (μA)

B.50 microamperes (μA)

C.100 microamperes (μA)

D.500 microamperes (μA)

Explanation: NFPA 99 (Health Care Facilities Code) specifies that patient-applied equipment must not exceed 10 μA of leakage current under normal conditions for devices with direct patient contact. This low threshold protects patients who may have reduced skin resistance or direct cardiac connections. Higher leakage limits apply to non-patient-contact equipment.

About the CRES Exam

The CRES credential certifies biomedical equipment technicians specializing in radiology/imaging equipment. The exam covers healthcare technology and function (25%), problem solving and troubleshooting (25%), healthcare IT including PACS/DICOM (25%), radiation safety (15% combined with electronics 10%), and anatomy (7%). Updated June 2025 content outline increases HIT weighting to reflect growing importance of networking and cybersecurity.

Questions

165 scored questions

Time Limit

3 hours

Passing Score

Criterion-referenced (modified Angoff, not disclosed)

Exam Fee

$410–$460 (ACI/AAMI)

CRES Exam Content Outline

25%

Healthcare Technology and Function

X-ray generators/tubes, CT, MRI, ultrasound, fluoroscopy, mammography, preventive maintenance, calibration

25%

Healthcare Technology Problem Solving

Troubleshooting methodology, image quality issues, mechanical/electrical/software failures, risk-based prioritization

25%

Healthcare Information Technology

PACS, DICOM, HL7, worklist, network security, cybersecurity, EMR integration, middleware, system configuration

10%

Electronics Fundamentals

Ohm's law, AC/DC circuits, capacitors, transformers, rectifiers, transistors, digital logic, power supplies

Public Safety

Electrical safety, radiation safety, patient safety, CDRH regulations, infection control

Anatomy and Physiology

Organ systems, anatomy-technique-positioning relationships across imaging modalities, basic pharmacology

How to Pass the CRES Exam

What You Need to Know

Passing score: Criterion-referenced (modified Angoff, not disclosed)
Exam length: 165 questions
Time limit: 3 hours
Exam fee: $410–$460

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CRES Study Tips from Top Performers

1Three domains at 25% each dominate — master imaging equipment function, troubleshooting methodology, and PACS/DICOM/networking

2Know x-ray tube construction (cathode/anode), kVp vs mA effects, and common failure modes for CT, MRI, and fluoroscopy

3PACS/DICOM is now 25% — understand DICOM conformance, worklist management, network architecture, and cybersecurity principles

4Practice systematic troubleshooting: identify symptoms, isolate subsystem, test components, verify repair

Frequently Asked Questions

How many questions are on the CRES exam?

165 multiple-choice questions in 3 hours. Administered twice yearly in May and November testing windows at CBT centers.

What are the prerequisites?

Associate degree + 2 years BMET experience, OR military BMET program + 2 years, OR 4 years BMET experience. At least 25-40% of recent experience must be in radiology/imaging.

What changed in the 2025 content update?

Healthcare IT increased to 25% (from 20%), reflecting PACS, DICOM, networking, and cybersecurity importance. Anatomy dropped to 7%, Safety to 8%.