CBET Diagnostic Imaging Equipment 2 — Questions and Answers
Question 1: What does 'kVp' control in an X-ray generator?
- Penetrating power (energy) of the X-ray beam (Correct answer)
- Total number of X-ray photons produced
- Rotation speed of the CT gantry
- Depth of ultrasound penetration
Correct answer: Penetrating power (energy) of the X-ray beam
Peak kilovoltage (kVp) sets the maximum energy of X-ray photons, determining how well the beam penetrates dense tissues like bone.
Question 2: Which imaging modality uses radiofrequency pulses and a strong magnetic field rather than ionizing radiation?
- MRI (Magnetic Resonance Imaging) (Correct answer)
- Fluoroscopy
- Computed Tomography (CT)
- Bone densitometry (DEXA)
Correct answer: MRI (Magnetic Resonance Imaging)
MRI aligns hydrogen protons with a strong magnetic field then uses RF pulses to disturb and detect their relaxation, producing images without ionizing radiation.
Question 3: A portable X-ray unit's collimator is found to be misaligned during PM. Why is this clinically significant?
- Misalignment exposes patients to unnecessary radiation outside the intended field (Correct answer)
- It makes images appear blurry
- It overheats the X-ray tube
- It increases patient dose to the intended field only
Correct answer: Misalignment exposes patients to unnecessary radiation outside the intended field
Collimator misalignment means the radiation field does not match the light field, potentially exposing unintended anatomy and violating ALARA principles.
Question 4: In a PACS (Picture Archiving and Communication System), what standard protocol is used to transfer images?
- DICOM (Digital Imaging and Communications in Medicine) (Correct answer)
- HL7 v2
- TCP/IP only
- IEEE 802.11
Correct answer: DICOM (Digital Imaging and Communications in Medicine)
DICOM is the universal standard for storing, transmitting, and displaying medical images across modalities and systems.
Question 5: What is the purpose of a daily QC phantom scan performed on a CT scanner?
- To verify image quality metrics such as noise, uniformity, and CT number accuracy (Correct answer)
- To warm up the gantry motor
- To sterilize the bore
- To back up the PACS database
Correct answer: To verify image quality metrics such as noise, uniformity, and CT number accuracy
Phantom QC scans detect day-to-day drifts in CT number (HU) accuracy, image noise, and uniformity before patients are scanned.
Question 6: Which component in an X-ray tube is the source of electrons?
- Cathode filament (Correct answer)
- Anode disc
- Rotor bearing
- Glass envelope
Correct answer: Cathode filament
The cathode filament is heated by current until thermionic emission releases electrons, which are then accelerated toward the anode.
CBET Diagnostic Imaging Equipment 2
What does 'kVp' control in an X-ray generator?