Diagnostic Imaging & Radiology Flashcards

According to ICRP recommendations, the annual occupational effective dose limit for radiation workers is:

Answer: 20 mSv averaged over 5 years (not exceeding 50 mSv in any single year)

ICRP Publication 103 recommends an effective dose limit of 20 mSv/year averaged over 5 consecutive years, with no single year exceeding 50 mSv for occupationally exposed workers.

Lead aprons worn during radiological procedures primarily protect against:

Answer: Scattered radiation

Lead aprons are designed to attenuate scattered X-rays that reach personnel outside the primary beam, reducing gonadal and abdominal dose during fluoroscopic procedures.

Which radiopharmaceutical is most widely used in PET (Positron Emission Tomography) oncology imaging?

Answer: Fluorine-18 FDG (18F-fluorodeoxyglucose)

18F-FDG is a glucose analogue taken up preferentially by metabolically active tissues; its avid uptake in malignant cells makes it the cornerstone of oncologic PET imaging.

Which protective accessory is recommended for thyroid gland shielding during dental or cervical spine radiography?

Answer: Thyroid collar

A thyroid collar (thyroid shield) is a lead-lined protective device placed around the neck to reduce radiation dose to the radiosensitive thyroid gland.

Mammography uses which type of X-ray beam to optimize soft-tissue contrast in breast imaging?

Answer: Low-energy soft X-rays (25–35 kVp)

Mammography uses low-energy X-rays (25–35 kVp) to maximize contrast between glandular, adipose, and malignant breast tissue, which are very similar in density.

Which chest X-ray finding is classically associated with aortic dissection and requires emergent evaluation?

Answer: Widened mediastinum (>8 cm)

A widened mediastinum greater than 8 cm on an AP chest radiograph is a classic but non-specific sign of aortic dissection, prompting urgent CT angiography for confirmation.

In radiation protection, the three fundamental principles that minimize dose to staff are:

Answer: Distance, shielding, and time

Maximizing distance from the source (inverse square law), using appropriate shielding, and minimizing time of exposure are the three cardinal principles of radiation protection.