CAMRT - Canadian Association of Medical Radiation Technologists Radiation Protection and Safety Questions and Answers — Questions and Answers
Question 1: According to the Canadian Nuclear Safety Commission (CNSC) Radiation Protection Regulations, what is the annual effective dose limit for a Nuclear Energy Worker (NEW)?
- 1 mSv in a calendar year
- 50 mSv in any one year, and 100 mSv over five consecutive years (Correct answer)
- 20 mSv per year averaged over a five-year period
- 4 mSv for the balance of a declared pregnancy
Correct answer: 50 mSv in any one year, and 100 mSv over five consecutive years
The CNSC sets the effective dose limits for a Nuclear Energy Worker at 50 mSv in any single year and 100 mSv over a five-year period. The 1 mSv limit is for the general public, the 20 mSv/year averaged limit is a common administrative control level but not the regulatory maximum, and the 4 mSv limit applies specifically to pregnant workers after declaration.
Question 2: A medical radiation technologist is performing a mobile chest X-ray on a patient in the intensive care unit. To adhere to the ALARA principle, which of the following is the most effective action the technologist can take to minimize their own radiation exposure?
- Wear a lead apron of 0.25 mm lead equivalency.
- Use the shortest possible exposure time.
- Collimate the beam tightly to the area of interest.
- Increase the distance from the patient and primary beam to at least 2 meters during the exposure. (Correct answer)
Correct answer: Increase the distance from the patient and primary beam to at least 2 meters during the exposure.
While all options are good radiation safety practices, the inverse square law states that radiation intensity decreases by the square of the distance from the source. Therefore, increasing distance is the most effective means for an operator to reduce their dose from scatter radiation during a mobile examination.
Question 3: Which of the following best describes the primary objective of Health Canada's Safety Code 35?
- To mandate specific exposure techniques for all diagnostic imaging procedures.
- To provide guidance for minimizing radiation exposure to patients, staff, and the public, while ensuring diagnostic image quality. (Correct answer)
- To set the purchase price and specifications for all new radiological equipment sold in Canada.
- To define the scope of practice for Medical Radiation Technologists and Radiologists.
Correct answer: To provide guidance for minimizing radiation exposure to patients, staff, and the public, while ensuring diagnostic image quality.
Health Canada's Safety Code 35 aims to provide guidance to achieve three main objectives: minimizing patient dose while maintaining diagnostic quality, ensuring adequate protection for equipment operators, and ensuring the protection of the public near X-ray facilities.
Question 4: During a fluoroscopic procedure, where should the operator and other staff position themselves to minimize their exposure to scatter radiation?
- As close to the X-ray tube as possible to monitor the equipment.
- On the side of the patient where the X-ray tube is located.
- Directly behind the radiologist, regardless of their position.
- On the side of the patient where the image receptor (image intensifier or flat-panel detector) is located. (Correct answer)
Correct answer: On the side of the patient where the image receptor (image intensifier or flat-panel detector) is located.
The patient is the primary source of scatter radiation. The highest intensity of scatter radiation is on the side where the X-ray beam enters the patient (the tube side). The image receptor absorbs a significant portion of the primary beam, resulting in lower scatter on that side. Therefore, standing on the image receptor side significantly reduces occupational dose.
Question 5: According to current Canadian guidelines and the position of the CAMRT, what is the recommended practice regarding gonadal shielding for most routine diagnostic X-ray procedures?
- It must be used for all patients of reproductive age.
- It is no longer recommended for routine use due to advancements in technology and the potential to obscure anatomy or interfere with automatic exposure control. (Correct answer)
- It should only be used for pediatric patients and pregnant patients.
- It is mandatory only when the gonads are within 5 cm of the primary beam.
Correct answer: It is no longer recommended for routine use due to advancements in technology and the potential to obscure anatomy or interfere with automatic exposure control.
Major Canadian and international bodies, supported by the CAMRT, no longer recommend the routine use of patient gonadal shielding. Modern equipment uses significantly lower doses, and shields can obscure relevant anatomy, interfere with automatic exposure control (potentially increasing dose), and provide minimal benefit due to the low risk from internal scatter.
Question 6: What is the annual effective dose limit for a member of the general public in Canada, as specified in the Radiation Protection Regulations?
- 0.1 mSv
- 5 mSv
- 1 mSv (Correct answer)
- 20 mSv
Correct answer: 1 mSv
The Canadian Nuclear Safety Commission's (CNSC) Radiation Protection Regulations set the effective dose limit for the public at 1 mSv in one calendar year.
CAMRT - Canadian Association of Medical Radiation Technologists Radiation Protection and Safety Questions and Answers
According to the Canadian Nuclear Safety Commission (CNSC) Radiation Protection Regulations, what is the annual effective dose limit for a Nuclear Energy Worker (NEW)?