Fluoroscopy Education and Test

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Minimizing Risks from Fluoroscopic X-rays – pdf

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1. Annual effective whole-body dose limit for physicians

0.5 mSv

1 mSv

50 mSv

6 Gy

18 Gy

2. Annual effective whole-body dose limit for a visitor to the hospital

0.5 mSv

1 mSv

50 mSv

6 Gy

18 Gy

3. Monthly dose limit to conceptus of pregnant worker

0.5 mSv

1 mSv

50 mSv

6 Gy

18 Gy

4. Threshold for radiation-induced delayed erythema at ~ 2 wks post procedure

0.5 mSv

1 mSv

50 mSv

6 Gy

18 Gy

5. Threshold for radiation-induced dermal necrosis

0.5 mSv

1 mSv

50 mSv

6 Gy

18 Gy

6. At an entrance skin dose rate of 250 mGy/minute, in how many minutes of fluorosopy on-time will the threshold for skin atrophy be reached?

120

7. Which one of the following actions is most likely to increase the entrance skin dose rate to a patient?

remove the grid

position the image receptor closer to the patient

position the x-ray tube closer to the patient

use a larger field of view

8. Why are entrance skin dose rates to larger patients generally greater than those to smaller patients?

Skin is physically more dense in larger patients

Amount of tissue in path of beam is greater

More scatter radiation is produced

Collimation is less effective

9. The principal threat to health from chronic very lowlevel whole-body exposure to radiation is:

radiation-induced heritable reproductive effects

radiation-induced cancer

radiation-induced cataract

radiation-induced hair loss

10. For an adult abdomen, the radiation level where the beam enters the patient is approximately how many times greater than that which exits the patient?

100

11. What does a personal radiation badge do?

protects the wearer from radiation

monitors exposures to radiation to identify whether safety should be improved

changes color if radiation levels are too high

alerts the wearer of the presence of radiation

12. Regarding radiation exposure to the hands, what action is the best practice philosophy?

wear radiation protective surgical gloves when you want to put your hands in the beam

keep your hands out of the beam except rarely when it is essential for the care of the patient

there is no particular concern about the hands since they are radio resistant extremities

wash your hands well after the procedure to remove residual radiation

13. In what year did the FDA issue an advisory on high radiation exposures to patients from fluoroscopy?

1994

1997

2000

2003

14. What is “high-level” control?

When engaged it delivers the lowest dose rate to the patient for highest benefit/risk.

This control manages only the quality of the image and has no affect on radiation dose rate to the patient.

High-level control is the standard mode of fluoroscopy operation.

High-level control boosts radiation output beyond standard levels and can be a dangerous mode.

15. In the variable pulsed mode of operation which one of the following is FALSE?

The x-ray beam is pulsed at a selectable number of times per second.

Dose rates are lower for lower pulse rates.

The dynamics of motion appear less fluid in the lower pulse rates.

Scatter radiation in the room is more intense.

16. Regarding the thyroid of a radiation worker, which one of the following is TRUE?

The maximum permissable regulatory dose for the thyroid is the lowest of all organs.

Wearing a thyroid shield during fluoroscopy is usually optional.

Exposure of the thyroid often leads to hormonal dysfunction.

The latent period from radiation exposure to the diagnosis of thyroid cancer is typically one year.

17. Using a C-arm with a fixed distance between the X-ray tube and the image intensifier, the X-ray source was 50 cm from the patient’s skin. The physician repositioned the patient’s table so that the skin was 60 cm from the source. What happened?

image magnification is increased by ~20%

scatter in the room went up by 50%

dose rate to patient decreased by ~35%

kVp increased by ~10 kVp, tube current went down

18. If a person moves twice as far away from the irradiated area of the patient, the air kerma rate at the new position will be:

increased by 10%

unchanged

decreased by 50%

decreased by 75%

19. A reduction in radiation output per pulse of pulsed fluoroscopy results in what change in the appearance of the image?

noisier image

motion blurred image

more contrast

less fluid (more jerky) motion

20. Collimation does NOT:

reduce dose rate to the entrance skin site.

reduce stochastic risks to the patient.

reduce scatter radiation in the room.

reduce scatter radiation reaching the image receptor.

21. Identify the appropriate location of the Separator cone.

22. Identify the appropriate location of the Collimator blades.

23. Identify the appropriate location of the Grid.

24. Identify the appropriate location of the Image intensifier.

25. Identify the appropriate location of the X-ray tube.