Health Physics

The ____ to an individual is directly related to the duration of radiation exposure

Dose

Health physics

The science that is concerned with the recognition, evaluation, and control of radiation hazards

True or false: We practice ALARA because of the linear, nonthreshold radiation dose-response relationships for stochastic effects, such as cancer, leukemia, and genetic effects

True

The cardinal rules of radiation protection include:

Maximizing time, minimizing distance, and using shielding

True or false: the 5-minute timer used in fluoroscopy reminds the radiologists that a considerable amount of time has passed

True

True or false: Buildings make use of both lead and concrete as a way of providing protective shielding

True

True or false: isometric lines represent portions of equal radiation exposure in the fluoroscopy exam room

False

True or false: During a fluoroscopic procedure, just by taking two steps back from normal position, can reduce the exposure rate to approximately 5 mR per hour

True

1 TVL is equal to _____ HVL’s

3.3

True or false: Effective dose is a method of converting a non-uniform radiation dose, as when a protective apron is worn, to a dose with respect to risk, as if the whole-body were exposed

True

True or false: A HVL can be defined as the thickness of absorber material necessary to reduce the x-ray beam to 1/10 its original value

False

What is used to account for the differences in tissue when determining effective dose to biological material?

• tissue weighing factor

• radiation weighting factor

• absorbed dose

True or false: the term effective dose refers to equivalent whole-body dose

True

HVL

The thickness of absorber material that is necessary to reduce the intensity of the beam to one-half its original value

Effective dose

• The equivalent whole-body dose following partial body radiation exposure and is the weighted average of the radiation dose to various organs and tissues

• Calculates the dose to the whole-body that would cause the sam harm as a partial or localized dose for a particular x-ray exam

Health physics

• The science that is concerned with the recognition, evaluation, and control of radiation hazards

• Is concerned with providing occupational radiation protection and minimizing radiation dose to the public

TVL

The thickness of absorber material that is necessary to reduce the intensity of the beam to one-tenth its original value

How is the dose to an individual related to the duration of radiation exposure?

Directly related

True or false: With fluoroscopy, the time may not be under the direct control of the technologist

True

List three fluoroscopic safety features to help reduce dose:

1. intermittent fluoroscopic foot switch

2. use of pulse-progressive fluoroscopy and grid controlled fluoroscopy

3. 5-minute cumulative timer

Do all fluoroscopic exams typically take less than 5 minutes? What is the exception?

No, IR/angiography have longer exposure times

At normal position, the exposure rate is approximately ____ mGy/hr

3

Take two steps back and the exposure rate is only approximately ____ mGy/hr

0.05

Where is the worst place to stand during fluoroscopy?

Head or foot of fluoroscopy table

The exposure rate for the head or the foot of the fluoroscopy table is ____ mGy/hr

5

How many HVLs are required to reduce the intensity of the x-ray beam to less than 6.25% of its original value?

5 HVLs

How many TVLs are required to reduce the intensity of the x-ray beam to less than 6.25% of its original value?

2 TVLs

We assume the occupational effective dose to be ____ or ____% of the occupational radiation monitor dose

1/10 or 10%

What does Wr mean?

Radiation weighting factor

What does Wt mean?

Tissue weighting factor

Effective dose=

Wr x Wt x absorbed dose