Health Physics

Question 1

Who was the first American fatality that resulted from radiation exposure

Answer 1

Thomas Edison’s assistant, Clarence Dally

Question 2

Define health physics

Answer 2

It is concerned with providing occupational radiation protection and minimizing radiation dose to the public and workers.

Question 3

What year was the first dose limiting recommendations made

Answer 3

1931

Question 4

NCRP

Answer 4

National Council on radiation protection and measures is today’s advisory committee for radiation protection

Question 5

Name three jobs of a health physicist

Answer 5

1. Design equipment
2. Calculate and construct barriers
3. Develop administrative protocols to maintain radiation exposures as low as reasonably achievable

Question 6

ALARA

Answer 6

As low as reasonably achievable

- it does not mean zero

Question 7

When was the term health physics coined

Answer 7

In the 1940s while the Manhattan project, which was a secret WW2 development of the Atomic Bomb.

The group of physicist and doctors responsible for radiation safety of people involved in the production of the atomic bombs were the first health physicist
1 employee died ARS

Question 8

We practice ALARA because of

Answer 8

The LNT linear NoN treshold radiation dose response for stochastic effects: cancer, leukemia, genetic effects

Question 9

What are three cardinal principles of radiation protection

Answer 9

Time
Distance
Shielding

Question 10

How is dose related to radiation exposure

Answer 10

The dose to a person is directly related to the duration of radiation exposure.

Question 11

If the time during which a person is exposed to radiation is doubled, the exposure will be?

Answer 11

Doubled

Question 12

Exposure =

Answer 12

Exposure rate x exposure time

Question 13

How can ALARA principles be used in fluoroscopy

Answer 13

1. Last image hold
2. Pulse fluoro rate: fast or slow
3. 5-minute reset timer

Question 14

Describe the use of pulse-progressive fluoroscopy

Answer 14

The radiologist depresses the fluoroscopy foot switch in a repeated up and down motion

Question 15

Point source of radiation means

Answer 15

source of radiation (as light) that is concentrated at a point and considered as having no spatial extension.

Question 16

If the distance from the source of radiation exceeds five times the source diameter, it can be treated as

Answer 16

A point source

Question 17

Isoexposure Lines

Answer 17

Lines on a plot plan represent positions of equal radiation exposure in the fluoroscopy room

Question 18

During portions of a fluoro exam when possible you should take two steps back why?

Answer 18

Two steps back, the exposure rate is only 50 uGy/hr

Question 19

Why does the reduction in exposure during fluoro, not follow the inverse square law?

Answer 19

Because the patient is an extended source of radiation because of scattered x-rays generated within the body.

Question 20

HVL

Answer 20

Half value layer is the amount of material required to reduce intensity by one half.

Question 21

TVL

Answer 21

TVL is the 10th value layer.

The thickness of absorber that reduces radiation intensity two 1/10 it’s original value.

Question 22

How can you estimate the amount that a protective barrier reduces radiation intensity?

Answer 22

If the half value layer or the 10th value layer of the barrier material is known.

Question 23

1 TVL=

Answer 23

3.3 HVL

Question 24

Protective aprons usually contain

Answer 24

0.5 eqPb

Question 25

Protective aprons are equivalent to –HVL?

Answer 25

2

Which should reduce occupational exposure to 25%

Question 26

Actual measurements show that protective aprons reduce exposure

Answer 26

By 90% because scattered x-rays are incident on the apron at an oblique angle