Chapter 2 - Radiation Protection

Question 1

Discovered calcium tungstate as an intensifying phospor and developed the fluoroscope

Answer 1

Thomas Edison

Question 2

Early effects of radiation exposure

Answer 2

Deterministic Effect

Question 3

Late effects of radition exposure, low dose of radiation exposures and may not occur for years is called

Answer 3

Stochastic effect

Question 4

Deterministic Effect are

Answer 4

☑️ Hematologic Depression - whole body(25rad)
☑️ Death - whole body (100rad)
☑️ Skin Erythema - small field (200rad)
☑️ Epilation - small field (300rad)
☑️ Chromosome Aberration - whole body (5rad)
☑️ Gonadal Dysfunction - local tissue (10rad)

100 rad - 1 Gy

Question 5

1 Becquerel = _____ Curie

Answer 5

3.7 x 10 10 dis/sec

Question 6

Unit of exposure is

Answer 6

Roentgen or C/kg (SI)

* 1 R = 10 mGy

Question 7

Deposition of energy by radiation exposure is called

Answer 7

Absorbed dose

• measured in Rads
• SI Unit - gray
• 1 Gy = 100 rad = 1 J/kg

Question 8

Dose equivalent is measured in

Answer 8

Rem

 * 1 Rem = 1 erg/g
 * 100 Rem = 1 Sv (SI)
 * 1 Sv = 1 J/kg
 * used only for radiation protection purposes, use only for occupational exposure

Question 9

The average occupational exposure receive by a radiographer is approximately

Answer 9

50mrem/yr

Question 10

3 principal sources of natural background radiation are

Answer 10

1. Terrestrial radiation - naturally ocurring radionuclides on earth
2. Cosmic Radiation - sun, sources outside our solar system and galaxy
3. Internal exposure from radionuclides - K40

Question 11

The dose response relationship for deterministic effect is

Answer 11

Non-Linear threshold

* there is a dose below which that response will not occur

Question 12

The dose response relationship for stochastic effects are

Answer 12

Linear non-threshold

* suggest that no radiation dose regardless how small is safe

Question 13

Unit of effective dose is

Answer 13

Sievert

Question 14

The dose limit to the skin is

Answer 14

500 mSv/yr

Question 15

The dose limit for lungs, gonads, thyroid and extremities is

Answer 15

500 mSv/yr

Question 16

The dose limit for the lens of the eye, tissues and organ is

Answer 16

150 mSv/yr

Question 17

The dose limit for fetus (unborn child) is

Answer 17

5 mSv/9months

*0.5 mSv/month

Question 18

Dose limit for public exposure

Answer 18

1 mSv/yr

Question 19

The dose received by patient during diagnostic radiologic examinations are usually expressed in one of three ways:

Answer 19

1. ESE
2. Organ dose
3. Fetal dose

Question 20

Bone marrow dose is used to estimate the population ___________ as an index of somatic effect of radiation exposure.

Answer 20

MMD - Mean Marrow Dose

Question 21

A helpful way to estimate the occupational radiation exposure to the radiographer during either dluoroscopy or radiography is to apply the _____

Answer 21

0. 1% rule

* the exposure 1 meter laterally from the patient is approximately 0.1% of the ESE

Question 22

A minimum of ________ mm Aluminum equivalent total filtration is required on all fluoroscopic xray tubes and radiographic tubes operating above 70 kVp

Answer 22

2.5 mm Aluminum

Question 23

Purpose of filtration

Answer 23

Is to reduce the intensity of low energy xrays which do not contribute to the image, from reaching the patient

Question 24

Gonald shields should be used in what situations

Answer 24

1. When a patient is of reproductive age
2. When the gonalds lie in or near the useful beam
3. When the use of such shielding will not compromise the required diagnostic information

Question 25

___________ image receptors have the potential for reducing the patient dose and are replacing the calcium tungstate screen-film combination.

Answer 25

Solid state

Question 26

The higher the kVp, the ________, the patient dose, because a small increase in kVp is compensated with large reduction in mAs.
Radiographic contrast is _________.

Answer 26

Lower the px dose

Contrast is reduce

Question 27

Cardinal principles of radiation protection

Answer 27

Time, distande, shielding

And with ALARA

Question 28

Ways to minimize radiation exposure during fluoroscopy

Answer 28

1. By activating the hand and foot control intermittently for minimum xray beam on time
2. By making certain that. 5-minute fluoroscopic reset timer is functioning and is used sparingly.
3. By taking one step back from the edge of fluoroscopic table when it is not abaolutely essential to stay there.
4. Must wear protective apparel ( most effective)

Question 29

What are the four types of radiation measuring devices

Answer 29

1. Pocket ionization chamber
   
   • they can be evaluated daily (seldom used)
2. Film badge
3. TLD -
4. Optical Stimulated Luminescense (OSL)
   
   • sensitive, accurate and can be worn for periods up to one year