IMAGING DURING PREGNANCY

Question 1

used as adjuncts for diagnosis and therapy during pregnancy which include:

Answer 1

• Radiography
• Sonography
• Magnetic resonance (MR) imaging

Question 2

refers to energy transmission and often applied not only to x-rays, but also to microwaves, ultrasound, diathermy, and radio waves.

Answer 2

Radiation

Question 3

have short wavelengths with very high energy and are ionizing radiation forms

Answer 3

x-rays and gamma rays

Question 3

long wavelengths and low energy

Answer 3

1. microwaves
2. ultrasound
3. diathermy, and
4. radio waves.

Question 4

refers to waves or particles-photons-of significant energy that can
* change the structure of molecules such as those in DNA or
* that can create free radical or ions capable of secondarily damaging tissue

Answer 4

Ionizing radiation

Question 5

dose is now expressed in

Answer 5

grays (Gy)

Question 6

relative effective dose is expressed in

Answer 6

sieverts (Sv)

Question 7

number of ions produced by xrays per kg of air

unit: roentgen (R)

Answer 7

exposure

Question 8

amount of energy deposited per kg of tissue

modern unit: gray (Gy) (1 Gy=100rad)
traditional unit: rad

Answer 8

dose

Question 9

amount of energy deposited per kg of tissue normalized for biological effectiveness

modern unit: sievert (Sv) (1 Sv=100 rem)
traditional unit: rem

Answer 9

Relative effective dose

Question 10

may result in abortion, growth restriction, congenital malformations, microcephaly, or mental retardation

Answer 10

Deterministic effects

Question 11

threshold level is the NOAEL—No Observed Adverse Effect Level

there is no risk belowa threshold dose which is how much

Answer 11

(0.05 Gyor 5 rad)

0.05 Sv

Question 12

the threshold for gross fetal malformations is more likely to be

Answer 12

0.2 Gy (20
rad)

or 0.2 Sv

Question 13

the increased risk of severe mental retardation was greatest between what weeks of gestation

Answer 13

8 and 15 weeks

Question 14

there may be a lower-threshold dose of

Answer 14

0.3 Gy (30 rad)

Question 15

the mean decrease in intelligence quotient (IQ) scores was

Answer 15

25 points per Gy or 100 rad

25/1Gy or 1 SV
25/100 rad or 100 rem

Question 16

fetus is most susceptible to radiation-induced mental retardation during what age?

Answer 16

8-15 weeks

Question 17

risk of severe mental retardation -how many percent?

Answer 17

• as low as 4% for 0.1 Gy (10 rad)
• as high as 60% for 1.5 Gy (150 rad)

Question 18

what age of gestation that the risk is less

Answer 18

16-25 weeks

Question 19

diagnostic x-rays seldom exceed

Answer 19

0.1 Gy (10 rad)

Question 20

refer to random, presumably unpredictable oncogenic or mutagenic effects of radiation exposure

Answer 20

Stochastic effects

Question 21

concern with associations between fetal diagnostic radiation exposureand increased risk of childhood cancers or genetic diseases

Answer 21

Stochastic effects

Question 22

excess cancers can result from in utero exposure to doses as low as

Answer 22

0.01 Sv or 1 rad

or 0.01 Gy

Question 23

estimated risk of childhood cancer following fetal exposure to 0.03 Gy or 3 rad

Answer 23

doubles the background risk of 1:600 to that of 2:60