Midterms | Unit 1: Half-life

Question 1

The radioactive matter is not here one day and gone the next. Rather, radioisotopes disintegrate into a (1) of different elements at a (2) rate so that the quantity of radioactive material never quite reaches zero.

Answer 1

1. stable isotope
2. decreasing

Question 2

Radioactive material is measured in —

Answer 2

becquerels

Question 3

1 Bq is equal to the disintegration of —

Answer 3

1 atom each second

Question 4

The rate of decay of radionuclides

Answer 4

Decay constant (λ)

Question 5

Formula for λ

Answer 5

λ= (ln(2) / T1/2)

Question 6

Unit of measurement for the original amount, amount decaying, and remaining amount of the time elapsed

Answer 6

milliCurie (mCi)

Question 7

Original amount, amount decaying, and remaining amount after 1 second

Answer 7

Original amount: 100 mCi
Amount decaying: 25 mCi
Remaining amount: 75 mCi

Question 8

Original amount, amount decaying, and remaining amount after 2 seconds

Answer 8

Original amount: 75 mCi
Amount decaying: 19 mCi
Remaining amount: 56 mCi

Question 9

Original amount, amount decaying, and remaining amount after 3 seconds

Answer 9

Original amount: 56 mCi
Amount decaying: 14 mCi
Remaining amount: 42 mCi

Question 10

Types of half-life

Answer 10

1. Radioactive/ Physical Half-Life (T½)
2. Biological Half-Life (Tb)
3. Effective Half-Life (Te)

Question 11

The time required for a quantity of Radioactivity to be reduced to one-half its original value

Answer 11

Radioactive/ Physical Half-Life (T½)

Question 12

Every radioactive material has its unique half-life value

Answer 12

Radioactive/ Physical Half-Life (T½)

Question 13

All Radioactivity never disappears

Answer 13

Radioactive/ Physical Half-Life (T½)

Question 14

The time required for the body to eliminate one-half of the administered dose of any substances by biological processes (perspiration, urine, feces, exhalation)

Answer 14

Biological Half-Life (Tb)

Question 15

Examples of biological processes

Answer 15

perspiration
urine
feces
exhalation

Question 16

Most radiopharmaceuticals are also cleared from organs by various physiologic processes

Answer 16

Biological Half-Life (Tb)

Question 17

In Biological Half-Life (TB), most radiopharmaceuticals are also cleared from organs by various — processes

Answer 17

physiologic

Question 18

Encompasses both T1/2 and Tb

Answer 18

Effective Half-Life (Te)

Question 19

Effective Half-Life (Te) must always be — than T1/2 and Tb

Answer 19

shorter

Question 20

The time required for a radioactive elimination in the body to be diminished by 50% as a result of the combined action of radioactive decay and biological elimination.

Answer 20

Effective Half-Life (Te)

Question 21

ln(2) = —

Answer 21

.693

Question 22

Drugs that emit radiation and are eliminated through biological processes

Answer 22

Radiopharmaceuticals

Question 23

Radioactivity remaining after 0 half-life (% and fraction)

Answer 23

100%
1

Question 24

Radioactivity remaining after 1 half-life (% and fraction)

Answer 24

50%
1/2

Question 25

Radioactivity remaining after 2 half-lives (% and fraction)

Answer 25

25%
1/4

Question 26

Radioactivity remaining after 3 half-lives (% and fraction)

Answer 26

12.5%
1/8

Question 27

Radioactivity remaining after 4 half-lives (% and fraction)

Answer 27

6.25%
1/16

Question 28

Radioactivity remaining after 5 half-lives (% and fraction)

Answer 28

3.125%
1/32

Question 29

Radioactivity remaining after 6 half-lives (% and fraction)

Answer 29

1.56%
1/64

Question 30

Radioactivity remaining after 7 half-lives (% and fraction)

Answer 30

0.78%
1/128

Question 31

Half-life of 99Tc

Answer 31

6 hours

Question 32

Half-life of 131I

Answer 32

8 days

Question 33

Half-life of 123I

Answer 33

13 hours

Question 34

Half-life of 223Ra

Answer 34

11 days

Question 35

Half-life of 226Ra

Answer 35

1600 years

Question 36

Half-life of 14C

Answer 36

5730 years

Question 37

Half-life of 192Ir

Answer 37

74 days

Question 38

Half-life of 60Co

Answer 38

5.26 years

Question 39

Half-life of 137Cs

Answer 39

30 years

Question 40

Half-life of 90Sr

Answer 40

28 years

Question 41

Half-life of 99Mo

Answer 41

66 hours

Question 42

equation for n (no. of half-life)

Answer 42

n= Time elapsed (T) / Half-life (T1/2)