Radioactivity

Question 1

Define activity

Answer 1

The rate at which the nuclei within the sample undergo transition and can be expressed in terms of the number of transitions per second

Question 2

What are the two units for activity?

Answer 2

1. becquerel (Bq)

2. curie (Ci)

Question 3

What is becquerel equivalent to?

Answer 3

1 tps

Question 4

What is curie equivalent to?

Answer 4

3.7 x 1010 tps

Question 5

What was curie first introduced as ?

Answer 5

activity of 1g of radium

Question 6

What are some useful conversions?

Answer 6

1 Ci = 3.7 x 1010 Bq

1 mCi = 37 MBq

1 MBq = 27 µCi

Question 7

What are two quantities used in clinical nuclear medicine related to?

Answer 7

1. the number of radioactive (untransformed) nuclei in the sample
2. Elapsed time

Question 8

What is the lifetime of radioactive material?

Answer 8

Time between formation of a radioactive nucleus and its radioactive transition

Question 9

What is the fundamental characteristic of radioactivity?

Answer 9

All nuclei, even of the same radioactive nuclide, do not have the same life time

Question 10

What is it possible to determine of a nucleus?

Answer 10

Average lifetime of the nuclei of a specific radioactive nuclide

Question 11

What is a unique characteristic of each specific nuclide?

Answer 11

The average lifetime

Question 12

What is the half-life?

Answer 12

Time required for one-half of the nuclei to undergo transition

Question 13

What is the specific relationship of half-life and average life?

Answer 13

T1/2 = 0.693 Ta, or

Ta = 1.44 T1/2

Question 14

What is proportional to average life?

Answer 14

Half-life

Question 15

What is another way to express life-tine characteristic of a radioactive substance?

Answer 15

Transformation constant - delta

decay constant

Question 16

What does the transformation constant actually express?

Answer 16

The probability that a nucleus will undergo a transition in a stated period of time

Question 17

What is the value of transformation constant inversely related to?

Answer 17

Lifetime

Question 18

What is the relationship between the transformation constant and lifetime?

Answer 18

T1/2 = 0.693/l .

Question 19

What is 0.693 a natural logarithm of?

Answer 19

number 2 and appears in relationship involving half-life

Question 20

What is the transformation constant 1 a reciprocal of?

Answer 20

1. Average life

2. l = 1/Ta .

Question 21

What can a characteristic lifetime be expressed in?

Answer 21

1. Half-life
2. Average life
3. Transformation constant

Question 22

What can the transformation constant, lambda be related the activity to?

Answer 22

The number of nuclei in a sample

Question 23

What is the equation of activity?

Answer 23

1 x N

Question 24

What is the amount of radioactive material?

Answer 24

Quantity of radioactive nuclei or atoms in a sample

Question 25

activity is inversely related to half-life

Answer 25

Activity = 0.693 x N / T1/2

Number of nuclei = 1.44 x Activity x T1/2

Question 26

Define cumulated activity?

Answer 26

The quantity of radioactive nuclei that undergo transition in a period of time

Question 27

relationship between cumulated activity, Ã, and the initial activity of a collection of radioactive material, A

Answer 27

à (mCi-hr) = 1.44 x A (mCi) x T1/2 (hr).

Question 28

What is one of the most important characteristic of a radioactive material ?

Answer 28

Quantity and activity constantly change with time

Question 29

What happens during transition?

Answer 29

One atom is removed from the parent radioactive material and converted into the daughter product

Question 30

Define radioactive decay

Answer 30

Both quantity and activity decrease continuously with elapsed time

Question 31

What is the build up of radioactivity a mirror image of?

Answer 31

Radioactive decay

Question 32

What does radioactive build up never reach?

Answer 32

saturation