Radiation and Radionuclides

Question 1

Typical distance traveled by an alpha particle (4-8 MeV) in tissue

Answer 1

.03 mm

Question 2

Amount the mass number (A) decreases in alpha decay

Answer 2

4

Question 3

Designated by “A”, refers to the number of protons plus neutrons

Answer 3

Mass Number

Question 4

Designated by “Z”, refers to the number of protons

Answer 4

Atomic Number

Question 5

The atomic number above which K shell electrons have an energy > 25 KeV (useful for imaging)

Answer 5

50

Question 6

Electron capture is sometimes called the inverse of

Answer 6

β- decay

Question 7

The force keeps the nucleus bound

Answer 7

Strong Nuclear Force

Question 8

Transition energy required for β+ decay

Answer 8

1.022 MeV

Question 9

True or False, transitions from any electron orbital shell to any other orbital shell are allowed

Answer 9

False, some transitions are not allowed due to selection rules of quantum mechanics

Question 10

The average β- energy is

Answer 10

1/3 E _{Beta Max}

Question 11

c = ?

Answer 11

c = λν

(wavelenth × frequency)

Question 12

Name two isotopes that decay solely by β- decay

Answer 12

³H

¹⁴C

³²P

Question 13

Internal conversion

Answer 13

Energy is transferred directly to an inner shell electron, which is ejected from the atom.

Question 14

In this decay chart, the atomic number does what?

Answer 14

Atomic number is increasing, going to ¹⁴N

Question 15

This chart illustrates what type of decay?

Answer 15

Isomeric Transition

Question 16

An alternative to γ emission

Answer 16

Internal conversion

Question 17

True or False

There can be subtle differences in chemical behavior based on varying isotope mass, e.g., ³H

Answer 17

True

Question 18

Internal conversion and electron capture can be very slightly altered by the chemical environment

Answer 18

True

Question 19

β- decay produces this massless particle

Answer 19

Anti neutrino

Question 20

β+ decay produces this massless particle

Answer 20

Neutrino

ν

Question 21

Two medically relevant isotopes that undergo β- decay are

Answer 21

¹³¹I

¹³⁷Cs

¹³³Xe

Question 22

A medically relevant isotope that undergoes isomeric transition

Answer 22

^99mTc

Question 23

This graph illustrates what type of decay

Answer 23

Internal conversion

Question 24

2 forms of radiation following internal conversion

Answer 24

characteristic x-rays

auger electrons

Question 25

True or False As compared to β- decay, electrons from internal conversion have a discrete series of energies.

Answer 25

True

Question 26

The most popular radionuclide for nuclear imaging studies.

Answer 26

^99mTc

Question 27

Medically important radionuclides that decay via (EC,γ)

Answer 27

⁵⁷Co ⁶⁷Ga ¹¹¹In ¹²³I ¹²⁵I ²⁰¹Tl

Question 28

In electron capture, Z

Answer 28

decreases

Question 29

True or False The K-xrays of lighter elements and all L-xrays are of lower energy and not suitable for external measurments.

Answer 29

True

Question 30

Sometimes called inverse beta decay

Answer 30

Electron Capture

Question 31

Average β+ energy

Answer 31

1/3 E _{β+, Max}

Question 32

In β+ decay, Z \_\_\_\_\_\_\_\_\_\_\_

Answer 32

decreases

Question 33

Medically important β+ radionuclides include

Answer 33

¹⁸F ¹⁵O ¹³N ¹¹C

Question 34

EC tends to occur in \_\_\_\_\_\_\_\_\_elements while β+ occurs more frequently in \_\_\_\_\_\_\_\_\_\_elements

Answer 34

heavier lighter

Question 35

Fraction of 18F decaying by β+

Answer 35

97%

Question 36

True or False Odd-odd nuclei tend to be more stable than even-even nuclei

Answer 36

False Even-even nuclei are relatively stable because of pairing of alike particles within the nucleus.

Question 37

For a giving decay mode, the branching ratio (B.R.) for the i^th decay mode is given by

Answer 37

B.R. = λ_i / λ

Question 38

For a nuclei with multiple decay paths, the decay constant =

Answer 38

λ = λ₁ + λ₂ + λ₃ + ...

Question 39

Given the half-life of an isotope, the decay constant can be calculated as

Answer 39

λ = ln(2) / t_½ or .693 / t½

Question 40

1 Ci = \_\_\_\_\_\_\_\_\_\_\_\_dps (Bq)

Answer 40

3.7 E10

Question 41

1 mCi = \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_MBq

Answer 41

37

Question 42

The average half-life of a radionuclide =

Answer 42

τ = 1 / λ or 1.44 t_½

Question 43

Image frame decay corrections may be needed when the imaging time is ____________ relative to the half-life of the isotope.

Answer 43

long e.g., F-18

Question 44

The effective decay factor for image count correction can be calculated as

Answer 44

DF_eff (t, Δt) ≈DF[t + Δt/2] accurate to within 1% for x\<0.5 where x = ln(2) × Δt/T_½

Question 45

The specific activity (Bq/g) of an isotope can be calculated as

Answer 45

Bq/g = λ × 6.023E23 / GAW GAW ≈ gram atomic weight [g/mol]

Question 46

The highest specific activity of a radionuclide is its \_\_\_\_\_\_\_\_\_\_\_

Answer 46

CFSA carrier-free specific activity

Question 47

For a mixture of radioisotopes, the total activity =

Answer 47

A = A₁ + A₂ + A₃ + ...

Question 48

The Bateman equation describes _________________ relationships.

Answer 48

parent-daughter

Question 49

The Bateman equation is given by \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ and describes the activity of the ________________ as a function of time

Answer 49

daughter

Question 50

In secular equilibrium, the relationship of the parent daughter half-lives is

Answer 50

λ_d\>\>λ_p or T_d \<\< T_p

Question 51

In secular equilibrium the Bateman equation simplifies to

Answer 51

Question 52

This graph illustrates

Answer 52

Secular equilibrium

Question 53

An example of medically relevant transient equilibrium is

Answer 53

⁹⁹Mo (T½ = 66 hr) ⇒ ^99mTc (T½ = 6 hr)

Question 54

This figure represents

Answer 54

Transient equilibrium

Question 55

For a radionuclide approaching secular equilibrium with a branching ratio of 1, the daughter activity at 1 and 2 daughter half-lives can be estimated as \_\_\_\_\_\_\_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. The activity of the daughter will effectively equal the activity of the parent after about ___________ .

Answer 55

A_d = (1/2) A_p A_d = (3/4) A_p 5 T_d

Question 56

In transient equilibrium, the ratio of daughter to parent is

Answer 56

A_d / A_p = [T_p/ (T_p - T_d)] × B.R. Remember in transient equilibrium T_p \> T_d so to keep things positive the equation must be T_p - T_d

Question 57

In transient equilibrium, the maximum daughter activity is at

Answer 57

t_max = [1.44 T_pT_d / (T_p - T_d)] ln(T_p/T_d) ln() must be positive so (T_p/T_d)

Question 58

No equilibrium occurs in what circumstance?

Answer 58

t_d\>t_p

Question 59

The parent isotope of ^99mTc is mainly ⁹⁹Mo, extraced from __________ \_\_\_\_\_\_\_\_\_\_\_

Answer 59

fission products

Question 60

An alternative approach to the production of ^99mTc is through an accelerator, based on the reaction \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 60

¹⁰⁰Mo(p,2n)^99mTc

Question 61

Most I-131 production is via

Answer 61

neutron activation irradiation of a tellurium (Te-130) target which becomes Te-131 and decays with a half-life of 25 min to I-131

Question 62

Neutron activated radionuclides of medical importance include

Answer 62

¹⁴C ³²P ¹²⁵I ¹³¹I

Question 63

Radionuclides produced via neutron activation tend to decay via \_\_\_\_\_\_\_

Answer 63

β-

Question 64

Two nuclear reactions commonly used to produce radionuclides using an accelerator are

Answer 64

(p,n) | (d,n)

Question 65

Cyclotron radionuclides of medical importance include

Answer 65

¹¹C ¹³N ¹⁵O ¹⁸F ⁶⁷Ga ¹¹¹In ¹²³I ²⁰¹Tl

Question 66

The branching ratio of Mo-99 to Tc-99m is

Answer 66

.876

Question 67

Reaction cross sections are measured in units of

Answer 67

barns | (1b = 10^-24 cm²)

Question 68

Flux density (ɸ) is measured in terms of

Answer 68

particles / unit area · sec

Question 69

Activation rate (R) per unit mass of target material is

Answer 69

R≈Δɸ/m R≈(6.023× 10²³) σ ɸ/A {activations / g sec} A = gram atomic weight

Question 70

Anion

Answer 70

negatively charged ion

Question 71

Effective half-life equation

Answer 71

1/t_e = 1/t_p + 1/t_b

Question 72

Roentgen

Answer 72

It is the amount of gamma or x-rays required to produce ions resulting in a charge of 0.000258 coulombs/kilogram of air under standard conditions. Named after Wilhelm Roentgen, the German scientist who discovered x-rays in 1895. 2.58E-4 C/kg

Question 73

Nuclie

Answer 73

A general term referring to all known isotopes both stable (279) and unstable (about 2700) of the chemical elements.

Question 74

Measurement errors at the bottom of the dose calibrator can be between

Answer 74

3-6 %

Question 75

Dose calibrator response can be up to ________ off for sources placed laterally from the central axis.

Answer 75

10%

Question 76

For the geometry test - when pulling saline into the syringe (diluting the source volume), use a bent needle to

Answer 76

break the vacuum and prevent backflow into the dilution vial

Question 77

In geometry test for dose calibrator, one approach is to use multiple syringe, reading at 20% intervals. Syring sizes could be

Answer 77

1cc 3cc 5cc 10cc

Question 78

Geometry testing fails if the error exceeds

Answer 78

5%

Question 79

Dose calibrators are very long-lived systems, often used for well over

Answer 79

a decade or more

Question 80

Survey meter (Geiger-Mueller Detector) checks should be performed

Answer 80

daily with use

Question 81

Three different quality control measures for survey meters are

Answer 81

battery check sealed source check calibration

Question 82

The selection, use, calibration and quality assurance of dose calibrators is described in AAPM TG Report

Answer 82

181 (June 2012)

Question 83

The PET technologist should ensure the clock in the hotlab matches the clock in the console room this frequently

Answer 83

daily

Question 84

Clock accuracy should be within

Answer 84

1 minute , synchronized to a standard time (e.g., values transmitted to a cellular telephone or those maintained by NIST

Question 85

Physical inspection of a radionuclide calibrator should include

Answer 85

visual check for damaged source holders, keypads, buttons, switches visual check for any small items in the well visual check of the display screen

Question 86

System electronics associated with a radionuclide calibrator are gennerally done

Answer 86

using a manufacturer-provided diagnostic test

Question 87

Ba-133 half-life, decay mechanism and primary radiation

Answer 87

10.74 yr e- capture 356 keV (62%) Energies of photons MeV (intensity %/d): .031 (.969), .035 (22.6%), .053 (2%), .0796 (3%), .081 (34%), .276 (7%), .303 (18%), .356 (62%), .383 (9%)

Question 88

Iodine escape peaks are more prominent with

Answer 88

lower energy x-rays due to the probability of photoelectric absorption interactions

Question 89

Secular equilibrium will occur when the half-life of the parent is roughly ________ x that of the daughter

Answer 89

100