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PM3B > (PM3B) Radiotherapy & Nuclear Pharmacy > Flashcards

(PM3B) Radiotherapy & Nuclear Pharmacy Flashcards

1
Q

What is radioactivity?

A

Spontaneous transformation of an unstable nucleus

To a more stable nucleus

With release of ionising radiation

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2
Q

What is ionising radiation?

A

Radiation with enough energy to remove bound electrons when interacting with an atom

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3
Q

What are some types of radiation?

A

(1) Alpha – positively charged helium nuclei (2 protons + 2 neutrons)

(2) Beta - electrons

(3) X-rays – electromagnetic radiation

(4) Gamma – electromagnetic radiation

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4
Q

How are X-rays emitted?

A

When a heavy metal target is bombarded by energetic electrons

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5
Q

What is the penetrating power of alpha radiation?

A

Stopped by paper

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6
Q

What is the penetrating power of beta radiation?

A

Paper

Stopped by thin plates (made of wood/ aluminium)

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7
Q

What is the penetrating power of x-ray radiation?

A

Paper/ thin plates

Stopped by lead/ iron/ thick metal plates

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8
Q

What is the penetrating power of gamma radiation?

A

Paper/ thin plates

Stopped by lead/ iron/ thick metal plates

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9
Q

What is the penetrating power of neutron radiation?

A

Paper/ thin plates/ lead/ iron/ thick metal plates

Stopped by water/ concrete

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10
Q

What is the charge of alpha radiation?

A

Positive

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11
Q

What is the charge of beta radiation?

A

Negative

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12
Q

What is the charge of X-ray radiation?

A

Neutral

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13
Q

What is the charge of gamma radiation?

A

Neutral

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14
Q

What is the particle mass of alpha radiation?

A

Heavy particles

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15
Q

What is the particle mass of beta radiation?

A

Light particles

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16
Q

What is the particle mass of X-ray radiation?

A

No mass

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17
Q

What is the particle mass of gamma radiation?

A

No mass

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18
Q

What are some harmful effects of radiation?

A

Depends on exposure time/ penetration power/ energy of radiation

(1) Nausea

(2) Skin burns

(3) Hair loss

(4) Sterility

(5) Cancer

(6) Death

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19
Q

What are some useful applications of radiation?

A

(1) Cancer treatment

(2) Medical instrument sterilisation

(3) Finding leaks

(4) Dating archaeological remains

(5) Generating electricity

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20
Q

From which source is alpha radiation most damaging?

A

Internal source

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21
Q

From which source is beta radiation most damaging?

A

Internal source

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22
Q

From which source is x-ray radiation most damaging?

A

External source

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23
Q

From which source is gamma radiation most damaging?

A

External source

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24
Q

What is half-life?

A

Time it takes for activity/ amount of radioisotope to fall by 50%

Shorter half-life = more unstable

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25
Q

What is a long-life radiopharmaceutical?

A

Half-life >12 hrs

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26
Q

What is a short-life radiopharmaceutical?

A

Half-life <12hrs

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27
Q

What is the activity of a radioactive substance?

A

The number of nuclear transformations per unit of time

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28
Q

What is the unit of disintegration per second?

A

Becquerel – Bq

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29
Q

What is the unit for 3.7x10^10 disintegrations per second?

A

Curie – Ci

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30
Q

What is 1 millicurie?

A

1mCi = 10^-3 curie

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31
Q

What is 1 microcurie?

A

1µCi = 10^-6 curie

32
Q

What is 1 megabecquerel?

A

1 MBq = 10^6 Bq

33
Q

What is 1 kilobecquerel?

A

1 kBq = 10^3 Bq

34
Q

What is the specific activity of a radioactive material?

A

Activity of particular radionuclide

per unit of mass of element/ compound

Usually expressed as activity per gram

35
Q

What is radioactive concentration?

A

Of a solution

Activity of particular radionuclide in a unit volume

36
Q

What is absorbed dose of radiation?

A

Energy deposited

per unit of mass of material

37
Q

What is dose equivalency in radiation?

A

Accounting for variation in biological effectiveness of different radiations

Measured in sieverts (Sv)

38
Q

What is dose equivalent?

A

Dose equivalent = Absorbed dose/ quality factor

39
Q

What is the quality factor of alpha radiation?

A

20 Sv

40
Q

What is the quality factor of gamma radiation?

A

1 Sv

41
Q

What is the quality factor of beta radiation?

A

1 Sv

42
Q

What radiation type is used diagnostically?

A

X-rays

43
Q

What is radiopharmacy?

A

Manufacture + use of radioactive medicines

44
Q

What are the categories of use for radiopharmaceutical?

A

(1) Diagnostic

(2) Therapeutic

45
Q

What factors are important to consider when implementing therapeutic use of radiation?

A

(1) Specific targeting

(2) Clearance of radioactivity from non-target radiosensitive tissues

(3) Decay properties of radionuclide

46
Q

What is the mechanism of action of radiation?

A

(1) Direct damage
- DNA single + double stranded breaks

(2) Indirect damage
- Hydrolysis of water
- Water reacts with components
- Single + double DNA breaks
- Breakage of disulfide bridges in proteins

47
Q

What are some approaches of radiotherapy to treat cancer?

A

(1) External beam radiation

(2) Sealed source radiotherapy – brachytherapy

(3) Unsealed source therapy

48
Q

What is external beam radiation?

A

Use of x-rays/ gamma rays

Higher energy than for diagnostic purposes

(1) Therapeutic: 1-25MeV (megaelectronvolts)

(2) Diagnostic: 20-150KeV (kiloelectronvolts)

Lower energy range used to treat skin cancer

Higher energy used to treat internal tumours

49
Q

When is the lower range of energy use in external beam radiation?

A

Skin cancer treatment

50
Q

When is the higher range of energy use in external beam radiation?

A

Internal tumours in cancer

51
Q

What is sealed source radiotherapy (brachytherapy)?

A

Delivers radioisotopes sealed into capsules/ wires

Radiation can escape but radioisotope cannot move

e.g. iodine-125 or caesium-131

Used for cervical/ prostate/ breast/ oesophageal/ skin cancer

52
Q

What types of cancer is brachytherapy (sealed source radiotherapy) used for?

A

Used for cervical/ prostate/ breast/ oesophageal/ skin cancer

53
Q

What are the dose rates for sealed source radiotherapy (brachytherapy)?

A

Low dose: ≤2 Gy/h

Medium dose: 2-12 Gy/h

High dose: >12 Gy/h

Usually use low and high dose

54
Q

What is low dose rate brachytherapy?

A

Permanent implantation of radioactive seeds at site of action

Administered over weeks/ months

e.g. iodine-125

Used to treat prostate cancer

55
Q

What is high dose rate brachytherapy?

A

Temporary insertion of radioactive wires into site of action

Potential for combination with external beam radiotherapy

e.g. iridium-192

56
Q

What is unsealed source radiotherapy?

A

Localised at specific targets

Targeting due to properties of chosen radiopharmaceutical, e.g. iodine in thyroid

Oral/ IV solution

e.g. iodine-131/ strontium-89/ radium-223

Alpha or beta emission usually required

57
Q

How can radiotherapy achieve pain relief?

A

Treatment with strontium-89 chloride

Beta radiation source

Unsealed source radiotherapy

58
Q

What is hyperthyroidism?

A

Excessive production of thyroid hormones

59
Q

How is radiotherapy used to treat thyroid cancer?

A

Iodine accumulates in thyroid

Because iodine is needed to make thyroid hormone

e.g. iodine-131 sodium (beta radiation source) used

Oral – solution/ capsule

60
Q

How are radiopharmaceuticals dispensed?

A

In units of activity, e.g. kBq/ MBq

Pharmacist is responsible for proper prescribed dose preparation

61
Q

How are radiopharmaceuticals used for diagnostics?

A

Require gamma emission

NOT alpha/ beta emission

Administered IV

Radiation is detected externally using a gamma-camera

62
Q

What is a gamma-camera?

A

Special scintillation detector

External radiation detection

63
Q

What is positron emission tomography?

A

Observation of metabolic processes

Uses radiolabelled glucose, e.g. fludeoxyglucose

Gamma source of radiation

Identification of tumours – due to increased number of mitochondria in rapidly growing malignant masses

64
Q

What is a renal isotope scan?

A

Used to test renal function

e.g. technetium-99

65
Q

What are the stages of a renal isotope scan?

A

(1) IV injection of radionuclide

(2) Kidney tubules secrete radionuclide into urine

(3) Rate of radionuclide removal vs time = renogram

66
Q

What is a renogram?

A

Results of renal isotope scan

Rate of radionuclide accumulation/ removal vs time

67
Q

What is technetium?

A

Lightest chemical element with no stable isotope

Most commonly used radioisotope in medicine

Emits gamma radiation only

Half-life = 6hrs

68
Q

How is technetium prepared for radiotherapy?

A

On site

In water

Injected into patient

69
Q

What is cardiolite treatment?

A

Most important myocardial imaging method

Non-invasive

70
Q

What is the most important myocardial imaging method?

A

Cardiolite treatment

71
Q

What is technetium-aerosol used for?

A

Lung ventilation imaging

72
Q

What is technetium-albumin used for?

A

Cardiac function imaging

73
Q

What is technetium-exametazime used for?

A

Brain imaging

74
Q

What is technetium-medronate used for?

A

Bone imaging

75
Q

What is technetium-succimer used for?

A

Kidney imaging

76
Q

What are some safety considerations for radiotherapy treatment?

A

(1) Shielding – shielding from rays

(2) Distance – radiation dose is inversely proportional to square of the distance

(3) Time – minimise time spent handling radioactive source

PM3B (33 decks)

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