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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
What is a long-life radiopharmaceutical?
Half-life >12 hrs
26
What is a short-life radiopharmaceutical?
Half-life <12hrs
27
What is the activity of a radioactive substance?
The number of nuclear transformations per unit of time
28
What is the unit of disintegration per second?
Becquerel – Bq
29
What is the unit for 3.7x10^10 disintegrations per second?
Curie – Ci
30
What is 1 millicurie?
1mCi = 10^-3 curie
31
What is 1 microcurie?
1µCi = 10^-6 curie
32
What is 1 megabecquerel?
1 MBq = 10^6 Bq
33
What is 1 kilobecquerel?
1 kBq = 10^3 Bq
34
What is the specific activity of a radioactive material?
Activity of particular radionuclide per unit of mass of element/ compound Usually expressed as activity per gram
35
What is radioactive concentration?
Of a solution Activity of particular radionuclide in a unit volume
36
What is absorbed dose of radiation?
Energy deposited per unit of mass of material
37
What is dose equivalency in radiation?
Accounting for variation in biological effectiveness of different radiations Measured in sieverts (Sv)
38
What is dose equivalent?
Dose equivalent = Absorbed dose/ quality factor
39
What is the quality factor of alpha radiation?
20 Sv
40
What is the quality factor of gamma radiation?
1 Sv
41
What is the quality factor of beta radiation?
1 Sv
42
What radiation type is used diagnostically?
X-rays
43
What is radiopharmacy?
Manufacture + use of radioactive medicines
44
What are the categories of use for radiopharmaceutical?
(1) Diagnostic (2) Therapeutic
45
What factors are important to consider when implementing therapeutic use of radiation?
(1) Specific targeting (2) Clearance of radioactivity from non-target radiosensitive tissues (3) Decay properties of radionuclide
46
What is the mechanism of action of radiation?
(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
What are some approaches of radiotherapy to treat cancer?
(1) External beam radiation (2) Sealed source radiotherapy – brachytherapy (3) Unsealed source therapy
48
What is external beam radiation?
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
When is the lower range of energy use in external beam radiation?
Skin cancer treatment
50
When is the higher range of energy use in external beam radiation?
Internal tumours in cancer
51
What is sealed source radiotherapy (brachytherapy)?
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
What types of cancer is brachytherapy (sealed source radiotherapy) used for?
Used for cervical/ prostate/ breast/ oesophageal/ skin cancer
53
What are the dose rates for sealed source radiotherapy (brachytherapy)?
Low dose: ≤2 Gy/h Medium dose: 2-12 Gy/h High dose: >12 Gy/h Usually use low and high dose
54
What is low dose rate brachytherapy?
Permanent implantation of radioactive seeds at site of action Administered over weeks/ months e.g. iodine-125 Used to treat prostate cancer
55
What is high dose rate brachytherapy?
Temporary insertion of radioactive wires into site of action Potential for combination with external beam radiotherapy e.g. iridium-192
56
What is unsealed source radiotherapy?
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
How can radiotherapy achieve pain relief?
Treatment with strontium-89 chloride Beta radiation source Unsealed source radiotherapy
58
What is hyperthyroidism?
Excessive production of thyroid hormones
59
How is radiotherapy used to treat thyroid cancer?
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
How are radiopharmaceuticals dispensed?
In units of activity, e.g. kBq/ MBq Pharmacist is responsible for proper prescribed dose preparation
61
How are radiopharmaceuticals used for diagnostics?
Require gamma emission NOT alpha/ beta emission Administered IV Radiation is detected externally using a gamma-camera
62
What is a gamma-camera?
Special scintillation detector External radiation detection
63
What is positron emission tomography?
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
What is a renal isotope scan?
Used to test renal function e.g. technetium-99
65
What are the stages of a renal isotope scan?
(1) IV injection of radionuclide (2) Kidney tubules secrete radionuclide into urine (3) Rate of radionuclide removal vs time = renogram
66
What is a renogram?
Results of renal isotope scan Rate of radionuclide accumulation/ removal vs time
67
What is technetium?
Lightest chemical element with no stable isotope Most commonly used radioisotope in medicine Emits gamma radiation only Half-life = 6hrs
68
How is technetium prepared for radiotherapy?
On site In water Injected into patient
69
What is cardiolite treatment?
Most important myocardial imaging method Non-invasive
70
What is the most important myocardial imaging method?
Cardiolite treatment
71
What is technetium-aerosol used for?
Lung ventilation imaging
72
What is technetium-albumin used for?
Cardiac function imaging
73
What is technetium-exametazime used for?
Brain imaging
74
What is technetium-medronate used for?
Bone imaging
75
What is technetium-succimer used for?
Kidney imaging
76
What are some safety considerations for radiotherapy treatment?
(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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