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Pharmaceutical Technology > Radiopharmacy > Flashcards

Radiopharmacy Flashcards

1
Q

What are radiopharmaceuticals (RPs) made up of?

A

*radioisotope- selected based on properties
*a non radioactive component- Na+ or Cl- ions- influences tissue distribution of radiopharm- minimal risk of toxicity

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2
Q

What factors should be considered when choosing the correct radiopharmaceuticals for diagnostics?

A

*minimum half life
*mode of decay
*cost, availability
*physical properties
*organ/tissue specificity ?

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3
Q

How long should half life be?

A

*long enough to synthesise radiopharmaceutical
*long enough to accumulate in target tissue
*BUT must minimise radiation dose to patient
*range from 2min (C15) to several days

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4
Q

What are the modes of decay of radiopharmaceuticals?

A

*Beta minus (B-) decay- radioactive atoms contain too many neutrons- decay= conversion to a proton arms and B- particle
*Positron (B+) decay- nuclei have too many protons - decay= conversion to neutron and B+ particle
*Gamma decay- nucleus changes energy status by emitting a gamma ray photon
*Electron capsure (EC)- nucleus captured inner orbital electrons converting proton to neutron

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5
Q

What is beta minus decay?

A

Too many neutrons- convert neutron to proton and B- particle

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6
Q

What is positron decay?( B+)

A

Too many protons, one converted to neutron and B+ particle

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7
Q

What is gamma decay?

A

Change in energy status higher to lower by emitting gamma ray photon

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8
Q

What instrument is most cost effective and ideal in radiopharmacy?

A

Radioisotope generators
-inexpensive
-long shelf lives

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9
Q

What are the most expensive ways to make isotopes?

A

Accelerator or cyclotron produced radioisotopes- only one isotope made at a time

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10
Q

What methods are used to detect radiopharmaceuticals?

A

*Gamma scintigraphy- radiopharmaceut emits gamma radiation- detected by gamma camera- need to match energy of decaying gamma photon is within energy window of camera (100-250keV)
Energies outside range- low quality images

*Positron emission tomography (PET)
Positron decay results in emission of 2 511keV gamma ray photons 180°C apart

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11
Q

What is [201TI]?

A

An analog of K+
Acts as marker for myocyte permeability (muscle cell)
Actively transported into cells by Na2+/K+ pump

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12
Q

What are the disadvantages of [201TI] thallous chloride?

A

Low emission energy range
Cyclotron produced

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13
Q

What is [99mTc]?

A

An isonitrile tracer - techetium sestamibi
- most widely used RP in nuclear med
-available by generator 24h a day
-T1/2= 6h
-optimal gamma ray emission for gamma imaging

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14
Q

What is the nuclear stress test used for?

A

Myocardial perfusion imaging
*RP such as 201TI or 99mTC injected IV
*lie 15-45mins
*scan when rested
*walk on treadmill- increase stress
*monitor blood pressure and rhythm whole time
*at peak exercise, inject RP again
*scan when stressed
*compare images

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15
Q

What Rp’s are used to look for myocardial necrosis?

A

[111In]- labelled anti myosin antibody- detect areas of irreversible damage
*[99mTC]- labelled glucarate- used in a&e

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16
Q

What RP is used to test for myocardial inflammation?

A

[111In]- labelled leukocytes
Heart cell death= acute inflammatory response= Leukos influx to site
*leukos isolated from blood, tagged with 111In
*injected back in

-long time- blood handling and prep

17
Q

What is brain imaging used for?

A

*screen for primary tumours
*evaluate patients with cerebrovascular disease
*detect intracranial injury
*study patients with intracranial disease eg meningitis

18
Q

What RP’s are used in brain imaging?

A

Non lipophilic RPs- only want passage through damaged brain barrier
- 99mTC- penetate and 99mTC-glucepate

19
Q

What does bone imaging show?

A

*mineral content
*trauma
*inflammation
*neoplastic injury

20
Q

What is the most requested diagnostic nuclear medicine procedure?

A

Bone seeking
Using 99mTC MDP

21
Q

Why is iodine used in thyroid imaging?

A

Thyroid traps and concentrates iodine from blood plasma
Prolonged storage in thyroid = easy visualisation

22
Q

What RP is used in thyroid imaging?

A

[123I] NaI orally 24 hours before test

23
Q

Why are radiopharmacueticals used in therapeutics for conditions such as cancer?

A

Rapidly dividing cells more radiosensitive
Goal= destroy diseased tissue whilst sparing healthy

24
Q

What RP is used in thyroid conditions such as thyroid carcinoma?

A

High dose 131I therapy
-can’t leave hospital until radiation below 1220MBq
-patients have probs had thyroid removed
-destroys thyroid carcinoma

25
Q

What does therapeutic use of RP’s usually involve?

A

*destruction of tumour cells
*palliative care

26
Q

What is a radio pharmacy?

A

Lab designed for prep and dispensing of solutions labelled with radioisotopes for therapeutic and diagnostic purposes

27
Q

How should a radio pharmacy be designed ?

A

*must allow preparation of sterile pyrogen free pharmaceuticals
*smooth surfaces and non absorbent for easy cleaning
*2 way protective laminar flow hood

28
Q

What are two potential health hazards to staff working in radio pharmacy?

A

External- gamma radiation exposure
Internal- ingestion inhalation etc- especially of long half life pharmaceuticals

29
Q

What protection should be used in radio pharmacy?

A

*appropriate shielding from source- tungsten syringe shield , generators housed behind lead bricks, bins should be lead shielded
*strength restriction of source
*restricted period of exposure

30
Q

What is the difference between wet and dry column generators ?

A

Wet- permanently installed reservoir of eluant (saline)
Dry- use of small vials of sterile eluant (saline)

31
Q

How is RP added to cold kits?

A

*generator eluate measured and diluted if necessary with saline
*appropriate volume of elite and required 99mTC added ASEPTICALLY to cold kit
*via syringe and needle (using tungsten shield)
*vial inverted few times
*incubated at room temp

32
Q

What is a rapid may to produce 99mTC in house?

A

Technetium generator

Pharmaceutical Technology (21 decks)

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