Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PSFC2 > Radiopharmacy > Flashcards

Radiopharmacy Flashcards

1
Q

Radionuclide

A

radioactive atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Radiochemical

A

radionuclide bound to a chemical ligand (radiolabelling)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Radiopharmaceutical

A
  • end product
  • Radioactive material in a form suitable for administration to a human for the purpose of therapy or diagnostic investigation
  • may be an injection, gas or capsule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Definition of units

A

• Each radionuclide emits radio activity with a characteristic energy
– Expressed in electron volts (eV)
• Radio activity measured as a function of disintegrations per second (dps)
– SI unit = becquerel (Bq)
– Non‐SI unit – curie (Ci)
– 1Ci = 37MBq
• Absorbed dose measured in grays (Gy)
– 1 Gy = 1 joule of energy absorbed in 1kg of tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Radioactive decay types

A
  • Internal conversion (e-)
  • gamma ray
  • a-particle
  • b+/b-
  • Electron capture (xray)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Radioactive decay

• a particles (alpha decay)

A
  • smallest distance travelled - easiest to stop
    – 2 protons, 2 neutrons (He nucleus)
  • large in size so easy to capture - blocked using lead shielding
    – Little penetration
    – Very damaging
  • not ideal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Radioactive decay

• B‐particles (positive & negative beta decay)

A
  • ideal
    – Positively charged electron (positron)
    – Negatively charged electron
    – Range 100 feet in air, completely absorbed in a thickness of several mm to several cm
    – High kinetic energy (1000s to 1000000s keV) depends on age of source
    -can be captured using lead shielding - thick lead shielding can completely absorb b particles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Radioactive decay

• gamma‐transmission (gamma rays)

A

– Result from isometric transition
– Electromagnetic vibrations (gamma photons)
– High energy (100s keV)
– Very penetrating (used to sterilise equipment)
- cannot be stopped - go on to affinity, lead shielding cannot be used
- lower energy than b particles so less damaging

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Radioactive decay

• Internal conversion (e‐)

A

– Electron drops from higher orbital to lower
– X‐ray emitted
– X‐ray hits higher orbital electron
– Electron expelled out of orbital (Auger electron – eA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Radioactive decay • Electron capture

A

– Emits characteristic x‐ray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Radioactive decay

• Spontaneous fission

A

– Neutrons
– Gamma photon
-for energy generation processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

which ones are most interesting for radio pharmacy

A

alpha, beta and gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Calculation of radioactivity

A

• Each radionuclide has a characteristic decay constant
• Governed by equation
At = Aoe‐t

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Radioactive half‐life

A

• Time taken for a given quantity to decay to half its activity
• Half‐life (t1/2) related to decay
t1/2 = ln2/
ln2 ≈ 0.693

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Commonly used radionuclides and half life

A

-Technetium-99m : 6hr (99mTc)
-Indium-113m : 100m
(113mIn)
-Krypton-81m : 13s (81mKr)
-Gallium-68 : 68m (68Ga)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Commonly used Parent and half life

A

-Molybdenum-99 : 66h (99Mo)
-Tin-113 : 115d (113Sn)
- Rubidium-81 : 4.5h
(81Rb)
-Germanium-68 : 270d
(68Ge)

17
Q

Properties of an ideal radionuclide

A

• Diagnostic–only emit gamma‐rays and have activity sufficient for purpose but not greater (should not damage)
• Therapeutic–emit B particles to deposit in target organ (designed to cause damage - used to shrink tissues for surgery)
• T1/2
– Sufficient for preparation, transportation, administration, imaging
– Sufficient to prevent unnecessary radiation remaining in the body

18
Q

Properties of an ideal radionuclide 2

A

• Readily available (& cost)
• Easy to formulate into different preparations
- Technetium‐99m (99mTc, Tc‐99m) best meets these properties

19
Q

Technetium‐99m

A

99Mo –> (T1/2 = 66h, B- and gamma) 99mTc - unstable

99mTc –> (T1/2 = 6h, gamma) 99Tc - stable

  • T1/2 = 6.01 hours
  • Emits gamma‐rays only (great for diagnostics)
  • Principal photon energy= 140keV (relatively low energy so less damaging)
  • Abundance= 89% (high yield)
20
Q

Tc‐99m Generation

A
  • Produced using Mo‐99 generator
  • Mo‐99 produced from fission of U‐235
  • Passed onto Al203 column
  • Eluted using 0.9% NaCl
  • Produces sodium pertechnetate (NaTcO4)
21
Q

What is elution

A

passing a liquid through a column to wash radioactivity out of the column

22
Q

Difference between wet and dry generator

A

Dry generator is a two port system and doesn’t have a permently conncected source of NaCl

23
Q

Radio pharmacy Isolator

A

Type II,

Grade D environment

24
Q

Shielding

A
  • Must be sufficient to absorb a and B particles and attenuate (slow them down) gamma‐rays
  • Tungsten most commonly used for syringes
  • Lead glass also available
  • Lead used to provide barriers
25
Q

Technique (1)

A
  • creating radiopharmaceutical containing ligand (inert carrier of radioactivity)
  • calculate volume of elute required
  • may be a dry powder of liquid
  • ready for dispensing
26
Q

Technique (2)

A
  • patient dose withdrawn from vial

- inserted into a dose calibrator: measures amount of radio-activity

27
Q

Tc‐99m common ligands

A

• DMSA: used to look at outside area of kidney
– Dimercaptosuccinic acid (99mTc Succimer injection BP)
– Renal cortex scintigraphy

• DTPA: used to look at kidney and lungs
– Diethylenetramine‐pentaacetic acid (99mTc Pentetate injection BP)
– Renal scintigraphy
– Lung ventilation (as aerosol)

• MAG3: used to look at how kidneys are working
– Mercaptoacetyltriglycine (99mTc Mertiatide injection BP)
– Renal dynamic scintigraphy

• MDP: used to look at bones
– Methylene diphosphonate (99mTc Medronate injection BP)
– Skeletal scintgraphy

28
Q

Tc‐99m common ligands

A

• DMSA: used to look at outside area of kidney
– Dimercaptosuccinic acid (99mTc Succimer injection BP)
– Renal cortex scintigraphy

• DTPA: used to look at kidney and lungs
– Diethylenetramine‐pentaacetic acid (99mTc Pentetate injection BP)
– Renal scintigraphy
– Lung ventilation (as aerosol)

• MAG3: used to look at how kidneys are working
– Mercaptoacetyltriglycine (99mTc Mertiatide injection BP)
– Renal dynamic scintigraphy

• MDP: used to look at bones
– Methylene diphosphonate (99mTc Medronate injection BP)
– Skeletal scintgraphy

• MAA: looks at issues of getting blood to lungs or liver, MAA can be used
– Macroaggregated albumin
– Pulmonary perfusion scintigraphy
– Liver intra‐arterial scintigraphy

• HMPAO: used for brain or white blood cell labelling
– Hexamethylpropylene amine oxime (99mTc
Exametazine injection BP)
– Cerebral perfusion scintigraphy 
– White blood cell labelling
29
Q

fever of unknown origin

A

take 50 ml blood sample spin it down to get white blood cells and bind them to HMPAO - re inject into patient to get an image of where infection is

30
Q

Tc‐99m common doses

A
  • DMSA 75 MBq
  • DTPA 200 MBq
  • MAG3 100 MBq
  • MAA 100 MBq
31
Q

Radioiodine

A

• 131I first important clinical radio-pharmaceutical
– T1/2 = 8 days
– B and gamma emissions (364 keV)
– Treatment of hyperthyroidism and differentiated thyroid cancer
-131I not used for diagnostic due to beta decay
• 123I now preferred for diagnostic purposes
– T1/2 = 13.2 hours
– gamma emissions only (159keV)
– 83% abundance

32
Q

Tc‐99m Ligands

A

• Pertechnetate (TcO4‐) has highest possible oxidation state for Tc
– Valency of +7
• Will not bind to ligand so need reducing agent
• Stannous salts most commonly used (e.g. SnCl2)

33
Q

What is the decay constant for Tc‐99m?

T1/2 = 6 hours
ln2 ≈ 0.693

A 
t1/2 = ln2/ v
v = In2/ t1/2

0.116

34
Q

What is the decay factor for 1 hour?

What is the decay factor for 2 hours?

A

e-vt

e-0.116 x 1 = 0.891

e-0.116 x 2 = 0.794

35
Q

Volume calculations

It is 8:30am. You have eluted your Tc‐99m generator and have obtained 10mL of eluate with activity of 300 MBq/mL. How much should you draw up to ensure a dose of 75 MBq at 10:30am?

A

75/ 0.794 = 94.4 MBq

94.4 / 300 = 0.315

dose / decay factor = answer

answer / activity =

PSFC2 (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions