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PHA 332 > radiopharmacy > Flashcards

radiopharmacy Flashcards

(47 cards)

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1
Q

what is a radiopharmaceutical?

A

A dosage form consisting of radioactive
compound used for either the diagnosis or
therapeutic treatment of human diseases

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2
Q

how are the atomic number and the number of neutrons properties of radionuclides?

A

• Unstable nuclides
– N/Z ratio away from stable isotopes
– Z ≥83

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3
Q

how do radionuclides decay?

A

emits particles and/ or energy- this gives a more stable nuclide

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4
Q

what are the forms in which it can emit particles?

A 
– Alpha (or 4He)
– Beta (- or e-)
– Positron (+)
– Neutrons (n)
– Gamma ()
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5
Q

what are the properties of an alpha decay emission?(a or 4He nucleus)

A

– 2 + charge, high energy and limited penetration range (~10-6 cm)

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6
Q

what are the properties of a beta decay emission?

A

– Various energy, random motion, negative charge
– “neutron rich”
e.g. 13153 I > 13154Xe + B- + u

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7
Q

what are the properties of a gamma ray decay?

A

– No mass, photon energy, high penetration range

– Isomeric transition

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8
Q

what are the properties of a positron decay emission?

A

– Positive charge; various energy, random motion
– Proton rich
– Annihilation (2 x 511 keV ~180°)

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9
Q

what are the properties of neutrons decay emission?

A

no charge, loss of mass

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10
Q

what kind of phenomenon is a radioactive decay?

A

Radioactive decay is a statistical phenomenon

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11
Q

what is the equation for the radioactive decay?

A

-dn/dt = a N
where dn/dt = disintegrating rate
a= decay constant; N = no. of radionuclides

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12
Q

why would we integrate the formula for radioactive decay?

A

Nt = Noe^-at
• where No= no. of radionuclide at time = 0;
Nt = no. of radionuclide at time = t

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13
Q

what is the equation for activity (A)?

A

Radioactivity of nuclide where At = Aoe^-at

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14
Q

what is the equation for exponential decay?

A

ln At = In Ao - at

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15
Q

what is the physical half life?

A

tp= Time required to reduce the initial disintegrating rate

or activity to one-half•

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16
Q

what is the equation for the physical half life?=outside the body

A

tp= ln2/ap , where 2- 0.693

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17
Q

what is the biological half life?

A

Time needed for half of the radiopharmaceutical or

radionuclide to disappear from the biological system

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18
Q

what is the equation for the biological half life?

A

tb=ln2/ab

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19
Q

what is the equation for the effective half life?

Study These Flashcards
A

1/te=t/tb+1/tp

20
Q

what are the units of radioactivity?- KNOW HOW TO CONVERT

Study These Flashcards
A

Curies (Ci)
1 Ci = 3.7 x 1010 dps (disintegrations per sec)
1 mCi = 3.7 x 107 dps
1 uCi = 3.7 x 104 dps

• Bacquerel (Bq) – SI Unit
1 Bq =    1  dps =  2.7 x 10-11 Ci
1 kBq = 103 dps
1 MBq = 106 dps
1 GBq = 109 dps
21
Q

what is a nuclear reactor?

Study These Flashcards
A

neurons
– Fission or (n, f) reaction of 235U or 239Pu
– Produce neutron rich radionuclides

22
Q

what is a cyclotron?

Study These Flashcards
A

charged particles
– (p,n), (d,n) reactions most common
– Produce proton rich radionuclides
• Expensive production facility → Site produced
• Monoisotropic or enriched source as target form
• Radionuclides with long half life

23
Q

what is a generator system?

Study These Flashcards
A 
• Radiopharmacy unit in hospital 
• Portable & reusable system 
• Lead shield 
• Radionuclides with short half life
• Reasonable half life of parent & 
daughter*
24
Q

how is 99MO made?

Study These Flashcards
A

from 235 fission

25
what method is mostly used for 99,o-99mtc?
generator | use imaging radionucllide
26
what are the benefits of using the generator
Simple elution method & reliable separation
27
what is the solid, solvent phase of the generator method?
Solid phase: alumina column | • Solvent phase: 0.9% saline
28
is the generator method sterile and pyrogen free?
yes
29
what forms do the radiopharmaceutical dosage forms come in?
solution, suspension, capsule and gas
30
what type of container do radiopharmaceutical dosage forms have?
lead
31
what is an appropriate form for a radiopharmaceutical?
– Ensure radionuclides distribute to target site– Remain stable in vitro & in vivo
32
what is direct labelling?
e.g. 125I-albumin Injection– Tagging radioisotope with biological molecules– Non-specific binding to antibodies, RBC, etc.
33
how to you label 99mTC with chelate?
• Oxidation state of Tc – Tc 7+ to lower values (1+, 3+, 4+, 5+) – Reducing agents, SnCl2 (stannous chloride) in acid • Chelating agent – Coordination donor atoms, e.g. N, O, S, P etc – Donate lone pair electrons – Coordinate covalent bond stabilises 99mTc
34
what makes up the strructure of 99m tc complex?
• Property of complex – Chelating agent – Ring size, charge and geometry – Determine distribution in the body
35
what is included in a labelling kit?
``` • No radioisotope • Reducing agent, e.g. SnCl2 • Chelating agent • Antimicrobial, e.g. benzyl alcohol • Antioxidant, e.g. Sodium bisulfite – Avoid re-oxidation of reduced Tc upon Sndepletion • Buffers, acid or base • Solution or lyophilised powder • Separate vials for reconstitution or reaction ```
36
how do you assure the quality of a radiopharmaceutical?
• Quality assurance scheme • Precursor & kit additives and their quality • Physicochemical tests -biological tests
37
what physiochemical tests are availible for quality tests?
– Radioactivity & specific radioactivity – Radionuclidic species & radionuclidic purity – Chemical purity for radiopharmaceuticals & radiochemical purity – Particle size – pH
38
define radionulidic purity
Fraction of total radioactivity in form of the desired radionuclide present in a radiopharmaceutical
39
what do impurities arise from?
– Extraneous nuclear reaction | – Isotope impurities in target materials
40
what is the specific activity?
Radioactivity per unit mass of a radionuclide or | labelled compounds
41
what do you account for with specific activity?
Accounted for radioactive and chemical substance concentrations – Radioactivity from radionuclide (radionuclidic purity)* – Chemical species (radiochemical purity)*
42
how does specific activity change?
changes with date and time
43
how do you determine the stability of a radiolabeled product?
• Radiolysis – Decomposition of radiopharmaceutical by radiation – Auto-radiolysis & indirect radiolysis – Absorption of radiation lead to free radical formation – e.g. water is irradiated to form H2O2 or HO2. radical – Depends on specific activity, energy of emitted radiation & half life – e.g. Particle emission is more damaging than ray
44
how does imaging of the thyroid gland work?
``` Sodium Iodide (131I) or (123I) capsule •Oral route •Monitored uptake •10-35% after 24hr • Hot spot (hyperthyroidism) •Cold spot (carcinoma) • Trapping iodine source in thyroid • Alternative 99mTc Pertechnetate preparation ```
45
how does thyroid imaging work?
``` • Trapping iodine source in thyroid • Alternative 99mTc Pertechnetate preparation ```
46
how are radiopharmaceuticals used ar rgerapeutic agents?
``` • Particle emitters, e.g. ,  • Ionization energy – Direct and indirect by free radical induction (e.g. R., OH., HOO.) • Permanent damage to DNA via strand cleavage & base pair mutation • Induce cellular apoptosis • Distance from site of action ```
47
give examples of radiopharmaceutics for therapeutic use
``` • Non-Hodgkin’s Lymphoma – 90Y-ibritumomab Tiuxetan(Zevalin®) – Active targeting • Bone metastasis – 32P-Sodium orthophosphate IV – Deposit in the bone • Hyperthyroidism – Excess thyroid hormone activity – NaI( 131I) emit - (90%) &  – Active uptake ```

PHA 332 (42 decks)

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