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HDT 3.2 > Radiopharmacy > Flashcards

Radiopharmacy Flashcards

1
Q

What are the

Radiation Measurement Units?

A

Measure of radiation energy in tissue

  • Sievert (Sv)
  • Use 1/1000 (milli Sievert – mSv)
  • Or 1/1000 000 (micro Sievert - Sv)

o Sievert = Gray x quality factor (QF)
o For and emitters, QF = 1

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2
Q

What is lung perfusion performed by?

A

Lung perfusion imaging performed by IV injection of 99mTc MAA (macroaggregates of albumin typically 30-50mm)

  • Lung ventilation carried out in conjunction with perfusion
  • Radioactive gases such as 81mKr may be used
  • More readily available is 99mTc Technegas (this is a machine)
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3
Q

What is the Most common indication for bone scan?

A
  • is to assess bone metastases usually 2o (secondary) to Ca (carcinoma) breast and prostate
  • Medronate or oxidronate (bisphosphonates) is injected and the patient scanned 3 hours later to look at skeleton
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4
Q

What is used for diagnosis and management of Coronary artery disease?

A

Nice guidelines 2003 state that MPI (Myocardial Perfusion) scintigraphy using SPECT

• Patients undergo MPI in 2 parts

  1. Heart stressed by exercise or pharmacologically using adenosine or dobutamine (to see if there is an increase of blood flow. Only do a rest scan if this scan is abnormal)
  2. Heart imaged at rest (for comparison)
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5
Q

What is the radiopharmaceutical used for Cerebral blood flow imaging?

A

HMPAO Ceretec

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6
Q

What is used to differentiate essential tremor from Parkinsonian syndrome in patients where diagnosis uncertain and DLB (form of dementia – course of disease is quicker) from Alzheimer’s disease?

A

123Ioflupane DaTSCAN

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7
Q

What can Salivary activity and secretion can be monitored by?

A

pertechnetate

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8
Q

What is used to study gastric emptying?

A

Tc-colloid mixed with food or drink

Oesophageal transit (for swallowing problems) measured using Tccolloid in tomato soup

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9
Q

What is used to assess GI bleeding?

A

• using Tc labelled RBC (in vitro test).

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10
Q

What is becqurel?

A

– rate of disintegration (1 d.p.s) – how many molecules are given off (1 disintegration per second is 1 becquerel)

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11
Q

What is a Gray unit?

A

Gray (Gy) - S.I. unit of absorbed dose.

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12
Q

What are the types of radioactive decay?

A

a - particles

B - particles
B + particles

Gamma rays

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13
Q

Describe alpha particles

A
  • He nucleus - charge + 2
  • comparatively large – collide with tissue, give up their energy, cause ion pairs (5000 cm-1)

Range - few mm
• can easily be shielded
• NO role in diagnostic agents, but have potential for therapeutic use

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14
Q

Describe Beta particles

A

• can have negative or positive charge

o smaller than alpha particles – less interaction with tissue (50 ion pairs cm-1 )
o less damage and greater range in tissue – not that good level of treatment
o range can be up to several cm. – depends on energy Emax and Emean
o valuable for THERAPY, but not diagnosis

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15
Q

What are B+ particles?

A
  • known as positrons – antimatter
  • immediately after B i particles emission from nucleus, they interact with - particle
  • Annihilation reaction – matter is converted into energy B+ + b- -> 2gamma
  • energy of each = 511keV, emitted at 180o to each other
  • valuable in DIAGNOSTIC procedures
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16
Q

What are gamma rays?

A
  • electromagnetic radiation – not particles
  • so therefore less interaction with tissue, cause less damage, have greater range in tissue
  • energy of emitted gamma ray(s) constant for a given radionuclide
  • valuable for DIAGNOSTIC use, especially when radiation can be detected externally
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17
Q

What are the Ideal Properties of Diagnostic Radionuclides ?

A
  1. Gamma ray emission only
    - high abundance
    - reduce radiation dose to patient
  2. For imaging studies, gamma energy 100 - 250 kev
    - high detection efficiency
    - no significant body attenuation
    - easy to shield

3.Physical half-life approx. 1.5 times duration of test

  1. Simple cheap and rapid production
    - lack of radionuclidic impurities
    - high specific activity
    - rapid prodyction reduces operator dose
  2. Versatile chemistry
  3. chemical quantity – no pharmacological effect
  4. Radiochemically pure – biodistribution profile
  5. Chemically stable – doesn’t break down in vivo
  6. Predictable biodistribution
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18
Q

What is Technitium -99m?

A

Sourced from Molybdenum (Mo99)

Technitium 99m produces a gamma photon to form technetium 99 and then another gamma photon to Ruthenium 99.

m = metastable state (one of electron is at a higher level – it drops to a lower state).

Ruthenium 99 is stable

Molybdenum and technetium have different chemical properties and can be separated.

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19
Q

How is Technitum generated?

A
  • Essential feature is a shielded glass column containing alumina
  • Mo-99, as molybdate is strongly adsorbed on to column
  • Column is sealed, sterilised, packed into generator
  • Dispatched to hospital radio-pharmacy department
  • On column Mo-99 decays to Tc-99m, which is separated
  • Separation achieved by passing saline through the column. Mo-99 doesn’t dissolve in saline.
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20
Q

What Happens On a Molybdenum Column?

A

Mo decays to Tc-99 and leaves Mo behind.

21
Q

What is the Radionucleic Purity / Identity?

A

o ‘The radionucleic, expressed as a percentage, of the radioactivity of the Radionuclide concerned to the total radioactivity of the source’

22
Q

What imaging is

Sodium (99m Tc) pertechnetate mostly used for?

A

• Most common indication is thyroid imaging
• Why is pertechnetate taken up by thyroid?
TcO4 has similar shape and size to iodide
TcO4 tetrahedral vol 4.0x10-23cm3
Iodide spherical vol 4.2x10-23cm3

23
Q

What happens inside a Technetium radiopharmaceuticals kit?

A

Tc99 eluted in most stable oxidation state (+7) - all 7 electrons shared with 4 oxygens

24
Q

What are the Precautions of a Technetium radiopharmaceuticals kit?

A
  • NEVER inject air into any Technetium radiopharmaceutical vial
  • The oxygen in 0.1ml air can oxidise the stannous ion used in many commercial kits as a reducing agent
25
Q

Drugs which should be stopped prior to mIBG

A
  • Reserpine
  • Tricyclic antidepressants
  • Sympathomimetics
  • Neuroleptics
  • Labetalol =
  • IV phenoxybenzamine
  • Calcium channel blockers
  • Amiodarone
26
Q

Drugs which should be stopped prior to DaTSCAN

A 
o	CNS stimulants – Dexamfetamine, Methylphenidate and Modafinil
o	Antidepressant - Amoxapine 
o	Anxiolytic – Buspirone 
o	Amfebutamine (Bupropion) 
o	Sibutramine
o	Pimozide 
o	Benzatropine
o	SSRI’s e.g. Sertraline - very weak DAT inhibitors 
o	[Cocaine]
27
Q

What is used for the investigation of Hepatobiliary function?

A

Hepatobiliary function is investigated using 99mTc labelled compounds of imino diacetic acid (IDA)

28
Q

Should be stopped prior to DaTSCAN

A

Opioid analgesics
Enzyme inducers
Anaesthetics

29
Q

Drugs which can affect thyroid imaging with 123I

A
  • Thyroxine
  • Amiodarone
  • Iodine containing contrast media
  • Vitamin preparations
  • Antihistamines
  • Steroids
  • Seafood containing high levels of iodine
  • Iodine based cough medicine
  • Hair dye
30
Q

What drug need to be stopped 1 week before Thyroid investigations or therapy FOR HYPERTHYROIDISM?

A

carbimazole and propylthiouracil

31
Q

What drugs need to be stopped before Thyroid investigations or therapy FOR HYPOTHYROIDISM?

A

stop T4 (Thyroxine) 28 days before test, use T3 (Liothyronine) for 14 days and then stop 14 days

32
Q

What drugs can could lead to false negative results for heart investigations with Heart investigations with 99mTc Tetrofosmin?

A

• Beta blockers may blunt the response to exercise induced
• stress – should be stopped for 5 half-lives 24-48 hours
• Rate limiting calcium channel blockers – Diltiazem and
• Verapamil
• Dipyridamole
• Nitrates
• Patients also instructed to abstain from caffeine for 12 hours
tea, coffee and soft drinks such as cola, energy drinks

33
Q

99m Tc Diphosphonates -

Which Drugs which alter biodistribution of MDP

A
  • Iron compounds
  • Cytotoxics
  • Corticosteroids
  • Nifedipine
  • Dextrose
34
Q

What are Hepatotoxic drugs ?

A
  • Paracetamol, aspirin, tetracycline – reduce liver uptake
  • TPN therapy – cause fatty liver disease
  • Erythromycin – false +ve scan with T-BIDA – erythromycin interferes with bile production
  • Methotrexate – diffuse accumulation of MDP
35
Q

What are Nephrotoxic drugs ?

A

aminoglycosides, penicillins, cytotoxics, amphotericin, cyclosporin

36
Q

What drug causes pulmonary toxicity?

A

Bleomycin

37
Q

What are factors that can alter handling of RP?

A
  1. Degree of hydration – renal studies
  2. Caffeine intake
  3. Fasting status – affects absorption and motility in the gut
  4. Alcohol
38
Q

Drugs which interfere with radiolabelling of blood cells

A

• Calcium channel blockers, Captopril, Sodium Valproate, Metronidazole, Allopurinol, Prednisolone, Aspirin, Ibuprofen, Azathioprine, Cyclosporin, Cyclophosphamide, Doxorubicin, Antibiotics, (most significant is steroids)

39
Q

What drugs are used to induce cardiac stress for cardiac studies?

A

Adenosine
Dobutamine
Regadenoson

40
Q

What drug is used in renal studies?

A

Furosemide

41
Q

What drug is used in the investigation of Sphincter of Oddi dysfunction (Liver)?

A

Morphine

42
Q

What is used for gall bladder investigation

A

CCK analogue Sincalide or fatty meal

43
Q

What are thyroid blocking agents?

A

• Potassium iodate 85mg x 2 daily – can induce hyperthyroidism
• Lugol’s iodine 0.1 – 0.2ml tds - very unpalatable
• Potassium iodide – can induce hyperthyroidism
Potassium perchlorate 200mg tds

44
Q

What is used to assess bone metasteses?

A

• Medronate or oxidronate (bisphosphonates) is injected and the patient scanned 3 hours later to look at skeleton

45
Q

What is used to assess GIT activity?

A
  • Salivary activity and secretion can be monitored using pertechnetate
  • Tc-colloid mixed with food or drink used for gastric emptying studies –pancake or scrambled egg. Needs to have protein In it to bind the pertechnetate.
  • Oesophageal transit (for swallowing problems) measured using Tccolloid in tomato soup
  • GI bleeding assessed using Tc labelled RBC (in vitro test).
46
Q

What is used to image the biliary system?

A

T-BIDA

47
Q

What are the 3 types of renal investigation?

A
  1. Study of GFR using 51Cr EDTA – chelating agent bound to an isotype of Cr. Has a small half-life so has to use a small amount. Measure Cr in the blood can measure how quickly kidney can excrete
  2. Renal perfusion using MAG 3
  3. Renal parenchymal function using DMSA

With the addition of furosemide or captopril these studies are used to identify renal vascular hypertension and renal obstruction

48
Q

What Radionucleotide Particle is used for thyroid imaging?

A

TcO4 -

123I

Parathyroid imaging: using Sestamibi (technium labelled product) and 123Iodine

49
Q

What RP can be used for investigating infection and inflammation?

A

White blood cells can be labelled using 99mTc or 111In (Indium)

• Tc labelled antibodies and antibody fragments eg Tc-sulesomab (Leukoscan)

HDT 3.2 (10 decks)

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