Radionuclide Therapy Flashcards

Question

Describe P-32 therapy.

Answer 1

Treats myeloproliferative disease (eg polycythaemia vera) where too many blood cells produced and blood gets thick, often associated with bone marrow hyperactivity. IV injection 111-222 MBq (chosen by clinical assessment). Costs ~ £400. (varies as air fare from Poland is shared by hospitals using it) Taken up in haemopoetic (blood forming) tissue and reduces cell viability & proliferation (radiation injury to cell precursors and bone marrow) Physical Half Life = 14 days. ``` Pure beta (b-) particle emitter Emax = 1.71 MeV Emean = 0.7 MeV (Beta gives off range of energies as has excess of neutrons – converts to proton & gives off beta and anti-neutrino, as energy gets less the anti-neutrino is carrying away more energy. So need to know mean energy for dose calcs.) ``` Radiation Protection: Flush toilet twice for 2 days, Don't donate blood for 2 weeks, given card explaining instructions.

Answer 2

Bremstrahlung (Radiative) Excitation (Collisional) Ionisation (Collisional)

Answer 3

Use to treat: Metastatic bone disease Chemical form: Radium chloride Physical half-life: 11 days Principal radiation: alpha particles (small amount of beta and gamma (roughly 3%)) Route: i.v. 6 injections at 4 weekly intervals Administration: Draw up the Radium immediately prior to injection 55 kBq per kg patient weight (manufacturer informed as delivered the correct amount with a small amount of excess) Check the cannula with 10ml saline (careful not to tissue) Slow IV injection using syringe shield. 10ml flush of saline Separate sharps bin - seperate radiation waste Return in 4 weeks ``` Radiation Protection: Flush toilet twice for 2 days Don’t give blood for 2 days Given card wtih instructions on Tiny amount of gamma - not bothered about proximity ```

Answer 4

Chemical form: Sodium Iodide Physical half-life: 8.02 days Principal radiation: 606 keV beta (87%), 364 keV gamma (82%) Made in: nuclear reactor as high atomic mass & decays by beta – as extra neutrons. Neutron bombardment, or fission product in reactor. Administered activity: hyperthyroid ~ 400-550 MBq, ca. thyroid ~ 1– 5 GBq Route: oral (capsule) Uptake : Active Transport Cost of capsule: £100 – 300

Answer 5

Dose given to damage cells to produce less hormone. Over-active thyroid: High levels of circulating T4 and T3 hormones Common symptoms: Increased metabolic rate, palpitations, sweating, weight loss, nervousness, cardiac and eye complications can occur Treat with Carbimazole / Propylthiouracil Long-term side effects of carbimazole (cardiotoxic) If not cured by drug therapy, may prefer alternatives – surgery (remove part or whole of thyroid) or radioiodine (reduce function) Out-patient therapy (usually) Careful workup to allow proper radiation risk assessment (e.g. are patients caring for children, incontinent, in a nursing home) Clinical follow-up required to assess response. Test blood levels of thyroid hormones & assess clinical symptoms. If not low enough, may need 2nd treatment (<10% patients), if too low -> give thyroxine tablets to replace hormones (often the aim). Usual practice is to give extra to reduce function to under par, then top up with hormones. Radiation protection: 5-6 days avoid long exposures (>1 hr) of close contact with everyone (limit dose) Up to 3 weeks avoid close contact with children & pregnant women No blood samples/invasive procedures for 1 month Carry instruction card for 1 month, 3 month for travelling abroad (radiation detectors at airports)

Answer 6

Purpose: Eliminate residual thyroid tissue after thyroidectomy. Method: I-131 capsule Patients stop taking medication or given thyrogen administration which raises Thyroid Stimulating Hormone (TSH) levels stimulating I-131 uptake and Thyroglobulin production Radiation Protection: In patient procedure with lead lined walls. Avoid close prolonged contacted dependent on rate of activity dispersion (Effective half life (= physical + biological)) Given card to keep for 3 months. Dose: 1.1 GBq – low risk, 3.7 GBq – high risk, 5.0 GBq – patients with known metastasis Post ablation scan taken 6-9 months later.