Radiation Oncology/Unsealed sources


 * See also: Isotopes used in Radiation Oncology

For bone metastases
These have usefulness in treating blastic bone lesions (basically anything that lights up a bone scan). The dose limiting toxicity is bone marrow. Observe platelet counts.
 * Please see the bone metastases page


 * Phosphorus 32 - beta emitter
 * Gets taken up in bone
 * Not commonly used


 * Strontium 89 (Metastron) - beta emitter
 * Calcium analog, gets taken up in bone
 * Long half life (50.5 days physical half-life)
 * Usual dose 4 mCi (supplied as a 4 mCi vial)
 * May also be dosed at 0.040-0.060 mCi/kg


 * Samarium 153 (Quadramet) - beta and gamma emitter
 * Bound to a tetraphosphonate, which gets taken up in area of active
 * Usual dose 1 mCi/kg (may use 0.5 mCi/kg)
 * Short half life (about 3 days)
 * Can repeat dose after about 6-8 weeks
 * Lowest effective range (compared to Sr and P) and thus lower bone marrow toxicity
 * Can be used for imaging also due to its photon component

P-32

 * ovarian cancer
 * endometrial cancer
 * uterine papillary serous carcinoma
 * pancreatic cancer


 * Pure Beta emitter
 * Energy: 1.71 MeV and 0.69 MeV electrons
 * Average tissue penetration: 1.4-3mm
 * T ½ : 14.3 days
 * Benefit: no photon contamination
 * Typical dose: 10-15 mCi
 * 10 mCi gives equivalent of 30Gy to the peritoneum
 * Distribution
 * Test intraperitoneal distribution with T-99mc prior to treatment
 * Inhomogeneous dose distribution.
 * Mainly absorbed in the peritoneal surface
 * Some enters systemic circulation via lymphatics and is removed by the liver
 * LNs receive low, subtheraputic doses
 * Little hemopoietic toxicity
 * Peripheral blood dose: 1.2 cGy
 * Bone marrow dose: 6 cGy

Research

 * Experimental antibody based methods - alpha emitters
 * At the ITU (Institute for Transuranium Research; website) work is being done on Alpha-Immunotherapy, an experimental method using antibodies bound to alpha isotopes. Bismuth-213 is one of the isotopes which has been used. This is made by the alpha decay of Ac-225. The generation of one shortlived isotope from longer lived isotope is a useful method of providing a portable supply of a shortlived isotope. This is similar to the generation of technetium-99m by a technetium cow. The actinium-225 is made by the irradation of radium-226 with a cyclotron.

Guidelines

 * see also: Guidelines at Bone metastases

Reviews
Samarium-153:
 * 2004 PMID 16985930 -- Full text "Overview of Samarium Sm 153 Lexidronam in the Treatment of Painful Metastatic Bone Disease" (Sartor O, Rev Urol. 2004;6 Suppl 10:S3-S12.)