Which is used in teletherapy & Brachytherapy both
Correct Answer: Cobalt 60
Description: B i.e. Cobalt-60 In brachytherapy the source of radiation is placed very close to the site of action. It can be invasive technique as it needs the implantation of needle into the tumor (interstitial) or in the cavity (intracavitary). It is often used in brain tumors & cervical cancers. It requires trained perssonels. Maximum radiation effect can be obtained in diseased tissue. Minimum risk of radiation exposure to the normal tissue. Interstitial brachy therapy uses variety of rodionucleide implants (not only Ir) inseed into the tumors like sauamous cell carcinoma of head and neck region, skin, breast tumor, soft tissue sarcomas and many others. These implants are allowed to remain their for a definite period (temporary implants) or indefinitely (permanent implants). It decreases damage to normal tissue. Radium-226 is a radioactive decay product of uranium- 238 series and is the precursor of radon - 222. It decays very slowly by emitting a-paicles. Earlier it was used for brachytherapy etc but now its use is obsolete due to its very long half life (1600 years)Q and associated hazards. Now radium (Ra-226) and radon (Rn-222) have been completely abondened for clinical useQ. 1125 (not 1131)is used for brachytherapy. Cesium-131 (t1/2 10 days) is used as permanent implant for brachytherapy not Cs-137 (half life 30 years)Q. Because of the hazard of breaking the needle within tissue substance, the utility of 60Co as interstitial implant remained questionableQ. Presently use of Co-60 in brachytherapy is restricted to ophthalmic applicators or for ceain after loading systems where small sources are loaded into spherical form. High dose rate (HDR) brachytherapy uses a dose of 20c Gy/minute. Isotopes used for HDR remote after loaders are Ir 192 (now most commonly used), Yb 169 and Co60Q (used in early version of HDR). Co-60Q & Cesium 137Q are used in Brachv & Teletherapy both. Carbon is used in carbon dating. Tc is used for bone scanning.
Category:
Radiology
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