Dose-reducing effect of Lipowitz metal-embedded spacers in interstitial brachytherapy for carcinoma of the mobile tongue.

Dose-reducing effects of spacers with and without a Lipowitz metal plate for the purpose of decreasing osteoradionecrosis after interstitial brachytherapy for tongue cancers were examined experimentally and clinically. The thicker the sample or spacer and the thicker the metal plate, the greater was the dose reduction achieved. A more marked dose reduction was achieved with iridium than with radium because of lower gamma ray energy of iridium. Iridium has been used widely as a radioactive source for interstitial brachytherapy. It was concluded therefore that a metal plate should be used as a shield into the spacer in interstitial brachytherapy both to reduce the radiation dose to surrounding normal tissues and to help prevent osteoradionecrosis.