Title: The correlation of hypersensitivity for HRS/IRR and the 'inverse' dose-rate effect – its potential influence on LDR brachytherapy: a review

Authors: Bobby E. Leonard, Arthur C. Lucas

Addresses: International Academy of Hi-Tech Services, Inc., 693 Wellerburn Avenue, Severna Park, Maryland 21146, USA. ' Department of Physics, Oklahoma State University, Stillwater, Oklahoma, USA

Abstract: The |Inverse| Dose-Rate Effect (IDRE) has been extensively studied (Leonard, 2000; 2007a; Leonard and Lucas, 2008a–b). We here consolidate these results. We have shown a correlation between Hyper-radiosensitivity and the Induced Radioresistance effect (HRS/IRR), and IDRE has the same threshold and transition behaviours. This supports a conclusion that IDRE is the dose-rate manifestation of HRS/IRR. We show that the low dose-rate hyper-radiosensitivity of IDRE can have a significant influence on cell killing in low dose-rate brachytherapy if the tumour tissues and/or the peripheral tissues and organs experience IDRE. We show that there can be a therapeutic gain in tumour control or there can be significant excess cell killing of the peripheral tissues increasing the normal tissue complication probability. We suggest and outline a coordinated dose and dose-rate cellular dose response programme of measurements on both carcinogenic and normal human tissues related to low dose-rate brachytherapy.

Keywords: low dose-rate brachytherapy; inverse dose-rate effect; IDRE; potential therapeutic gain; normal tissue complications; hyper-radiosensitivity; radiation induced radioresistance; low radiation; cell killing; tumour control; prostate cancer; cervical cancer.

DOI: 10.1504/IJLR.2008.020981

International Journal of Low Radiation, 2008 Vol.5 No.4, pp.310 - 355

Available online: 29 Oct 2008 *

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