The determination of radiobiologically optimized half-lives for radionuclides used in permanent brachytherapy implants

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dc.contributor.author Armpilia, CI en
dc.contributor.author Dale, RG en
dc.contributor.author Coles, IP en
dc.contributor.author Jones, B en
dc.contributor.author Antipas, V en
dc.date.accessioned 2014-03-01T01:19:36Z
dc.date.available 2014-03-01T01:19:36Z
dc.date.issued 2003 en
dc.identifier.issn 0360-3016 en
dc.identifier.uri http://hdl.handle.net/123456789/15598
dc.subject Linear-quadratic en
dc.subject Permanent implants en
dc.subject Radiobiologic modeling en
dc.subject Therapy radionuclides en
dc.subject.classification Oncology en
dc.subject.classification Radiology, Nuclear Medicine & Medical Imaging en
dc.subject.other Growth kinetics en
dc.subject.other Implants (surgical) en
dc.subject.other Tissue en
dc.subject.other Tumors en
dc.subject.other Biologically effective dose en
dc.subject.other Radioisotopes en
dc.subject.other cesium 131 en
dc.subject.other gold 198 en
dc.subject.other iodine 125 en
dc.subject.other palladium 103 en
dc.subject.other radioisotope en
dc.subject.other unclassified drug en
dc.subject.other ytterbium 169 en
dc.subject.other article en
dc.subject.other dose calculation en
dc.subject.other drug delivery system en
dc.subject.other drug half life en
dc.subject.other nonhuman en
dc.subject.other priority journal en
dc.subject.other prostate adenocarcinoma en
dc.subject.other prostate tumor en
dc.subject.other radiation dose en
dc.subject.other radiation dose fractionation en
dc.subject.other radioisotope therapy en
dc.subject.other tumor growth en
dc.subject.other Brachytherapy en
dc.subject.other Cell Division en
dc.subject.other Half-Life en
dc.subject.other Humans en
dc.subject.other Linear Models en
dc.subject.other Neoplasms en
dc.subject.other Radiation Tolerance en
dc.subject.other Radiobiology en
dc.subject.other Radioisotopes en
dc.subject.other Relative Biological Effectiveness en
dc.title The determination of radiobiologically optimized half-lives for radionuclides used in permanent brachytherapy implants en
heal.type journalArticle en
heal.identifier.primary 10.1016/S0360-3016(02)04208-6 en
heal.identifier.secondary http://dx.doi.org/10.1016/S0360-3016(02)04208-6 en
heal.language English en
heal.publicationDate 2003 en
heal.abstract Purpose: To use tumor growth kinetics and other biologic parameters in an extended version of the linear-quadratic (LQ) formulation to determine radiobiologically optimized half-lives of radionuclides which might be used in permanent brachytherapy implants. Methods and Materials: A version of the LQ model suitable for the analysis of permanent brachytherapy implants has been modified to investigate the radionuclide half-lives that will maximize the biologically effective dose (BED) delivered to tumors with repopulation rates (K values) in the range 0.01-1.1 Gyday(-1). The method assumes that part of the physical dose delivered to the tumor may be radiobiologically wasted because of the repopulation phenomenon, whereas adjacent normal tissues will exhibit little or no wastage. To perform the analysis, it is necessary to stipulate alpha/beta ratios and sublethal damage recovery rates together with the normal tissue tolerance BED. The analysis also takes into account a range of likely relative biological effectiveness (RBE) values. Results: Rapidly growing tumors require the shortest radionuclide half-lives, but even slow-growing tumors such as prostate adenocarcinomas can be satisfactorily treated with radionuclides possessing half-lives substantially less than that associated with I-125. The likelihood that prostate tumors possess an alpha/beta value which is comparable with, or lower than, that associated with late-responding normal tissues would also mitigate against the use of long-lived radionuclides. Although a number of parameter assumptions are involved, the results suggest that, for a wide range of tumor types, shorter-lived radionuclides are more versatile for achieving reasonable clinical results. The theoretically derived optimum half-lives typically range from around 0-5 days for fast-repopulating tumors (K 1.1 Gyday(-1)) to approximately 14-50 days for slow-growing tumors (K similar to 0.1 Gyday(-1) or less). For prostate implantation, Pd-103 is overall a better choice than I-125. Conclusion: With so many variables and parameter uncertainties, it is not appropriate to attempt to define optimum radionuclide half-lives too closely. However, this study suggests that half-lives in the approximate range 4-17 days are likely to be significantly better for a wide range of tumor types for which the radiobiologic characteristics may not be precisely known in advance. (C) 2003 Elsevier Science Inc. en
heal.publisher ELSEVIER SCIENCE INC en
heal.journalName International Journal of Radiation Oncology Biology Physics en
dc.identifier.doi 10.1016/S0360-3016(02)04208-6 en
dc.identifier.isi ISI:000181323400012 en
dc.identifier.volume 55 en
dc.identifier.issue 2 en
dc.identifier.spage 378 en
dc.identifier.epage 385 en

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