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SU‐FF‐T‐315: Multiple‐Radionuclide Brachytherapy Sources: Dosimetry Characteristics, Prescription Dose and DVH
Author(s) -
Nuttens V,
Lucas S
Publication year - 2007
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2760977
Subject(s) - brachytherapy , dosimetry , radiation treatment planning , nuclear medicine , dose volume histogram , radionuclide , medical physics , monte carlo method , radionuclide therapy , radioactive source , internal dosimetry , medicine , radiation therapy , physics , mathematics , detector , radiology , statistics , nuclear physics , optics
Purpose: To study the potentiality of brachytherapy seeds loaded with two radionuclides from a dosimetric point of view and from a Dose‐Volume Histogram point of view. Method and Materials: First the AAPM TG43U1 dosimetry formalism has been adapted in order to implement multiple radionuclide brachytherapy sources in present Treatment Planning System. Monte Carlo simulations have been performed to derive the dosimetric characteristics of a source based on a mixture of103 Pd with125 I and103 Pd with131 Cs . The linear quadratic model has then been used to derive the prescribed dose for such bi‐radionuclide sources, using the103 Pd ,125 I or131 Cs brachytherapy experience as benchmarks. The prescribed dose has been determined for different biological parameter (α, β, T rep , T pot ) and edema characteristics (resolving rate, magnitude). Dose‐volume histograms of virtual patients implanted with bi‐radionuclide seeds have been computed using commercialized Treatment Planning Systems. Results: The derived prescription dose is similar if103 Pd or125 I are use as benchmarks but differs by about 30 Gy if131 Cs brachytherapy is used as a reference. Dose‐volume histograms show that these bi‐radionuclide sources decrease the dose and dose rate to the surrounding organs at risk and reduce also the number of cold spots caused by dose inhomogeneity. Conclusions: We present how we adapted the AAPM TG43U1 dosimetry formalism to make the use of multiple radionuclide brachytherapy sources compatible with current treatment planning. We also describe the method used to derive the prescription dose for such sources. Finally, the effect on the DVH is highlighted.