ABSTRACT
Permanent implantation of the iodine-125 brachytherapy sources is an irradiation technique for the treatment of the localized cancer. As described by the American Association of Physicists in Medicine (AAPM) Task group 43 (TG-43U1), it is crucial to determine the dose distribution around the brachytherapy seed before its effective clinical practice or even before releasing the sources for the treatment. In the present work, according to TG-43U1 report, the dosimetric parameters of BEBIG iodine-125 Low Dose Rate brachytherapy IsoSeed® I25.S06 source model was investigated. To perform the dose calculations, we have used GEANT4 Application for Emission Tomography (GATE) Monte Carlo simulations. Interesting results have been found. In particular, the dosimetric quantities like the radial dose function gL(r), the anisotropy function F(r,θ) and the dose rate constant Λ have been obtained. In addition, our data are in good agreement with the previous published works. It is also remarked that, GATE Monte Carlo code reproduces accurate dosimetric parameters results.
Subject(s)
Brachytherapy , Iodine Radioisotopes , Anisotropy , Brachytherapy/methods , Iodine Radioisotopes/therapeutic use , Monte Carlo Method , Radiometry , Radiotherapy DosageABSTRACT
The dose optimization algorithm based on anatomical points is developed to produce rapidly uniform doses over target distances generated on the target volume edges in high-dose-rate (HDR) brachytherapy stepping source application for a treatment length of 6 cm. Monte Carlo modeling of the 60Co HDR brachytherapy source and the surrounding medium were performed using PHITS code. The source dwell times were optimized using Tikhonov regularization in order to obtain uniform dose distribution at the anatomical points located at predefined target distances. The computed dose rates at distances from 0.25 up to 20 cm away from the source were first verified with the literature data sets. Then, the simulation results of the optimization process were compared to the calculations of commercial treatment planning system (TPS) SagiPlan. As a result, the dose uniformity was observed in the isodose curves at the target distances of 10 and 15 mm of the treatment length and the prescribed dose achieved the anatomical points uniformly. The algorithm developed in the present study can be applied for achieving the dose uniformity around the brachytherapy stepping source as a quicker tool for different treatment lengths and different target distances while maintaining the high quality of the treatment plans, saving time by avoiding the manual isodose shaping and then better suitable treatment for patients.
Subject(s)
Algorithms , Brachytherapy , Anisotropy , Dose-Response Relationship, Radiation , Humans , Monte Carlo Method , Radiotherapy Planning, Computer-AssistedABSTRACT
Radon concentrations are measured in the tap water collected in different areas in Marrakech (Morocco) by using liquid scintillation techniques. The concentrations due to radon and its short-lived decay products emanating from the tap water used inside different compartments of the house were determined. Alpha activities due to the (218)Po and (214)Po short-lived radon decay products were evaluated in various compartments of the respiratory tract of adult members of the public. The committed equivalent doses due to the (218)Po and (214)Po short-lived progeny of radon were evaluated in different tissues of the respiratory tract by the frequencies of using the various parts of the house.
