There are no statistical significant dosimetric differences among the three seed orientations in this study (i.e., ideal, vertical, and diagonal). However, the observed differences between the calculated and measured values could be explained by the measurement uncertainty and the configuration of the resin beads within the capsule and capsule orientation.

No abstract

This work presents experimental dosimetry results for a new normalP103d brachytherapy seed, in accordance with the AAPM TG‐43U1 recommendation that all new low‐energy interstitial brachytherapy seeds should undergo one Monte Carlo (MC) and at least one experimental dosimetry characterization. Measurements were performed using TLD‐GR200A circular chip dosimeters using standard methods employing thermoluminescent dosimeters in a Perspex phantom. The Monte Carlo N‐particle (MCNP) code, version 5 was used to evaluate the dose‐rate distributions around this model normalP103d source in water and Perspex phantoms. The consensus value for dose‐rate constant of the IR06‐normalP103d source was found equal to 0.690 cG⋅normalh−1⋅normalU−1. The anisotropy function, F(r, θ), and the radial dose function, normalgnormalL(r), of the seed were measured in Perspex phantom and calculated in both Perspex and liquid water phantom. The measured values were also found in good agreement with corresponding MC calculations.PACS number: 87.53.Jw

In this study version 5 of the MCNP photon transport simulation was used to calculate the dosimetric parameters for new palladium brachytherapy source design following AAPM Task Group No. 43U1 report. The internal source components include four resin beads of 0.6 mm diameters with (103)Pd uniformly absorbed inside and one cylindrical copper marker with 1.5 mm length. The resin beads and marker are then encapsulated within 0.8 mm in diameter and 4.5 mm long cylindrical capsule of titanium. The dose rate constant, Λ, line and point-source radial dose function, g(L)(r) and g(P)(r), and the anisotropy function, F(r,θ) of the IR01-(103)Pd seed have been calculated at distances from 0.25 to 5 cm. All the results are in good agreement with previously published thermoluminescence-dosimeter measured values [3] for the source. The dosimetric parameters calculated in this work showed that in dosimetry point of view, the IR01-(103)Pd seed is suitable for use in brachytherapy of prostate cancer.

Brachytherapy dose distributions are calculated for 15 mm ROPES eye plaque loaded with model Theragenics200 and IR06-(103)Pd seeds. The effects of stainless steel backing and Acrylic insert on dose distribution along the central axis of the eye plaque and at critical ocular structure are investigated. Monte Carlo simulation was carried out with the Version 5 of the MCNP. The dose at critical ocular structure by considering the eye composition was calculated. Results are compared with the calculated data for COMS eye plaque loaded with Theragenics200 palladium-103 seeds and model 6711 iodine-125 seed. The air kerma strength of the IR06-(103)Pd seed to deliver 85 Gy in apex of tumor in water medium was calculated to be 4.10 U/seed. Along the central axis of stainless steel plaque loaded with new (103)Pd seeds in Acrylic insert, the dose reduction relative to water is 6.9% at 5 mm (apex). Removal of the Acrylic insert from the plaque (replacing with water) did not make significantly difference in dose reduction results (~0.2%). The presence of the stainless steel backing results in dose enhancement near the plaque relative to water. Doses at points of interest are higher for ROPES eye plaque when compared to COMS eye plaque. The dosimetric parameters calculated in this work for the new palladium seed, showed that in dosimetry point of view, the IR06-(103)Pd seed is suitable for use in brachytherapy. The effect of Acrylic insert on dose distribution is negligible and the main effect on dose reduction is due to the presence of stainless steel plaque backing.