Ronald Sloboda

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PURPOSE Recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) on dose calculations for high-energy (average energy higher than 50 keV) photon-emitting brachytherapy sources are presented, including the physical characteristics of specific (192)Ir, (137)Cs, and (60)Co(More)
This paper presents the recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Therapeutic Radiology and Oncology (ESTRO) on the dosimetric parameters to be characterized, and dosimetric studies to be performed to obtain them, for brachytherapy sources with average energy higher than 50 keV that are(More)
This paper introduces an automatic method to visualize 3D needle shapes for reliable assessment of needle placement during needle insertion procedures. Based on partial observations of the needle within a small sample of 2D transverse ultrasound images, the 3D shape of the entire needle is reconstructed. An intensity thresholding technique is used to(More)
Monte Carlo dose rates on the transverse axis in water and air kerma strengths normalized to unit source activity were calculated for a low dose rate steel-clad 192Ir source. MicroSelectron high dose rate and pulsed dose rate 192Ir sources, and a VariSource high dose rate 192Ir source, as well as five other hypothetical cylindrical 192Ir source designs.(More)
Model 6711 125I seeds are commonly used in permanent brachytherapy implants. While recommended dose distribution parameters for these sources have been published by AAPM TG-43, several investigators have recently questioned the presence of seemingly unphysical fluctuations in the anisotropy function data. Seeking to understand these, we measured the(More)
In needle-based medical procedures, beveled-tip flexible needles are steered inside soft tissue with the aim of reaching pre-defined target locations. The efficiency of needle-based interventions depends on accurate control of the needle tip. This paper presents a comprehensive mechanics-based model for simulation of planar needle insertion in soft tissue.(More)
In this work, we propose a framework for calculating brachytherapy dose distributions in heterogeneous media. The approach taken includes analytical calculation of the primary dose, and separately treats contributions of the once-scatter photons and multiple-scatter photons to the total scatter dose. This paper focuses on the evaluation of the once-scatter(More)
The presence of heterogeneous media can produce significant perturbations of dose distribution in brachytherapy. In a companion paper, we proposed a dose decomposition approach for dose calculation in a heterogeneous medium, which separately treats dose contributions from primary, once-scattered and multiple-scattered photons. The companion paper also(More)
PURPOSE To quantify the time course of postimplant prostatic edema magnitude and spatial isotropy using serial magnetic resonance imaging (MRI). METHODS AND MATERIALS Forty patients with histologic diagnosis of prostate cancer received an iodine-125 seed implant (Day 0) and consented to 1.5-T MRI on Days -1, 0, 14, and 28. Seeds of strength 0.39mCi were(More)
An algorithm based on the method of simulated annealing is presented for optimizing brachy-therapy dose distributions. The algorithm accommodates either static configurations of multiple sources or single stepping sources, hence in principle can be used to optimize both low- and high-dose rate treatments delivered with remote afterloading equipment.(More)