Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
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The two main modalities to deliver high dose to the prostate and prevent high doses to neighboring organs are intensity modulated radiotherapy (IMRT) or external beam radiotherapy combined with brachytherapy. Because of the different biological effectiveness the physical dose distributions were converted to 3-dimensional linear quadratic dose at 2 Gy per fraction (EQD(2)). From the latter, cumulative EQD(2)-volume histograms were determined for comparison of the modalities. ⋯ Because of the high doses within an implant, the dose in 50% of the prostate volume is much higher with the brachytherapy modalities than IMRT-only which may have clinical consequences. With brachytherapy the doses to the OAR are lower or similar to IMRT-only. Dose escalation for prostate tumors is more easily achieved with brachytherapy than with IMRT alone. Therefore, brachytherapy might be the preferred modality to achieve further dose escalation.
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Lower urinary tract symptoms are frequently observed after I-125 seed implantation of the prostate. More knowledge about causes and predictors is necessary to be able to develop less toxic implantation techniques. The aim of this study was to identify implantation related factors that contribute to post-implant urinary morbidity. ⋯ Bladder hotspot dose appears to be an important dosimetric predictor for urinary morbidity both at 3 months and at 6 months after implantation. Other predictors are prostate volume, or equivalently, the number of implanted seeds.
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Randomized Controlled Trial Comparative Study
Dosimetric effects of the prone and supine positions on image guided localized prostate cancer radiotherapy.
To compare target coverage and doses to rectum and bladder in IMRT of localized prostate cancer in the supine versus prone position, with the inclusion of image guidance. ⋯ Soft-tissue alignment combined with 5mm planning margins is appropriate in minimizing treatment planning and delivery uncertainties in both the supine and prone positions. Alignment based on bony structures showed improved results over the use of skin marks for both supine and prone setups. Under bony alignment, the dose coverage and PTV overlap index for prone setup were statistically better than for supine setup, illustrating a more consistent geometric relationship between the prostate and the pelvic bony structures when patients were treated in the prone position.
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Comparative Study
MRI-based preplanning in low-dose-rate prostate brachytherapy.
To compare the dosimetric results between MRI-based and TRUS-based preplanning in permanent prostate brachytherapy, and to estimate the accuracy of MRI-based preplanning by comparing with CT/MRI fusion-based postimplant dosimetry. ⋯ Prostate volume estimation and DVH-related parameters in MRI-based preplanning were almost identical to TRUS-based preplanning. From the results of CT/MRI fusion-based postimplant dosimetry, MRI-based preplanning was therefore found to be a reliable and useful modality, as well as being helpful for TRUS-based preplanning. MRI-based preplanning can more accurately predict postimplant rectal dose than TRUS-based preplanning.
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Randomized Controlled Trial
A randomized comparison of interfraction and intrafraction prostate motion with and without abdominal compression.
To quantify inter- and intrafraction prostate motion in a standard VacLok (VL) immobilization device or in the BodyFix (BF) system incorporating a compression element which may reduce abdominal movement. ⋯ Intrafraction motion became the major source of error during radiotherapy after online correction of interfraction prostate motion. The addition of 120 mbar abdominal compression to custom pelvic immobilization influenced neither interfraction nor intrafraction prostate motion.