Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
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Comparative Study
A phase II trial for the optimisation of treatment position in the radiation therapy of prostate cancer.
Patient immobilisation and position are important contributors to the reproducibility and accuracy of radiation therapy. In addition the choice of position can alter the external contour of the treated area and has the potential to alter the spatial relationship between internal organs. The published literature demonstrates variation in the use of the prone and supine position for prostate cancer radiation therapy. Previous investigators using different protocols for patient preparation, imaging and target volume definition have demonstrated changes in the calculated therapeutic ratio comparing the two positions. We did not use rigid immobilisation, laxatives, rectal catheters or bladder voiding and assessed if in the prone position would cause a reduction of the dose to the rectum. We performed a prospective comparison of the two positions in 26 patients to determine if the differences in the spatial relation between the rectum and the planning target volume (PTV) would impact on dose-volume histograms to organs at risk (OAR). We also determined if any such improvement might permit dose escalation. ⋯ The use of the prone position reduced the dose to the unprepared rectum and unvoided bladder in the majority of cases. It should be considered particularly in cases where large posterior seminal vesicles cause significant overlap between the planning target volume and the rectum.
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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.
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To compare the dose coverage of planning and clinical target volume (PTV, CTV), and organs-at-risk (OAR) between intensity-modulated (3D-IMRT) and conventional conformal radiotherapy (3D-CRT) before and after internal organ variation in prostate cancer. ⋯ Dose coverage of the PTV and OAR was better with 3D-IMRT for each patient and remained so after internal volume changes.
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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.