International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Oct 2005
Effect of patient setup errors on simultaneously integrated boost head and neck IMRT treatment plans.
The purpose of this study is to determine dose delivery errors that could result from random and systematic setup errors for head-and-neck patients treated using the simultaneous integrated boost (SIB)-intensity-modulated radiation therapy (IMRT) technique. ⋯ Head-and-neck SIB-IMRT dosimetric accuracy would benefit from methods to reduce patient systematic setup errors. When GTV, CTV, or nodal volumes are used for dose evaluation, plans simulated including the effects of random and systematic errors deviate substantially from the nominal plan. The use of PTVs for dose evaluation in the nominal plan improves agreement with evaluated GTV, CTV, and nodal dose values under simulated setup errors. PTV concepts should be used for SIB-IMRT head-and-neck squamous cell carcinoma patients, although the size of the margins may be less than those used with three-dimensional conformal radiation therapy.
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Int. J. Radiat. Oncol. Biol. Phys. · Oct 2005
Comparative StudyProton beam radiotherapy versus fractionated stereotactic radiotherapy for uveal melanomas: A comparative study.
A comparative treatment planning study was undertaken between proton and photon therapy in uveal melanoma to assess the potential benefits and limitations of these treatment modalities. A fixed proton horizontal beam (OPTIS) and intensity-modulated spot-scanning proton therapy (IMPT), with multiple noncoplanar beam arrangements, was compared with linear accelerator-based stereotactic radiotherapy (SRT), using a static and a dynamic micromultileaf collimator and intensity-modulated RT (IMRS). ⋯ These results suggest that the use of SRT photon techniques, compared with protons, can result in similar levels of dose conformation. IMPT did not increase the degree of conformality for this small tumor. Tumor dose inhomogeneity was, however, always increased with photon planning. Except for the lacrimal gland, the use of protons, with or without intensity modulation, did not increase homolateral OAR dose sparing. The dose to all the contralateral OARs was, however, completely eliminated with proton planning.
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Int. J. Radiat. Oncol. Biol. Phys. · Oct 2005
Dose-volume based ranking of incident beam direction and its utility in facilitating IMRT beam placement.
Beam orientation optimization in intensity-modulated radiation therapy (IMRT) is computationally intensive, and various single beam ranking techniques have been proposed to reduce the search space. Up to this point, none of the existing ranking techniques considers the clinically important dose-volume effects of the involved structures, which may lead to clinically irrelevant angular ranking. The purpose of this work is to develop a clinically sensible angular ranking model with incorporation of dose-volume effects and to show its utility for IMRT beam placement. ⋯ The EUD-based function is a general approach for angular ranking and allows us to identify the potentially good and bad angles for clinically complicated cases. The ranking can be used either as a guidance to facilitate the manual beam placement or as prior information to speed up the computer search for the optimal beam configuration. Thus the proposed technique should have positive clinical impact in facilitating the IMRT planning process.
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Int. J. Radiat. Oncol. Biol. Phys. · Oct 2005
Prostate-specific antigen doubling time predicts clinical outcome and survival in prostate cancer patients treated with combined radiation and hormone therapy.
To determine whether prostate-specific antigen (PSA) doubling time predicts clinical outcomes in patients with prostate cancer that has been treated with combined radiation and hormone therapy. ⋯ In men with prostate cancer that has been treated with combined hormone and radiation therapy, a posttreatment PSADT of < or =8 months is associated with worse clinical outcomes and may be an early surrogate marker for decreased survival. These patients should be considered for more aggressive salvage therapy protocols.
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Int. J. Radiat. Oncol. Biol. Phys. · Oct 2005
Intensity-modulated radiation treatment for head-and-neck squamous cell carcinoma--the University of Iowa experience.
To review the University of Iowa experience with intensity-modulated radiotherapy (IMRT) in the treatment of head-and-neck squamous cell carcinoma. ⋯ Our results have confirmed the effectiveness of IMRT in head-and-neck cancer. It offers excellent outcomes in local-regional control and overall survival. More studies are necessary to further improve the outcomes of laryngeal cancer as well as oral cavity cancer.