International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Nov 2004
Comparative StudyDose conformation of intensity-modulated stereotactic photon beams, proton beams, and intensity-modulated proton beams for intracranial lesions.
This study evaluates photon beam intensity-modulated stereotactic radiotherapy (IMSRT) based on dynamic leaf motion of a micromultileaf collimator (mMLC), proton beams, and intensity-modulated proton therapy (IMPT) with respect to target coverage and organs at risk. ⋯ The addition of intensity modulation improves the conformality of mMLC-based SCRT. Conformation of dose to the PTV is comparable for IMSRT, protons, and IMPT. Concerning the sparing of OAR, IMSRT is equivalent to IMPT, and IMPT is superior to conventional protons. The advantage of protons lies in the lower integral dose.
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Int. J. Radiat. Oncol. Biol. Phys. · Nov 2004
Development of methods for beam angle optimization for IMRT using an accelerated exhaustive search strategy.
The purpose of this article is to explore the use of the accelerated exhaustive search strategy for developing and validating methods for optimizing beam orientations for intensity-modulated radiation therapy (IMRT). Combining beam-angle optimization (BAO) with intensity distribution optimization is expected to improve the quality of IMRT treatment plans. However, BAO is one of the most difficult problems to solve adequately because of the huge hyperspace of possible beam configurations (e.g., selecting 7 of 36 uniformly spaced coplanar beams would require the intercomparison of 8,347,680 IMRT plans). ⋯ Exhaustive search with fast IMRT algorithms provides a novel and realistic approach to study the characteristics of IMRT dose distributions as a function of beam angles and to design practical BAO strategies for IMRT planning.
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Int. J. Radiat. Oncol. Biol. Phys. · Nov 2004
Both pretreatment prostate-specific antigen level and posttreatment biochemical failure are independent predictors of overall survival after radiotherapy for prostate cancer.
To assess the impact of pretreatment prognostic factors plus subsequent biochemical failure on overall survival after radiotherapy for prostate cancer. ⋯ In addition to previously identified factors, the pretreatment PSA level and occurrence of biochemical failure after radiotherapy for prostate cancer are associated with an increased overall mortality risk. Both pretreatment PSA level and posttreatment biochemical failure are independent predictors of overall survival after radiotherapy for prostate cancer.
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Int. J. Radiat. Oncol. Biol. Phys. · Nov 2004
Long-term results using local excision after preoperative chemoradiation among selected T3 rectal cancer patients.
To assess the pelvic failure among patients with T3 rectal cancer treated with local excision after preoperative chemoradiation. ⋯ In an experience stimulated by patient refusal of APR, highly selected patients who responded well to conventional external-beam radiotherapy (CXRT) were selected to undergo local excision. Most of these patients had pathologic complete response. Local control and survival rates are comparable to those achieved with chemoradiation followed by mesorectal excision. This strategy should be prospectively studied in a group of patients with low rectal cancer who have no clinical evidence of tumor after chemoradiation.
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Int. J. Radiat. Oncol. Biol. Phys. · Nov 2004
Rectal bleeding after hypofractionated radiotherapy for prostate cancer: correlation between clinical and dosimetric parameters and the incidence of grade 2 or worse rectal bleeding.
To investigate the incidence and severity of rectal bleeding after high-dose hypofractionated radiotherapy (RT) for prostate cancer, and to explore the factors affecting the incidence of Grade 2 or worse rectal bleeding. ⋯ A history of diabetes mellitus was the most statistically significant risk factor for the occurrence of Grade 2 or worse rectal bleeding after high-dose hypofractionated RT, although dosimetric factors were also closely associated with the risk of rectal bleeding.