International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Significant correlation between rectal DVH and late bleeding in patients treated after radical prostatectomy with conformal or conventional radiotherapy (66.6-70.2 Gy).
Investigating the correlation between dosimetric/clinical parameters and late rectal bleeding in patients treated with adjuvant or salvage radiotherapy after radical prostatectomy. ⋯ DVHs of the rectum are significantly correlated with late bleeding for patients irradiated at 66.6-70.2 Gy after radical prostatectomy.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Biologically effective dose (BED) for interstitial seed implants containing a mixture of radionuclides with different half-lives.
To develop a tool for evaluating interstitial seed implants that contain a mixture of radionuclides with different half-lives and to demonstrate its utility by examining the clinical implications of prescribing to an isodose surface for such an implant. ⋯ Total dose alone is no longer sufficient for a complete characterization of a permanent seed implant containing a mixture of radionuclides with different half-lives due to the presence of cell proliferation and sublethal damage repair in the protracted dose delivery. BED provides a tool for evaluating the radiobiologic effects of mixing different type of radionuclides in the same implant. When radionuclides of different half-lives are mixed in a permanent implant, using the dose prescription established from existing clinical experience of implants with the longer half-life radionuclide would help to avoid radiobiologic "cold" spots.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Multicenter Study Comparative StudyComparing different NTCP models that predict the incidence of radiation pneumonitis. Normal tissue complication probability.
To compare different normal tissue complication probability (NTCP) models to predict the incidence of radiation pneumonitis on the basis of the dose distribution in the lung. ⋯ The maximum likelihood method revealed that the underlying local dose-effect relation for radiation pneumonitis was linear (the MLD model), rather than a step function (the V(Dth) model). Thus, for the studied patient population, the MLD was the most accurate predictor for the incidence of radiation pneumonitis.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Procedures for high precision setup verification and correction of lung cancer patients using CT-simulation and digitally reconstructed radiographs (DRR).
In a recent study, large systematic setup errors were detected in patients with lung cancer when a conventional simulation procedure was used to define and mark the treatment isocenter. In the present study, we describe a procedure to omit the session at a conventional simulator to remove simulation errors entirely. Isocenter definition and verification was performed at a computed tomography (CT) simulator, and digitally reconstructed radiographs (DRRs) were used for setup verification and correction at the treatment unit. ⋯ Because the distributions of treatment setup errors measured against DRRs obtained in our CT simulation were equal to previously obtained distributions measured against simulator films, conventional simulation can be omitted and DRRs are well-suited for setup verification. By adopting our CT simulation procedure, the large systematic simulation setup errors, which remain hidden if a conventional simulation is performed, can be avoided.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2003
Megavoltage cone-beam computed tomography using a high-efficiency image receptor.
To develop an image receptor capable of forming high-quality megavoltage CT images using modest radiation doses. ⋯ The acquisition of megavoltage CT images with soft-tissue contrast is possible with irradiations as small as 16 cGy.