International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2001
Analysis and reduction of 3D systematic and random setup errors during the simulation and treatment of lung cancer patients with CT-based external beam radiotherapy dose planning.
To determine the magnitude of the errors made in (a) the setup of patients with lung cancer on the simulator relative to their intended setup with respect to the planned treatment beams and (b) in the setup of these patients on the treatment unit. To investigate how the systematic component of the latter errors can be reduced with an off-line decision protocol for setup corrections. ⋯ Setup errors at the simulator, which become systematic errors if the simulation defines the reference setup, were comparable to the systematic setup errors at the treatment unit in case no off-line protocol would have been applied. Hence, the omission of a separate simulation step can reduce systematic errors as efficiently as the application of an off-line correction protocol during treatment. The random errors were sufficiently small to make an off-line protocol feasible.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2001
Late rectal bleeding after conformal radiotherapy of prostate cancer. II. Volume effects and dose-volume histograms.
Late rectal bleeding is a potentially dose limiting complication of three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. The frequency of late rectal bleeding has been shown to increase as the prescription dose rises above 70 Gy. The purpose of this study is to identify features of the cumulative dose-volume histogram (DVH) for the rectal wall that correlate with late rectal bleeding after 3D-CRT for prostate cancer. ⋯ Significant volume effects were found in the probability of late rectal bleeding for patients undergoing 3D-CRT for prostate cancer with prescription doses of 70.2 and 75.6 Gy. The percent volumes exposed to 71 and 77 Gy in the 70.2 and 75.6 Gy dose groups respectively were significantly correlated with rectal bleeding. The independent correlation of small V(RW) with rectal bleeding may indicate the existence of a functional reserve for the rectum. The independent association with larger percent volumes exposed to intermediate doses ( approximately 46 Gy) seen in both dose groups may indicate that a large surrounding region of intermediate dose may interfere with the ability to repair the effects of a central high dose region.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2001
Evaluation of the safety and efficacy of repeated sedations for the radiotherapy of young children with cancer: a prospective study of 1033 consecutive sedations.
A prospective observational study to examine our current practice of either conscious sedation (C.S.) or general anesthetic (G.A.) for children undergoing radiation therapy (we use the term sedation to include both C.S. and G.A.). Specifically, the study examines the reasons for selection of patients, choice of drugs, safety and effectiveness of the procedure, side effects of repeated daily sedation, and compliance of the family with the regimen. ⋯ In this study, there were no serious complications of sedation in 1033 procedures. As a result of the study, we developed improved methods for better preparation of the patient and family to try to reduce the need for sedation, and reduce the indications for C.S., while confirming the safety and efficacy of a G.A. with propofol for children needing sedation for daily radiation therapy.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2001
Complications and patient satisfaction following expander/implant breast reconstruction with and without radiotherapy.
To compare the rates of complications and patient satisfaction among breast cancer patients treated with mastectomy and tissue expander/implant reconstruction with and without radiotherapy. ⋯ Irradiated patients had a higher rate of expander/implant reconstruction failure and complications than nonirradiated patients. Despite these differences, our pilot data suggest that both general satisfaction and patient esthetic satisfaction were not significantly different following radiotherapy compared to patients who did not receive RT. Although statistical power was limited in the present study and larger patient numbers are needed to validate these results, this study suggests comparable patient assessment of cosmetic outcome with or without radiotherapy in women who successfully complete expander/implant reconstruction.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2001
Portal imaging for evaluation of daily on-line setup errors and off-line organ motion during conformal irradiation of carcinoma of the prostate.
To use portal imaging to measure daily on-line setup error and off-line prostatic motion in patients treated with conformal radiotherapy to determine an optimum planning target volume (PTV) margin incorporating both setup error and organ motion. ⋯ Taking into account both setup errors and target organ motion, optimum PTV margins to ensure 95% coverage are 10.0 mm AP and 5.9 mm SI. The portal imaging protocol established in this study allows radiation therapists to accept or adjust a treatment setup based upon daily on-line image matching results. The successful localization of radiopaque fiducial markers on a significant number of portal images acquired in the study gives hope that more accurate on-line targeting verification may soon be possible through the visualization of the prostate itself as opposed to the surrounding bony structures of the pelvis.