International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Apr 2002
Is uniform target dose possible in IMRT plans in the head and neck?
Various published reports involving intensity-modulated radiotherapy (IMRT) plans developed using automated optimization (inverse planning) have demonstrated highly conformal plans. These reported conformal IMRT plans involve significant target dose inhomogeneity, including both overdosage and underdosage within the target volume. In this study, we demonstrate the development of optimized beamlet IMRT plans that satisfy rigorous dose homogeneity requirements for all target volumes (e.g., +/-5%), while also sparing the parotids and other normal structures. ⋯ Sparing of both parotids in patients receiving bilateral neck radiation can be achieved without compromising strict target dose homogeneity criteria. The geometry of the normal tissue and target anatomy are shown to be the major factor necessary to predict the parotid sparing that will be possible for any particular case.
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Int. J. Radiat. Oncol. Biol. Phys. · Apr 2002
Dose optimization of fractionated external radiation and high-dose-rate intracavitary brachytherapy for FIGO stage IB uterine cervical carcinoma.
To determine the optimal dose combination scheme of external beam radiotherapy (EBRT) and high-dose-rate (HDR) intracavitary radiation (ICR) for maximizing tumor control while conferring an acceptable late complication rate in the treatment of Stage IB uterine cervical cancer. ⋯ In treating Stage IB carcinoma of the uterine cervix with HDR-ICR, using fractions of 3 Gy, it is crucial to keep the point A BED at
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Int. J. Radiat. Oncol. Biol. Phys. · Apr 2002
Dose-effect relationship for cataract induction after single-dose total body irradiation and bone marrow transplantation for acute leukemia.
To determine a dose-effect relationship for cataract induction, the tissue-specific parameter, alpha/beta, and the rate of repair of sublethal damage, mu value, in the linear-quadratic formula have to be known. To obtain these parameters for the human eye lens, a large series of patients treated with different doses and dose rates is required. The data of patients with acute leukemia treated with single-dose total body irradiation (STBI) and bone marrow transplantation (BMT) collected by the European Group for Blood and Marrow Transplantation were analyzed. ⋯ The alpha/beta value of 0.75 Gy and mu value of 0.65 h(-1) found for the eye lens are characteristic for late-responding tissues. The incidence of cataract formation can now be quantified, taking into account the values calculated for alpha/beta and mu, TBI dose, and dose rate. Also, the reduction in cataract incidence as a result of lens dose reduction by eye shielding can be estimated.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2002
Adjuvant irradiation for axillary metastases from malignant melanoma.
To evaluate the outcome and treatment-related toxicity for patients with axillary lymph node metastases from malignant melanoma treated with surgery and radiation, with or without systemic therapy. ⋯ Adjuvant radiation therapy using a hypofractionated regimen resulted in an 87% 5-year axillary control rate, superior to the 50-70% local control achieved with surgery alone for lymph node metastases from melanoma when high-risk features are present. Improvements are needed for patients with bulky nodal masses >6 cm in size. Mild-to-moderate arm edema was common, but manageable. The degree to which radiotherapy adds to the risk of arm edema after axillary dissection alone cannot be addressed in the present analysis.
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Int. J. Radiat. Oncol. Biol. Phys. · Mar 2002
Relationship between prostate volume, prostate-specific antigen nadir, and biochemical control.
In patients treated with definitive three-dimensional conformal radiotherapy (3D-CRT) for localized prostatic adenocarcinoma, we sought to evaluate the relationship between pretreatment prostate gland volume and posttreatment prostate-specific antigen (PSA) nadir, as well as the relationship of prostate volume and PSA nadir with biochemical control (bNED). Two subgroups were studied: favorable (PSA <10 ng/mL, Gleason score 2-6, and T1-T2A) and unfavorable (one or more: PSA >/=10 ng/mL, Gleason score 7-10, T2B-T3). ⋯ This report is the first demonstration that prostate volume is predictive of PSA nadir for patients who are bNED in both favorable and unfavorable subgroups. PSA nadir did not correlate with bNED status in the favorable patients, but it was strongly predictive in the unfavorable patients. Prostate gland volume was also predictive of bNED failure in the favorable but not the unfavorable group.