International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1997
Transperineal ultrasound-guided radioactive seed implantation for organ-confined carcinoma of the prostate.
This retrospective study was undertaken to: (a) determine the prognostic significance of pretreatment and 1-year nadir serum prostate specific antigen (PSA) levels in organ-confined carcinoma of the prostate treated with ultrasound-guided radioactive 125I seed implantation; (b) determine the factors associated with postimplant morbidity and whether modification of the technique would reduce morbidity; (c) evaluate the local control rate and disease-free survival of patients undergoing seed implantation. ⋯ Ultrasound-guided radioactive seed implantation provides excellent local control of 97%, with a median 30 month follow-up. Morbidity is comparable to other curative modalities and by modifying Blasko's technique to reduce radioactive seed strength in the periurethral area, significant morbidity is rare. Pretreatment PSA and the nadir PSA at 1 year are important predictors of subsequent disease outcome. With a liberal definition of systemic recurrence as two consecutive increases in PSA levels, the 5-year disease-free survival is 76%.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1997
Effect of low-density lateral interfaces on soft-tissue doses.
Doses at the interface between tissue and low-density inhomogeneities with the interface positioned perpendicular to the beam direction have been well studied. When the inhomogeneity lies parallel to the beam direction (i.e., a lateral interface), the resulting dose distribution is not as well known. Lateral lung-soft-tissue interfaces are common in many fields used to treat malignancies in the thorax region including tangential breast fields and anteroposterior fields for lung and esophageal cancer. The purpose of this study was to evaluate the dose distribution along lateral interfaces and to determine the implications for treatment. ⋯ Underdosing will occur in the soft tissues adjacent to low-density inhomogeneities. The magnitude depends primarily on the width of the inhomogeneity seen in the treatment field, but also on field size, depth, and beam energy. For treatment fields with a lateral lung interface, a segment of tissue approximately 3-4 mm thick for 6 MV and 6-7 mm thick for higher-energy beams may be underdosed. Lung widths of > or = 1.75 cm as observed on film will generally guarantee doses of at least 96% of those calculated with no inhomogeneity corrections. High-energy beams are often used to treat sites in the thorax or breast to improve dose homogeneity throughout the treatment volume. Potential underdosing due to the presence of lung should be considered and may require a decrease in beam energy or an increase in the margin between the target volume and the field edge to ensure adequate treatment.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1997
The effect of treatment positioning on normal tissue dose in patients with prostate cancer treated with three-dimensional conformal radiotherapy.
To prospectively assess the effect of supine vs. prone treatment position on the dose to normal tissues in prostate cancer patients treated with the three-dimensional conformal technique. ⋯ Three-dimensional conformal radiotherapy for prostate cancer in the prone position is associated with significant reduction of the dose to the rectum and bowel resulting in an improvement in the therapeutic ratio.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1997
Pulsed brachytherapy as a substitute for continuous low dose rate: an in vitro study with human carcinoma cells.
Pulsed dose rate (PDR) brachytherapy as a substitute for continuous low dose rate (CLDR) has the potential to be a useful option in brachytherapy. However, the frequency and duration of pulses that will produce results practically equivalent to CLDR is still an open and important question. This study was designed to compare the survival of human tumor cells, cultured in vitro, and exposed to continuous or pulsed irradiation where the pulse frequency was varied. ⋯ This study provides some evidence to support the suggestion that a 10-min pulse, repeated every 1 to 2 h, would be functionally equivalent to a continuous low dose rate irradiation, at least in terms of early responding endpoints. Longer intervals between pulses might result in loss of equivalence in some cases.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1997
A retrospective quality of life analysis using the Lung Cancer Symptom Scale in patients treated with palliative radiotherapy for advanced nonsmall cell lung cancer.
To measure symptom palliation in patients treated with radiation therapy for advanced nonsmall cell lung cancer (NSCLC). ⋯ These results suggest symptomatic benefit from radiotherapy even in those NSCLC patients with advanced disease and a limited life expectancy. Treatment should be given to patients whose symptoms are most amenable to palliation. A site-specific quality of life instrument such as the LCSS should be included within any future clinical trial of NSCLC management so that symptom control may be scored as a treatment outcome in addition to disease-free survival.