International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Comparative StudyPulsed brachytherapy: the conditions for no significant loss of therapeutic ratio compared with traditional low dose rate brachytherapy.
Pulsed brachytherapy consists of using a stronger radiation source than for traditional low dose-rate brachytherapy, but giving a series of short exposures of 10 to 30 min in every hour, to approximately the same total dose in the same overall time as with the low dose-rate. Calculations based on the linear quadratic model, in which the beta x dose squared component only is assumed to be repairable, and at a monoexponential rate, show that there is no significant loss of therapeutic ratio, defined as tumor damage for a given level of late damage. Some loss of therapeutic ratio would in principle be expected when dose rates are increased, but, in the presently proposed applications, there are so many small pulses (fractions at medium or low dose-rate) that even though repair is not usually complete between them, the relative increase of late damage (in units proportional to log cell kill) is less than 10% more than the increase of tumor damage, except in unlikely conditions that we define. Although these calculations suggest that pulsed brachytherapy should be safe for pulse repetition frequencies up to about 2 hr, using dose rates not exceeding about 3 Gy/hr, we discuss the radiobiological reservations and the limitations of such calculations.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Parameters predictive for complications of treatment with combined hyperthermia and radiation therapy.
Pretreatment and treatment related factors were reviewed for 996 hyperthermia sessions involving 268 separate treatment fields in 131 patients managed with hyperthermia for biopsy confirmed local-regionally advanced or recurrent malignancies to ascertain parameters associated with the development of complications. A subset of 249 fields were identified in which multipoint or mapped temperature data were available for at least one treatment session per field. A total of 198 fields involved superficially located tumors (less than or equal to 3 cm from the surface), whereas 51 fields involved more deeply located tumors. ⋯ The average of the maximum measured tumor temperature for fields without complications was 44.6 degrees C compared with 45.9 degrees C for fields with complications. The complication rate increased from 7.5% (9/120) in fields that received one or two hyperthermia treatments to 18.6% (24/129) in fields that received greater than two hyperthermia treatments. Multivariate logistic regression analyses revealed the best bivariate model predictive of the development of complications included average of the maximum tumor temperature and the number of treatments per field (p = 0.00012 for the bivariate model).(ABSTRACT TRUNCATED AT 400 WORDS)
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Microinvasive ductal carcinoma of the breast treated with breast-conserving surgery and definitive irradiation.
An analysis was performed of 39 consecutive women with microinvasive ductal carcinoma of the breast treated with breast-conserving surgery and definitive irradiation during the period 1977 to 1988. Microinvasive ductal carcinoma was defined as predominantly intraductal carcinoma with microscopic or early invasion. Surgical treatment of the primary tumor included excisional biopsy or wide resection. ⋯ Comparison of the patients with microinvasive ductal carcinoma with two control groups of intraductal carcinoma and invasive ductal carcinoma was performed. Although the rate of local failure was significantly higher for patients with microinvasive ductal carcinoma as compared to the two control groups, the rates of survival and freedom from distant metastases for patients with microinvasive ductal carcinoma were intermediate to the two control groups. Because of the high rates of survival and freedom from distant metastases and because of the ability to salvage patients with local recurrence, breast-conserving surgery and definitive irradiation should continue to be considered as an alternative to mastectomy for appropriately selected and staged patients with microinvasive ductal carcinoma of the breast.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Interstitial brachytherapy for newly diagnosed patients with malignant gliomas: the UCSF experience.
Although interstitial brachytherapy appears to be effective in treating recurrent malignant gliomas, it has been studied less extensively in patients with newly diagnosed tumors. To examine the effect of this treatment when used at the time of primary diagnosis, we retrospectively reviewed the records of 88 patients who received temporary interstitial implants of 125I for newly diagnosed malignant gliomas. This brachytherapy was preceded by a course of external radiation therapy and followed, in some cases, by chemotherapy. ⋯ Our results support the conclusion that interstitial brachytherapy used at the primary diagnosis lengthens survival in selected patients with glioblastoma multiforme. However, the toxicity is significant in terms of the need for surgical resection of symptomatic necrosis. In patients with anaplastic gliomas, the toxicity associated with the treatment probably outweighs its advantages.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Recent patterns of growth in radiation therapy facilities in the United States: a patterns of care study report.
The Patterns of Care Study conducted its seventh survey of radiation oncology facilities with megavoltage equipment. The aims were to identify the basic structural characteristics of the radiation oncology specialty, to allow comparison with previous surveys, to identify trends in the patterns of equipment and personnel usage, and to measure the capabilities of facilities to deliver modern radiotherapy. All radiation oncology facilities in the United States and Puerto Rico were surveyed. ⋯ The results also showed that 6% of facilities did not have the capability of simulating patients and 7% of facilities did not have treatment planning capability. Of all facilities 9% reported doing intraoperative radiation therapy and 18% doing hyperthermia. For recent years in the specialty of radiation oncology the number of facilities and treatment machines increased at a more rapid rate than the number of new patients.