[en] The present experimental study has been designed and carried out to investigate the effects of various doses and timings of fractionated irradiation of 6 MV X-rays obtained from a linear accelerator on sarcoma 180 solid tumors produced in DDO/Lee mouse. A total of 2700 to approx. 2800 cGy(or rad) was delivered with daily dose of 250/ cGy, 350cGy, and 450cGy every other day to the inoculated site starting on day 2,4,6, and 8 post-inoculation and the tumor size change was observed by measuring a maximum circumference of tumor bearing region. The dose experimentally established in the mouse for one half of animals to produce a solid tumor (TSD₅₀) from ascitic mouse sarcoma 180 was 10/sup 3.87/ cells/ml. The effect of fractionated irradiation on days 2 and 4 post-inoculation was inhibitory to the growth of solid form tumor of experimentally produced sarcoma 180 (p<0.001). The growth of tumor was also inhibited when irradiated on days 6 and 8 post-inoculation but the grade was less. Histologically tumor cells of mouse sarcoma 180 produced in the experimental animal were shown to be destroyed and eradicated by radiation once they were responsive to X-irradiation. The present study suggests that a small or early tumor is benefitted by a small daily dose(e.g. 250 cGy) irradiation whereas a moderately advanced tumor is beneficially treated with a relatively high dose (e.g. 450 cGy) irradiation. A large tumor responded very poorly to irradiation

[en] One hundred and thirty three patients were given radiotherapy after subtotal resection of glioblastoma with different total doses and fractionation schedules including 38 patients receiving continuous accelerated fractionation with 3 fractions of 1.6 Gy per day up to 60 Gy in 2 weeks. Tolerance of the accelerated schedule was as good as of the conventional schedules but overall survival was not improved. 10 refs.; 4 figs.; 4 tabs

[en] Fraction size in radiotherapy of malignant melanoma remains a point of controversy. Among 139 patients treated at the University of Illinois Hospital in 1979-1988, 36 were considered potentially curable (not counting ocular melanomas); 20 were treated by the Princess Margaret Hospital (PMH) hypofractionated schedule using 800 cGy per fraction and achieved a permanency of local control lasting > 6 months since the beginning of radiotherapy in 10/22 (45.5%) courses. Comparable results were obtained in 11 patients treated by standard fractionation to at least threshold curative levels. A modification of PMH regimen in 5 patients (but with 13 courses) by decreasing fraction size to 400 cGy while keeping total dose and course duration unchanged, resulted in a 100% loss of focal control within 6 months. Patients considered incurable and irradiated by PMH schedule responded in 83% of courses compared to 51.4% response rate in patients irradiated with other schedules (except) modified PMH regimen). Other aspects of melanoma management are analyzed. (author) 12 tabs., 3 figs., 32 refs

[en] Background and purpose: Single fraction radiation treatment (SFRT) is recommended for its equivalence to multiple-fraction (MF) RT in the palliation of uncomplicated bone metastases (BM). However, adoption of SFRT has been slow. Materials and methods: Literature searches for studies published following 2014 were conducted using online repositories of gray literature, Ovid MEDLINE, Embase and Embase Classic, and the Cochrane Central Register of Controlled Trials databases. Results: A total of 32 articles detailing patterns of practice and clinical practice guidelines were included for final synthesis. The majority of organizations have released high level recommendations for SFRT use in treatment of uncomplicated BM, based on evidence of non-inferiority to MFRT. There are key differences between guidelines, such as varying strengths of recommendation for SFRT use over MFRT; contraindication in vertebral sites for SFRT; and risk estimation of pathologic fractures after SFRT. Differences in guidelines may be influenced by committee composition and organization mandate. Differences in patterns of practice may be influenced by individual center policies, payment modalities and consideration of patient factors such as age, prognosis, and performance status. Conclusion: Although there is some variation between groups, the majority of guidelines recommend use of SFRT and others consider it to be a reasonable alternative to MFRT.

[en] To determine the safety and effectiveness of accelerated hyperfractionated radiotherapy in the treatment of supratentorial malignant astrocytomas. Between June 1995-July 1997, 75 patients were enrolled to a prospective phase 11 study. A total dose of 60 Gy was delivered in 2 Gy b.i.d. fractions with an interval of 6-8 h, 5 days per week, in an overall time of 3 weeks. The treatment protocol was planned to give 40 Gy to a treatment volume covering the contrast-enhancing lesion and oedema (+ 3-cm margin) and additional 20 Gy to the volume encompassing the contrast-enhancing lesion alone with a 1-cm margin based on preoperative magnetic resonance imaging and/or CT findings. The patients had a median age of 46 years and a median Karnofsky performance status score of 80. Histology consisted of anaplastic astrocytoma (AA) in 16 (21%) and glioblastoma multiforme (GBM) in 59 (79%) patients. Median survival was 11 months for all patients; 10 months for GBM patients and 40 months for AA patients. Survival rates at 1 and 3 years were 41 %, 11% for all patients; 62, 37% for AA patients and 35, 6% for GBM patients, respectively. Multivariate analysis revealed significant impact of age, histology and neurological functional class on survival. The incidence of grade 3 or worse late neurological toxicity was 5.3%. Although accelerated hyperfractionated radiotherapy showed no significant advantage on survival, it shortened the treatment period from 6 to 3 weeks. Radiotherapy was well tolerated and the incidence of late toxicity is acceptable. (author)

[en] Purpose. To analytically investigate the possibility of a parameter invariant ranking of radiotherapy (RT) plans based on comparing the tumor control probabilities (TCPs) produced by the competing plans for different values of the radiobiological model parameters determining the radiation response. Method. Individual TCP models based on the Single hit model of cell kill and on the linear-quadratic (LQ) model of cell damage, with and without repopulation, are considered. The tumor dose distributions in case of heterogeneous dose irradiation are described by a Gaussian distribution function on the basis of which a TCP expression is derived depending only on the mean dose to the tumor and its standard deviation and the TCP model parameters. Results. It is shown that in case of homogeneous dose to the tumor the plan ranking in terms of TCP is parameter invariant. In case of heterogeneous dose to the tumor there are cases when the plan ranking is parameter invariant and cases when the parameter invariance is violated. An interesting dependence of the extent of the parameter invariance violation on the model of cell kill as well as on the size and repopulation rate of the tumor is noted. Conclusion. We conclude that in many cases RT plan ranking in terms of TCP is parameter invariant. However, since there exist cases where the parameter invariance is lost an investigation of the specific plans to be ranked should be performed applying the proposed approach

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[en] Proton treatment slots are a limited resource. Therefore, we consider combined proton–photon treatments in which most fractions are delivered with photons and only a few with protons. We demonstrate how both modalities can be combined to optimally capitalize on the proton’s ability to reduce normal tissue dose.

No abstract available