[en] Based on the LQ model examples of biologically equivalent doses LDR, HDR and external beams were calculated. The biologically equivalent doses for LDR were calculated by appending to the LQ model the corrector for the time of repair of radiation sublethal damages. For radiation continuously delivered at a low dose rate the influence of sublethal damage repair time changes on biologically equivalent doses were analysed. For fractionated treatment with high dose rate the biologically equivalent doses were calculated by adding to the LQ model the formula of accelerated repopulation. For total biologically equivalent dose calculation for combine LDR-HDR-Tele irradiation examples are presented with the use of different parameters of the time of repair of sublethal damages and accelerated repopulation. The calculations performed show, that the same biologically equivalent doses can be obtained for different parameters of cell kinetics changes during radiation treatment. It also shows, that during biologically equivalent dose calculations for different radiotherapy schedules, ignorance of cell kinetics parameters can lead to relevant errors

[en] Hundred twenty seven patients with carcinoma of the middle segment of the larynx were treated at the Institute of Oncology in Gliwice between 1970 and 1979. Advanced neoplastic process was diagnosed in 77% of the patients. Thirty five percent of the patients were over sixty. Irradiation dose of ⁶⁰Co was 60-65 Gy. Three-year survival period without the symptoms of carcinoma was achieved in 41% of patients at the early stage of the disease. Fourteen percent of the patients died within 3 years due to other causes. In 5 patients the radiation injuries were observed. Local advancement of carcinoma and extensive metastases into the lymphatic nodes in the neck worsen prognosis. 11 refs., 4 tabs. (author)

[en] The importance of measurements of the potential doubling time (T_pot.) and of the survival fraction at 2.0 Gy (SF₂), and a method modifying acute radiation response of normal oral mucosa are discussed. Tumor clonogen repopulation accelerates around day 28 of the treatment, and the rate of repopulation is not constant but continuously increases from about 0.3 Gy/day to 1.0-1.3 Gy/day between day 28 and 65 of the treatment. This may suggest that T_pot. values decrease correspondingly. The relevance of prior-to-treatment T_pot. measurements to clinical situations is discussed. The SF₂ value reflects the intrinsic radiosensitivity of human tumors. The SF₂ values are expected to be valuable as predictors for tumor response to irradiation. Variations in the SF₂ values depending on tumor characteristics and assay methods are discussed in relation to the dose response and tumor cure probability. The effect of modifying the repopulation rate in the oral mucosa by stimulation with a 2% silver nitrate solution is discussed. Although these prognosticators are different in their nature, they might provide a rational basis for selecting patients into optimal irradiation treatment and might allow to modify the radiation response of dose-limiting normal tissues. (author). 5 figs., 1 tab., 28 refs

No abstract available

[en] Short communication

[en] The aim of this study was to evaluate radiosensitizing effect of normobaric oxygen breathing in radiotherapy for advanced head and neck cancers. Forty seven patients with advanced squamous cell carcinomas of the head and neck (7% in Stage III and 93% in Stage IV) were entered in the study. Breathing the pure, normobaric oxygen was given for 15-20 min in the treatment room. Irradiation started immediately after oxygen breathing. Conventional, megavoltage radiotherapy to the total doses in the range of 46-67.5 Gy was used. The control group was 46 patients with the same diagnosis and stage treated by radiotherapy alone. Locoregional tumor control was 36 % in the study group compared to 15 % in the control (p<0.05). Mean survival time was 15.8 and 11.8 months, and 3-year survival was 19 % and 2 %, respectively (p<0.05). Survival depended on total tumor dose and total nodal dose. No significant influence of the tumor location on local control and importance of the size of dose per fraction and overall treatment time were found. The most common failure in both groups was persistent tumor. Mean recurrence time was 5 months in the study group and 8 months in the control. Present results suggest that the use of normobaric oxygen breathing prior to irradiation could increase effectiveness of conventional radiotherapy for advanced squamous cell carcinomas of head and neck.(author)

[en] The ROC (receiver operating characteristic) analysis of optimization of radiation treatment of cancer of oral cavity was carried out. Material of 210 patients with squamous cell carcinoma of the oral cavity was included into the study. Based on dose-response curves for tumor and late mucosal reactions, iso-utility curves and optimal k values were estimated. Optimal k values decreased from 0.792 to 0.584 with extension of overall treatment time from 35 to 49 days. This may suggest that the planning of additional dose to compensate tumor clonogens repopulation during prolonged treatment does not improve the therapeutic gain in radiotherapy for cancer of the oral cavity. The ROC is a useful model to estimate the optimal radiation treatment for a given tumor because it is independent of any arbitrary consensus or theoretical assumption. (author) 1 tab., 3 figs., 5 refs

No abstract available

[en] Theoretical bases and method of the ROC model (receiver operating characteristic) for optimalization in radiotherapy for human tumours are presented. Clinical data on laryngeal cancer T_3-4 published by Overgaard and Maciejewski were used to estimate iso-utility carves and k values. For T_3-4 laryngeal cancer k value was 0.77 for 42 days and 0.5 for 70 days of overall treatment time. These values correspond with total dose of 65 Gy, and 70 Gy respectively. Practical use of the ROC model needs precise and quantitative clinical data. (author)

[en] The ROC model is used to estimate optimal radiation treatment for cancer of the oral cavity. For 210 patients with cancer of the oral cavity iso-utility curves and k values were determined for various tumors stages and overall treatment times. Optimal k value decreases from 0.792 to 0.584 when overall treatment time is prolonged from 35 to 49 days. It may suggest that the planning of extra dose to balance the effect of extension of overall treatment time does not really improve therapeutic gain. (author)