From 1971 to 1990, sixteen patients with craniopharyngioma were treated by postoperative radiotherapy (RT). Fourteen patients underwent partial removal and RT as primary treatment. In two patients, partial removal and RT were performed for treatment of recurrence after total removal. Total dose was between 40 Gy to 60 Gy. Five year survival and 5-year relapse free rates after RT were 100% and 71.7%, respectively. Computed tomography raised suspicion of radiation necrosis in two patients, each treated with two opposing lateral ports. The following hormonal replacements were needed: adrenal in 73% of the patients, thyroid in 66%, growth hormone in 50% of the children, and antidiuretic homrone in 21%. The amounts of thyroid and adrenal hormones for substitution have increased gradually with elapsed time after RT. To minimize these complications and to achieve tumor control, a multiport technique including radiosurgery, and a total dose of 50-55 Gy with 2 Gy per fraction is suggested to be optimal.

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Twenty-eight patients with brain metastases received brain radiotherapy with a total dose of 48 Gy, at 2 Gy per fraction, twice a day with a minimum interfractional period of 4 hours, and 5 days per week. This was intended to shorten the treatment period without increasing the morbidity, since most of these patients had a limited survival expectancy. Twenty-six of the 28 patients completed the radiotherapy. Three of the 26 patients experienced nausea and/or vomitting during the treatment. Radiotherapy was interrupted in two patients: one developed hemiplegia, and the other somnolence, both of which resulted from the progressive intracerebral disease. This radiotherapy regimen appears to be comparable to the conventional scheme in alleviation of symptoms. No patient needed interruption of the planned course of treatment because of acute irradiation toxicity. Based on theses results, a multi-institutional randomized trial has been initiated to compare the twice-a-day an once-a-day radiotherapy schemes on patients with brain metastases.

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Between 1971 and 1991, 66 patients with squamous cell carcinoma of the hypopharynx were treated with irradiation. Two patients with T1NOMO were treated with local irradiation alone; the primary sites were controlled, but epi-, oropharyngeal metastasis occurred in one of the patients. In the 30 patients without nodal disease, the nodal recurrent free rates of 6 patients who received prophylactic neck irradiation and 9 patients who did not were 100% and 55.5%, respectively (p<0.05). In 36 patients with nodal disease, the 3-year nodal control rates of 18 patients who received neck dissection and neck irradiation for the lesions and 18 patients who received neck irradiation alone were 55.7% and 17.7%, respectively (p<0.05). All the nodal relapses (5 patients) occurred in low dose areas (under 45 Gy). Thirty-three patients were controlled in primary sites, and 13 patients received prophylactic irradiation with a large field encompassing the epi-, oropharynx. In these 13 patients, no metastasis of epi-, oropharynx was seen. It seems that a dose of over 45 Gy with large fields encompassing the epi-, oropharynx and supraclavicular fossa may reduce the recurrence rates of hypopharyngeal carcinoma.

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A set of applicator units for intraoperative electron beam irradiation has been developed, and is utilized for clinical practice. The applicator system includes a lead tube, a lead containing acrylic cone, and attachment devices. The lead tube is attached to a commercially available electron tube, and the acrylic cone is placed at the tip of the lead tube for better visualization of treatment fields. Measurements before clinical applications revealed that the system provides clinically acceptable dose distribution for intraoperative electron beam irradiation. Clinical utilization suggests the following advantages of theapplicator: 1) Sterilization is easy. 2) It is inexpensive and easy to handle. 3) Treatmentfi elds are clearly visualized using endoscopy. The acrylic cone is useful to verify relations between treatment fields and outer structures. 4) It is safe since collision inter-locking is available.

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Relations between the radiosensitizing effect of the hypoxic radiosensitizer, RP-170, and its intratumoral concentration when injected intratumoral-intratumorally or intraperitoneally, was studied in Lewis lung carcinoma. Intratumoral injection of 400 mg/kg of RP-170 5 min before irradiation had a greater radiosensitizing effect on subcutaneous tumors than intraperitoneal injection 30 min before irradiation. In intramuscular tumors, the effect of the drug injected intraperitoneally 30 min before irradiation was larger than that injected intratumorally 5 min before irradiation, and the same as that of RP-170 injected intratumorally 30 min before irradiation. Intratumoral concentration of the drug injected intratumorally had higher mean values with larger deviation than that injected intraperitoneally. The drug concentration in tumors was only 0.5% of the dose administered 10 minafter intratumoral injection and the concentrations 10 min and 30 min after injection were not different. The sensitizing effect on post-irradiated tumors was not so much different from that on non-irradiated tumors for either route of administration, even though the drug concentrations in the tumors were much different. Although epinephrine reduced the radiation effect when injected intratumorally, it inhibited the efflux of intratumorally injected sensitizer from the tumors, so the sensitizing effect with epinephrine was the same as that without. Thus, between its radiosensitizing effect and intratumoral concentration were poorly correlated. This indicates that other factors, such as blood supply, presence of hypoxic cells, and diffusion of the drug in tumors, are related to the radiosensitizing effect. Limited diffusion and easy efflux of drugs injected intratumorally are discussed. We conclude that intratumoral injection of hypoxic radiosensitizer is useful for some tumors, especially tumors with low blood flow.

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A megavoltage X-ray CT scanner has been devoloped in our department. Clinicalapplication of the system for positioning verification was investigated. Megavoltage X-ray CT scanning was performed in treatment position just prior to irradiation. The patient's positioning was verified by comparing the megavoltage X-ray CT section with diagnostic CT slices used for treatment planning. Contours of the anatomical structures on the diagnostic CT section at the isocenter level were traced and then superimposed onto the megavoltage X-ray CT section for quantitative comparison on the axial plane. Superimposition was done by moving the traced contours in parallel such that the isocenter on the diagnostic CT coincided with the image center of the megavoltage X-ray CT. Clinical application of this method in 15 cases suggested good prospects for the system.

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