Effect of a phantom motion on isodose curves during irradiation was examined. While a phantom made of Mix-Dp executed a reciprocating motion, isodose curves in the principal plane were obtained with a 10 MV linear-accelerator operating at a source to skin distance of 100 cm by the film method. The field size at the surface, and distance of the phantom motion were varied from 5×5 to 20×20 cm² and from 0 to 4.0 cm, respectively. The width of the field defined by 20, 50, and 80 per cent isodose curves was obtained at a depth of 5 cm in the direction of the phantom motion. The field size defined by an 80 per cent isodose curve decreased with increase of the phantom motion. The field size defined by a 20 per cent isodose curve increased. The ratio of field size defined by an 80 per cent isodose curve to that defined by a 50 per cent isodose curve decreased. The phantom motion had great effect when the field size was small and the motion was great. The result indicates that organ motion decreases the treatment volume and relatively increases exposure to surrounding normal tissue, especially when the field size is small.

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Twenty-six patients with limited small cell lung cancer (SCLC) were treated by induction chemotherapy (IC) and sequential radiotherapy (RT). To clear the benefit of RT, response was evaluated separately after IC and after RT. The CR rate was: 19% after IC, and 50% after RT. The response rate was: 77% after IC and 85% after RT. Thus, RT had an impact on upgrading the response after IC, however, two patients became worse during RT because of the progression of out-of-field disease. The patients were also divided into two groups by their responses to IC; five patients had a CR to IC (CR-IC) and 21 patients had a PR or NC (PR, NC-IC). The two groups were compared to determine the optimal status of response for RT. Comparing CR-IC and PR, NC-IC patients: survival was 100% versus 56% at 1 year and 20% versus 10% at 3 years, respectively. Median duration of response (MDR) in the local sites for the CR-IC patients was 14 months versus 8 months for the PR, NC-IC patients. MDR in the distant sites was 12 months for the CR-IC patients and 9 months for the PR, NC-IC patients. The results lead to the conclusion that RT after IC is more beneficial to CR-IC patients than to PR, NC-IC patients in the treatment of limited SCLC.

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Proton beams have the physical characteristics that provide dose distribution superior to that of X-rays, allowing precise delivery of high radiation doses to the tumor while avoiding irradiation of adjacent normal tissue. Because of this quality, in carrying out proton radiotherapy, the special effort in obtaining a high precision of field placement is warranted. Accordingly, we have developed a localize-and-verify system consisting of a fluoroscopy and digital image processing unit. With this system field localizations have been performed for each treatment, and if there were any difference in position between the current field and the field previously determined, it was corrected and the distance correction was measured. In this study an accuracy of the field localizations was evaluated in 788 localization attempts for 52 patients (53 tumors sites). The average distance correction for all localization attempts was 3.5 mm. Field positions were corrected by<3mm in 60.7%, 3-5 mm in 16.2%, and > 5 mm in 23.1% of the radiation treatments. Various risk factors were evaluated that may influence the accuracy or reproducibility of field localization. Among these, the most significant factors were the site of irradiation and patients age; the frequency and amount of corrections increased with increasing age and in movable tumors of the digestive tract. The sex, use of an immobilization device, and beam directions appeared to be less important. From these results, it is strongly emphasized that in certain tumor sites the daily localization could only offer precise deposition of high doses to the target volume. This can also be applied to conventional irradiation, especially when attempting definitive irradiation with curative intent.

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From 1977 through 1990, 31 patients with metastatic cancer of unknown primary site were treated with radiation therapy. The incidence was 0.7%(31/4654) of new patients in this period. Average age of this series was 56 years (39-86) and ratio of males to females was 25: 6. Fourteen patients showed single metastasis and the other 17 were multiple metastases. Bones, lymph nodes, and central nervous system were common sites of metastases, and adenocarcinoma was the most common histologic type (15 cases). Among the patients survival was: 1-year, 31%; and 2-year, 16%. Two patients who had only cervical nodes metastases from unknown primary sites were treated for the head and neck region, and are still alive with no evidence of disease. We have concluded that in patients with metastatic carcinoma to the upper and middle cervical lymph nodes from unknown primary sites, radiation therapy in the suspected primary head and neck areas of disease may be curative in early stages of disease.

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Human teratoid tumors are considered to arise in the process of dedifferentiation of primitive germ cells. Some experiments on yolk sac tumors in rats induced by fetectomy have been reported. By almost the same fetectomy methods, a slow growing yolk sac tumor with a distant metastatic potential could be established in rats. This paper reports a study of the biological and histopathological characteristics and usefulness of radiotherapeutic experiments on these induced tumors. In an experiment on induction, tumors were induced in inbred Wistar rats (Wistar Mishima, WM/Ms), but not in closed colony rats (Wistar and Donryu strain). The induction of these tumors was completely inhibited by 200 cGy irradiation after fetectomy. Therefore, the radiation sensitivity of the tumor origin was considered to be extremely high. These tumors induced in inbred strain rats (WM/Ms) were transplantable to closed colony strain rats (Wistar). In an experiment on implantation, WM/Ms and Wistar rats were used. One biological characteristic of these tumors may be slow growth with potential for distant metastasis. At autopsy, remarkable lymphnode metastases were observed and hematogenous metastases were also seen in the lung, kidney and liver. The histopathological features of the tumor were almost the same as those reported in other strains of rats. Typical findings included abundant intracellular PAS positive substance that appeared to be laminated in electron microscopy of primary developed, implanted and metastatic sites. The take rate of the tumor, and the survival rate of rats with the tumor after implantation of tumor cells irradiated in vitro depended on the radiation dose. The BrdUrd labeling index of irradiated tumors likewise depended on the radiation dose. Radiotherapeutic experiments on hyperfractionation, or combinations of biological response modifiers, usually needed long observation to check for radiation injury in normal tissue and prolongation of the life span. Because few animals with experimental tumors have long survival time and few of those tumors have metastatic potential, this slow growing tumor with a lymphnode metastatic potential may be useful in experimental models requiring long term observation.

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Prognostic factors were reviewed in ninety-seven patients who underwent postoperative radiotherapy for uterine cervical cancer. All were treated by radical hysterectomy and pelvic lymphadenectomy. Indications for adjuvant radiotherapy included pelvic lymph node metastases, parametrial infiltration, vascular space involvement, a very close surgical margin, large primary lesion, adenocarcinoma/adenosquamous cell carcinoma, and uninvolved cervical tissue less than 3mm. They were given 6 MV X ray to the whole pelvic space (ninety-three cases treated with center split). The total dose was 30-60 Gy, and four received intracavitary irradiation. Thirty-seven patients were in clinical stage Ib, fifteen were in Ila, and forty-five were in IIb. The five-year survival rate was 80.4%, 78.8%, 84.1% and the overall rate was 81.5%. There were twenty-five recurrences, four recurrences at local sites, fi fteen at distant, and six at both. Of the recurrences, 60% were evident within 2 years, and the one-year survival rate from recurrences was 50%, which was comparatively good. As mentioned, postoperative radiotherapy for uterine cervical cancer appears to be effective. The prognostic factors included the number of pregnancy, abortion, histologic type, parametrial infiltration, pelvic lymph node metastases. Those with these prognostic factors were in the high risk group. It is necessary for those in the high risk group to receive some adjuvant therapy, such as chemotherapy.

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Late radiation brain injury after treatment for pituitary adenomas was analyzed retrospectively. From 1970 to 1983, 53 patients with pituitary adenomas were treated at our clinic with postoperative radiation therapy (RT) or RT alone. During the period under study, patients were treated with various fractionation schedules. Initially, each fraction size was 2-2.5Gy, 5 days per week for a total delivered dose of 50-60Gy. Later the fraction size was changed to 3Gy, 3 days per week, for a total dose of 51-60Gy, to increase the rate of control of the tumor. The field size ranged from 9cm² to 40cm², and parallel opposed portals were used. Radiation brain injury was diagnosed clinically and radiographically with CT, ²⁰¹T1-SPECT, ¹⁸FDG-PET. Radiation brain injury occured in 6 patients (1 patient had reversible injury, and the others had irreversible injury). Irreversible radiation injury occurred in patients who received more than 51Gy at 3Gy per fraction (51Gy, 1 case; 60 Gy, 2 cases), but did not occur in patients who received 50-60Gy at 2-2.5Gy per fraction. The case with irreversible injury who received 51Gy had severe complications after surgery, and that was suspected to be one of the causes of the injury. There was no relation between field size and radiation injury. We conclude that, radiation doses of 60Gy at 3 Gy per fraction do not seem to have any therapeutic advantage.

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To establish the optimal dose of FAR-therapy (radiotherapy with 5-FU and Vitamin A) relative to the local control rate and the normal tissue tolerance dose, 309 patients with laryngeal squamous cell carcinoma, who were treated initially by FAR-therapy at the Department of Radiology, Kyushu University, between 1973 and 1988, were analyzed in retrospect. The local control rate increased with increase in the radiation dose, and the radiation injury rate increased substantially. Radiation complication, such as long-standing edema or ulceration, was observed in 5% of the patients with glottic cancer and supraglottic cancer at doses of TDF 100 and TDF85, respectively. The local control rates for glottic cancer at TDF 100 were 96%, 87%, 63%, and 10% for T1, T2, T3 and T4, respectively. In supraglottic cancer at TDF 85, they were 93%, 85%, 75% and 47% for T1, T2, T3 and T4, respectively. TDF 100 is recommended as the optimal dose for glottic cancer and TDF 85 is recommended for supraglottic cancer.

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