Atsuo Akanuma

Factors possibly influencing the prognosis of oligodendroglioma.

&NA; Fifty‐seven cases of oligodendroglioma (including eight cases of malignant oligodendroglioma) treated at the University of Tokyo Hospital between 1961 and 1985 were analyzed for factors influencing the survival rate. Factors related to a poor outcome were findings of malignancy and symptoms of dementia. Survival rate and postoperative survival period were not influenced significantly by radiation therapy, extent of resection, tumor characteristics, or ABO blood groups.

Parameter analysis of Gompertzian function growth model in clinical tumors

Abstract In analysis of clinical tumors a conventional exponential growth model is often insufficient in clinical practice. Gompertzian function growth model is one of the practical alternatives. The way to obtain the parameters of the function is discussed with application to tumors in clinical practice. The function can be extrapolated forward and backward, which is one of the major points of interest in the practice of malignant therapy. Tumor characteristics differences are also discussed in relation to the growth parameters.

Dosimetry of Radiation Scattered to Thyroid Gland from Prophylactic Cranial Irradiation for Childhood Leukemia

Dosimetry of radiation scattered to the thyroid gland was performed in 17 children (9 boys, 8 girls) who were treated for acute lymphoblastic leukemia and received cranial irradiation for prophylaxis against central nervous system leukemia at a median age of 4 years and 2 months (range, 1 year and 1 month to 14 years). The absorbed dose to the thyroid gland in these children ranged from 0.7% to 7.3% of the dose delivered to the cranium. Thus the total dose to the thyroid gland ranged from 0.13 to 1.32 Gy by the end of the entire course of cranial irradiation. Doses tended to be larger in younger children, but the radiation source also had a large influence on the dose to the thyroid gland; that is, the absorbed dose to the thyroid gland with delivery by linear accelerator was smaller than that by cobalt irradiation. Long-term survivors treated with cranial irradiation for acute leukemia during childhood should be followed for the possible development of thyroid diseases, including malignant tumors, for a long period.

High-dose rate intracavitary radiation therapy for advanced head and neck tumors

Fifty‐seven treatments were performed on 27 head and neck patients with recurrent or residual tumors on a high dose rate, remote controlled afterloading unit: There were 16 cases of maxillary sinus tumors, 6 epipharynx, 3 alveolar ridge, 1 hard palate and 1 floor of mouth. All patients have been followed up more than 2 years except one. Five patients are alive without local recurrence for more than 2 years. In 13 patients local tumors disappeared once and normal mucosa covered the tumor sites. Two patients died from local bleeding. In six patients this method failed to destroy tumors. Our purpose was palliative local control: therefore, in two‐thirds of cases treated we were successful with this easy method of nonfractionated acute intracavitary radiation. This result is favorable, considering that all cases treated here were failures following full dose external radiation, although the treatment had to be repeated more than twice in 15 cases. Relief of symptoms is excellent when this therapy is used.

COMPENSATION TECHNIQUES IN NIRS PROTON BEAM RADIOTHERAPY

Proton beam has the dose distribution advantage in radiation therapy, although it has little advantage in biological effects. One of the best advantages is its sharp fall off of dose after the peak. With proton beam, therefore, the dose can be given just to cover a target volume and potentially no dose is delivered thereafter in the beam direction. To utilize this advantage, bolus techniques in conjunction with CT scanning are employed in NIRS proton beam radiation therapy planning. A patient receives CT scanning first so that the target volume can be clearly marked and the radiation direction and fixation method can be determined. At the same time bolus dimensions are calculated. The bolus frames are made with dental paraffin sheets according to the dimensions. The paraffin frame is replaced with dental resin. Alginate (a dental impression material with favorable physical density and skin surface contact) is now employed for the bolus material. With fixation device and bolus on, which are constructed individually, the patient receives CT scanning again prior to a proton beam treatment in order to prove the devices are suitable. Alginate has to be poured into the frame right before each treatments. Further investigations are required to find better bolus materials and easier construction methods.

Effects of antileukemic therapy of endocrine functions and development of children

Twenty-six children with acute lymphocytic leukemia and non-Hodgkins lymphoma were examined for endocrine function and development at the time of cessation of a 3 to 7 year therapy. Eleven children had received no cranial irradiation (Group 1) and 15 received cranial irradiation of 1,800 to 3,000 rad (Group 2). Linear growth and bone age were significantly retarded in Group 2 compared to normal but the differences between Groups 1 and 2 were not significant. In 1 child in Group 1 and 4 children in Group 2, retardation of linear growth seemed to be irreversible. Endocrine function abnormalities were not remarkable except for significantly high levels of thyroxine in Group 2 and triiodothyronine in both groups. Developmental retardation was thought to be the result of a combined effect of chemotherapy and cranial irradiation, being reversible in the majority of children. Antileukemic therapy, bone age, cranial irradiation, development, endocrine functions.