Radiation therapy of carcinoma of the tonsillar region.

From 1960 through 1976, 353 consecutive patients with carcinoma of the tonsillar region were primarily treated with radiation therapy. The mean age of patients was 58 years with males predominating (78%). Patients were classified according to a TNM and stage classification. Most of the tumors were large, and the specific site of origin could not be determined in 33% of the patients. The predominant identifiable sites were the soft palate and uvula, 18%, the anterior tonsillar pillar, 18%, and the tonsillar fossa, 13%. Patients were treated with radiation to doses of 6700 rad given in 48 days and 33 fractions using Cobalt 60 radiation. We found a 91.7% control rate for patients with T1 disease and 76.9%, 49.5%, and 25% for T2, T3, and T4 patients, respectively. The overall local control rate was 62.3%. Surgery was used most often in recurrences for Stage III patients. Salvage surgery was carried out in 93 patients. Surgery was more successful in controlling the disease in patients in whom the primary was controlled by irradiation. Overall, the tumors in 43% of the patients who had surgery were subsequently controlled as a result of this treatment. Metastasis occurred rapidly, with 75 of the patients exhibiting metastases by 18 months. Complications were not related to dose but were slightly higher in patients who had surgery (5%). We conclude that radiation therapy is the preferred treatment for Stage I and II squamous cell carcinoma of the tonsillar region. No satisfactory results were obtained in Stage IV; other approaches should be tried.

Evaluation of irradiated mandibles using emission tomography, bone scans, and radiography.

This study compared radiographs, bone scans, and computed emission tomograms with histologic findings in irradiated mandibles of adult Rhesus monkeys. Although osteocytes were lost in the path of the beam, many vessels were partially or totally occluded, the periosteum degenerated, the marrow became fibrotic, and cancellous bone proliferated abundantly, no changes were noted with radiography, conventional bone scanning, or computed emission tomograms. These clinical methods of examination may misrepresent the true condition of irradiated bone because of inadequate sensitivity or balance among factors that control radioactive tracer uptake in bone.

Dosimetry of small radiation fields for 10-MV x rays.

Dosimetry for 10-MV x rays has been extended to radiation fields smaller than 4 X 4 cm which may be suitable for radiation therapy of small lesions, e.g., intracranial tumors, benign or malignant. Special consideration in this study was given to (i) the variation of dose with field size (collimator and phantom scatter), (ii) the central axis percentage depth doses, and (iii) the moving-beam therapy dose distribution. We conclude that simple dosimetric techniques can provide adequate physics background for stereotaxic radiosurgery with small radiation fields and high-energy x rays.

Stereotaxic radiotherapy technique for small intracranial lesions.

A stereotaxic radiotherapy technique that permits accurate delivery of highly localized dose to a small intracranial target has been developed. The technique facilitates precise integration of the diagnostic and therapeutic procedures including target localization, treatment planning, simulation, repetitive patient irradiation, and daily treatment verification. A conventional linear accelerator and computed tomography scanner as well as special diagnostic and therapeutic guides are used. A suitable dosimetric distribution is achieved using arc therapy with small radiation fields and 10-MV x rays.

Management of malignant salivary gland tumors.

A total of 54 patients with major salivary gland tumor were treated with radiation therapy at the University of Michigan from 1955 to 1975, inclusive. Fifteen had total resection and radiation, 16 had subtotal resection and radiation, and 23 were inoperable and received radiation only. Local control rate was different between these groups, 86.7%, 75%, 21.7% respectively, as was survival rate at 5 years, 78.4%, 59.8%, 29.9%. In patients with facial nerve palsy, with combined surgery and radiation, 65.3% local control and 49.7% 5-year survival was obtained. Regional neck node metastasis was noted in 25.5% and distant metastasis in 24.1%. Local tumor control was found to be a very important factor in survival: 70.2% survival in patients with local control and 28.7% without. The authors conclude that a combined radical surgery and postoperative radiation would improve the prognosis of these patients with major salivary gland tumors.

An after loading colpostat (using standard source tubes).

An afterloading system for the treatment of gynaecological patients is described. It uses a rigid tandem to which afterloading colpostats are attached. The catheters for afterloading the colpostats are flexible thus minimizing patient discomfort. A constant 90 deg. alignment of source tubes between the uterine tandem and colpostats is achieved.

Computer controlled hyperthermia unit for cancer therapy.

A versatile hyperthermia control system, based on a microcomputer, provides automated temperature regulation (1 channel) and monitoring (3 channels) and control of microwave output (both on/off and power level), and displays temperature (degree C) and microwave output (watts) graphically in real time; all data are stored on floppy diskette.

The role of radiotherapy in salivary gland neoplasms.

The role of radiation in the treatment of carcinoma of the salivary glands is expanding. It has a definite role in controlling the primary tumor, particularly in those postoperative cases with microscopic residua in the surgical field. Radiotherapy also plays a significant role in controlling the primary tumor in carcinomas that are inoperable or have recurred after surgery. The doses employed must be high (between 6000 and 7000 rads, given over six to seven weeks). The complications are tolerable and depend upon the area irradiated.