Treatment planning with heavy charged particles at Lawrence Berkeley laboratory

Treatment planning with heavy charged particles at Lawrence Berkeley laboratory

(137) TOTAL LUNGIRRADIATIONAND COMBINATION CHEMOTHERAPY IN PULMONARY METASTASES FROM NON-OVARIAN GYNECOLDGIC CARCINOMA Nejat Akbiyik, Abdul Mundia, ...

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TOTAL LUNGIRRADIATIONAND COMBINATION CHEMOTHERAPY IN PULMONARY METASTASES FROM NON-OVARIAN GYNECOLDGIC CARCINOMA

Nejat Akbiyik, Abdul Mundia, Engracio P. Cortes, Sidney Chen, and Burton Krumholz Queens Hospital Center Affiliation of Long Island Jewish Medical Center, 82-68 164th St., Jamaica, N.Y., and State University of New York at Stony Brook

Despite the radiocurability of Stages I and II squamous cell carcinoma (SCC) of the cervix, palliation of patients with pulmonary metastases has been disappointing. Four patients with pulmonary metastases (3 from cervix and 1 from endometrial carcinoma) were treated with total lung irradiation followed two and three weeks after termination of radiothehapy with combination chemotherapy consisting of vincristine - 1.4 mg/m IV f adriamycin 50 mg/m2 IV + cyclophosphamide - 500 mg/m2 IV repea&d every 4 week intervals. Radiotherapy was delivered through a Co teletherapy unit in a daily dosage of 100 rad in anterior and posterior opposing fields. After completion of irradiation in one lung, the other lung was similarly treated if involved with gross disease. Two out of 4 patients (both with cervix SCC) obtained complete tumor regression, whereas the other two patients had stabilization of their pulmonary lesions. The survival of the 2 responders was 216+ and 621 days from the start of irradiation. The 2 non-responders survived 56 and 109 days. Except for one patient who died of pulmonary metastases, the remaining 3 patients died of metastases elsewhere. While Ionly one patient dejeloped radiation pneumonitis, all 4 had alopecia and leukopenia <4OOO/mm from chemotherapy. Total lung irradiation and combination chemotherapy appear to have activity in the treatment of pulmonary metastases from SCC of the cervix and warrants further explor,ation. (138)

TREATMENT PLANNING WITH HEAVY CHARGED PARTICLES AT LAWRENCE BERKELEY LABORATORY

George T.Y. Chen, Ph.D., John T. Lyman, Ph.D., Jeanne M. Quivey, M.D., Joseph R. Castro, M.D., Radiotherapy Section, Building 55, Room 123, Donner Laboratory, Lawrence Berkeley Laboratory, Berkeley, California

Representative treatment plans are presented for the six sites of interest in the helium/heavy ion therapy clinical trials at the Lawrence Berkeley Laboratory. These sites include pancreas, para-aortic nodes, advanced cervix, head and neck, esophagus, and brain. The perturbation of isodose and isoeffect distributions by inhomogeneites is computed by two methods, one an averaging technique, and the second a pixel by pixel calculation on CT scan data. The integral dose from these multiport treatments as well as the dose to limiting organs is calculated and 133

compared with megavoltage photon plans. In addition, setup, immobilization, bolus and compensation techniques developed for particle therapy are described, as are dosimetry techniques used to verify beam penetration.

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INHOMOGENEITY CORRECTIONS FOR NEGATIVE PI-MESON THERAPY

J. W. Somers, C.A. Kelsey, R. G. Lane, A. R. Smith, K. R. Hogstrom and I. I. Rosen Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico

Patients are now being treated routinely with negative pi mesons at the LAMPF accelerator in conjunction with the joint University of New Mexico-Los Alamos Scientific Laboratory pion therapy project. The major problem in treatment planning for pion therapy is the correction for tissue inhomogeneities. The effect of inhomogeneities is to shift the peak dose region and to significantly distort the isodose contours from those measured in a water phantom. The basic physics will be discussed briefly and the results of measurements on various inhomogeneities will be presented. The methods used to correct for inhomogeneities during patient treatment will be discussed, showing how compensating bolus is designed using measured data and information obtained from CAT scans.

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IN-VIVO DOSIMETRY FOR NEGATIVE PION THERAPY

K. R. Hogstrom, A. R. Smith, J. W. Somers Biomedical Physics Section, Cancer Research and Treatment Center, The University-of New Mexico, Albuquerque, New Mexico

In-vivo dosimetry for pion radiotherapy clinical trials at LAMPF has recently become feasible. Because dosimeters have a changing response with depth due to the variation of beam quality, two or more dosimeters are required for in-vivo measurements. LiF TLD 100, aluminum activation, and silicon diodes have been evaluated as in-vivo dosimeters. A weighted sum of the individual responses yield doses that agree to approximately 10% or better with central axis depth dose in a water phantom as measured by a .l cc EGG ionization chamber. Each dosimeter has a constant response in the plane transverse to the incident pion beam. In addition to total dose, sodium-24 activation from aluminum is responsive only to stopping pions, hence giving a measure of high LET star dose. Supported by USPHS research grants CA-14052 and CA-16127 from the NC1 and ERDA.