Radiation dose monitoring in a breast cancer patient with a pacemaker: a case report.

A pacemaker-bearing patient with left-sided breast cancer was treated with adjuvant external beam radiation therapy to the intact breast. She was treated via tangential fields and a single anterior supraclavicular field using 6-MV x-rays. The pacemaker, originally in the treatment field, was removed and a new one placed 4 cm outside the radiation field prior to treatment. Silicon diode chamber Keithley-Farmer type 0.6 cc ionization chamber, and lithium fluoride (LiF) (TLD) chips were used to measure, in vivo, the dose to the pacemaker. From all the fields treated, total dose to the pacemaker was 164 cGy by diode measurements, 182 cGy by ionization chamber measurements, and 171 cGy by TLD measurements. The pacemaker functioned normally throughout the course of treatment.

The first simultaneous intraoperative hyperthermia and radiotherapy procedure: dog experiment and technique.

The Department of Radiation Therapy of Howard University Hospital was the first to revive (1976) the use of intraoperative radiotherapy, or direct view irradiation, using electron beam (IORTe(-)) in the United States. Since that time, this pioneering effort has gained both national and international acceptance. Now, many leading centers employ this investigational treatment modality. Recently, a new mode of cancer therapy has been gaining acceptance, namely hyperthermia (the treatment of cancer by heat). Hyperthermia has been shown, both experimentally and clinically, to improve the rate of local control (thermal enchancement ratio [TER]) when combined with radiation therapy in the treatment of cancer. Maximal TER has been observed with simultaneous or immediate application of radiation and hyperthermia for both tumor and normal tissues. Therefore, to achieve maximum therapeutic gain, selective, intraoperative, simultaneous heating and irradiation of the tumor with mechanical retraction of the normal and sensitive structures from the treatment field seems a promising alternative.There have been no published reports, to the authors' knowledge, on the combination of simultaneous IORTe(-) with intraoperative hyperthermia (IOHT). To employ this combination in human subjects, several questions must be answered first using animal models, including the technical and practical feasibility, the toxicity and morbidity, as well as the pathologic changes that may arise. The technical aspects of the first animal case, using a mongrel dog, applying simultaneous IORTe(-) and IOHT are presented.

Use of interstitial hyperthermia to produce homogeneous heat distribution patterns.

The preliminary experience of the use of a prototype hyperthermia unit (Astro 200) for tumor regression in Howard University Hospital's Department of Radiotherapy is described. The purpose of this study was to produce homogeneous heat distribution patterns within a 5-cm cylinder in the middle of a phantom (ground beef) using radio frequency conducted through electrodes implanted in the medium. Homogeneous heat distribution was achieved by finding the optimal spatial distribution of electrodes within the phantom and by sequencing the radio frequency in the electrodes. Monitored observation revealed a steady state homogeneous temperature of 42.5 °C within a 4-cm diameter. There was a temperature difference of 0.5 °C within 1 cm of the periphery.Heat in the clinical range of 42 to 43 °C has caused tumor regression, and was found to be most effective when combined with another modality of radiation. At Howard University Hospital, hyperthermia is used in conjunction with conventional modalities-surgery, radiotherapy, and chemotherapy-in the treatment of tumors.