Max L. M. Boone

Prospects for hyperthermia in human cancer therapy. Part II: implications of biological and physical data for applications of hyperthermia to man.

Laboratory data from studies of hyperthermia as a potential antitumor agent indicate that: (a) tumor cells may be more sensitive to heat than normal tissue; (b) hyperthermia enhances response to irradiation and can increase the therapeutic ratio; (c) cells are most sensitive to hyperthermia during the S-phase, when they are resistant to ionizing radiations; (d) the oxygen effect is absent for hyperthermic cell killing, and radiation effects are less oxygen-dependent when potentiated by heat treatment; and (e) biological damage changes more rapidly at temperatures above 43 degrees C. Methods of heat production and dosimetry need to be refined further before these findings can be put to practical use in tumor therapy.

The Potential of Localized Heating as an Adjunct to Radiation Therapy1

Experimental studies have shown that (a) tumor cells may be more sensitive to heat than normal cells; (b) hyperthermia inactivates cellular repair mechanisms for radiation damage; and (c) heat may lower the OER for ionizing radiation (anoxic cells are at least as sensitive to hyperthermia as oxygenated cells). Localized hyperthemia produced by localized current fields in the range of 100 kHz-10 MHz by direct contact electrodes offers two major advantages: the eletrode configurations may be manipulated to obtain desired thermal dose distributions, and, since the mode of heating is essentially instantaneous, accurate temperature control can be maintained during treatment.

The Relationship of Reactions to Complications in the Radiation Therapy of Cancer of the Cervix

A review was made of the reactions and complications associated with high-dose radiation therapy of invasive carcinoma of the cervix in 410 patients. In all patients a combination of intracavitary and external therapy had been given. Either a bowel or urinary tract reaction or both developed in 133 of the 410 patients; one or more complications occurred in 94. As the severity of bowel reactions increased, the subsequent complication rate increased significantly, but 39% of those with bowel complications and 88% of those with urinary tract complications had no warning reaction.

High-Energy Electron Dose Perturbations in Regions of Tissue Heterogeneity

High-energy electron dose perturbations produced by variations in density and structure of the irradiated material have been demonstrated in phantoms by a number of investigators (5, 6, 10, 14–17, 19, 20), sometimes employing anatomical specimens such as bone (10, 25, 27). In one study (11), dose distortions produced by bone and air spaces in electron treatment of the nasopharynx were mapped in sectioned cadaver heads. We have investigated these dose perturbations in living tissues, using lithium fluoride thermoluminescent dosimeters. Several excellent reviews of the properties of lithium fluoride as a radiation dosimeter (7, 13) and of its use in measuring doses in irradiated patients (18, 21) and experimental animals (2) are available. In our experience, accuracies of ± 3 per cent are obtainable for lithium fluoride dosimeters in vivo, and ± 1 per cent for carefully controlled laboratory exposures. Over 500 in vivo dose determinations in 75 dogs and 25 patients comprise the data from this two-year inves...

The Effects of Sternum upon the Central Axis Depth-Dose Curves for High-Energy Electrons1

In planning treatment of the internal mammary chain of lymph nodes with high-energy electron beams, we have become interested in the effect of the sternum on dose distribution. Studies have been carried out with fresh specimens of human sternum in a water phantom. Doses were recorded with an ion chamber held in an x−y plotter. Due to the curvature of the bone, the probe can be brought only as close as 1 to 2 cm to the bone. A depth-dose curve is then obtained for points behind the bone. The bone is removed, a normal curve is obtained, and all readings are expressed as percentages of the maximum for this curve. It was found that thicknesses of bone up to about 1 cm do not attenuate the beam as much as water, and that for the thicker sternum, with its relatively greater investment of cortical bone, there was some increased attenuation relative to water (Fig. 1). Previous publications have described marked reduction in depth dose due to sternum. An absorption-equivalent thickness relative to water (A.E.T.) o...

Malignant tumors of the paranasal sinuses

Abstract The detection of malignant disease of the paranasal sinuses in its early stages is largely in the province of roentgen examination, since physical signs and symptoms seldom reveal the presence of an underlying malignancy until it is advanced. Identifying the site of origin and the anatomic extent of the tumor also depends upon careful analysis of detailed roentgenograms. This analysis serves as the basis for treatment planning. From a review of 121 cases of primary malignant tumors of the paranasal sinuses and nasal cavity, the frequency of various roentgen findings has been tabulated, their significance discussed, and their appearance illustrated. A knowledge of head and neck anatomy and of the natural history and routes of spread of sinus cancer are essential in interpreting the roentgenograms. Many of the changes are subtle and require judicious interpretation. Others are quite straightforward and easily recognized if they have been seen before. Constant attention to detail and a willingness to obtain additional views to resolve a point in question are necessary if the maximum contribution to diagnosis, evaluation and management of these lesions is to be achieved.