X-irradiation of the contusion site improves locomotor and histological outcomes in spinal cord-injured rats

We have determined whether X-irradiation of the injury site can oppose tissue loss and improve recovery of locomotor function following contusion injury of the spinal cord. Contusion injury was produced in rats at the level of T10 with a weight drop device. Localized X-irradiation (20 Gy) of the injury site was performed at 20 min and 1, 2, 4, 7, and 17 days postinjury. Locomotor recovery was then determined with the 21-point Basso, Beattie, and Bresnahan (BBB) scale. X-irradiation enhanced recovery of locomotor function during a subsequent 6-week observation period when administered 20 min and 1 or 2 days following contusion injury (final BBB score approximately 7-8). X-irradiation at 4-17 days postinjury did not significantly affect final locomotor scores compared with unirradiated rats (final BBB score approximately 2), in marked contrast to previous studies where X-irradiation applied only at 17-18 days benefitted transection injury. The extent of recovery was directly related to measurements of sparing of spinal cord tissue at the contusion center. Because the treatment time window occurred earlier in contusion than reported for transection injury, the results suggest that contusion injury rapidly initiates underlying radiation-sensitive processes that occur only following a delay of several weeks after transection injury. Further optimization of X-ray treatment may lead to a useful therapeutic modality for use in spinal cord contusion injury.

Permanent interstitial implantation using palladium-103: the New York Medical College preliminary experience

Palladium-103 is a low energy photon emitter available for permanent interstitial implantation. Pd-103 has energy and safety characteristics similar to Iodine-125, but its initial peripheral dose rate is approximately three times greater. This may provide improved control of rapidly proliferating tumors. At the Westchester Campus of New York Medical College, 15 patients with residual or recurrent unresectable lesions were implanted with Pd-103. There were five males and 10 females with an age range of 41 to 93 years (median 58). Implanted sites included the chest wall, nasopharynx, vagina, and zygomatic region. Peripheral doses ranged from 55 to 203 Gy (median 107 Gy). A complete response was achieved in eight patients and a partial response in seven patients, for an overall response rate of 100%. We noted improved control with smaller volumes and peripheral doses at or above 115 Gy. No unusual skin or mucosal reactions were recorded. Possible advantages of Pd-103 as a substitute for I-125 include improved control of rapidly proliferating tumors and a more rapid clinical response of lesions. Disadvantages include current higher cost and an impracticality in maintaining a running inventory because of the short half-life of the isotope. Our experience suggests that Pd-103 is an attractive alternative to I-125.

Improved response of a murine fibrosarcoma (Meth-A) to interstitial radiation when combined with hyperthermia

Removable Iridium-192 implants provided a dose of 10 Gy/day or 41.5 cGy/hr at 0.5 cm from the center of 1.0 cm diameter tumors. The total radiation (x) alone was 20, 40 or 60 Gy, representing 2, 4, or 6 days of continuous radiation. The doses used for the combined treatments at elevated temperatures were 10, 20 or 30 Gy. The local tumor hyperthermia (LTH) treatment (43.6 for 35 min, water bath) was administered once for each 10 Gy of dose. The combined radiation + LTH was clearly superior to that achieved with radiation or LTH alone and yielded Thermal Enhancement Ratios (TER) of 3.4-3.9. Local tumor control rate was 67% and 89% for the 20 and 30 Gy x + LTH groups, respectively. A comparison of the results obtained in this study with those of earlier studies on the same tumor system indicate that the effects of Iridium-192 alone on this rapidly proliferating tumor were comparable to similar total doses of fractionated external beam radiation. Iridium + LTH produced a tumor response comparable to that achieved with external fractionated radiation + LTH. Combined treatment effect of elevated temperature appears to be less dose rate dependent in the range of 40 cGy/hr to 100 cGy/min and more dependent upon total dose accumulation.

Internal mammary implantation: the need for revival of a simple technique

Available statistics on breast cancer indicate a high frequency of positive internal mammary nodes, which is associated with decreased five-year survival rates. The close proximity of the majority of internal mammary nodes (87 percent within 1 cm) to the internal mammary vessels makes them easily accessible to high-dose intravascular continuous irradiation by afterloading radioactive ribbons (iridium 192) in the internal mammary vessels that are surgically exposed. This is a simple technique that can be carried out at the time of mastectomy or as a separate procedure, either as a primary radiation modality, for post-XRT recurrence, or as a boost in combination with conventional parasternal radiation therapy. The step-by-step technique, indications, need for revival, and future implications are presented.

Intraluminal radiation for esophageal cancer: a Howard University technique

The objective of radiotherapeutic management in esophageal cancer is to accomplish maximum tumor sterilization with minimal normal tissue damage. This sincere effort is most often countered by the differential in tumor dose response vs normal tissue tolerance. Intraluminal isotope radiation, with its inherent advantage of rapid dose falloff, spares the lungs, the spinal cord, and other vital structures, yet yields adequately high doses to esophageal tumor. Though in existence since the turn of the century, the method of intracavitary radium bougie application dropped out of favor due to technical difficulties imposed by the size of the radium source and radiation exposure to the personnel involved. The authors describe a simple "iridium 192 afterloading intraluminal technique" that eliminates technical problems and reduces radiation exposure considerably.