Rat liver tolerance for partial resection and intraoperative radiation therapy: regeneration is radiation dose dependent.

We studied the feasibility of delivering a large single dose of intraoperative radiation as an adjuvant to partial hepatic resection. Intraoperative radiation therapy (IORT) was delivered to the remaining liver of 84 rats after partial hepatectomy to determine the acute and chronic effects of treatment on blood chemistry values, histology, survival, hepatic regeneration, and cellular appearance of the normal liver. Transient elevations in SGOT, SGPT, and alkaline phosphatase were attributed both to hepatectomy and to liver parenchymal damage induced by IORT. Microscopic examination upon necropsy, performed at frequent intervals post-treatment revealed hepatic capsular thickening with some alteration of liver architecture mainly underneath the capsule, with localized inflammation and some areas of necrosis. Survival in all groups was 100% at 45 days. Liver weight increase proved to be dose-dependent and displayed a bisphasic pattern. This study demonstrated that IORT is a feasible adjunct to surgical resection of the liver in the rat model.

The effects of fractionated hyperthermia on normal canine muscle blood flow.

This study investigates the changes in normal canine muscle blood flow occurring during three fractions of 43 degrees C (60 min) hyperthermia. Blood flow was measured during heating at 1-, 3-, and 5-day intervals with a laser Doppler flowmeter. For 1-day intervals, blood flow oscillated during the first treatment reaching peak values of approximately 39 ml/min per 100 g of tissue after 8 min and 47 ml/min per 100 g of tissue after 40 min. Heatings at 1-day intervals showed both peaks in perfusion to persist during subsequent treatments with higher blood flows during later heatings. Results of the 3-day fractionated heating demonstrated lower blood flows during the second and third heatings than those at 1-day intervals. The third treatment of the 3-day fractionations showed a disappearance of the first peak and only a small increase in perfusion at the second peak (50 ml/min per 100 g of tissue). Perfusion studies at 5-day intervals demonstrated two peaks at approximately 15 and 40 min. Compared with the first treatment at 5-day intervals, the second and third treatments demonstrated decreased and increased peak perfusion values, respectively. This study suggests that the kinetics of blood flow changes during hyperthermia may be the result of several different mechanisms. There appear to be three different peaks which can be quantified during heating. These peaks may change during subsequent heating independently from one another. Further work must be performed to examine the physiological mechanisms responsible for each peak.

Treatment of cancer of the pancreas by precision high dose (PHD) external photon beam and intraoperative electron beam therapy (IOEBT).

Twenty-five patients with a diagnosis of unresectable adenocarcinoma of the pancreas were explored in the Clement O. Miniger (COMROC) IOEBT operating amphitheater at the Medical College of Ohio. Seventeen were treated with IOEBT (20-30 Gy, 15 or 18 meV electrons) PHD external beam radiation therapy (40-60 Gy, 1.8 Gy per fraction) plus appropriate operative biliary and gastrointestinal bypass procedures. No intraoperative complications were observed. Two patients died of causes that may have been treatment-related. Two patients developed abdominocutaneous fistulae. Pain was ameliorated in eleven of twelve patients. Jaundice was relieved in all patients. Four of ten patients with weight loss showed a reversal of that trend. Patient survival was not significantly different from that of patients treated with high-dose precision therapy alone.