Effect of fractionated doses of pions on normal tissues: Part II. Mouse jejunum

Response of mouse small intestine to fractionated doses of pions

“…A RBE value of 1.32 is estimated by Jordan et al (1981) for inducing kidney injury and Raju et al (1980) have reported a RBE of about 1.3 based on acute skin reaction where 300 kV X-rays served as reference radiation in both cases. However under similar experimental conditions as we used, Peters et al (1980) have obtained a RBE value of 1.42 which is higher than that observed in this study. This may be, at least in part, due to a different reference radiation used or due to the variations in the pion beam configuration at LAMPF and SIN or due to the different strains of mice used.…”

“…For two fractions delivered at a 3-h interval, the proportion of dose recovered was 0.38 and 0.31 for X-rays and pions respectively. The amount of dose repaired was more for X-rays than for pions but the difference between the two values was not so pronounced as reported by Peters et al (1980) for two The difference between the proportion of dose recovered for two fractions of pions and gamma rays observed by the above-stated authors is about 4 times more than our estimate. With reference to them, the fractional recovery of pion induced gut damage in our experiments is about 1.7 times higher.…”

“…For instance, therapeutic neutron beams have an effective range of dose-mean lineal energies. Consequently neutrons have higher RBE values than pions as confirmed by mouse gut experiment (Peters et al 1980). However pions have a therapeutically advantageous depth-dose distribution which compensates for the lower RBE observed.…”

“…where D N and D1 are the total doses needed in N fractions or as a single dose for the isoeffect of 20 surviving crypt cells per jejunal circumference (Peters et al 1980). The estimates for the fraction of dose repaired for pions and X-rays under different experimental conditions are given in Table 2.…”

“…This ratio is compatible with the other reported single dose pion RBE values for normal tissue damage. Peters et al (1980) have observed that for the isoeffect of 20 surviving crypt cells per circumference, pions were more effective by a factor of 1.22 than Co 6° gamma rays. A dose of 20.83 Gy of X-rays or 16.04 Gy of pions is reported to cause spinal cord paralysis in 50% of the irradiated rats, which means a pion/300 kV X-ray RBE value of 1.3 (Amols and Juhas 1981).…”