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KMID : 0352119890050010021
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Journal of Kyung Hee University
1989 Volume.5 No. 1 p.21 ~ p.31
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THE EFFECT OF FRACTIONATED IRRADIATION ON REPAIR KINETICS OF SUBLETHAL DAMAGE IN MOUSE LIP MUCOSA
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崔智裵/Choi, Ji Bai
洪性彦/林在勳/Hong, Seong Eon/Lim, Jae Hoon
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Abstract
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To provide basic data for human mucosal reaction during radiation therapy of the head and neck cancer, the authors studied the kinetics and capacity of cellular repair of sublethal damage in mouse lip mcosa during single and fractionated irradiations.
The results were summarized as follows;
1) In single irradiation group, mucosal reaction was developed within 6 days after irradiation. The response was maximum in 13-14 days after exposure and recovered rapidly within 4-5 days thereafter.
2) In single irradiation group, mean score of mucosal reaction was 2.2 at 15 Gy, 2.7 at 17 Gy, 3.1 at 19 Gy, and 3.8 at 21.6 Gy, respectively.
3) Isoeffect dose for average reaction at level 3 was 18.4 Gy in single irradiation group, 21.2 Gy in 217/1 hour, 22,0 Gy in 2F/2 hour, 23.7 Gy/4 hour, and 24.3 Gy in 2F/4 hour irradiation group, respectively.
4) Recovery rate to maximum recovery at 24 hour as 100% was 47% at 1 hour, 61% at 2 hour, and 90% at 4 hour, respectively. The result indicates that cellular repair starts immediately after irradiation and progresses rapidly.. About a half of the repairable damage can be recovered in 1 hour.
5) Capacity of repair increased with increase in number of fractions as observing dose-survival curve.
6) The slope of the isoeffect curve was 0.26 on double logarithmic plot.
7) The a//f ratio was 16 Gy, indicating that the capacity of cellular repair of lip mucosa is similar to those of acutely responding tissues.
Capacity of repair of the subethal danage is larger in the late responding tissues, while the kinetics of repair of sublethal damage is faster in the acutely responding tissues. There are considerable differences in the repair ch -racteristics between acutely and late responding tis Sues. These features have to be considered when friction schedules are markedly altered.
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