LET 증가에 따른 회복 생존 모델의 파라미터 값 비교 = Comparison of Parameter Using the Repair Survival Model Irradiated High-LET

국문 초록 (Abstract)

방사선 생물학적 효과(Radio biological effectiveness, RBE)를 선량에 대부분 의존하는 X선과 달리 탄소빔의 경우 LET의 변화량은 반드시 고려되어야할 사항이다. 이는 X선 과는 극히 대조적인 선량 분포도를 갖고 있기 때문이며 LET의 변화량이 중요한 이유가 된다. 따라서 기존의 LQ 모델이나 회복생존모델의 경우 이러한 점이 감안되지 않아 탄소빔의 분할 조사 시 문제점을 보이며 오류를 보이고 있다. 본 연구에서는 약 75keV/μm의 고LET 탄소빔 분할 조사 시 Potentially Lethal Damage Repair (PLDR)의 발생양을 확인하고 약 13keV/μm 저LET 조사와 비교하여 현저히 감소하였음을 확인하였다. PLDR의 감소에 따라 생존율 또한 감소하였다. 따라서 탄소빔의 생물리학적 모델 개발에 LET의 변화량은 반드시 고려되어져야 할 것으로 보 인다.

다국어 초록 (Multilingual Abstract)

Dose response curves using absorbed dose to the biological effect are usually available in case of conventional X beam. However, absorbed dose is not consider in treatment planning for carbon beam such as heavy ions.
Because the biological effects also depend on other quantities such as the local variation, which is often characterized by the linear energy transfer (LET). So LQ model cannot explain the entire response of fractionated carbon beam irradiation. The variation in LET with penetration depth leads to substantial differences in biological effect of carbon beam. And it is therefore essential in treatment planning to calculate not only the absorbed dose but also the LET to estimate the biological outcome of the radiation of interest. LET variation plays an important role in the fractionated irradiations. It is suggested that consideration of LET is necessary in biophysical model.

목차 (Table of Contents)

• Ⅰ. INTRODUCTION
• Ⅱ. MATERIAL AND METHODS
• Ⅲ. RESULT
• Ⅳ. DISCUSSION AND CONCLUSION

참고문헌 (Reference)

1 Alejandro carabe-fernandez, "The incorporation of the concept of minimum RBE into the linear-quadratic model and potential for improved daiobiological anal ysis of high-LET tratments" 83 (83): 27-39, 2006

2 Anatoly Dritschilo, "Repair of radiation damage in plateau-phase mammal ian cells: relationship between sub-lethal and potentially lethal damage states" 30 (30): 565-569, 1976

3 Marchese MJ, "Potentially lethal damage repair in human cells" 9 : 57-65, 1987

4 Michael J. Marchese, "Potentially lethal damage repair in cell lines of radioresistant human tumours and normal skin fibroblasts" 48 (48): 431-439, 1985

5 Stanley B. Curtis, "Lethal and potentially lethal lesio ns induced by radiation-A unified repair model" 252-270, 1986

6 Ang KK, "Is the rate of repair of radiation-induced sublethal damage in rat spinal cord dependent on the size of dose perfraction?" 557-562, 1987

7 Jack E Fowler, "Is Repair of DNA Strand Break Da mage from Ionizing Radiation Second-Order Rather T han First-Order? A Simpler Explanation of Apparentl y Multiexponential Repair" 124-136, 1999

8 Akifumi Miyakawa, "Applicability of the linear-quadratic model to single and fractionated radiotherapy schedules" 1-4, 2013

9 Wedenberg M, "Analytical Description of the LET Depen dence of cell survival using the Repairable-Conditiona lly Repairable damage model" 517-525, 2010

10 Nilsson P, "A generalized fo rmulation of the 'incomplete-repair' model for cell sur vival and tissue response to fractionated low dose-rat e irradiation" 127-142, 1990

11 Roger G. Dale, "A New Incomplete-repair Model Based on a 'Reciprocal-t ime' Pattern of Sublethal Damage Repair" 919-929, 1999