MEDRADSC 2X03 Lecture Notes - Lecture 3: Srf 1, Point Mutation, Stratum Basale

• School: McMaster University
• Department: Medical Radiation Sciences
• Course: MEDRADSC 2X03
• Professor: ALL

Document Summary

D0 (cid:858)(cid:373)ea(cid:374) lethal dose(cid:859: quantity of dose that delivers, on average, one inactivating event per cell, some cells will be hit once, others more, and others not at all, but on average radiation hits once per cell. Limitation of math expression of curve: expression addresses straight line portion only, does not tell exact shape of initial shoulder since all curves start at sf = 1. Does indicate where shoulder meets straight line portion. Linear quadratic model of cell survival: 2 parallel components to cell killing, one is proportional to dose, other is proportional to square of dose, recognizes that chromosome damage could be due to, single radiation (ex. Electronic passes through one dna molecule) causing one. Dsb or point mutation: two radiations causing two separate breaks resulting in a lethal aberration, fractionation leads to better tumour control. Disadvantages space out too long you can increase tumour cell proliferation. Large alpha beta rations 10-20, early or acute reacting tissues.