Radiotherapy Fractionation 2D: The Linear-Quadratic Model

This simulator renders a 2D cross-section of a tumor mass surrounded by a ring of healthy tissue and lets you deliver a real fractionated radiotherapy course to it. Every fraction is scored against the linear-quadratic cell-survival model — the same SF = exp(-(αd + βd²)) equation oncologists use to plan real treatment — with the tumor's higher α/β ratio and the normal tissue's lower one producing genuinely different survival curves as you change the dose per fraction and course length. A live chart plots the per-fraction survival curve for both tissues over the full dose range, while stat panels track surviving cell fraction, cumulative biologically effective dose (BED) for both tissues, and the therapeutic ratio between them — making visible the biological reason cancer treatment is split into many small doses instead of one large one.