A computer-based method of evaluating a radiation therapy treatment plan for a treatment volume, divided into sub-volumes and having a target volume and one or more organs at risk, OAR. The method includes obtaining (S100) a radiation therapy treatment plan； calculating (S102) the linear energy transfer, LET, in each sub-volume； dividing (S104) the dose distribution into doses of a first category and a second category in each sub-volume, wherein the first category comprises doses with energy depositions with an LET below a first LET threshold and the second category comprises doses with energy depositions with an LET above a second LET threshold； determining (S106) amounts of doses of the first and of the second category in each sub-volume； and performing (S108) an analysis of the quality of the radiation therapy treatment plan by metrics based on the obtained distribution of doses of the first and of the second category in the target volume and in the OAR.
