comparison of radiobiological models for radiation therapy plans of prostate cancer: threedimensional conformal versus intensity modulated radiation therapy

Purpose: in the current study, using different radiobiological models, tumor control probability (tcp) and normal tissue complication probability (ntcp) of radiotherapy plans were calculated for threedimensional conformal radiation therapy (3dcrt) and intensity modulated radiation therapy (imrt) of prostate cancer. methods and materials: 10 prostate plans were randomly selected among patients undergoing radiation therapy of prostate cancer. for each patient, 3dcrt and imrt plans were designed to deliver, on average 76 gy and 82 gy to planning target volume, respectively. using different radiobiological models including poisson, equivalent uniform dose (eud) and lymankutcherburman (lkb), tcp and ntcp were calculated for prostate and critical organs including bladder, rectum and femoral heads.results: imrt plans provided significantly lower ntcp for bladder, rectum and femoral heads using lkb and eud models (pvalue <0.05). the eudcalculated tcp for prostate cancer revealed no considerable improvement for imrt plans relative to 3dcrt plans. however, the tcps calculated by poisson model were dependent on α/β, and higher tcp for imrt relative to 3dcrt was seen for α/β higher than 5.conclusion: it can be concluded that imrt plans were superior to 3dcrt plans in terms of estimated ntcp for studied critical organs. on the other hand, different mathematical models provided different quantitative outcome for tcp of prostate cancer plans. more clinical studies are suggested to confirm the accuracy of studied radiobiological models.