RBE calculation using radiobiological computation software ‘Survival’ for human salivary gland cell

[Purpose] The clinical dose in heavy ion radiotherapy is defined by calculating the biological dose based on RBE for human salivary gland (HSG) cells, and normalizing it to the clinical RBE value obtained by neutron radiotherapy. However, since irradiated various tumors and normal tissues are not HSG cells, the predicted biological dose for irradiated field may have large uncertainty. In this study, we introduced radiobiological computation software ‘Survival’ to estimate the RBE for various cells, and tried to calculate the RBE using ‘Survival’ for irradiation of HSG cells with 12C, 20Ne and 3He, ions. [Methods] The biological dose analysis software used was ‘Survival'. PIDE ver.3.1 was used as literature data on past cell irradiation. RBE (RBESurvival) was calculated by analyzing cell survival rate with the ‘Survival’ using PEID irradiation conditions. By comparing this with RBE(RBEPEID) calculated from PEID, the accuracy of RBE calculation using the ‘Survival’ was evaluated. Microdosimetric Kinetic Model (MKM) was used for the biological effect model, and the values of each parameter required were those of previous studies. The target cells were HSG, and the irradiated particles were 12C, 20Ne, and 3He. The linear energy transfer (dose averaged LET: LETD) described in PIDE was used. [Results] RBESurvival was generally consistent with RBEPEID. This suggests that RBE can be roughly estimated. The area where RBESurvival cannot reproduce RBEPEID was different for each particle. Also, the relationship with LET is not shown. [Conclusion] The ‘Survival’ roughly could estimate the RBE for irradiation of HSG cells with 12C, 20Ne and 3He, ions. In the future, we will evaluate the RBE calculation accuracy of the ‘Survival’ for various cells.
第119回日本医学物理学会学術大会