M Suga^1,3*, T Honma², S Lee³, M Suzuki³, H Katou¹, M Hashimoto², K Tanimoto³, R Kohno³, (1) Kanagawa Cancer Center, Kanagawa, JP(2)International University of Health and Welfare Graduate school, Tochigi, JP(3)National Institute of Radio. Sciences, Chiba, JP

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  M Suga

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: The clinical dose in carbon ion radiotherapy with wobbler method at National Institute of Radiological Sciences in Japan 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, irradiated various tumors and normal tissues are actually different from HSG cells. Therefore, the predicted biological dose for irradiated field may have large uncertainty. In order to estimate the RBE for various cells, we introduced radiobiological computation software ‘Survival’, and tried to calculate the RBE using the ‘Survival’ for three typical cells irradiated by each ions.

Methods: We used the biological dose analysis software ‘Survival’. Particle Irradiation Data Ensemble (PIDE) ver.3.2 was used as literature data on past cell irradiation. RBE (RBESurvival) values were calculated by analyzing cell survival rate with the ‘Survival’ using PIDE irradiation conditions. Microdosimetric Kinetic Model (MKM) as a biological effect model was used in this study. The target cells were HSG, V79 and CHO cells, and the irradiated particles were 12C, 20Ne, and 3He. The linear energy transfer (dose averaged LET: LETD) described in PIDE was used. By comparing these with RBE (RBEPIDE) values obtained from the PIDE, the RBE values calculated by using the ‘Survival’ was evaluated.

Results: We calculated the RBE values for HSG, V79 and CHO cells irradiated by 12C, 20Ne, and 3He ions by using the ‘Survival’. The RBESurvival values were generally consistent with RBEPIDE values for them.

Conclusion: RBE calculations by using the ‘Survival’ for HSG, V79 and CHO cells irradiated by 12C, 20Ne, and 3He ions were evaluated in this study. The ‘Survival’ could roughly estimate the RBE for three typical cells. In the future, we will evaluate the RBE calculation accuracy of the ‘Survival’ for various cells.

Funding Support, Disclosures, and Conflict of Interest: This study was supported by JSPS KAKENHI Grant Number JP19K08188.

Keywords

Heavy Ions, RBE, LET

Taxonomy

TH- External Beam- Particle/high LET therapy: Carbon ion therapy – computational dosimetry-deterministic

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