Assessment And Regularity Of Boron Neutron Capture Therapy For Secondary Cancer Risks Based On The Computational Phantom

Boron neutron capture therapy(BNCT)is a binary targeted radiotherapy technology that has unique advantages in treating of head and lung tumors with high biological effects and specific killing of tumors.At present,more and more attention has been paid to the secondary cancer risk induced by radiotherapy.For cancer survivors,the secondary cancer risk caused by radiation seriously threatens the quality of life for patients.With the development of neutron source and boron drug,BNCT will be used in clinical treatment for more cancer patients.However,there are few studies on secondary cancer risk in healthy organs for patients after BNCT.The purpose of this paper is to explore the secondary cancer risk in organs of tumor patients treated with BNCT,using a radiation computational phantom with Chinese physiological characteristics and Monte Carlo software TOPAS.The main research contents and results are as follows:(1)Based on the human body structure provided by Anatonium TM 3D P1 V5.0,according to the reference human data for radiation protection in China,the 10-year-old,15-year-old and adult male /female radiation computational phantom with Chinese physiological characteristics were established by using the software Rhinoceros.Meanwhile,Based on the high incidence of lung cancer and the characteristics of the population,the 4D dynamic phantoms were established for adult male according to the law of respiratory movement to improve the dose accuracy of BNCT treatment for lung cancer patients in simulation.(2)To assess the secondary cancer risks for head tumor patients caused by BNCT,the secondary cancer risk of healthy organs in the 10-year-old female patients under three KUR neutron beam irradiation geometries(Top to bottom,Right lateral,Posterior to anterior)was firstly studied.The results showed that the secondary cancer risk was the lowest under the PA irradiation geometry.On the basis of this geometry,the effects of tumor volume and depth,patient age and gender,neutron spectrum on the secondary cancer risk of brain tumor patients were studied.The results showed that the larger or deeper the tumor is,the greater the secondary cancer risks will be.The secondary cancer risks for healthy organs in male patients were mostly lower than that in female patients,and the total secondary cancer risk decreased with age.The time of different neutron spectrum to achieve the same treatment effect is different,the secondary cancer risk will also be different.Finally,based on the CT images of NPC patients,combined with phantom and Monte Carlo simulation,the secondary cancer risks of healthy organs with BNCT treatment were predicted.(3)To assess the secondary cancer risks caused by BNCT in lung tumor patients,the secondary cancer risks of phantom organs in single phase and composite phase in respiratory cycle were firstly studied.The results showed that the organs secondary cancer risk in different single phase was quite different,and the organs secondary cancer risk in composite phase was more representative of the real situation.Based on the composite phase,the effects of tumor location,tumor volume and neutron energy spectrum on the organs secondary cancer risk of lung tumor patients were studied.The results showed that tumor location had great influence on the secondary cancer risk in the healthy organs near the lung.Various tumor volume and neutron spectrum need different irradiation time to achieve the same treatment effect,the risk of secondary cancer of organs is also different.Finally,based on the 4D-CT images of lung cancer patients,combined with four-dimensional phantom and Monte Carlo simulation,the organs secondary cancer risk induced by BNCT in this patient was predicted.In this paper,the secondary cancer risks in healthy organs were evaluated when BNCT was used to treat head tumor patients and lung tumor patients,as well as the change rule of the secondary cancer risk under different influencing factors,which provided a reference for the clinical application of BNCT.Under the condition of abundant data,the organs secondary cancer risk may become one of the basis for the choice of BNCT treatment plan in the future.