金刚石探测器在Flash照射实时剂量测量中的应用

Feasibility of diamond detector on Flash radiation dosimetry online

目的通过实验探究人工金刚石探测器用于Flash照射剂量测量的可行性。方法采用CIVIDEC^(TM) B1HV金刚石探头,设计了基于预积分方法的大动态范围电流测量电路,研制了一款实时输出脉冲电流的金刚石探测器样机,分别在电子束和X射线超高剂量率照射下测试其剂量和剂量率响应,并使用医用加速器对该金刚石探测器进行剂量标定。结果电子束0.08~0.50 Gy/pulse范围内探测器输出积分电荷与参考脉冲剂量呈现较好的线性相关(R^(2)=0.99),在电子束超高平均剂量率(400 Gy/s)和常规平均剂量率(0.3 Gy/s)照射模式下,剂量线性响应较好(R^(2)=0.99),在X射线超高平均剂量率(75.5 Gy/s)和常规平均剂量率(0.5 Gy/s)照射模式下探测器输出积分电荷和参考剂量达到严格线性相关(R^(2)=1),获得电荷(电流)-剂量(率)实用转换系数0.7517μC/Gy和0.7535μA·Gy·s^(-1)。结论该金刚石探测器在电子和X射线超高剂量率束流照射下均体现了较好的剂量线性响应,能够为Flash预临床实验提供较快速、准确的剂量监测,有潜力用于未来Flash放疗质量控制。

Objective To explore the feasibility of synthetic diamond detector in use for Flash radiation dosimetry by designing a diamond dosimeter and conducting a series of dosimetric characteristic tests.Methods A diamond detector system prototype with real-time current output was developed using a CIVIDEC^(TM) B1HV diamond sensor and designing a large dynamic range current measurement circuit based on the pre-integration method.The dose(dose-rate)response linearity was tested under irradiation from both electron beam and X ray ultra-high dose rate.Dose(dose-rate)calibration was performed against a medical accelerator to gain the charge-dose transfer coefficient.Results Good linear correlation(R^(2)=0.99)between detector output charge and reference dose per pulse was shown under electron beam irradiation of 0.08-0.50 Gy/pulse.Good linearity(R^(2)=0.99)is also shown under irradiation from electron beam with ultra-high dose rate(400 Gy/s)and conventional dose rate(0.5 Gy/s).Strictly linear correlation(R^(2)=1)was shown between detector output integrated charge and reference dose under X ray irradiation at ultra-high average dose rate(75.5 Gy/s)and conventional average dose rate(0.5 Gy/s).The charge-dose and current-dose rate conversion factors for practical use were 0.7517μC/Gy and 0.7535μA·Gy·s^(-1),respectively.Conclusions Considerable linearity of the diamond detector dose responses were shown under irradiation both from electron beam and X-ray beam,which could provide a relatively rapid and accurate dosimetry for Flash preclinical experiments.Furthermore,diamond detectors have great potential in the quality assurance for Flash radiotherapy.