X-ray computed tomography （CT） related to computer-processed combination or X-ray images obtained from different angles to create patient＇s cross-sectional body parts images. CT ensures to have imaging various orga...X-ray computed tomography （CT） related to computer-processed combination or X-ray images obtained from different angles to create patient＇s cross-sectional body parts images. CT ensures to have imaging various organs, bones, blood vessel etc. and more advantageous than normal plain X-ray devices in consequence of 360 degree image of internal organs, the spine and vertebrae. For decades, Radiation protection became a main topic in research areas since CT uses various dose of X-ray for imaging body. Distance factor is the one of fundamental principle of radiation protection. Maximum dose occurs around gantry and dose rate is decreases by distance in CT facilities. To know the rate of reduction of the amount of dose by distance is very significant for radiation protection procedure especially for apply criteria of International Commission on Radiological Protection （ICRP） on radiation protection. Our study aimed to measure scattered dose rates during abdominal CT scan by considering small distance ranges from gantry until exit door and comparing the empirical result with Monte Carlo （MC） calculations. As a next step of study, we modeled a simulation input for CT facility by using MCNP-X （version 2.4.0）. We obtained the changes of dose rate on distance factor by using Monte Carlo method, We achieved that MCNP-X calculations were in concordance with clinical experimental measurements. It can be concluded that Monte Carlo （MC） is an effective tool for obtain dose rate variations around CT gantry and especially radiation protection calculations in CT facilities.展开更多
文摘1病例资料
患者男性,55岁,因间断胸闷、胸痛,伴气短1年,加重5d于2015年10月29日入住我科.患者于1年前运动后出现胸闷、胸痛,伴气短、汗出,伴左侧肩背部酸胀感,无恶心、呕吐、发热、咳嗽等,休息3～5 min后症状好转,未予重视,此后症状间断发作.5d前患者于活动后再次出现上述症状,休息约5 min可缓解.为求进一步诊治就诊于我院门诊.行运动试验示：阳性,Ⅱ、Ⅲ、AVF、V4～V6导联ST段运动中、后动态改变（Ⅱ、Ⅲ、AVF导联ST段压低0.20～0.25 mV,V4～V6导联ST压低0.1～0.2 mV）,门诊以“冠状动脉粥样硬化性心脏病、不稳定型心绞痛”收入我科.患高血压15年,血压最高160/100 mm Hg（1 mm Hg=0.133 kPa）,平日口服尼群地平10 mg,2次/d,血压波动在130～140/80～90 mm Hg,否认糖尿病病史,脑梗死病史5年,有磺胺类药物过敏史,吸烟史20余年,每日30支左右,已戒烟10余年,饮酒史40余年,平均每天100 ml.
文摘X-ray computed tomography （CT） related to computer-processed combination or X-ray images obtained from different angles to create patient＇s cross-sectional body parts images. CT ensures to have imaging various organs, bones, blood vessel etc. and more advantageous than normal plain X-ray devices in consequence of 360 degree image of internal organs, the spine and vertebrae. For decades, Radiation protection became a main topic in research areas since CT uses various dose of X-ray for imaging body. Distance factor is the one of fundamental principle of radiation protection. Maximum dose occurs around gantry and dose rate is decreases by distance in CT facilities. To know the rate of reduction of the amount of dose by distance is very significant for radiation protection procedure especially for apply criteria of International Commission on Radiological Protection （ICRP） on radiation protection. Our study aimed to measure scattered dose rates during abdominal CT scan by considering small distance ranges from gantry until exit door and comparing the empirical result with Monte Carlo （MC） calculations. As a next step of study, we modeled a simulation input for CT facility by using MCNP-X （version 2.4.0）. We obtained the changes of dose rate on distance factor by using Monte Carlo method, We achieved that MCNP-X calculations were in concordance with clinical experimental measurements. It can be concluded that Monte Carlo （MC） is an effective tool for obtain dose rate variations around CT gantry and especially radiation protection calculations in CT facilities.
