【摘 要】
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Purpose: This paper reports the relationship between Body Mass Index(BMI),tube voltages,tissue weighting factors,gender and the conversion factors of DLP,that can be used to estimate effective dose of
【机 构】
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School of Nuclear Science and Technology,University of Science and Technology of China,Hefei,Anhui P
【出 处】
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The 15th Asia-Oceania Congress of Medical Physics (AOCMP2015
论文部分内容阅读
Purpose: This paper reports the relationship between Body Mass Index(BMI),tube voltages,tissue weighting factors,gender and the conversion factors of DLP,that can be used to estimate effective dose of patient in CT examination.Sex-,obese-and tube voltage-specific conversion factors are provided for overweight and obese patients with body CT scanning to estimate effective dose.Moethod: The VirtualDose software was used to calculate effective dose for male and female obese phantoms representing normal-weight,over-weight,obese 1,obese 2 and obese 3 patients.Five anatomic regions(chest,abdomen,pelvis,abdomen/pelvis,and chest/abdomen/pelvis(CAP))were investigated for each phantom.Result: Effective dose computed using ICRP-103 weighting factors was found to be 24%higher than those from ICRP-60 weighting factors for chest CT examination and 21%lower for pelvis CT examinations for the same protocols.For body CT scans,increasing the tube voltage from 80kVp to 140kVp would increase the conversion factors by as much as 19%-54%depending on the patients BMI.The conversion factors were found to decrease with increasing BMI in five scan regions.For the abdomen scan,the conversion factors for patients of normal weights were found to be 1.4-2.5 folds relative to those for patients who are in the category of Obese-3.A similar trend was also found for the pelvis scan.Conversion factor of female patients was approximately 7%higher than the factors of male patients.Conclusion: This study suggests that,when using conversion factors and DLP to compute effective dose,we need to consider the effect of tube voltage,BMI and tissue weighting factors on conversion factors.The result of this study can be used to improve existing CT dosimetry by adopting size-specific and protocol-specific effective dose data.
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