两种CT胸部扫描模式下DLP值的测量与分析

目的 通过对CT胸部常规扫描与低剂量扫描模式下的剂量长度乘积（DLP）值进行比较，为CT胸部扫描时的条件选择提供数据参考。方法 采用CT-DP检测探头和标准CT剂量体模，测量GE Revolution型256排CT胸部常规扫描模式与低剂量扫描模式下的DLP。结果 对胸部低剂量模式，Chest_Lowdose LARGE SIZE模式，DLP测量值60.16 mGy·cm；Chest_Lowdose SMALL SIZE模式，DLP测量值33.65 mGy·cm。胸部常规扫描模式，DLP测量值276.68 mGy·cm。胸部常规扫描模式DLP值是Chest_Lowdose SMALL SIZE模式的8.22倍，是Chest_Lowdose LARGE SIZE模式的4.60倍。而同为胸部低剂量扫描，根据受检者体型不同，选择Chest_Lowdose LARGE SIZE模式DLP值是Chest_Lowdose SMALL SIZE模式的1.79倍。结论 选择低剂量CT进行胸部扫描能显著降低受检者剂量，对体型瘦小的受检者选择合适的胸部低剂量扫描模式也会明显降低所受剂量。

Measurement and analysis of DLP values in two chest CT scanning modes

Objective By comparing the dose length product (DLP) values of routinechest CT scanand low-dose CT chest scan, we can provide data for the selection of chest CT scan conditions.Methods Using a CT Dose Profiler(CT-DP) and a standard CT dose phantom, we measured DLPs in the routineand low-dose chest CT scanning modes by GE revolution 256-slice CT.Results Forlow-dose chest scanning modes:in Chest_Lowdose LARGE SIZE mode, DLP measured was 60.16 mGy·cm; in Chest_Lowdose SMALL SIZE mode,DLP was 33.65 mGy·cm;and for routine chest scan, DLP was 276.68 mGy·cm.The DLP value ofthe routine chest scanning mode is 8.22 times larger than that ofChest_Lowdose SMALL SIZE mode, and 4.60 times larger than that in the Chest_Lowdose LARGE SIZE mode.And for the two low-dose chest scans, depending on the size of the subject,the DPL of Chest_Lowdose LARGE SIZE mode was 1.79 times larger than that of Chest_Lowdose SMALL SIZEmode.Conclusion Low-dose chest scan can significantly reduce the dose of the subject, and choosing a suitable low-dose chest scan for the subject with a small size will also significantly reduce the dose.