数字化体层融合在胸部检查中辐射剂量的研究

Evaluation of radiation dosage in chest digital tomosynthesis

目的通过评价数字化体层融合（DTS）在胸部检查中的辐射剂量，探讨DTS应用于胸部病变筛查的可行性。方法采用自动曝光控制技术对Fluke肺一胸体模分别进行后前位、左侧位数字x线平片与DTS检查，应用RTIDoseGuard剂量面积乘积仪和RTIWinODS剂量软件检测并计算出胸部数字x线平片与DTS的剂量面积乘积与有效剂量。采用CareDose技术对Fluke肺一胸体模进行MSCT与低剂量MSCT扫描，得出剂量长度乘积，依据转换系数（k）将剂量长度乘积转化为有效剂量。4种检查方法分别进行5次成像，所得辐射剂量数据取均值，采用配对t检验比较DTS与数字X线平片、DTS与低剂量MSCT有效剂量的差异性。结果胸部数字X线平片、DTS、低剂量MSCT与MSCT胸部扫描的有效剂量分别为0．13、0．11、1．13与6．38mSv。胸部DTS的有效剂量基本与数字X线平片相当，差异无统计学意义（t=3．514，P〉0．01）；为低剂量MSCT的1／10和MSCT的1／60，差异有统计学意义（扭178．769，P〈0．01）。结论与低剂量MSCT相比，DTS作为一种新的体层成像方法，应用于胸部病变筛查具有明显的低辐射剂量优势。

Objective To evaluate the feasibility of chest digital tomosynthesis （DTS） for lung lesion screening by comparing the effective dose of chest DTS with chest digital radiography（ DR）, low-dose MSCT and MSCT examinations. Methods The Fluke lung/chest phantom underwent posterior-anterior （PA）, left lateral （LAT） chest DR and DTS with automatic exposure control technique. Using RTI DoseGuard and WinODS, the dose area product （DAP） and effective dose of PA, LAT and total DTS were calculated. CareDose technique was used for MSCT and low-dose MSCT scans, the dose length products （DLP） was acquired. According to the DLP to E （k） conversion coefficient in ICRP 103, the effective dose of low-dose MSCT and MSCT were calculated. Paired t test was used for comparison of the mean effective dose of DTS, DR and low-dose MSCT. Results The mean effective dose was 0. 13 roSy for chest DR and 0. 11 mSv for DTS examination. The mean effective dose of low-dose MSCT and MSCT scans were 1.13 mSv and 6. 38 mSv. The effective dose of chest DTS was comparable to that of chest DR, and was approximately 1/10 and 1/60 times lower than that of low-dose MSCT and MSCT scans. There was no statistical difference between chest DTS and DR （t = 3. 514 ,P 〉 0. 01 ）, and there was a significant difference between chest DTS and low-dose MSCT （t = 178. 769,P 〈 0. 01 ）. Conclusion DTS is a new X-ray tomography which has the advantage of low radiation dosage in chest examination for lung lesion screening comparing with low-dose MSCT.