不同CT扫描中心联合ATCM技术对乳腺辐射剂量的影响

目的观察不同X线计算机断层摄影(CT)扫描中心联合全自动管电流调制(ATCM)技术对乳腺辐射剂量的影响。 方法对成人胸部模体予以CT螺旋扫描,采取ATCM技术,取乳腺向上5 cm(mam+5)与4 cm(mam+4)、乳腺(mam)、腋前线(pre-axilla)、腋中线(mid-axilla)、腋后线(post-axilla)6种扫描中心,各扫描中心需要定位像扫描3次,并进行一次螺旋扫描,详细记录肺算法与标准软组织算法所得对比噪声比(CNR);采取热释光剂量计(TLD)进行乳腺辐射剂量的测定,同时记录容积CT剂量指数(CTDI_vol)。结果扫描中心为post-axilla时CTDI_vol累积值最小(3.531 mGy),为pre-axilla时CTDI_vol累积值最大(4.126 mGy);扫描中心为post-axilla时乳腺辐射剂量累积值最小(4.793 mGy),为mam时乳腺辐射剂量累积值最大(6.471 mGy)。 结论联合ATCM技术进行胸部CT螺旋扫描时,扫描中心的选取可直接影响乳腺辐射剂量,建议以post-axilla为扫描中心,能够在一定程度上降低辐射剂量。

Effects of different CT scan centers combined with ATCM technology on breast radiation dose

AimTo observe the effects of different X-ray computed tomography (CT) scan centers combined with automatic tube current modulation (ATCM) technology on breast radiation dose. MethodsCT spiral scans were performed on the adult chest. ATCM technology was applied to collect six scan centers [5 cm above mammary gland (mam+5), 4 cm above mammary gland (mam+4), mammary gland (mam), anterior axillary line (pre-axilla), midaxillary line (mid-axillary), and posterior axillary line (post-axilla)]. In each scan center, location image scans were conducted for three times, and once spiral scan was needed. The contrast noise ratio (CNR) obtained by lung algorithm and standard soft tissue algorithm was recorded. The breast radiation dose was measured by thermoluminescence dosimeter (TLD), and CT dose index volume (CTDI_vol) was recorded. ResultsWhen the scan center was post-axilla, the cumulative value of CTDI_vol was the smallest (3.531 mGy). When the scan center was pre-axilla, the cumulative value of CTDI_vol was the largest (4.126 mGy). When the scan center was post-axilla, the cumulative value of breast radiation dose was the smallest (4.793 mGy). When the scan center was mam, the cumulative value of breast radiation dose was the largest (6.471 mGy). ConclusionWhen ATCM technology is combined with chest CT spiral scan, the selection of scan centers will directly affect breast radiation dose. It is recommended to apply post-axilla as the scan center, which can reduce the radiation dose to a certain extent.