Tao Shengzhen, Sheedy Emily, Bruesewitz Michael, Weber Nikkole, Williams Kyle, Halaweish Ahmed, Schmidt Bernhard, Williamson Eric, McCollough Cynthia, Leng Shuai
Department of Radiology, Mayo Clinic, Jacksonville, FL, USA.
Department of Radiology, Mayo Clinic, Rochester, MN, USA.
Med Phys. 2021 Mar;48(3):1307-1314. doi: 10.1002/mp.14663. Epub 2021 Jan 9.
To determine the accuracy of CT number and calcium score of a kV-independent technique based on an artificial 120 kV reconstruction, and its potential to reduce radiation dose.
Anthropomorphic chest phantoms were scanned on a third-generation dual-source CT system equipped with the artificial 120 kV reconstruction. First, a phantom module containing a 20-mm diameter hydroxyapatite (HA) insert was scanned inside the chest phantoms at different tube potentials (70-140 kV) to evaluate calcium CT number accuracy. Next, three small HA inserts (diameter/length = 5 mm) were inserted into a pork steak and scanned inside the phantoms to evaluate calcium score accuracy at different kVs. Finally, the same setup was scanned using automatic exposure control (AEC) at 120 kV, and then with automatic kV selection (auto-kV). Phantoms were also scanned at 120 kV using a size-dependent mA chart. CT numbers of soft tissue and calcium were measured from different kV images. Calcium score of each small HA insert was measured using commercial software.
The CT number difference from 120 kV was small with tube potentials from 90 to 140 kV for both soft tissue and calcium (maximal difference of 4/5 HU, respectively). Consistent calcium scores were obtained from images of different kVs compared to 120 kV, with a relative difference <8%. Auto-kV provided a 25-34% dose reduction compared to AEC alone.
A kV-independent calcium scoring technique can produce artificial 120 kV images with consistent soft tissue and calcium CT numbers compared to standard 120 kV examinations. When coupled with auto-kV, this technique can reduce radiation by 25-34% compared to that with AEC alone, while providing consistent calcium scores as that of standard 120 kV examinations.
基于人工120 kV重建技术，确定一种与管电压无关的技术的CT值及钙化积分的准确性，以及其降低辐射剂量的潜力。
在配备人工120 kV重建功能的第三代双源CT系统上对仿真人体胸部模型进行扫描。首先，在胸部模型内，于不同管电压（70 - 140 kV）下扫描一个包含直径20 mm羟基磷灰石（HA）插入物的模型模块，以评估钙CT值的准确性。接着，将三个小的HA插入物（直径/长度 = 5 mm）插入一块猪排中，并在模型内进行扫描，以评估不同管电压下钙化积分的准确性。最后，使用自动曝光控制（AEC）在120 kV下对相同设置进行扫描，然后采用自动管电压选择（自动kV）。还使用基于尺寸的毫安图表在120 kV下对模型进行扫描。从不同管电压图像中测量软组织和钙的CT值。使用商业软件测量每个小HA插入物的钙化积分。
对于软组织和钙，管电压在90至140 kV时，与120 kV相比，CT值差异较小（分别最大差异为4/5 HU）。与120 kV相比，不同管电压图像获得的钙化积分一致，相对差异<8%。与单独使用AEC相比，自动kV可降低25 - 34%的剂量。
与标准120 kV检查相比，一种与管电压无关的钙化积分技术能够生成具有一致软组织和钙CT值的人工120 kV图像。当与自动kV结合使用时，该技术与单独使用AEC相比可减少25 - 34%的辐射，同时提供与标准120 kV检查一致的钙化积分。
