Department of Radiography, Faculty of Health Sciences, University of Malta, Msida, Malta.
Radiography (Lond). 2023 Jul;29(4):738-744. doi: 10.1016/j.radi.2023.05.001. Epub 2023 May 18.
To investigate optimising a computerised tomography pulmonary angiogram (CTPA) scan protocol in terms of radiation dose and image quality using a low kV technique combined with high iterative reconstruction (IR) parameters (>50%) and apply the optimised protocol in clinical practice on patients irrespective of their body weight.
CTPA examinations were performed on 64 patients equally divided into control and experimental groups. Patients in the control group were scanned using the current protocol (100 kV with 50% IR) while patients in the experimental group were scanned using an optimised protocol (80 kV with 60%IR). The radiation dose indices volume computerised tomography dose index (CTDIvol), dose length product (DLP), size specific dose estimates (SSDE) and effective dose (ED) were recorded. Subjective image quality was evaluated by 3 radiologists through absolute visual grading analysis (VGA) using an image quality scoring tool. The resultant image quality scores were analysed using Visual Grading Characteristics (VGC). Objective image quality was recorded in terms of contrast-to-noise-ratio (CNR) and signal-to-noise-ratio (SNR).
The application of the optimised protocol resulted in a statistically significant (p < 0.05) reduction in mean CTDIvol (-49%), DLP (-48%), SSDE (-52%) and ED (-49%). Objective image quality was significantly (p < 0.05) improved both in CNR (32%) and SNR (13%). Subjective image quality scores were higher for the current protocol but variation between the two protocols was not significant (p = 0.650).
When applying the low kV technique combined with high IR parameters, a significant dose reduction may be achieved while still maintaining diagnostic image quality.
The low kV technique combined with high IR parameters is an effective optimisation technique which can be easily implemented for the CTPA protocol.
为了在使用低千伏技术结合高迭代重建（IR）参数（>50%）优化计算机断层肺动脉造影（CTPA）扫描方案的辐射剂量和图像质量，并将优化后的方案应用于患者在不考虑体重的情况下进行临床实践。
将 64 例患者等分为对照组和实验组。对照组患者采用现行方案（100kV，IR 50%）扫描，实验组患者采用优化方案（80kV，IR 60%）扫描。记录辐射剂量指标体积计算机断层扫描剂量指数（CTDIvol）、剂量长度乘积（DLP）、体型特异性剂量估计（SSDE）和有效剂量（ED）。3 名放射科医生通过使用图像质量评分工具的绝对视觉分级分析（VGA）评估主观图像质量。使用视觉分级特性（VGC）分析图像质量评分。以对比噪声比（CNR）和信噪比（SNR）记录客观图像质量。
应用优化方案后，CTDIvol（-49%）、DLP（-48%）、SSDE（-52%）和 ED（-49%）的平均值显著降低（p<0.05）。客观图像质量显著提高（p<0.05），CNR（32%）和 SNR（13%）均有所提高。现行方案的主观图像质量评分较高，但两种方案之间的差异无统计学意义（p=0.650）。
在应用低千伏技术结合高 IR 参数时，可以在保持诊断图像质量的同时，显著降低剂量。
低千伏技术结合高 IR 参数是一种有效的优化技术，可轻松应用于 CTPA 方案。
