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目的:分析不同摄影条件下,乳腺数字化X线摄影图像质量和辐射剂量的变化,探讨在不影响图像质量的前提下,有效降低辐射剂量的摄影方法。方法:采用全视野乳腺数字化X线机,在不同摄影条件下[手动曝光模式(manual exposure control,MEC)、自动曝光模式(automatic exposure control,AEC)]对标准乳腺模体进行重复曝光测试,记录每种摄影条件下的体表入射剂量(entrance surface dose,ESD)和平均腺体剂量(average glandular dose,AGD)。由3名高年资影像科医师,按照美国放射学院乳腺模体影像评价标准对影像进行评分,并对ESD、AGD及图像质量评分进行统计学分析。结果:固定管电压(28 k V)时,ESD和乳腺AGD随着管电流的上升而上升;固定管电流(56 m As)时,ESD和乳腺AGD随着管电压的上升而上升,固定管电压和固定管电流这2组摄影参数改变的图像评分差异均无统计学意义(χ~2=0.434,P均>0.05)。结论:在乳腺数字化X射线摄影检查中,MEC模式更适合个体化诊断,能够有效降低受检者的辐射剂量,达到剂量最优化。
OBJECTIVE: To analyze the changes of digital mammography image quality and radiation dose under different photographic conditions, and to explore the photographic method of effectively reducing the radiation dose under the premise of not affecting the image quality. Methods: The full-field mammary gland digital X-ray machine was used to carry out repeated exposure test of standard mammary gland in different photographic conditions [manual exposure control (MEC) and automatic exposure control (AEC)], recording The entrance surface dose (ESD) and average glandular dose (AGD) under each photographic condition. Three high-grade imaging physicians scored the images according to the American College of Radiation Oncology Imaging Criteria, and analyzed ESD, AGD and image quality scores. Results: ESD and mammary gland AGD increased with the increase of tube current at a fixed tube voltage (28 kV). When the tube current (56 mAs) was fixed, the ESD and the mammary gland AGD increased with the increase of the tube voltage. There was no significant difference between the two groups (P <0.05). There was no significant difference in voltage and fixed tube current between the two groups (χ ~ 2 = 0.434, P> 0.05). Conclusion: In the digital mammography examination, MEC mode is more suitable for individual diagnosis, which can effectively reduce the radiation dose of the subjects and achieve the dose optimization.