To the Editor In response to the recently published Original Investigation by Demb and colleagues¹ regarding computed tomography (CT) radiation doses for lung cancer screening scans, I have concerns about the statements made about effective doses. The National Lung Screening Trial reported an average radiation effective dose of 1.5 mSv for CT scans performed in the trial.² Demb and colleagues state that “[the American College of Radiology] recommends that [lung cancer screening] scans have…an effective dose of 1 mSv or lower.”^1(p1651) This dose is 33% less than the dose in the National Lung Screening Trial, which validated this screening test. However, the pertinent American College of Radiology–Society of Thoracic Radiology practice parameter does not mention a 1 mSv effective dose goal.³ The practice parameter notes a CT dose index (CTDIvol) target of 3 mGy, which only applies to a standard-sized patient (defined as a height of 170 cm and a weight of 70 kg). The American Association of Physicists in Medicine (AAPM) mentions effective doses and the value of 1 mSv but does not recommend an effective dose of 1 mSv as a patient, laboratory, or population target.⁴ The 1 mSv figure cited by AAPM is not a recommendation for lung cancer screening, but rather a descriptive measure obtained by simply converting a CTDIvol of 3 mGy into the equivalent effective dose for an idealized standard-sized patient.

To the Editor In response to the recently published Original Investigation by Demb and colleagues¹ regarding computed tomography (CT) radiation doses for lung cancer screening scans, I have concerns about the statements made about effective doses. The National Lung Screening Trial reported an average radiation effective dose of 1.5 mSv for CT scans performed in the trial.² Demb and colleagues state that “[the American College of Radiology] recommends that [lung cancer screening] scans have…an effective dose of 1 mSv or lower.”^1(p1651) This dose is 33% less than the dose in the National Lung Screening Trial, which validated this screening test. However, the pertinent American College of Radiology–Society of Thoracic Radiology practice parameter does not mention a 1 mSv effective dose goal.³ The practice parameter notes a CT dose index (CTDIvol) target of 3 mGy, which only applies to a standard-sized patient (defined as a height of 170 cm and a weight of 70 kg). The American Association of Physicists in Medicine (AAPM) mentions effective doses and the value of 1 mSv but does not recommend an effective dose of 1 mSv as a patient, laboratory, or population target.⁴ AAPM引用的1 mSv数据不是建议进行肺癌筛查，而是通过将3 mGy的CTDIvol简单地转换为理想的标准体重患者的等效有效剂量而获得的描述性措施。