Meeting ACR Dose Guidelines for CT Lung Cancer Screening in an Overweight and Obese Population

Lung cancer screening adoption coincides with a growing obesity epidemic. Maintaining high-quality imaging at low radiation dose is challenging in obesity. We investigate the feasibility of meeting American College of Radiology (ACR) dose guidelines for lung cancer screening in a predominantly overweight and obese population.

Radiation dose (Volumetric CT dose index [CTDIvol], dose-length product), and body mass index (BMI) were collected for baseline screening CTs December, 2012-December, 2017. Dose metrics were analyzed according to BMI classification (normal <25, overweight 25-29, obese ≥30 kg/m²), using k = 0.014 mSv/mGy*cm. Results were compared to ACR dose guidelines and mean national 2017 Lung Cancer Screening Registry dose metrics. Analysis used Kruskal-Wallis (SPSS, version 24.0.0, IBM corp, Armonk, NY).

Study population comprised 1478 patients (49.2% [727] women: mean BMI 28.1 ± 6.5 kg/m², 26.9% [397] normal weight, 35.9% [530] overweight, 37.2% [551] obese). ACR dose requirements were met for both genders in all BMI classifications. Dose metrics were higher in men than in women; median effective dose and CTDIvol were 1.39 (0.8-1.58) mSv and 2.78 (1.41-2.80) mGy in men versus 1.16 (0.71-1.43) mSv and 2.70 (1.4-2.78) mGy in women. There were significant differences in dose metrics between men and women in the same BMI classification and between BMI classifications (p < 0.001). Mean dose metrics in our program were considerably lower than 2017 national average- mean CTDIvol and effective dose 2.45 ± 1.14 mGy and 1.26 ± 0.59 mSv versus 3.24 mGy and 1.35 mSv, respectively for our program and nationally. Mean dose metrics were also lower in our obese patients versus obese patients nationally.

ACR dose metrics for lung cancer screening were met and can be appropriately tailored in a predominantly overweight and obese population clinical program.