Variability of radiation dose in low-dose CT lung cancer screening: A real-world multi-centre protocol comparison

Low-dose computed tomography (LDCT) is an effective tool for early lung cancer detection, although radiation doses may differ between institutions. This study evaluated patient dose variability across three LDCT screening centers in Vojvodina, Serbia, during baseline examinations in 2024, assessing compliance with international recommendations.

A total of 3479 high-risk participants (43.2 % male, 56.8 % female; mean age 62.2 ± 6.6 years; BMI 26.7 ± 4.8 kg/m²) underwent baseline LDCT. Inclusion criteria were age 50-74 years and smoking status (current smokers with ≥30 pack-years, ≥20 pack-years with additional risks, or former smokers who quit ≤10 years ago). Exclusion criteria were prior chest CT within 12 months or previous lung cancer. Recorded parameters included CT dose index (CTDIvol), dose-length product (DLP), tube voltage (kVp), and tube current-time product (mAs). Multiple linear regression identified CTDIvol predictors, including center, kVp, mAs, and patient factors.

Significant inter-center dose variability was found for all parameters (p < 0.001). Mean CTDIvol ranged 0.58-1.63 mGy, DLP 21.0-65.2 mGy cm, and effective dose 0.29-0.92 mSv. Center Screening site (β = -0.756) and kVp (β = 0.544) were the strongest predictors of CTDIvol, explaining 91 % of dose variance (R² = 0.910, p < 0.001). All doses were below 2 mSv, corresponding to a low lifetime cancer risk (∼0.05-0.1 %), consistent with ALARA principles.

This first multicenter analysis in Serbia confirms LDCT screening doses comply with international recommendations and ALARA principles. Inter-site variability highlights the need for continuous monitoring to optimize image quality and minimize exposure.

Systematic dose tracking, protocol harmonization, and medical physicist involvement are essential to ensure consistent, safe, and effective LDCT lung cancer screening.