Low-Dose Chest CT Recommendations
Low-dose CT screening programs should follow the American College of Radiology (ACR)/Society of Thoracic Radiology (STR) protocols for performing low radiation dose chest CT scans to minimize radiation exposure while maintaining diagnostic quality. 1
Eligibility Criteria for Low-Dose Chest CT Screening
- Annual low-dose CT screening is recommended for high-risk individuals aged 55-77 years with at least a 30 pack-year smoking history who currently smoke or have quit within the past 15 years 1
- For individuals aged 50-80 with at least 20 pack-years of smoking and additional risk factors, low-dose CT screening may be appropriate, though evidence is less conclusive 1, 2
- Screening is not recommended for individuals younger than 50, older than 80, with less than 20 pack-years smoking history, or who quit smoking more than 15 years ago 1
- Screening should not be performed in individuals with comorbidities that substantially limit life expectancy or ability to tolerate evaluation of findings or treatment 1
Technical Parameters for Low-Dose CT
- CT dose volume index should be maintained at ≤3.0 mGy for average-sized patients, with adjustments for larger or smaller patients 1
- Images should be optimized to avoid artifacts while maintaining high spatial resolution 1
- Non-contrast helical studies should be performed with slice thickness ≤2.5 mm (with <1 mm preferred) 1
- Radiation dose from low-dose CT is approximately 1.4-2.4 mSv, compared to 7 mSv for standard-dose chest CT 3, 4
- Reducing tube current (to 50 mAs) and tube potential (to 80-120 kVp) are effective methods for dose reduction while maintaining diagnostic quality 4, 5, 6
Implementation of Low-Dose CT Screening Programs
- Programs should develop a dedicated LDCT protocol reviewed annually by supervising radiologists, medical physicists, and radiology technologists 1
- Structured reporting systems (such as ACR Lung-RADS) should be used to standardize findings and recommendations 1
- Programs should implement strategies to determine whether patients have symptoms suggesting lung cancer, directing symptomatic patients to diagnostic testing rather than screening 1
- Effective counseling and shared decision-making visits should occur prior to screening, including discussion of benefits, harms, and follow-up procedures 1
- Smoking cessation interventions should be integrated into screening programs 2
Quality Assurance Measures
- Programs should develop data collection and reporting tools for quality improvement initiatives 1
- Technicians performing screening LDCT scans should be trained in the specific protocol 1
- Quality checks using training sets of screening LDCTs can ensure consistent application of structured reporting systems 1
- Programs should develop strategies to guide management of non-nodule findings (e.g., coronary calcification, thyroid nodules) 1
Potential Benefits and Harms
- Low-dose CT screening reduces lung cancer mortality by approximately 20% and all-cause mortality by 6.7% in high-risk populations 2
- Potential harms include false positives leading to unnecessary procedures, radiation exposure, and overdiagnosis of indolent cancers 2
- Studies demonstrate that 50% radiation dose reduction (compared to standard protocols) still provides acceptable image quality for evaluating normal anatomic structures 7, 5
Special Considerations
- The American Association of Physicists in Medicine provides a free library of optimized protocols for LDCT screening scans for commonly installed CT scanners 1
- Tube potential reduction is particularly advantageous for smaller patients but may require higher tube current for satisfactory image quality 4
- Iterative reconstruction methods can further reduce radiation dose while maintaining image quality 4
By following these evidence-based recommendations, low-dose CT screening programs can maximize benefits while minimizing potential harms to patients.