Cervical and lumbar spine imaging after traffic and occupational accidents: Evaluation of the use of imaging techniques, cumulative radiation dose and associated lifetime cancer risk.

PURPOSE: To study number and type of imaging techniques, cumulative radiation exposure and radiation-induced risk from repeated imaging of cervical and lumbar spine attained after traffic or occupational accident. METHOD: The study cohort comprised of 500 patients after traffic or occupational accident. Amount of radiography, CT and MRI procedures and injury severity were tallied for each patient. Cumulative effective dose (CED), expressed in millisieverts (mSv), was estimated by summing up typical effective dose values. Total lifetime cancer risks and associated risk category were estimated by using risk coefficients, specified according to sex, age at exposure and exposed region. RESULTS: A total of 2,107 imaging procedures were performed of which 30% were radiographs (n = 631), 21% were CT (n = 438) and 49% were MRI (n = 1,038). Abbreviated Injury Scale was low (1-2) in all cases (except one). The cohort included 352 patients after traffic accident and 148 after occupational accident. Mean CED of these two groups were 4.4 mSv and 9.4 mSv, respectively. No patient had a CED higher than 100 mSv. Nineteen patients fell into the 'moderate risk' group, meaning that the additional risk of fatal cancer from accumulated radiation exposure lies between 1 in 1,000 and 1 in 100. CONCLUSIONS: MRI was the most used imaging technique. No CED from repeated imaging procedures after minor or moderate traffic or occupational accident exceeded 100 mSv. However, nineteen patients fell into the 'moderate risk' group of developing radiation-induced cancer. Tracking radiation exposure can be beneficial in identifying those with high CED, although education on its proper use is necessary.

Belgian multicentre study on lumbar spine imaging: Radiation dose and cost analysis; Evaluation of compliance with recommendations for efficient use of medical imaging.

PURPOSE: To assess compliance of lumbar spine imaging referrals with national imaging recommendations and to evaluate the impact of inappropriate imaging on the collective radiation dose and health insurance costs. METHOD: In 2011 and 2015, 633 lumbar spine imaging referrals were evaluated across 9 Belgian hospitals. For each patient, a new clinical anamnesis and physical examination were performed. Together with the referral, this data were confronted with the national imaging recommendations. Collective radiation dose was estimated for the radiography and CT procedures. Cost analysis was based on national reimbursement fees. Statistical analysis was performed using multilevel linear and logistic regression models. RESULTS: The fraction of unjustified imaging referrals decreased from 50 % in 2011 to 41 % in 2015 (p = 0.255). The odds of a justified examination are 3.1 times higher when the referral is done by a specialist instead of a general practitioner. The highest percentage of unjustified examinations was found for CT (85 % in 2011, 81 % in 2015; p = 0.044). Seventy-five percent of the collective dose of both the 2011 and the 2015 study population was not justified. Adherence to the recommendations could result in an estimated 16 % and 5 % cost reduction for the 2011 and 2015 study samples, respectively. CONCLUSIONS: Between 2011 and 2015, no significant improvement was found in requesting justified lumbar spine imaging procedures, although a positive trend was observed for CT. A shift from CT to MRI is necessary to improve the appropriateness of lumbar spine imaging referrals and to reduce the collective radiation dose.

The effective and collective dose to patients undergoing abdominopelvic and trunk computed tomography examinations: A Belgian multicentre study.

OBJECTIVES: This study aims to evaluate the radiation exposure to patients undergoing an abdominopelvic or a chest and abdominopelvic (trunk) CT examination and to assess compliance to imaging referral guidelines. METHODS: To this end, 357 standard abdominopelvic and trunk CT scans were collected from 8 Belgian institutions in 2011 and 2015. Effective dose (E) and collective dose were calculated using CT dose descriptors (CTDIvol and DLP), which were obtained from dose reports generated by the CT scanner. Subsequently, these CT requests were compared against the national referral guidelines to assess compliance. Population estimates for dose and compliance were obtained using multilevel linear regression and generalized estimating equation models. RESULTS: Between 2011 and 2015, a significant decrease of 28% in CTDIvol and DLP was found for abdominopelvic CT. The corresponding E decreased by 27%, and the collective dose by 23%. For trunk CT, a non-significant decrease of 6% was found in CTDIvol and a significant decrease of 14% in both DLP and E. However, the collective dose of trunk examinations increased by 39%. In 2011, 24% of the abdominopelvic examinations were not compliant with the guidelines, whereas this percentage dropped to 17% in 2015. Non-justified examinations accounted for 8% and 12% of all trunk CT scans in 2011 and 2015, respectively. CONCLUSION: Between 2011 and 2015, there was a decrease in dose for patients undergoing abdominopelvic or trunk CT in Belgium. However, a fraction of the estimated doses are linked to unnecessary CT examinations, which should be avoided.

Evaluation of automatic image quality assessment in chest CT - A human cadaver study.

PURPOSE: The evaluation of clinical image quality (IQ) is important to optimize CT protocols and to keep patient doses as low as reasonably achievable. Considering the significant amount of effort needed for human observer studies, automatic IQ tools are a promising alternative. The purpose of this study was to evaluate automatic IQ assessment in chest CT using Thiel embalmed cadavers. METHODS: Chest CT's of Thiel embalmed cadavers were acquired at different exposures. Clinical IQ was determined by performing a visual grading analysis. Physical-technical IQ (noise, contrast-to-noise and contrast-detail) was assessed in a Catphan phantom. Soft and sharp reconstructions were made with filtered back projection and two strengths of iterative reconstruction. In addition to the classical IQ metrics, an automatic algorithm was used to calculate image quality scores (IQs). To be able to compare datasets reconstructed with different kernels, the IQs values were normalized. RESULTS: Good correlations were found between IQs and the measured physical-technical image quality: noise (ρ=-1.00), contrast-to-noise (ρ=1.00) and contrast-detail (ρ=0.96). The correlation coefficients between IQs and the observed clinical image quality of soft and sharp reconstructions were 0.88 and 0.93, respectively. CONCLUSIONS: The automatic scoring algorithm is a promising tool for the evaluation of thoracic CT scans in daily clinical practice. It allows monitoring of the image quality of a chest protocol over time, without human intervention. Different reconstruction kernels can be compared after normalization of the IQs.