Contemporary CT scanners are designed with many features to optimize radiation dose and apply it more efficiently. These include automatic tube current modulation, individual kVp optimization, and iterative reconstruction. However, continuous education of personnel to ensure that they are knowledgeable about and proactively apply dose optimization features is essential. A study from Austria published online in the European Journal of Radiology reinforces the fact that training and retraining increases awareness, compliance and continuous optimization.
Lead author Azadeh Hojreh, M.D. of the Division of General and Pediatric Radiology of the Medical University of Vienna, and colleagues emphasize the importance of using multiple tools and techniques to adapt radiation dose and scan protocols for pediatric patients based on their size and age and clinical needs to keep radiation dose exposure at the lowest possible level. Techniques include correct patient positioning in the scanner isocenter, individually adjusted scan boundaries, appropriate reduction of the Scan Projection Radiograph (SPR) dose, and the choice of an anterior-posterior or posterior-anterior supine projection. They also recommend comparing the doses delivered to Diagnostic Reference Levels (DRLs).
DRLs, representing the third quartile of doses from dose surveys, represent values which when often exceeded, should serve as an alert that efforts should be undertaken to reduce them. DRLs differ from country to country, and are not available for all types of pediatric CT scans. Additionally DRLs can only be applied on average does and cannot be used on an individual basis.
For the study, the researchers statistically compared pediatric patient doses from 1,426 scans using five CT scanners performed before a staff training program and doses from 2,566 scans afterwards. Examinations included cranial CT, thoracic, abdomen-pelvis and trunk scans. Dose length products (DLPs) per series were extracted from archived CT dose reports.
A mandatory training program for radiologists and clinical support staff of the radiology department is conducted annually, as a series of 90 minute presentations and discussions. General topics focus on dosimetry concepts and optimization measures, DRLs, radiation protection rules, new research studies and peer-review articles and publications of importance. In 2010, the main topic was about newly published national DRLs for pediatric examinations including CT scans The presentation of NDRL for pediatric cranial and body CT enabled a radiation dose reduction for most pediatric CT examinations that proved to be sustainable, the authors reported.
The statistical analysis showed that a statistically significant reduction in dose for cranial, thoracic, and abdomen/pelvis scans was achieved. The percentage of scans performed with DLPs exceeding the German DRLs was reduced from 41% to 7% for cranial CTs, from 19% to 5% for thoracic CT, from 9% to zero for abdomen-pelvis CT, and from 26% to zero for trunk CTs. When Austrian DRLs for cranial CTs were used, the reduction was from 21% to 3%; DRLs for thoracic CT had a similar impressive reduction, from 15% to 2%.
The authors noted that the radiologists and radiographers at the Medical University of Vienna were highly experienced and very well trained. They point out that methods to reduce radiation dose are continually being refined and improved upon, and that continuous education is critical to keep everyone utilizing these to achieve the greatest potential for radiation dose reduction.
Hojreh A, Weber M, Homolka P. Effect of staff training on radiation dose in pediatric CT. Eur J Radiol. Published online May 12, 2015.Back To Top
Continuous staff training reduces radiation doses of pediatric CT exams. Appl Radiol.
Cynthia E. Keen is a New York City area-based medical writer specializing in clinical subjects and healthcare technology. She writes feature articles for Applied Radiology and the contents of the Applied Radiology newsletter.