Dose optimization possible on multiple fronts
Despite efforts that have been made to reduce CT radiation dose levels in routine practice, greater dose reduction is achievable throughout the CT workflow, according to an article published in the March issue of the Journal of the American College of Radiology.
Destabilizing the idea of a “one size fits all” approach to dose reduction, lead author Jack Lambert, PhD, of the University of California in San Francisco, and colleagues investigated concepts proposed at the Virtual Symposium on Radiation Safety in Computed Tomography held in May 2013 and discussed future developments for dose optimization in their article.
Lambert and colleagues first suggested targeting means of radiation dose eradication prior to performing CT acquisitions. The scan should be justifiable, eliminate the need for repeat scans, and use nonionizing radiation techniques whenever possible. Substituting the modality itself for MRI or ultrasound should be considered, especially in pediatric patients. Multiphase exams should be limited and overlapping scan regions should be avoided, according to the authors.
Dose efficiency can be maximized through use of the CT localizer for tube current modulation. Special care should be taken when screening children, and operator experience is vital in implementing dose reduction strategies.
Scan parameters must be monitored to ensure that dose is reduced and high image quality is maintained. Scan protocols should utilize specific iterative reconstruction algorithms when possible to fully achieve dose reduction.
Though options are currently available for dose optimization, future developments hold promise for the continued betterment of patient safety. “Software advances will represent the primary dose reduction method in coming years,” wrote the authors. Reconstruction time is also expected to decline, which will enable iterative reconstruction adoption in all scenarios. Implementation of tube current modulation is predicted to evolve, allowing for organ-specific modulation that will lower the dose in sensitive, peripheral organs.
Additionally, automatic tube potential settings will tailor scans to each patient. Dual-energy CT is also forecasted to reduce dose in some studies, as it performs determination of material types and attenuation. Noncontrast phase acquisition will not be necessary with this technology, thereby potentially reducing the study’s total exposure.
In at least five years, detectors that count photons instead of measuring integrated x-ray energy are likely to be released and will greatly reduce radiation dose.
Lambert and colleagues re-emphasize the importance of dose optimization for pediatric patients. “This patient group often represents the ultimate challenge to testing novel concepts for dose reduction because imaging small moving parts is difficult, and the rewards for optimizing dose reduction and image quality have the greatest ramifications in this at-risk group,” they wrote.