Expert Opinion
John Mayo, MD
Supplemental Digital Content
Approach to Optimizing Radiation Dose:
While all three alternatives are important in reducing CT dose to the population, the most
efficient approach to rapid CT radiation dose reduction is achieved by optimizing
radiation dose. The initial step in this process lies in performing an audit to ensure dose
length product values for CT examinations in your institution lie within the diagnostic
reference levels (DRLs) established by national bodies (e.g. European Commission,
American College of Radiology or others). Examinations with dose greater than the
DRLs should be individually reviewed to determine if these exceptions are exempt or
improper. Examples of exempt examinations are; misclassified examinations, justified
exceptions based on either the clinical question or the patient body habitus. Improper
exams include; poorly designed protocols, lapses in radiologist or technologist education.
Following this initial review, CT scanning protocols should be assessed using a team
composed of radiologists, technologists and medical physicists. This team should search
for potential radiation dose reduction additions to CT protocols including; utilization of
automatic tube current modulation, highly reduced dose protocols for high throughput
examinations investigating intrinsic high contrast lesions (e.g. lung nodule follow up,
renal stone exams), justification of each acquisition phase for all multiple acquisition
protocols, weight adjusted kVp selection, ECG tube current modulation for helical
retrospective cardiac exams, non helical (step and shoot) cardiac CT exams when
functional imaging not required, the use of iterative reconstruction algorithms for dose
reduction. All available radiation dose reduction tools should be specified for new
equipment purchases and maintenance agreements should be structured to cover the
implementation of new dose reduction tools. Using these approaches, many institutions
will be able to achieve immediate dose reductions of 50% with no impact on referring
clinicians and current scanning patterns.