Strategies for Reducing Radiation Exposure Risks
<< Radiation Doses and Risks
The CT Department at Santa Barbara Cottage Hospital has been proactive at monitoring and modifying exam protocols to keep exposure at lowest levels in order to produce quality diagnostic images.
Following the Cedars-Sinai disclosures in 2009, SBCH radiologists discussed perfusion scan protocol and agreed to reduce the GE recommended dose by 50%. The staff also discussed indications for the exam with a neuro-interventionalist and a plan to decrease multiple exams per patient.
Radiation physicist Don James tested SBCH and CCAI scanners and reviewed all of our CT protocols. All were found to be within guidelines.
A special meeting of the CHS Radiation Safety Committee was held to review and discuss the FDA warnings. The committee includs four radiologists, the radiology manager, and the CT supervisor. The committee continues to meet monthly.
Bismuth shield reduces the CT x-ray dose by 34 percent to the breast and 50 percent to the lens without excessively affecting image quality. The shield proved easy to use, and did not increase the examination time.
Specific Steps for Maximum Safety
To reduce CT radiation exposure, radiologists and ordering physicians must follow the "ALARA" principle of lowering doses: "as low as reasonably achievable." Ideally, doses should be lowered as much as possible but still maintain diagnostic quality.
Measures taken at SBCH in the past two years to minimize radiation exposure include:
- Decreasing CT Perfusion scanning parameters. (Reduces doses by 50 percent)
- Increasing the scanning thickness through the posterior fossa on routine Brain CTs. (Reduces dose 10 percent)
- Review of all body protocols with decrease of max allowable mA.
- Decreasing the number of sequences on A/P CTs. (Reduces dose by 20 percent)
- Implementing GE "Feather Lite" pediatric protocols. (Reduces dose 50-75 percent)
- Implementing a low dose chest CT protocol. (Reduces dose by 50 percent)
- Decreasing dose on thin patients from 120 kV to 100 kV. (Reduces dose 30 percent)
- New GE cardiac CT protocols. (Reduces dose by 85 percent)
- Boron or Bismuth shields placed on breasts, thyroid, and gonads. (Reduces dose by up to 80 percent)
- Not allowing rescanning (i.e. because of patient motion) unless approved by the radiologist.
- Techs cannot change protocols without checking with a radiologist.
- Threshold doses trigger review by department radiation safety committee.
The SBCH radiology safety committee is looking at ways to identify "frequent flyers," a minor but worrisome subset of patients who receive frequent CT exams.
The department is also compiling a list of diagnoses that can be imaged with MRI or ultrasound instead of CT. This list will be shared with other departments when complete.
Clinicians remain the gatekeepers and must ensure that the studies they order are indicated and necessary. The American College of Radiology has developed appropriateness criteria and imaging pathways to help guide clinicians in their imaging decision-making (available at www.ACR.org). Additional resources for clinicians can be found at www.imagewisely.com and www.imagesafely.com.
Education of new physicians as well as patients is critical for improving utilization and decreasing overall radiation doses. An interesting survey performed in 2006 showed that 1% of patients, 9% of ER physicians, and only 70% of radiologists were aware of the radiation-cancer correlation. A recent study of ER patients receiving CTs showed that 95% of those scans were interpreted as negative. Another survey showed that up to 60% of CT requests generated by pediatric residents at a major U.S. medical center were considered inappropriate.