Answer to Question #8603 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
We work in a busy interventional cardiac catheterization laboratory and interventional peripheral vascular laboratory. Our hospital practices the ALARA (as low as reasonably achievable) concept for all departments. The ALARA policy has exposure values set at Level 1 = 1.25 mSv per quarter and Level II = 3.75 mSv per quarter. We find it difficult to stay below this number in the catheterization laboratory. We do practice good radiation protection and have all of the recommended shielding in place. On average our high-volume interventional cardiologist and scrub technicians receive approximately 7 mSv per quarter, which triggers a Level II investigation but still falls well short of the 50 mSv per year maximum dose. Is it appropriate to set different exposure levels under the ALARA concept for departments that are inherently going to be exposed to more radiation? I am not an advocate for increasing the number for the sake of not doing an investigation, as safety is a great concern of mine.
Investigation levels in an ALARA program are not dose limits, but levels set to take some appropriate action. ICRP Report 26, "Recommendations of the International Commission on Radiological Protection," notes that investigational levels serve as checkpoints above which the results are considered sufficiently important to justify investigation or other action.
Setting levels, below limits, to trigger certain actions is a tool used in the ALARA philosophy. And as with most cases, one tool may not be the right one for all occasions. Some tools may be adjustable.
In cases where a worker's dose or the dose for a group of workers needs to exceed an investigational level, a new, higher level may be established for that individual or group on the basis that it is consistent with good ALARA practices. With that said, the reestablishment of a new level should be made with consideration of radiation safety programs as a whole. Adjustments should be made to make the tool of actions levels as efficient and effective as possible, making it work for you and your program—and not become a burden on one end or frivolous administrative procedure on the other. These levels should not be frequently moving targets, either. Setting actions levels should be a decision made from experience, past history, and future endeavors. The radiation safety officer plays a major part in setting these levels and performing the investigation when levels are exceeded. But action levels in an ALARA program are part of an overall radiation safety program, and adjustments can involve the staff or department being exposed and management (e.g., radiation safety committee) also.
Justification for new investigational levels should be documented.
Joseph DeCicco, CHP
Cynthia Jones, PhD