Purpose:
In Ontario, shielding for all X‐ray machines, including CT scanners, must be evaluated according to Safety Code 20A (Health Canada, 1983) which is based on NCRP‐49 (NCRP, 1976).
NCRP‐147 (NCRP, 2004) is the international standard for shielding calculations of CT scanners and is also referenced in Safety Code 35 (Health Canada, 2008) which, was published to supersede SC20A. The goal of this work is to demonstrate the cost effectiveness of NCRP‐147 for CT scanner shielding.
Methods:
CT scanner shielding calculations are performed using SC20A and NCRP‐147:
A room located on the third floor with the nearest building 75m away
A room with high occupancy uncontrolled adjacent spaces
Two side by side rooms on the main floor
Results:
1. SC20A: The exterior windows required 0.1mm of Pb to protect the public who may occupy the building at 75m.
1. NCRP‐147: No additional shielding required.
2. SC20A: Two walls adjacent to high occupancy uncontrolled space required an additional 1.58mm Pb.
2. NCRP‐147: No additional shielding required.
3. SC20A: The entire floor and ceiling slabs in both rooms required an additional 0.79mm Pb. In addition, 0.79mm Pb was added to the walls from the ceiling to overlap the existing Pb shielding in the walls.
3. NCRP‐147: No additional shielding required.
Conclusion:
The application of NCRP Report No. 147 affords the required protection to staff and the public, in the true spirit of the ALARA principle, taking into account relevant social and economic factors.
This poster will be strictly based on the Healing Arts Radiation Protection (HARP) Act, Regulation 543 under this Act (X‐ray Safety Code), and personal communication the presenting author has had. In Ontario, the process of approval of an X‐ray machine installation by the Director of the X‐ray Inspection Service (XRIS) follows a certain protocol. Initially, the applicant submits a series of forms, including recommended shielding amounts, in order to satisfy the law. This documentation is then transferred to a third‐party vendor (i.e. a professional engineer – P. Eng.) outsourced by the Ministry of Health and Long‐term Care (MOHLTC). The P.Eng. then evaluates the submitted documentation for appropriate fulfillment of the HARP Act and Reg. 543 requirements. If the P.Eng.'s evaluation of the documentation is to their satisfaction, the XRIS is then notified. Finally, the Director will then issue a letter of approval to install the equipment at the facility. The methodology required to be used by the P.Eng. in order to determine the required amounts of protective barriers, and recommended to be used by the applicant, is contained within Safety Code 20A. However, Safety Code 35 has replaced the obsolete Safety Code 20A document and employs best practices in shielding design. This talk will focus further on specific intentions and limitations of Safety Code 20A. Furthermore, this talk will discuss the definition of the “practice of professional engineering” in Ontario. COMP members who are involved in shielding design are strongly encouraged to attend.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.