MO‐D‐105‐03: The Medical Physicist's Role in the Oversight of Lead Shielding Installation in Nuclear Medicine: What to Look For

Abstract

Purpose: All diagnostic medical physicists are familiar with postinstallation lead shielding surveys in radiographic and CT imaging rooms. Survey techniques ranging from visual inspection to transmission measurements are detailed for these types of procedure rooms in NCRP‐147. However, shielding requirements in PET/CT are vastly different, with little published guidance on post installation physics survey techniques. Methods: A complex PET/CT shielding installation is used as a pictorial example of the issues faced by a medical physicist performing a survey of newly installed shielding in nuclear medicine. In this example, every common thickness of lead shielding is used, from 1/32″ lead laminated sheetrock to 3/8″ lead laminated plywood. Even the use of 3/4″ interlocking lead bricks is discussed along with the necessary supporting structure for a lead wall of this thickness . Particular attention will be paid to penetrations and ductwork with specific regard to the increased difficulty associated with shielding these items in PET/CT suites. Results: The PET/CT shielding installation in question has been completed. At different stages through the installation, many issues were identified by physicists and were subsequently addressed by shielding contractors. An example of such an issue was the need to install overlapping lead astragals at the abutment between adjacent sheets of lead laminated plywood‐‐a practice which is not necessary for lead laminated sheetrock. Similar examples where installation requirements of lead shielding in PET/CT differ significantly from the requirements in X‐ray are presented. Conclusion: As technology improves, modern PET/CT systems are able to perform full body imaging in far less time than was previously required. As a Result, higher patient workloads are possible, thereby increasing facility shielding requirements. Medical physicists will need to familiarize themselves with the differences in the post‐installation lead shielding survey techniques required for PET with those traditionally used for X‐ray imaging rooms.