[Technical Report: Quality Assurance for ¹²⁵I Seed Sources in Permanent Prostate Brachytherapy]

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance

Context:

• Permanent Prostate Brachytherapy (PPB) using Iodine-125 (¹²⁵I) seeds is increasingly common.
• Traceability of ¹²⁵I seed source strength measurements is established in Japan.
• Challenges exist in maintaining traceability and ensuring consistent quality control in medical facilities.

Purpose:

• To report on the current status and issues of ¹²⁵I seed source strength measurement quality control in Japan.
• To investigate management methods for source strength measurement in medical facilities.
• To discuss ideal and practical methods for source management, including seed count and strength verification.

Summary:

• A survey of 95 Japanese facilities offering ¹²⁵I seed brachytherapy revealed that 41% do not confirm seed count or measure source strength.
• Reasons include reliance on supplier QA, pre-sterilized seeds, and insufficient staff.
• Most facilities do not perform single-seed assays, the internationally standardized method, with some using less accurate batch assays.

Impact:

• Highlights critical gaps in quality assurance for ¹²⁵I brachytherapy in Japan.
• Emphasizes the need for medical facilities to actively participate in quality assurance, not solely rely on suppliers.
• Aims to provide a technical reference for facilities to improve their internal quality assurance processes for ¹²⁵I seed sources.