Recommendations on detectors and quality control procedures for brachytherapy beta sources

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Quality Control

Background:

• A significant portion of institutes using clinical beta sources do not conduct independent dosimetry.
• The Netherlands Commission on Radiation Dosimetry (NCS) has published guidelines for quality control and detector selection for beta source dosimetry.

Purpose of the Study:

• To summarize key recommendations from NCS Report 14 regarding beta source dosimetry.
• To assess current dosimetry practices and identify areas for improvement in clinical beta source applications.

Main Methods:

• A dosimetry survey was conducted across 23 institutes in The Netherlands and Belgium.
• Various detectors (ionization chambers, scintillator, diode, radiochromic film) were used to measure source strength and uniformity.
• Measurements were compared against manufacturer specifications for intravascular and ophthalmic beta sources.

Main Results:

• Source strength measurements showed a standard deviation of approximately 3%, with variations from 0.8% to 15.8%.
• Average non-uniformity was 7% for intravascular and 20% for ophthalmic sources.
• Recommended maximum deviations are 10% for source strength and below 10% (intravascular) and 30% (ophthalmic) for non-uniformity.

Conclusions:

• Implementing dosimetric and non-dosimetric quality control procedures for beta sources is recommended.
• Standardized measurements of relative source strength and non-uniformity can be achieved.
• Accurate absolute calibrations for clinical beta sources await the establishment of primary standards.