Shielding design for a Cs-137 rod-type standard point source for well chamber constancy checks

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiological Instrumentation

Background:

• Well type chambers are crucial for brachytherapy source calibration but lack inherent radiation shielding.
• Routine constancy checks are essential for maintaining accurate patient dose delivery between secondary standard laboratory calibrations.
• Existing methods for constancy checks may involve suboptimal radiation shielding, posing risks to users.

Purpose of the Study:

• To develop and evaluate a method for providing effective radiation shielding for a Cs-137 rod-type point source.
• To enable safe and reliable constancy checks of well type chambers used in brachytherapy.
• To minimize radiation exposure to users during routine quality assurance procedures.

Main Methods:

• Design and construction of a novel plunger-type shielded housing for a Cs-137 point source.
• Integration of the shielded source housing with a suitably shielded well-chamber container.
• Implementation and utilization of a constancy test routine over a 16-month period.

Main Results:

• The designed shielding effectively minimized user radiation exposure during constancy checks.
• The well chamber demonstrated consistent performance, deviating only 0.12 ± 0.18% from the baseline.
• No increase in radiation exposure was detected on users' personal radiation badges.

Conclusions:

• The developed shielded housing provides a safe and effective solution for brachytherapy well chamber constancy checks.
• The routine use of this method ensures consistent device performance and reliable patient dose delivery.
• This approach significantly enhances radiation safety for medical physicists and technicians performing quality assurance.