Radiotherapy technologist dose from high-energy electron medical accelerators

Area of Science:

• Medical Physics
• Radiation Oncology
• Occupational Health

Background:

• Radiation therapy technologists operate high-energy medical linear accelerators (LINACs).
• Understanding occupational radiation doses is crucial for ensuring technologist safety and adhering to the ALARA (As Low As Reasonably Achievable) principle.

Purpose of the Study:

• To quantify whole-body radiation doses for technologists working with 18-MV and 24-MV LINACs.
• To identify the primary sources of radiation exposure in the treatment room.
• To assess the effectiveness of current safety measures and explore further dose reduction.

Main Methods:

• Whole-body doses were measured using sensitive solid-state personal dosimeters on technologists during routine procedures.
• Measurements were conducted at two clinical sites under normal working conditions.
• Data were collected over 84 treatments, including patient and technologist time in and out of the treatment room.

Main Results:

• Average monthly doses for technologists were estimated between 12-19 mrem for approximately 30 daily treatments.
• Activated components within the LINAC's treatment head accounted for 76% of the in-room radiation dose.
• The remaining dose was attributed to activated concrete shielding.
• Film dosimetry records did not detect any significant doses for technologists with these machines.

Conclusions:

• Occupational radiation doses for technologists operating 18-MV and 24-MV LINACs are generally low under normal conditions.
• Activated components in the treatment head are the predominant source of technologist radiation exposure.
• Further material selection and engineering controls can further minimize residual radiation activities, aligning with ALARA principles.