Reduction in stray radiation dose using a body-shielding device during external radiation therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Dosimetry

Background:

• Stray radiation dose (SRD) in the out-of-field region (OFR) during intensity-modulated radiation therapy (IMRT) poses a risk for secondary cancers.
• Minimizing SRD is crucial for patient safety in modern radiotherapy techniques.

Purpose of the Study:

• To develop and evaluate a body-shielding device (BSD) for reducing SRD in the OFR during 6 MV IMRT.
• To determine optimal shielding materials and configurations for effective SRD reduction.

Main Methods:

• Experimental testing of shielding materials (lead and bolus) using thermoluminescent dosimeters (TLDs).
• Measurement and analysis of SRD in a phantom for a nasopharyngeal carcinoma IMRT plan, with and without the developed BSD.
• Assessment of SRD in multiple directions and at the treatment couch.

Main Results:

• Shielding rates of 50%-80% were achieved with tested materials.
• A combination of 1 mm lead and 10 mm bolus was optimal, with the bolus absorbing back-scattered radiation.
• The developed BSD reduced total SRD in the OFR by approximately 50% compared to unshielded conditions.
• Shielding resulted in more uniform SRD distribution across different directions.

Conclusions:

• The developed body-shielding device (BSD) significantly reduces stray radiation dose in the out-of-field region during IMRT.
• This reduction in SRD is critical for minimizing the risk of secondary malignancies in patients undergoing radiotherapy.
• The BSD offers a practical solution for enhancing patient safety in radiation oncology.