Evaluation of Proton Therapy Accuracy Using a PMMA Phantom and PET Prediction Module

Area of Science:

• Medical Physics
• Radiotherapy Physics

Background:

• Positron emission tomography (PET) scanning is a crucial tool for verifying proton therapy.
• Accurate verification of proton radiotherapy is essential for patient safety and treatment efficacy.

Purpose of the Study:

• To develop and test a proton radiotherapy accuracy verification process by comparing predicted and measured PET data.
• To assess the reliability of PET prediction modules for proton therapy verification.

Main Methods:

• Irradiation of polymethyl methacrylate (PMMA) phantoms with 2 and 4 Gy doses at varying depths (5-20 cm).
• Comparison of predicted PET data from a calculation module with measured data from a PET/CT device.
• Analysis of depth and lateral profiles, including gamma index analysis, to evaluate positional errors.

Main Results:

• Mean depth errors were between -1 and 1 mm, with deviations <2 mm for both dose groups.
• Mean lateral errors were around 1 mm (2 Gy) and <1 mm (4 Gy), with standard deviations <1 mm.
• All tested cases demonstrated a gamma passing rate exceeding 95%.

Conclusions:

• Good agreement was found between predicted and measured PET data in PMMA phantom tests, with positional errors <2 mm.
• PET predictions are reliable for single proton beam therapy verification in phantom studies.
• Further investigation is warranted to extend these findings to human treatment verification.