Dose intercomparison at Italian hadrontherapy centers.

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Proton therapy offers precise radiation delivery for cancer treatment.
• Accurate dosimetry is critical for ensuring effective and safe proton therapy.
• International protocols like IAEA TRS-398 provide guidelines for dosimetry intercomparisons.

Purpose of the Study:

• To conduct the first dosimetric intercomparison for proton beams in Italy.
• To evaluate the accuracy and consistency of absorbed dose measurements using ionization chambers.
• To ensure adherence to the IAEA TRS-398 code of practice for proton dosimetry.

Main Methods:

• Measurements were performed at three Italian proton therapy centers: CNAO, CTP, and CATANA.
• Both single pseudo-monoenergetic proton layers and Spread-Out Bragg Peaks (SOBP) were delivered.
• A 6 MV photon beam was included for comparative analysis.
• PTW Farmer 30010-1 and PTW Advanced Markus 34,045 ionization chambers were utilized.

Main Results:

• Absorbed dose measurements showed good consistency across all participating proton therapy sites.
• The weighted mean absorbed dose was 1.99 ± 0.01 Gy, closely matching the nominal 2 Gy target.
• Standard deviations were below 1% for both single layer and SOBP beams.
• Percent deviations for single layer measurements were within 1.5%.

Conclusions:

• The dosimetric intercomparison confirmed high consistency in absorbed dose measurements for proton beams in Italy.
• Results align with international standards, indicating reliable proton therapy delivery.
• The weighted means of absorbed doses for clinical proton beams were consistent within 1%, meeting acceptable national intercomparison criteria.