Range verification in heavy-ion therapy using a hadron tumour marker

Area of Science:

• Medical Physics
• Radiation Oncology
• Nuclear Medicine

Background:

• Heavy-ion therapy offers precise dose deposition but is limited by range uncertainties.
• Accurate range verification is crucial for optimizing treatment plans and minimizing dose to healthy tissues.

Purpose of the Study:

• To investigate a novel method for estimating heavy-ion beam range using hadron tumour markers (HTMs).
• To assess the feasibility of using characteristic gamma-ray emissions from HTMs for real-time range verification during therapy.

Main Methods:

• A hadron tumour marker (HTM) was placed near the target area.
• Nuclear reactions within the HTM, induced by the therapeutic ion beam, produced characteristic gamma-ray emissions.
• Two distinct reaction channels were analyzed to determine the ratio of gamma-ray intensities, correlating with residual beam range.

Main Results:

• A proof-of-principle experiment using an 16O ion beam and silver (Ag) foils as HTMs was successfully conducted.
• The 107Ag(16O,x)112Sb and 107Ag(16O,x)114Sb reaction channels were identified as suitable for HTM application.
• Utilizing both reaction channels reduced the theoretical range uncertainty to ±290 μm, significantly improving upon single-channel measurements (0.5 mm scale).

Conclusions:

• The HTM technique offers a promising approach for precise heavy-ion beam range verification in clinical settings.
• This method can enable treatment plans to fully exploit the Bragg peak's sharp dose fall-off, enhancing therapeutic efficacy and patient safety.