Calibration and Evaluation of a MicroPattern Gaseous Detector for Proton Radiography

Proton therapy is a type of cancer treatment that uses high-energy protons to target tumors with high precision, reducing damage to surrounding healthy tissue. Protons deposit most of their energy at a specific depth depending on the integrated tissue density, so accurate treatment planning requires precise knowledge of this property. Proton radiography is a form of imaging that produces 2D maps of integrated tissue density and uses the same type of radiation as proton therapy. This makes it well-suited for improving treatment planning by providing more accurate tissue information. Reliable proton radiographs require sensitive detectors to measure subtle variations in how protons interact with tissue. A MicroPattern Gaseous Detector (MPGD) uses finely patterned electrodes and gas amplification to precisely track charged particles, making it well-suited for this task. However, constructing accurate MPGD proton radiographs is challenging due to detector limitations and the need for data calibration to correct for spatial non-uniformities. To evaluate the MPGD, a clinical proton beam was used with a computed tomography (CT) phantom mimicking various tissue densities such as bone and muscle. This allowed assessment of the detector’s ability to distinguish different materials. Additional runs without the phantom were used to measure the detector’s spatial uniformity. Using Jupyter Notebook with a ROOT kernel, gain correction factors were calculated and applied to ensure consistent signal response across the detector when exposed to a uniform beam. The MPGD successfully distinguished tissues with varying integrated densities, including dense bone and

soft tissue. Data calibration significantly improved spatial resolution. This enhanced imaging capability has the potential to improve proton therapy by enabling more accurate treatment planning. Ultimately, advancements in MPGD-based 2D proton radiography could lead to more precise proton beam delivery and improved patient outcomes.