Program Information
High Resolution Proton Radiography Using Sophisticated Image Processing Methods and a Commercial Plug and Play Detector
N Krah1*, L De Marzi2 , A Patriarca2 , G Pitta'3 , I Rinaldi1 , (1) Institute of Nuclear Physics of Lyon, Lyon, France, (2) Institut Curie - Proton Therapy Center, Orsay, France, (3) DE.TEC.TOR. Devices & Technologies Torino S.r.l., Torino
Presentations
SU-F-601-4 (Sunday, July 30, 2017) 2:05 PM - 3:00 PM Room: 601
Purpose: We measured proton radiographies employing commercial plug and play detectors and developed sophisticated data and image processing methods to increase the water equivalent thickness (WET)accuracy of proton radiographies.
Methods: We have conducted a series of experiments at the Curie Institute - Proton Therapy Center Orsay to acquire proton radiographies of various phantoms. We used a commercial multi layer ionization chamber with 128 channels and absorber slabs of 2.35 mm WET in combination with pencil beam scanning. We developed post-processing tools to produce proton radiographies of high WET accuracy. The methods are designed for imaging systems measuring only the residual range and position of protons. They include a calibration procedure to correct for proton scattering causing signal decays with depth leading to a degradation of the Bragg peak (BP). They decompose each measured Bragg curve into a series of base curves, each corresponding to a specific WET value, and the effective WET for each scan spot is obtained as a weighted recombination.
Results: Thanks to the post processing, almost the entire sensitive area of the detector can be exploited. The WET accuracy was verified with a CIRS electron density phantom with a series of tissue substitute inserts and by comparing with reference values measured with a water column system. The WET values corresponded to better than 1% accuracy. The processing methods allowed to increase the WET resolution of the set-up by a factor of 10 compared to the nominal resolution despite the thickness of the absorber slabs.
Conclusion: We have successfully acquired proton radiographies using a commercial plug and play range telescope. The image processing methods lead to a significant increase of the WET resolution allowing to recover image details that are not visible in non-optimized radiographies. These results represent a major step towards clinical application of proton radiography.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by a postdoc fellowship of the German Academic Exchange Service (DAAD).
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