Program Information
Multiple-Coulomb-Scatter Based Proton Radiography with Pencil Beam Scanning
W Yao*, R Windmueller , St. Jude Children's Research Hospital, Memphis, TN
Presentations
TU-C3-GePD-I-4 (Tuesday, August 1, 2017) 10:30 AM - 11:00 AM Room: Imaging ePoster Lounge
Purpose: Multiple Coulomb Scatter (MCS) keeps challenge for proton radiography to improve its resolution and contrast. We propose to use the statistics of the proton fluence to form proton radiographs.
Methods: The MCS fluence at a detector plane can be well approximated as Gaussian distribution, particularly in the proton radiography scenario. The standard deviation (SD) of the distribution increases as the water equivalent thickness along the pencil beam path. Thus the image of the SD displays unique anatomic information of the patient body and can be used for patient positioning.Prior to obtaining the radiograph with our proton pencil beam scanning facility, a TOPAS Monte Carlo code was developed to simulate the radiograph of a patient’s head. This particular scan utilized 40,000 individual proton pencil beams in 1 mm separation at energy of 221.28 MeV, with a total dosage of 0.5 mGy. The fluence from each pencil beam was recorded and the SD was calculated. The calculation of all the SDs took about 40 seconds on an Intel® Xeon® E5-2680 v3 at 2.50GHz.The acquisition of the fluence from our proton facility was conducted by a Lynx® 2D scintillator detector with a CCTV that provides a read out of the proton exposure. The spots were positioned with a 2.76 mm separation and covered 20 cm x 25 cm. A pediatric head phantom was used in this study.
Results: The Monte Carlo simulation produced a high quality radiograph where the patient anatomic structures were recognizable. On the contrary, the radiograph by the fluence itself is very blur. The results from the proton beam verified the MC simulation.
Conclusion: Our proton radiography based on the statistical property of MCS gives high quality image of the patient’s anatomic structures with low patient dose.
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