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Characteristics of a Neutron Imaging Flat Panel Detector (FPD) for Proton Therapy

C Cheng

C Cheng1,2*, S Lee1 , J Yuan1,2 , M Lu3 , (1) University Hospitals Cleveland Medical Center, Cleveland, OH, (2) Case Western Reserve University, Cleveland, OH (3) PerkinElmer Optoelectronics, Santa Clara, CA


SU-K-702-16 (Sunday, July 30, 2017) 4:00 PM - 6:00 PM Room: 702

Purpose: A neutron imaging flat panel detector(FPD) from PerkinElmer (a-Si XRD0822 AP8 IND) is explored for its potential real time imaging application in proton therapy.

Methods: Neutrons are produced by impinging a proton beam from a Mevion S250 unit on a brass plug (water-equivalent thickness 30cm) and a solid water phantom (9cm thick). The FPD response characteristics to proton dose and dose-rate and its imaging performance such as MTF and contrast resolution are characterized . Gain correction images are obtained with dose rates in the range 100MU/min to 350MU/min without a phantom in the beam path. To investigate the detector response with dose, MU is varied from 100-400 at the dose rate of 200 MU/min. A Leeds and a Las Vegas phantom are used to determine the MTF and the contrast resolution of the neutron detector. The neutron images of the Leeds/Las Vegas phantoms are offset and gain corrected for the MTF and contrast resolution determinations. The results are compared with those obtained with 6MV x rays. Neutron images of a set of keys are also obtained to demonstrate the imaging capability of the neutron panel.

Results: The detector response increases linearly with MU and MU/min. The MTF and the contrast resolution of the neutron imaging FPD are comparable to those of the MV FPD from the Elekta machines. Images of a keyset are obtained from neutrons produced in a solid water phantom, illustrating the potential application of neutron imaging in proton therapy.

Conclusion: The neutron FPD imaging performance is similar to that of the MV panel on an Elekta machine. A byproduct in proton therapy is the generation of neutrons inside the patients. These neutrons can be used for real time imaging in proton therapy. Future work includes NPS and DQE measurements as well as imaging on anthropomorphic phantoms.

Funding Support, Disclosures, and Conflict of Interest: The neutron imaging panel is supplied by PerkinElmer Optoelectronics via a research agreement between PerkinElmer Optoelectronics and University Hospitals Cleveland Medical Center.

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