title: A Fast Experimental Scanner for Proton CT: Technical Performance and First Experience with Phantom Scans.
abstract: We report on the design, fabrication, and first tests of a tomographic scanner developed for proton computed tomography (pCT) of head-sized objects. After extensive preclinical testing, pCT is intended to be employed in support of proton therapy treatment planning and pre-treatment verification in patients undergoing particle-beam therapy. The scanner consists of two silicon-strip telescopes that track individual protons before and after the phantom, and a novel multistage scintillation detector that measures a combination of the residual energy and range of the proton, from which we derive the water equivalent path length (WEPL) of the protons in the scanned object. The set of WEPL values and the associated paths of protons passing through the object over a 360° angular scan are processed by an iterative, parallelizable reconstruction algorithm that runs on modern GP-GPU hardware. In order to assess the performance of the scanner, we have performed tests with 200 MeV protons from the synchrotron of the Loma Linda University Medical Center and the IBA cyclotron of the Northwestern Medicine Chicago Proton Center. Our first objective was calibration of the instrument, including tracker channel maps and alignment as well as the WEPL calibration. Then we performed the first CT scans on a series of phantoms. The very high sustained rate of data acquisition, exceeding one million protons per second, allowed a full 360° scan to be completed in less than 10 minutes, and reconstruction of a CATPHAN 404 phantom verified accurate reconstruction of the proton relative stopping power in a variety of materials.
authors.affiliation: Santa Cruz Institute for Particle Physics and Physics Department, University of California at Santa Cruz, Santa Cruz, CA 95064, rjohnson@ucsc.edu.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Johnson
authors.affiliation: Division of Radiation Research, Loma Linda University, Loma Linda, CA 92354, vbashkirov@llu.edu.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Bashkirov
authors.affiliation: Santa Cruz Institute for Particle Physics and Physics Department, University of California at Santa Cruz, Santa Cruz, CA 95064, langleydewitt@gmail.com.
authors.forename: Langley
authors.initials: L
authors.lastname: DeWitt
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia, valentina8giacometti@gmail.com.
authors.forename: Valentina
authors.initials: V
authors.lastname: Giacometti
authors.affiliation: Division of Radiation Research, Loma Linda University, Loma Linda, CA 92354, ford.hurley@gmail.com.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hurley
authors.affiliation: Division of Radiation Research, Loma Linda University, Loma Linda, CA 92354, pierluigi.piersimoni@gmail.com.
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Piersimoni
authors.affiliation: Santa Cruz Institute for Particle Physics and Physics Department, University of California at Santa Cruz, Santa Cruz, CA 95064, tiaplautz@gmail.com.
authors.forename: Tia E
authors.initials: TE
authors.lastname: Plautz
authors.affiliation: Santa Cruz Institute for Particle Physics and Physics Department, University of California at Santa Cruz, Santa Cruz, CA 95064, hartmut@ucsc.edu.
authors.forename: Hartmut F-W
authors.initials: HF
authors.lastname: Sadrozinski
authors.affiliation: School of Engineering and Computer Science, Baylor University, Waco, TX 76798, Keith_Schubert@baylor.edu.
authors.forename: Keith
authors.initials: K
authors.lastname: Schubert
authors.affiliation: Division of Radiation Research, Loma Linda University, Loma Linda, CA 92354, rschulte@llu.edu.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schulte
authors.affiliation: School of Engineering and Computer Science, Baylor University, Waco, TX 76798, blake@r2labs.org.
authors.forename: Blake
authors.initials: B
authors.lastname: Schultze
authors.affiliation: Santa Cruz Institute for Particle Physics and Physics Department, University of California at Santa Cruz, Santa Cruz, CA 95064, zatserkl@ucsc.edu.
authors.forename: Andriy
authors.initials: A
authors.lastname: Zatserklyaniy
keywords: Biomedical imaging; Calorimetry; Computed tomography; Data acquisition; Particle tracking; Reconstruction algorithms; Silicon radiation detectors