200 MeV Proton Radiography Studies With a Hand Phantom Using a Prototype Proton CT Scanner

Abstract

Proton radiography has applications in patient alignment and verification procedures for proton beam radiation therapy. In this paper, we report an experiment which used 200 MeV protons to generate proton energy-loss and scattering radiographs of a hand phantom. The experiment used the first-generation proton CT scanner prototype, which was installed on the research beam line of the clinical proton synchrotron at Loma Linda University Medical Center (LLUMC). It was found that while both radiographs displayed anatomical details of the hand phantom, the energy-loss radiograph had a noticeably higher resolution. Nonetheless, scattering radiography may yield more contrast between soft and bone tissue than energy-loss radiography, however, this requires further study. This study contributes to the optimization of the performance of the next-generation of clinical proton CT scanners. Furthermore, it demonstrates the potential of proton imaging (proton radiography and CT), which is now within reach of becoming available as a new, potentially low-dose medical imaging modality.

Scattering proton CT

“…This has been pointed out e.g. by Plautz et al (2014). The true limiting factor in scattering proton CT, however, is the higher image noise so that SNR and CNR turn out to be less favourable.…”

“…An appealing practical aspect of scattering proton CT is that the imaging system is simpler than in energy-loss proton CT: it only requires tracking devices (to measure a proton's direction upstream and downstream of the object), but no detector to measure a proton's residual energy. It has also been observed that scattering proton CT might provide higher contrast images than energy-loss proton CT (Plautz et al, 2014).…”

An experimental demonstration of a new type of proton computed tomography using a novel silicon tracking detector

“…It is appropriate to note that imaging using the angular deflection of protons has been proposed before and planar images of median scattering-angle have been demonstrated experimentally. 22 Tomographic reconstructions of inverse scattering length (closely related to absolute scattering-power) have been demonstrated in simulation. 23,24 Further, we note that nuclear scattering tomography (NST) with protons has long been established, but this relies on very different principles (wide-angle single scattering).…”

Proton Radiography by Multiple Coulomb Scattering with Nuclear Emulsion Detectors

“…This modality would definitely improve with a clinical use of proton radiography, which provides direct information on the density of the tissues, enhancing the precision of treatment planning. In this framework, different proton radiography systems have been tested [1][2][3]. Our group investigated the possibility of using emulsion detectors [4] to image different phantoms of the proton therapeutic beam at the Paul Scherrer Institut (PSI) in Villigen, Switzerland.…”