Proton computed tomography as a tool for proton therapy planning: preliminary computer simulations and comparisons with x-ray CT basics

Autor: Margio Cezar Loss Klock, Joaquim Teixeira de Assis, Olga Yevseyeva, D.C. Williams, Hugo R. Schelin, Ricardo Tadeu Lopes, Reinhard W. Schulte, Ivan Evseev, Sergei Anatolyevich Paschuk
Rok vydání: 2005
Předmět:
Zdroj: X-Ray Spectrometry. 34:481-492
ISSN: 1097-4539
0049-8246
Popis: Proton beams can destroy tumors better than other radiation treatment options because they deliver their energy in a very accurate way, while leaving the surrounding tissue undamaged. However, it requires a very accurate prediction of the Bragg peak position within the patient's body. In existing proton treatment centers, the dose calculations are performed based on x-ray computed tomography (CT) and the patient is positioned with x-ray radiographs. During the 1970s and early 1980s, it was shown that the use of proton beams rather than conventional x-rays could have some advantages. With the development of specialized medical proton gantries at Loma Linda University Medical Center (USA) and several other proton treatment centers worldwide, interest in this question has been renewed. The modern approach has advanced from simple proton film radiography to CT reconstructions from proton energy loss measurements employing individual proton tracking techniques. This permits image degradation due to multiple Coulomb scattering, one of the main problems of proton CT, to be reduced. Current work is devoted to the comparison of conventional x-ray CT and proton computed tomography (pCT) as two alternative tools for measuring the physical properties of the human body, required for proton treatment planning. In this paper, a brief comparative overview of the physical basics of both methods are followed by the analysis of Monte Carlo simulation results. The first-generation CT scheme was assumed for simplicity. The precisions relative to water volumetric electron density distributions, extracted from CT and pCT images, and the sources of absolute errors are discussed.
Databáze: OpenAIRE