Computerized tomography with high-energy proton beams: tomographic image reconstruction from computer-simulated data

Evseev, Ivan; Klock, Margio Cezar Loss; Paschuk, S.A.; Schelin, H.R.; Setti, João Antônio Palma; Lopes, Ricardo Tadeu; Schulte, R.; Williams, D. C.

doi:10.1590/s0103-97332004000500025

Cited by 11 publications

(8 citation statements)

References 7 publications

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“…More acceptable protons accumulated in each pixel provide more statistics and thus better image. In previous pCT studies, [33][34][35] linear, cubic spline and the most probable tracks were used to improve the spatial resolution by improv- ing image reconstruction. In this study, a linear track approximation algorithm with event rejection was tested and explored to construct proton WEL map.…”

Section: Iic Proton Wel Map Image Reconstructionmentioning

confidence: 99%

Proton radiography and fluoroscopy of lung tumors: A Monte Carlo study using patient‐specific 4DCT phantoms

Han

Chen

2011

Medical Physics

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Purpose: Monte Carlo methods are used to simulate and optimize a time-resolved proton range telescope ͑TRRT͒ in localization of intrafractional and interfractional motions of lung tumor and in quantification of proton range variations. Methods: The Monte Carlo N-Particle eXtended ͑MCNPX͒ code with a particle tracking feature was employed to evaluate the TRRT performance, especially in visualizing and quantifying proton range variations during respiration. Protons of 230 MeV were tracked one by one as they pass through position detectors, patient 4DCT phantom, and finally scintillator detectors that measured residual ranges. The energy response of the scintillator telescope was investigated. Mass density and elemental composition of tissues were defined for 4DCT data. Results: Proton water equivalent length ͑WEL͒ was deduced by a reconstruction algorithm that incorporates linear proton track and lateral spatial discrimination to improve the image quality. 4DCT data for three patients were used to visualize and measure tumor motion and WEL variations. The tumor trajectories extracted from the WEL map were found to be within ϳ1 mm agreement with direct 4DCT measurement. Quantitative WEL variation studies showed that the proton radiograph is a good representation of WEL changes from entrance to distal of the target. Conclusions: MCNPX simulation results showed that TRRT can accurately track the motion of the tumor and detect the WEL variations. Image quality was optimized by choosing proton energy, testing parameters of image reconstruction algorithm, and comparing to ground truth 4DCT. The future study will demonstrate the feasibility of using the time resolved proton radiography as an imaging tool for proton treatments of lung tumors.

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Section: Iic Proton Wel Map Image Reconstructionmentioning

confidence: 99%

Proton radiography and fluoroscopy of lung tumors: A Monte Carlo study using patient‐specific 4DCT phantoms

Han

Chen

2011

Medical Physics

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“…The modern approach to pCT technology involves High Energy Physics (HEP) solutions. Therefore, the GEANT4 Simulation Toolkit [2], which was initially designed to support the development of such HEP system, is very useful for pCT modeling as well [3]. It should be stressed out that here we are concerned with the code ability to support the pCT system development, and not yet for the medical applications.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

GEANT4 Tuning For pCT Development

Yevseyeva¹,

Assis²,

Evseev³

et al. 2011

AIP Conference Proceedings

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Abstract. Proton beams in medical applications deal with relatively thick targets like the human head or trunk. Thus, the fidelity of proton computed tomography (pCT) simulations as a tool for proton therapy planning depends in the general case on the accuracy of results obtained for the proton interaction with thick absorbers. GEANT4 simulations of proton energy spectra after passing thick absorbers do not agree well with existing experimental data, as showed previously. Moreover, the spectra simulated for the Bethe-Bloch domain showed an unexpected sensitivity to the choice of low-energy electromagnetic models during the code execution. These observations were done with the GEANT4 version 8.2 during our simulations for pCT. This work describes in more details the simulations of the proton passage through aluminum absorbers with varied thickness. The simulations were done by modifying only the geometry in the Hadrontherapy Example, and for all available choices of the Electromagnetic Physics Models. As the most probable reasons for these effects is some specific feature in the code, or some specific implicit parameters in the GEANT4 manual, we continued our study with version 9.2 of the code. Some improvements in comparison with our previous results were obtained. The simulations were performed considering further applications for pCT development. The interest in proton computed tomography (pCT) development is now reopened with the spread of the proton beam treatment [1]. The idea is to use the same medical proton therapy beam for diagnosis with pCT, i.e. for tumor localization and data acquisition for further irradiation planning. Potentially it can improve the quality of proton therapy and decrease the dose delivered to patients. The Monte Carlo simulations have a successful history in varied fields of study and could also be a helpful instrument in the case of pCT.

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“…It shape create a region of maximum energy deposition that can be positioned into the target [3]. This implies that proton radiation therapy requires a precise form of imaging technique to predict the position of Bragg peak inside of the patient [4].…”

Section: Introductionmentioning

confidence: 99%

“…One of them is the multiple Coulomb scattering (MCS) that reduce the spatial resolution. It is improved by the determination of scattering angle the proton leave the material [4]. In this way, the purpose of our study is to compare Monte Carlo calculation of lateral deflection of proton beam with analytical calculation based on Molière's theory [6] and Rutherford scattering [7].…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo and Analytical Calculation of Lateral Deflection of Proton Beams in Homogeneous Targets

Pazianotto¹,

Inocente²,

Silva³

et al. 2010

AIP Conference Proceedings

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Abstract. Proton radiation therapy is a precise form of radiation therapy, but the avoidance of damage to critical normal tissues and the prevention of geographical tumor misses require accurate knowledge of the dose delivered to the patient and the verification of his position demand a precise imaging technique. In proton therapy facilities, the X-ray Computed Tomography (xCT) is the preferred technique for the planning treatment of patients. This situation has been changing nowadays with the development of proton accelerators for health care and the increase in the number of treated patients. In fact, protons could be more efficient than xCT for this task. One essential difficulty in pCT image reconstruction systems came from the scattering of the protons inside the target due to the numerous small-angle deflections by nuclear Coulomb fields. The purpose of this study is the comparison of an analytical formulation for the determination of beam lateral deflection, based on Molière's theory and Rutherford scattering with Monte Carlo calculations by SRIM 2008 and MCNPX codes.

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Computerized tomography with high-energy proton beams: tomographic image reconstruction from computer-simulated data

Cited by 11 publications

References 7 publications

Proton radiography and fluoroscopy of lung tumors: A Monte Carlo study using patient‐specific 4DCT phantoms

Proton radiography and fluoroscopy of lung tumors: A Monte Carlo study using patient‐specific 4DCT phantoms

GEANT4 Tuning For pCT Development

Monte Carlo and Analytical Calculation of Lateral Deflection of Proton Beams in Homogeneous Targets

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