George Coutrakon

George Coutrakon
Northern Illinois University · Department of Physics

About

109
Publications
10,148
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1,721
Citations
Citations since 2017
25 Research Items
447 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100

Publications

Publications (109)
Article
Purpose: Currently, calculations of proton range in proton therapy patients are based on a conversion of CT Hounsfield Units of patient tissues into proton relative stopping power. Uncertainties in this conversion necessitate larger proximal and distal planned target volume margins. Proton CT can potentially reduce these uncertainties by directly...
Article
Purpose: To reduce image artifacts of proton computed tomography (pCT) from a preclinical scanner, for imaging of the relative stopping power (RSP) needed for particle therapy treatment planning using a simple empirical artifact correction method. Methods: We adapted and employed a correction method previously used for beam-hardening correction in...
Article
Full-text available
Proton CT (pCT) is a promising new imaging technique that can reconstruct relative stopping power (RSP) more accurately than x-ray CT in each cubic millimeter voxel of the patient. This, in turn, will result in better proton range accuracy and, therefore, smaller planned tumor volumes (PTV). The hardware description and some reconstructed images ha...
Article
Purpose: Verification of patient specific proton stopping powers obtained in the patient's treatment position can be used to reduce the distal and proximal margins needed in particle beam planning. Proton radiography can be used as a pre-treatment instrument to verify integrated stopping power consistency with the treatment planning CT. Although a...
Article
Purpose To reduce imaging artifacts and improve image quality of a specific proton computed tomography (pCT) prototype scanner by combining pCT data acquired at two different incident proton energies to avoid protons stopping in sub-optimal detector sections. Methods Image artifacts of a prototype pCT scanner are linked to protons stopping close t...
Article
Purpose: To demonstrate a proton imaging system based on well-established fast scintillator technology to achieve high performance with low cost and complexity, with the potential of a straightforward translation into clinical use. Methods: The system tracks individual protons through one (X, Y) scintillating fiber tracker plane upstream and dow...
Preprint
Currently, calculations of proton range in proton therapy patients are based on a conversion of CT Hounsfield Units of patient tissues to proton relative stopping power. Uncertainties in this conversion necessitate larger proximal and distal planned target volume margins. Proton CT can potentially reduce these uncertainties by directly measuring pr...
Preprint
Purpose: To demonstrate a proton imaging system based on well-established fast scintillator technology to achieve high performance with low cost and complexity, with the potential of a straightforward translation into clinical use. Methods: The system tracks individual protons through one (X, Y) scintillating fiber tracker plane upstream and downst...
Preprint
Verification of patient specific proton stopping powers obtained in the patient treatment position can be used to reduce the distal margins needed in particle beam planning. Proton radiography can be used as a pre-treatment instrument to verify integrated stopping power consistency with the treatment planning CT. Although a proton radiograph is a p...
Article
Full-text available
Proton computed tomography (pCT) has high accuracy and dose efficiency in producing spatial maps of the relative stopping power (RSP) required for treatment planning in proton therapy. With fluence-modulated pCT (FMpCT), prescribed noise distributions can be achieved, which allows to decrease imaging dose by employing object-specific dynamically mo...
Article
Full-text available
Objective Proton beam therapy is an emerging modality for cancer treatment that, compared to X-ray radiation therapy, promises to provide better dose delivery to clinical targets with lower doses to normal tissues. Crucial to accurate treatment planning and dose delivery is knowledge of the water equivalent path length (WEPL) of each ray, or pencil...
Article
Full-text available
Purpose Proton CT (pCT) has the ability to reduce inherent uncertainties in proton treatment by directly measuring the relative proton stopping power with respect to water, thereby avoiding the uncertain conversion of X‐ray CT Hounsfield unit to relative stopping power and the deleterious effect of X‐ ray CT artifacts. The purpose of this work was...
Article
One of the major challenges to proton beam therapy at this time is the uncertainty of the true range of a clinical treatment proton beam as it traverses the various tissues and organs in a human body. This uncertainty necessitates the addition of greater “margins” to the planning target volume along the direction of the beam to ensure safety and tu...
Article
Proton computed tomography (pCT) has recently seen considerable research interest as a means of reducing range uncertainties in proton therapy, by reconstructing directly relative stopping power to water (RSP). Recent detector developments have permitted the development of two list-mode pCT scanner prototypes based on broad (passively scattered) pr...
Article
Full-text available
Proton computed tomography (pCT) is a novel medical imaging modality for mapping the distribution of proton relative stopping power (RSP) in medical objects of interest. Compared to conventional X-ray computed tomography, where range uncertainty margins are around 3.5%, pCT has the potential to provide more accurate measurements to within 1%. This...
Article
Full-text available
We are exploring low-dose proton radiography and computed tomography (pCT) as techniques to improve the accuracy of proton treatment planning and to provide artifact-free images for verification and adaptive therapy at the time of treatment. Here we report on comprehensive beam test results with our prototype pCT head scanner. The detector system a...
Article
Full-text available
This simulation study presents the application of fluence field modulated computed tomography (FFMCT), initially developed for x-ray CT, to proton computed tomography (pCT). By using pencil beam (PB) scanning, fluence modulated pCT (FMpCT) may achieve variable image quality in a pCT image and imaging dose reduction. Three virtual phantoms, a unifo...
Article
Full-text available
Northern Illinois University in collaboration with Fermi National Accelerator Laboratory (FNAL) and Delhi University has been designing and building a proton CT scanner for applications in proton treatment planning. The Phase II proton CT scanner consists of eight planes of tracking detectors with two X and two Y coordinate measurements both before...
Article
Full-text available
Computer tomography is one of the most promising new methods to image abnormal tissues inside the human body. Tomography is also used to position the patient accurately before radiation therapy. Hadron therapy for treating cancer has become one of the most advantageous and safe options. In order to fully utilize the advantages of hadron therapy, th...
Article
Full-text available
The design, construction, and preliminary testing of a second generation proton CT scanner is presented. All current treatment planning systems at proton therapy centers use X-ray CT as the primary imaging modality for treatment planning to calculate doses to tumor and healthy tissues. One of the limitations of X-ray CT is in the conversion of X-ra...
Article
Full-text available
We describe the development of a proton Computed Tomography (pCT) scanner at Northern Illinois University (NIU) in collaboration with Fermilab and Delhi University. This paper provides an overview of major components of the scanner and a detailed description of the data acquisition system (DAQ).
Article
Proton computed tomography (pCT) is an imaging modality that has been in development to support targeted dose delivery in proton therapy. It aims to accurately map the distribution of relative stopping power. Because protons traverse material media in non-linear paths, pCT requires individual proton processing. Image reconstruction then becomes a t...
Article
Full-text available
This paper discusses the design and operation of the 1st proton CT scanner for 3D imaging. Reduction of proton range uncertainties and improved dose accuracy in the patient for treatment planning are central goals. A central CT slice acquired by reconstruction of 134 million proton tracks through a 14 cm spherical polystyrene phantom with high and...
Article
The design, construction, and preliminary testing of a 2nd generation proton CT scanner is presented. All current treatment planning systems at proton therapy centers use x-ray CT as the primary imaging modality for treatment planning to calculate doses to tumor and healthy tissues. One of the limitations of x-ray CT is in the conversion of x-ray a...
Conference Paper
Proton computed tomography (pCT) is an imaging modality being developed to support targeted dose delivery in proton therapy. It aims to accurately map the distribution of relative stopping power in the imaged body. Because protons traverse material in non-linear paths, pCT requires individual proton processing and image reconstruction becomes a tim...
Article
The authors present a calibration method for a prototype proton computed tomography (pCT) scanner. The accuracy of these measurements depends upon careful calibration of the energy detector used to measure the residual energy of the protons that passed through the object. A prototype pCT scanner with a cesium iodide (CsI(Tl)) crystal calorimeter wa...
Conference Paper
Full-text available
CONCLUSION Proton CT has the potential to substantially improve the range accuracy of proton beams and to provide a low-dose imaging modality for daily image guidance. Careful evaluation of this novel technique is underway. BACKGROUND Proton CT is a novel tomographic imaging modality, which has become a realistic possibility with the increasing av...
Conference Paper
BACKGROUND Proton CT can provide improved dose accuracy in treatment planning for proton therapy. In addition, lower doses than X-ray CT are theoretically possible and streaking artifacts will be reduced or eliminated. The first proton CT scanner has now been tested in a proton beam and the results are presented. This paper focuses on the detector...
Article
Full-text available
Proton Computed Tomography (pCT) is being developed in support of proton therapy and treatment planning. The aim of pCT, to reconstruct an accurate map of the stopping power (S.P.) in a phantom and, in the future, in patients, is being pursued with a diverse list of detector systems, using the entire arsenal of tracking and energy detectors develop...
Article
Multiple groups have hypothesised that the use of scanning beams in proton therapy will reduce the neutron component of secondary radiation in comparison with conventional methods with a corresponding reduction in risks of radiation-induced cancers. Loma Linda University Medical Center (LLUMC) has had FDA marketing clearance for scanning beams sinc...
Article
All particle beam scanning systems are subject to dose delivery errors due to errors in position, energy and intensity of the delivered beam. In addition, finite scan speeds, beam spill non-uniformities, and delays in detector, detector electronics and magnet responses will all contribute errors in delivery. In this paper, we present dose errors fo...
Article
Full-text available
This study compared the effects of photons (gamma rays), protons and simulated solar particle event protons (sSPE) on the expression of profibrotic factors/extracellular matrix (ECM) regulators in lung tissue after whole-body irradiation. TGF-beta1, matrix metalloproteinase 2 and 9 (MMP-2, -9), and tissue inhibitor of metalloproteinase 1 and 2 (TIM...
Article
Full-text available
As aggressive, 3D‐conformal treatment has become the clearly accepted goal of radiation oncology, heavy charged‐particle treatment with protons and heavier ions has concurrently and relentlessly ascended to the forefront. Protons and helium nuclei, with relatively low linear‐energy‐transfer (LET) properties, have consistently been demonstrated to...
Article
Full-text available
Maintaining a high degree of spatial resolution in proton computed tomography (pCT) is a challenge due to the statistical nature of the proton path through the object. Recent work has focused on the formulation of the most likely path (MLP) of protons through a homogeneous water object and the accuracy of this approach has been tested experimental...
Article
Full-text available
Determination of the Bragg peak position in proton therapy requires accurate knowledge of the electron density and ratio of effective atomic number and mass (Z/A) of the body tissues traversed. While the Z/A ratio is fairly constant for human tissues, the density of tissues varies significantly. One possibility to obtain accurate electron density i...
Article
Full-text available
To evaluate cluster of differentiation 4(+) (CD4(+)) T cell gene expression and related parameters after whole-body exposure to proton radiation as it occurs in the spaceflight environment. C57BL/6 mice were irradiated to total doses of 0, 0.01, 0.05, and 0.1 gray (Gy) at 0.1 cGy/h. On day 0 spleens were harvested from a subset in the 0, 0.01 and 0...
Article
Full-text available
The health consequences of exposure to low-dose radiation combined with a solar particle event during space travel remain unresolved. The goal of this study was to determine whether protracted radiation exposure alters gene expression and oxidative burst capacity in the liver, an organ vital in many biological processes. C57BL/6 mice were whole-bod...
Article
Full-text available
The goal of this study was to evaluate, for the first time, the response of bone marrow-derived cell populations to protons mimicking a space radiation environment. C57BL/6 mice were exposed to 2 Gray (Gy) simulated solar particle event protons (sSPE) over 36 h; energies ranged from 15 to 215 MeV/n and were administered in 10 MeV increments. Acute...
Article
Proton beams offer several advantages over conventional radiation techniques for treating cancer and other diseases. These advantages might be negated if the leakage and scatter radiation from the beamline and patient are too large. Although the leakage and scatter radiation for the double scattering proton beamlines at the Loma Linda University Pr...
Article
This paper focuses on current and future designs of medical hadron accelerators for treating cancers and other diseases. Presently, five vendors and several national laboratories have produced heavy-particle medical accelerators for accelerating nuclei from hydrogen (protons) up through carbon and oxygen. Particle energies are varied to control the...
Article
A radiation biology experiment was performed in the research room of the proton therapy facility at Loma Linda University Medical Center to simulate the proton exposure produced by a solar particle event. The experiment used two scanning magnets for X and Y deflection of the proton beam and covered a usable target area of nearly 1m2. The magnet sca...
Article
Delivery of therapeutic proton beams requires an absolute energy accuracy of +/-0.64 to 0.27 MeV for patch fields and a relative energy accuracy of +/-0.10 to 0.25 MeV for tailoring the depth dose distribution using the energy stacking technique. Achromatic switchyard tunes, which lead to better stability of the beam incident onto the patient, unfo...
Article
Purpose:Treatment planning study for proton passive, active beam with and without bolus and aperture. Method and materials: Most beam delivery systems in proton therapy use passive beam spreading techniques to conform the dose to the target. Chordoma, meningioma, GBM and other head and neck cases are routinely treated with passively scattered beams...
Article
A new method of calculating beam emittances at the extraction point of a particle accelerator is presented. The technique uses the optimization programs NPSOL and MINOS developed at Stanford University in order to determine the initial values of beam size, divergence and correlation parameters (i.e. beam sigma matrix, σij) that best fit measured be...
Article
Simulations of the beam optics of the LLUMC proton accelerator injection line have been modeled using the computer codes Parmila [Los Alamos Nat’l Lab, Internal Report LA-UR-98-4478, Los Alamos Accelerator Code Group, Los Alamos, NM] and Trace 3D [Distributed by AccelSoft Inc, P.O. Box 2813. Del Mar, CA 92014, United States]. These simulations give...
Conference Paper
Full-text available
The MINOS nonlinear constrained optimization program, working in concert with the beam optics code TRANSPORT, has been shown in recent work to provide a fast, efficient and reliable procedure for determining the parameters of the beam extracted from the Loma Linda University Medical Center (LLUMC) proton therapy synchrotron. MINOS and TRANSPORT wor...
Article
Full-text available
Two detectors for fast two-dimensional (2D) and quasi-three-dimensional (quasi-3D) verification of the dose delivered by radiotherapy beams have been developed at University and Istituto Nazionale di Fisica Nucleare (INFN) of Torino. The Magic Cube is a stack of strip-segmented ionization chambers interleaved with water-equivalent slabs. The parall...
Article
Beam scanning in proton therapy is a medical technique to lower the dose to healthy tissue while irradiating a tumor volume. Scanned proton beams for proton radiation therapy require small beam sizes at the tumor location. In beam scanning, a small beam usually less than 1 cm diameter is swept across the tumor volume with two magnets located sever...
Article
Synchrotrons have long been recognized for their superior capabilities in proton and heavy ion therapy. Their compactness and ease of beam energy control make them ideally suited to this application. The range of available intensities insures safety against high dose accidents such as have occurred with conventional electron accelerators. For heavy...
Article
The method of scanning a proton beam across a target region for radiation therapy requires a uniform beam intensity throughout the beam spill time. Achieving uniform intensity using feedback to an air core quadrupole in the Loma Linda synchrotron accelerator is described in this paper. Frequency domain transfer functions and time domain intensity r...
Article
More than eight years have passed since Loma Linda University Medical Center treated its first cancer patient with the world’s first hospital based proton therapy accelerator. Using a synchrotron with extracted energies in the range of 70 to 250 MeV, nearly one hundred patients per day have been treated at the facility. Over the past five years, mo...
Conference Paper
The design requirements for current heavy-particle accelerators operated within a hospital to deliver radiation therapy must satisfy both clinical and research needs. Advances in dedicated beam delivery systems for clinical utilization and biological studies add requirements that previous accelerators did not have. Eight years experience using the...
Article
Hadron therapy uses heavy particles to deliver therapeutic ionizing energy. Each particle's inherent attributes determine the pattern of energy deposited by its beam, expressed in macro (conformability to a three-dimensional target volume) and micro (radiobiologic properties) distributions. Mass and charge regulate the inherent properties; beam ene...
Article
Protons have long been recognized as low LET radiation in radiotherapy. However, a detailed account of LET (linear energy transfer) and RBE (relative biological effectiveness) changes with incident beam energy and depth in tissue is still unresolved. This issue is particularly important for treatment planning, where the physical dose prescription i...
Article
We have used the energy-energy angular pattern of hadrons in inelastic muon-deuteron scattering to study perturbative QCD effects and to extract the gluon distribution functionηG(η) of the nucleon, whereη is the fractional momentum carried by the gluon. The data were taken with the E665 spectrometer using the Fermilab Tevatron muon beam with a mean...
Article
The production of charged hadrons is studied in Xe and D interactions at 490 GeV beam energy. The data were taken at the Tevatron at Fermilab with the E665 spectrometer, equipped with a streamer chamber as vertex detector. Differences between the Xe and D data are explained by cascading of hadrons in the Xe nucleus. The average multiplicity of char...
Article
The development of a hospital-based proton-beam therapy system at Loma Linda University Medical Center is one step of a historical trend toward more precise radiation therapy. It exploits available technology and, in doing so, may point the way toward other, similar facilities; it is hoped that it may also point the way to true selective cell irrad...
Article
More than three years have passed since Loma Linda treated the first cancer patient with the world's first proton accelerator dedicated to radiation therapy. Since that time, over 1000 patients have completed treatments and the facility currently treats more than 45 patients per day. With a typical intensity of 3 x 10(10) protons per pulse and 27 p...
Article
The production ofK 0, [`(L)]\bar \Lambda particles is studied in the E665 muon-nucleon experiment at Fermilab. The average multiplicities and squared transverse momenta are measured as a function ofx F andW 2. Most features of the data can be well described by the Lund model. Within this model, the data on the K0/ ratios and on the averageK 0 mul...
Article
We have studied radiation effects utilizing the new 250 MeV Synchrotron at Loma Linda University Medical Center. In this paper we present the data collected for the survival of Chinese hamster lung (V79) cells, that were irradiated with a beam of mixed energy protons up to 200 MeV. The RBE for protons, when compared to 60Co gamma rays, ranged from...
Article
Results on density integrals Fq(Q2) and correlation integrals Kq(Q2) are presented for the first time in muon-nucleon scattering at ∼ 490 GeV, using data from the E665 experiment at the Tevatron of Fermilab. A clear rise of the Fq integrals with decreasing size of the phase-space cells (“intermittency”) is observed for pairs and triplets of negativ...
Article
Full-text available
Fermilab Experiment-665 measured deep-inelastic scattering of 490 GeV muons off deuterium and xenon targets. Events were selected with a range of energy exchange ν from 100 GeV to 500 GeV and with large ranges of Q2 and xBj: 0.1 GeV2/c2<Q2<150 GeV2/c2 and 0.001<xBj<0.5. The fractional energy (z) distributions of forward-produced hadrons from the tw...