1
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Götz S, Dickmann J, Rit S, Krah N, Khellaf F, Schulte RW, Parodi K, Dedes G, Landry G. Evaluation of the impact of a scanner prototype on proton CT and helium CT image quality and dose efficiency with Monte Carlo simulation. Phys Med Biol 2022; 67. [PMID: 35086073 DOI: 10.1088/1361-6560/ac4fa4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/27/2022] [Indexed: 11/12/2022]
Abstract
Objective.The use of ion computed tomography (CT) promises to yield improved relative stopping power (RSP) estimation as input to particle therapy treatment planning. Recently, proton CT (pCT) has been shown to yield RSP accuracy on par with state-of-the-art x-ray dual energy CT. There are however concerns that the lower spatial resolution of pCT compared to x-ray CT may limit its potential, which has spurred interest in the use of helium ion CT (HeCT). The goal of this study was to investigate image quality of pCT and HeCT in terms of noise, spatial resolution, RSP accuracy and imaging dose using a detailed Monte Carlo (MC) model of an existing ion CT prototype.Approach.Three phantoms were used in simulated pCT and HeCT scans allowing estimation of noise, spatial resolution and the scoring of dose. An additional phantom was used to evaluate RSP accuracy. The imaging dose required to achieve the same image noise in a water and a head phantom was estimated at both native spatial resolution, and in a scenario where the HeCT spatial resolution was reduced and matched to that of pCT using Hann windowing of the reconstruction filter. A variance reconstruction formalism was adapted to account for Hann windowing.Main results.We confirmed that the scanner prototype would produce higher spatial resolution for HeCT than pCT by a factor 1.8 (0.86 lp mm-1versus 0.48 lp mm-1at the center of a 20 cm water phantom). At native resolution, HeCT required a factor 2.9 more dose than pCT to achieve the same noise, while at matched resolution, HeCT required only 38% of the pCT dose. Finally, RSP mean absolute percent error (MAPE) was found to be 0.59% for pCT and 0.67% for HeCT.Significance.This work compared the imaging performance of pCT and HeCT when using an existing scanner prototype, with the spatial resolution advantage of HeCT coming at the cost of increased dose. When matching spatial resolution via Hann windowing, HeCT had a substantial dose advantage. Both modalities provided state-of-the-art RSP MAPE. HeCT might therefore help reduce the dose exposure of patients with comparable image noise to pCT, enhanced spatial resolution and acceptable RSP accuracy at the same time.
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Affiliation(s)
- S Götz
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), D-85748 Garching bei München, Germany
| | - J Dickmann
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), D-85748 Garching bei München, Germany
| | - S Rit
- University of Lyon, INSA-Lyon, Unversité Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS, UMR 5220, U1294 F-69373, Lyon, France
| | - N Krah
- University of Lyon, INSA-Lyon, Unversité Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS, UMR 5220, U1294 F-69373, Lyon, France.,IP2I, UMR 5822 F-69622, Villeurbanne, France
| | - F Khellaf
- University of Lyon, INSA-Lyon, Unversité Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS, UMR 5220, U1294 F-69373, Lyon, France
| | - R W Schulte
- Division of Biomedical Engineering Sciences, Loma Linda University, Loma Linda, CA 92354, United States of America
| | - K Parodi
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), D-85748 Garching bei München, Germany
| | - G Dedes
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), D-85748 Garching bei München, Germany
| | - G Landry
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), D-85748 Garching bei München, Germany.,Department of Radiation Oncology, University Hospital, LMU Munich, D-81377 Munich, Germany.,German Cancer Consortium (DKTK), D-81377 Munich, Germany
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2
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Dickmann J, Sarosiek C, Götz S, Pankuch M, Coutrakon G, Johnson RP, Schulte RW, Parodi K, Landry G, Dedes G. An empirical artifact correction for proton computed tomography. Phys Med 2021; 86:57-65. [PMID: 34058718 DOI: 10.1016/j.ejmp.2021.05.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/20/2021] [Accepted: 05/12/2021] [Indexed: 12/31/2022] Open
Abstract
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 x-ray CT which makes use of a single scan of a custom-built homogeneous phantom with known RSP. Exploiting the linearity of the filtered backprojection operation, a function was found which corrects water-equivalent path lengths (RSP line integrals) in experimental scans using a prototype pCT scanner. The correction function was applied to projection values of subsequent scans of a homogeneous water phantom, a sensitometric phantom with various inserts and an anthropomorphic head phantom. Data were acquired at two different incident proton energies to test the robustness of the method. RESULTS Inaccuracies in the detection process caused an offset and known ring artifacts in the water phantom which were considerably reduced using the proposed method. The mean absolute percentage error (MAPE) of mean RSP values of all inserts of the sensitometric phantom and the water phantom was reduced from 0.87% to 0.44% and from 0.86% to 0.48% for the two incident energies respectively. In the head phantom a clear reduction of artifacts was observed. CONCLUSIONS Image artifacts of experimental pCT scans with a prototype scanner could substantially be reduced both in homogeneous, heterogeneous and anthropomorphic phantoms. RSP accuracy was also improved.
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Affiliation(s)
- Jannis Dickmann
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), Am Coulombwall 1, Garching bei München, Germany.
| | - Christina Sarosiek
- Department of Physics, Northern Illinois University, 1425 W. Lincoln Highway, DeKalb, Illinois, United States.
| | - Stefanie Götz
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), Am Coulombwall 1, Garching bei München, Germany.
| | - Mark Pankuch
- Northwestern Medicine Chicago Proton Center, 4455 Weaver Parkway, Warrenville, Illinois, United States.
| | - George Coutrakon
- Department of Physics, Northern Illinois University, 1425 W. Lincoln Highway, DeKalb, Illinois, United States.
| | - Robert P Johnson
- Department of Physics, U.C. Santa Cruz, 1156 High Street, Santa Cruz, California, United States.
| | - Reinhard W Schulte
- Division of Biomedical Engineering Sciences, Loma Linda University, 11175 Campus Street, Loma Linda, California, United States.
| | - Katia Parodi
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), Am Coulombwall 1, Garching bei München, Germany.
| | - Guillaume Landry
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), Am Coulombwall 1, Garching bei München, Germany; Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, Munich, Germany; German Cancer Consortium (DKTK), Marchioninistraße 15, Munich, Germany.
| | - George Dedes
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), Am Coulombwall 1, Garching bei München, Germany.
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3
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Meyer S, Pinto M, Parodi K, Gianoli C. The impact of path estimates in iterative ion CT reconstructions for clinical-like cases. Phys Med Biol 2021; 66. [PMID: 33765672 DOI: 10.1088/1361-6560/abf1ff] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 03/25/2021] [Indexed: 11/11/2022]
Abstract
Ion computed tomography (CT) promises to mitigate range uncertainties inherent in the conversion of x-ray Hounsfield units into ion relative stopping power (RSP) for ion beam therapy treatment planning. To improve accuracy and spatial resolution of ion CT by accounting for statistical multiple Coulomb scattering deflection of the ion trajectories from a straight line path (SLP), the most likely path (MLP) and the cubic spline path (CSP) have been proposed. In this work, we use FLUKA Monte Carlo simulations to investigate the impact of these path estimates in iterative tomographic reconstruction algorithms for proton, helium and carbon ions. To this end the ordered subset simultaneous algebraic reconstruction technique was used and coupled with a total variation superiorization (TVS). We evaluate the image quality and dose calculation accuracy in proton therapy treatment planning of cranial patient anatomies. CSP and MLP generally yielded nearly equal image quality with an average RSP relative error improvement over the SLP of 0.6%, 0.3% and 0.3% for proton, helium and carbon ion CT, respectively. Bone and low density materials have been identified as regions of largest enhancement in RSP accuracy. Nevertheless, only minor differences in dose calculation results were observed between the different models and relative range errors of better than 0.5% were obtained in all cases. Largest improvements were found for proton CT in complex scenarios with strong heterogeneities along the beam path. The additional TVS provided substantially reduced image noise, resulting in improved image quality in particular for soft tissue regions. Employing the CSP and MLP for iterative ion CT reconstructions enabled improved image quality over the SLP even in realistic and heterogeneous patient anatomy. However, only limited benefit in dose calculation accuracy was obtained even though an ideal detector system was simulated.
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Affiliation(s)
- Sebastian Meyer
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America.,Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany
| | - Marco Pinto
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany
| | - Katia Parodi
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany.,Shared senior authorship
| | - Chiara Gianoli
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany.,Shared senior authorship
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4
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Dickmann J, Kamp F, Hillbrand M, Corradini S, Belka C, Schulte RW, Parodi K, Dedes G, Landry G. Fluence-modulated proton CT optimized with patient-specific dose and variance objectives for proton dose calculation. Phys Med Biol 2021; 66:064001. [PMID: 33545701 DOI: 10.1088/1361-6560/abe3d2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Particle therapy treatment planning requires accurate volumetric maps of the relative stopping power, which can directly be acquired using proton computed tomography (pCT). With fluence-modulated pCT (FMpCT) imaging fluence is concentrated in a region-of-interest (ROI), which can be the vicinity of the treatment beam path, and imaging dose is reduced elsewhere. In this work we present a novel optimization algorithm for FMpCT which, for the first time, calculates modulated imaging fluences for joint imaging dose and image variance objectives. Thereby, image quality is maintained in the ROI to ensure accurate calculations of the treatment dose, and imaging dose is minimized outside the ROI with stronger minimization penalties given to imaging organs-at-risk. The optimization requires an initial scan at uniform fluence or a previous x-ray CT scan. We simulated and optimized FMpCT images for three pediatric patients with tumors in the head region. We verified that the target image variance inside the ROI was achieved and demonstrated imaging dose reductions outside of the ROI of 74% on average, reducing the imaging dose from 1.2 to 0.3 mGy. Such dose savings are expected to be relevant compared to the therapeutic dose outside of the treatment field. Treatment doses were re-calculated on the FMpCT images and compared to treatment doses re-recalculated on uniform fluence pCT scans using a 1% criterion. Passing rates were above 98.3% for all patients. Passing rates comparing FMpCT treatment doses to the ground truth treatment dose were above 88.5% for all patients. Evaluation of the proton range with a 1 mm criterion resulted in passing rates above 97.5% (FMpCT/pCT) and 95.3% (FMpCT/ground truth). Jointly optimized fluence-modulated pCT images can be used for proton dose calculation maintaining the full dosimetric accuracy of pCT but reducing the required imaging dose considerably by three quarters. This may allow for daily imaging during particle therapy ensuring a safe and accurate delivery of the therapeutic dose and avoiding excess dose from imaging.
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Affiliation(s)
- J Dickmann
- Department of Medical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU Munich), D-85748 Garching bei München, Germany
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Dickmann J, Sarosiek C, Rykalin V, Pankuch M, Rit S, Detrich N, Coutrakon G, Johnson RP, Schulte RW, Parodi K, Landry G, Dedes G. Experimental realization of dynamic fluence field optimization for proton computed tomography. ACTA ACUST UNITED AC 2020; 65:195001. [DOI: 10.1088/1361-6560/ab9f5f] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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6
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Meyer S, Bortfeldt J, Lämmer P, Englbrecht FS, Pinto M, Schnürle K, Würl M, Parodi K. Optimization and performance study of a proton CT system for pre-clinical small animal imaging. ACTA ACUST UNITED AC 2020; 65:155008. [DOI: 10.1088/1361-6560/ab8afc] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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7
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Dedes G, Dickmann J, Giacometti V, Rit S, Krah N, Meyer S, Bashkirov V, Schulte R, Johnson RP, Parodi K, Landry G. The role of Monte Carlo simulation in understanding the performance of proton computed tomography. Z Med Phys 2020; 32:23-38. [PMID: 32798033 PMCID: PMC9948882 DOI: 10.1016/j.zemedi.2020.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 05/18/2020] [Accepted: 06/16/2020] [Indexed: 01/28/2023]
Abstract
Proton computed tomography (pCT) is a promising tomographic imaging modality allowing direct reconstruction of proton relative stopping power (RSP) required for proton therapy dose calculation. In this review article, we aim at highlighting the role of Monte Carlo (MC) simulation in pCT studies. After describing the requirements for performing proton computed tomography and the various pCT scanners actively used in recent research projects, we present an overview of available MC simulation platforms. The use of MC simulations in the scope of investigations of image reconstruction, and for the evaluation of optimal RSP accuracy, precision and spatial resolution omitting detector effects is then described. In the final sections of the review article, we present specific applications of realistic MC simulations of an existing pCT scanner prototype, which we describe in detail.
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Affiliation(s)
- George Dedes
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching b. München, Germany.
| | - Jannis Dickmann
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching b. München, Germany
| | - Valentina Giacometti
- The Patrick G Johnston Centre for Cancer Research, Queen's University of Belfast, Northern Ireland Cancer Centre, Belfast, Northern Ireland, United Kingdom
| | - Simon Rit
- University of Lyon, CREATIS, CNRS UMR5220; Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, Lyon, France
| | - Nils Krah
- University of Lyon, CREATIS, CNRS UMR5220; Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, Lyon, France,University of Lyon, Institute of Nuclear Physics Lyon (IPNL), CNRS UMR 5822, Villeurbanne, France
| | - Sebastian Meyer
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching b. München, Germany,Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Vladimir Bashkirov
- Division of Biomedical Engineering Sciences, Loma Linda University, Loma Linda, CA, United States of America
| | - Reinhard Schulte
- Division of Biomedical Engineering Sciences, Loma Linda University, Loma Linda, CA, United States of America
| | - Robert P. Johnson
- Department of Physics, U. C. Santa Cruz, Santa Cruz, CA, United States of America
| | - Katia Parodi
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching b. München, Germany
| | - Guillaume Landry
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Garching b. München, Germany,Department of Radiation Oncology, Department of Medical Physics, University Hospital, LMU Munich, Munich, Germany,German Cancer Consortium, (DKTK), Munich, Germany
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8
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Dickmann J, Rit S, Pankuch M, Johnson RP, Schulte RW, Parodi K, Dedes G, Landry G. An optimization algorithm for dose reduction with fluence‐modulated proton CT. Med Phys 2020; 47:1895-1906. [DOI: 10.1002/mp.14084] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 01/30/2020] [Accepted: 02/05/2020] [Indexed: 01/12/2023] Open
Affiliation(s)
- J. Dickmann
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München Am Coulombwall 1 85748 Garching b. München Germany
| | - S. Rit
- Univ Lyon INSA‐Lyon Université Claude Bernard Lyon 1 UJM‐Saint Étienne CNRS, Inserm CREATIS UMR 5220 U1206 F‐69373 Lyon France
| | - M. Pankuch
- Northwestern Medicine Chicago Proton Center Warrenville IL 60555 USA
| | - R. P. Johnson
- Department of Physics University of California Santa Cruz Santa Cruz CA 95064 USA
| | - R. W. Schulte
- Division of Biomedical Engineering Sciences Loma Linda University Loma Linda CA 92354 USA
| | - K. Parodi
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München Am Coulombwall 1 85748 Garching b. München Germany
| | - G. Dedes
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München Am Coulombwall 1 85748 Garching b. München Germany
| | - G. Landry
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München Am Coulombwall 1 85748 Garching b. München Germany
- Department of Radiation Oncology University Hospital, LMU Munich 81377 Munich Germany
- German Cancer Consortium (DKTK) 81377 Munich Germany
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9
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Parodi K. Latest developments in in-vivo imaging for proton therapy. Br J Radiol 2020; 93:20190787. [PMID: 31794249 PMCID: PMC7066959 DOI: 10.1259/bjr.20190787] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 11/18/2019] [Accepted: 11/28/2019] [Indexed: 12/11/2022] Open
Abstract
Owing to the favorable physical and biological properties of swift ions in matter, their application to radiation therapy for highly selective cancer treatment is rapidly spreading worldwide. To date, over 90 ion therapy facilities are operational, predominantly with proton beams, and about the same amount is under construction or planning.Over the last decades, considerable developments have been achieved in accelerator technology, beam delivery and medical physics to enhance conformation of the dose delivery to complex shaped tumor volumes, with excellent sparing of surrounding normal tissue and critical organs. Nevertheless, full clinical exploitation of the ion beam advantages is still challenged, especially by uncertainties in the knowledge of the beam range in the actual patient anatomy during the fractionated course of treatment, thus calling for continued multidisciplinary research in this rapidly emerging field.This contribution will review latest developments aiming to image the patient with the same beam quality as for therapy prior to treatment, and to visualize in-vivo the treatment delivery by exploiting irradiation-induced physical emissions, with different level of maturity from proof-of-concept studies in phantoms and first in-silico studies up to clinical testing and initial clinical evaluation.
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Affiliation(s)
- Katia Parodi
- Department of Experimental Physics – Medical Physics, Ludwig-Maximilians-Universität München, Faculty of Physics, Munich, Germany
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10
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Schultze B, Censor Y, Karbasi P, Schubert KE, Schulte RW. An Improved Method of Total Variation Superiorization Applied to Reconstruction in Proton Computed Tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:294-307. [PMID: 30998460 PMCID: PMC8145778 DOI: 10.1109/tmi.2019.2911482] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Previous work has shown that total variation superiorization (TVS) improves reconstructed image quality in proton computed tomography (pCT). The structure of the TVS algorithm has evolved since then and this paper investigated if this new algorithmic structure provides additional benefits to pCT image quality. Structural and parametric changes introduced to the original TVS algorithm included: (1) inclusion or exclusion of TV reduction requirement, (2) a variable number, N , of TV perturbation steps per feasibility-seeking iteration, and (3) introduction of a perturbation kernel . The structural change of excluding the TV reduction requirement check tended to have a beneficial effect for 3 ≤ N ≤ 6 and allows full parallelization of the TVS algorithm. Repeated perturbations per feasibility-seeking iterations reduced total variation (TV) and material dependent standard deviations for 3 ≤ N ≤ 6 . The perturbation kernel α , effectively equal to α = 0.5 in the original TVS algorithm, reduced TV and standard deviations as α was increased beyond α = 0.5 , but negatively impacted reconstructed relative stopping power (RSP) values for . The reductions in TV and standard deviations allowed feasibility-seeking with a larger relaxation parameter λ than previously used, without the corresponding increases in standard deviations experienced with the original TVS algorithm. This paper demonstrates that the modifications related to the evolution of the original TVS algorithm provide benefits in terms of both pCT image quality and computational efficiency for appropriately chosen parameter values.
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Dickmann J, Wesp P, Rädler M, Rit S, Pankuch M, Johnson RP, Bashkirov V, Schulte RW, Parodi K, Landry G, Dedes G. Prediction of image noise contributions in proton computed tomography and comparison to measurements. ACTA ACUST UNITED AC 2019; 64:145016. [DOI: 10.1088/1361-6560/ab2474] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Parodi K, Polf JC. In vivo range verification in particle therapy. Med Phys 2018; 45:e1036-e1050. [PMID: 30421803 DOI: 10.1002/mp.12960] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/11/2018] [Accepted: 05/01/2018] [Indexed: 12/19/2022] Open
Abstract
Exploitation of the full potential offered by ion beams in clinical practice is still hampered by several sources of treatment uncertainties, particularly related to the limitations of our ability to locate the position of the Bragg peak in the tumor. To this end, several efforts are ongoing to improve the characterization of patient position, anatomy, and tissue stopping power properties prior to treatment as well as to enable in vivo verification of the actual dose delivery, or at least beam range, during or shortly after treatment. This contribution critically reviews methods under development or clinical testing for verification of ion therapy, based on pretreatment range and tissue probing as well as the detection of secondary emissions or physiological changes during and after treatment, trying to disentangle approaches of general applicability from those more specific to certain anatomical locations. Moreover, it discusses future directions, which could benefit from an integration of multiple modalities or address novel exploitation of the measurable signals for biologically adapted therapy.
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Affiliation(s)
- Katia Parodi
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching b. Munich, 85748, Germany
| | - Jerimy C Polf
- Deparment of Radiation Oncology, Maryland Proton Treatment Center, University of Maryland School of Medicine, 22 South Greene St., Baltimore, MD, 21201, USA
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13
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Rädler M, Landry G, Rit S, Schulte RW, Parodi K, Dedes G. Two-dimensional noise reconstruction in proton computed tomography using distance-driven filtered back-projection of simulated projections. Phys Med Biol 2018; 63:215009. [PMID: 30277469 DOI: 10.1088/1361-6560/aae5c9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We present a formalism for two-dimensional (2D) noise reconstruction in proton computed tomography (pCT). This is necessary for the application of fluence modulated pCT (FMpCT) since it permits image noise prescription and the corresponding proton fuence optimization. We aimed at extending previously published formalisms to account for the impact of multiple Coulomb scattering (MCS) on projection noise, and the use of filtered back projection (FBP) reconstruction along curved paths with distance driven binning (DDB). 2D noise reconstruction for a beam of protons with parallel initial momentum vectors, and for projections binned both at the rear tracker and with DDB, was established. Monte Carlo (MC) simulations of pCT scans of a water cylinder were employed to generate pCT projections and to calculate their noise for use in 2D noise reconstruction. These were compared to results from an analytical model accounting for MCS for rear tracker binning as well as against the previously published central pixel model which ignores MCS. Image noise reconstructed with the formalism for rear tracker binning and DDB were compared to MC results using annular regions of interest (ROIs). Agreement better than 8% was obtained between the noise of projections calculated with MC simulation and our model. Noise from annular ROIs agreed with our noise reconstructions for rear tracker binning and DDB. The central pixel model ignoring MCS underestimated projection and thus image noise by up to 40% towards the object's edge. The use of DDB decreased the image noise towards the object's edge when compared to rear tracker binning and yielded more uniform noise throughout the image. MCS should not be neglected when predicting image noise for pixels away from the center of an object in a pCT scan due to the increasing influence of the gradient of the object's hull closer to the edges.
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Affiliation(s)
- Martin Rädler
- Department of Medical Physics, Ludwig-Maximilians-Universität München, 85748 Garching b. München, Germany. Authors contributed equally
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14
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Hillbrand M, Landry G, Ebert S, Dedes G, Pappas E, Kalaitzakis G, Kurz C, Würl M, Englbrecht F, Dietrich O, Makris D, Pappas E, Parodi K. Gel dosimetry for three dimensional proton range measurements in anthropomorphic geometries. Z Med Phys 2018; 29:162-172. [PMID: 30249351 DOI: 10.1016/j.zemedi.2018.08.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 08/14/2018] [Accepted: 08/26/2018] [Indexed: 11/27/2022]
Abstract
Proton beams used for radiotherapy have potential for superior sparing of normal tissue, although range uncertainties are among the main limiting factors in the accuracy of dose delivery. The aim of this study was to benchmark an N-vinylpyrrolidone based polymer gel to perform three-dimensional measurement of geometric proton beam characteristics and especially to test its suitability as a range probe in combination with an anthropomorphic phantom. For single proton pencil beams as well as for 3×3cm2 mono-energy layers depth dose profiles, lateral dose distribution at different depths and proton range were evaluated in simple cubic gel phantoms at different energies from 75 to 115MeV and different dose levels. In addition, a 90MeV mono-energetic beam was delivered to an anthropomorphic 3D printed head phantom, which was filled with gel. Subsequently, all phantoms underwent magnetic resonance imaging using an axial pixel size of 0.68-0.98mm and with slice thicknesses of 2 or 3mm to derive a 3-dimensional distribution of the T2 relaxation time, which correlates with radiation dose. Indices describing lateral dose distribution and proton range were compared against predictions from a treatment planning system (TPS, for cubic and head phantoms) and Monte Carlo simulations (MC, for the head phantom) after manual rigid co-registration with the T2 relaxation time datasets. For all pencil beams, the FWHM agreement with TPS was better than 1mm or 7%. For the mono-energetic layer, the agreement with TPS in this respect was even better than 0.3mm in each case. With respect to range, results from gel measurements differed no more than 0.9mm (1.6%) from values predicted by TPS. In case of the anthropomorphic phantom, deviations with respect to a nominal range of about 61mm as well as in FWHM were slightly higher, namely within 1.0mm and 1.1mm respectively. Average deviations between gel and TPS/MC were similar (-0.3mm±0.4mm/-0.2±0.5mm). In conclusion, polymer gel dosimetry was found to be a valuable tool to determine geometric proton beam properties three-dimensionally and with high spatial resolution in simple cubic as well as in a more complex anthropomorphic phantom. Post registration range errors of the order of 1mm could be achieved. The additional registration uncertainty (95%) was 1mm.
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Affiliation(s)
| | - Guillaume Landry
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Sandy Ebert
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - George Dedes
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Eleftherios Pappas
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece
| | | | - Christopher Kurz
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Matthias Würl
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Franz Englbrecht
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Olaf Dietrich
- Department of Radiology, University Hospital, LMU Munich, Munich, Germany
| | - Dimitris Makris
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece
| | - Evangelos Pappas
- Radiology & Radiotherapy Sector, Department of Biomedical Sciences, University of West Attica, Athens, Greece
| | - Katia Parodi
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany.
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15
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Dedes G, Johnson RP, Pankuch M, Detrich N, Pols WMA, Rit S, Schulte RW, Parodi K, Landry G. Experimental fluence‐modulated proton computed tomography by pencil beam scanning. Med Phys 2018; 45:3287-3296. [DOI: 10.1002/mp.12989] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 05/14/2018] [Accepted: 05/14/2018] [Indexed: 01/22/2023] Open
Affiliation(s)
- George Dedes
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München (LMU Munich) 85748 Garching b. München Germany
| | | | - Mark Pankuch
- Northwestern Medicine Chicago Proton Center Warrenville IL 60555 USA
| | - Nick Detrich
- IBA and Northwestern Medicine Chicago Proton Center Warrenville IL 60555 USA
| | - Willemijn M. A. Pols
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München (LMU Munich) 85748 Garching b. München Germany
| | - Simon Rit
- Université de Lyon CREATIS CNRS UMR5220 Inserm U1044 INSA‐Lyon Université Lyon 1 F69373 Lyon France
| | - Reinhard W. Schulte
- Division of Radiation Research Loma Linda University Loma Linda CA 92354 USA
| | - Katia Parodi
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München (LMU Munich) 85748 Garching b. München Germany
| | - Guillaume Landry
- Department of Medical Physics Faculty of Physics Ludwig‐Maximilians‐Universität München (LMU Munich) 85748 Garching b. München Germany
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