Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoring
Compton-based prompt gamma (PG) imaging is being investigated by several groups as a potential solution for in vivo range monitoring in proton therapy. The performance of this technique depends on the detector system as well as the ability of the reconstruction method to obtain good spatial resoluti...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2023-05-01
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| Series: | Zeitschrift für Medizinische Physik |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0939388922000605 |
| _version_ | 1827578740049182720 |
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| author | Ingrid Valencia Lozano George Dedes Steve Peterson Dennis Mackin Andreas Zoglauer Sam Beddar Stephen Avery Jerimy Polf Katia Parodi |
| author_facet | Ingrid Valencia Lozano George Dedes Steve Peterson Dennis Mackin Andreas Zoglauer Sam Beddar Stephen Avery Jerimy Polf Katia Parodi |
| author_sort | Ingrid Valencia Lozano |
| collection | DOAJ |
| description | Compton-based prompt gamma (PG) imaging is being investigated by several groups as a potential solution for in vivo range monitoring in proton therapy. The performance of this technique depends on the detector system as well as the ability of the reconstruction method to obtain good spatial resolution to establish a quantitative correlation between the PG emission and the proton beam range in the patient. To evaluate the feasibility of PG imaging for range monitoring, we quantitatively evaluated the emission distributions reconstructed by a Maximum Likelihood Expectation Maximization (MLEM) and a Stochastic Origin Ensemble (SOE) algorithm. To this end, we exploit experimental and Monte Carlo (MC) simulation data acquired with the Polaris-J Compton Camera (CC) prototype. The differences between the proton beam range (RD) defined as the 80% distal dose fall-off and the PG range (RPG), obtained by fitting the distal end of the reconstructed profile with a sigmoid function, were quantified. A comparable performance of both reconstruction algorithms was found. For both experimental and simulated irradiation scenarios, the correlation between RD and RPG was within 5 mm. These values were consistent with the ground truth distance (RD-RPGg≈ 3 mm) calculated by using the expected PG emission available from MC simulation. Furthermore, shifts of 3 mm in the proton beam range were resolved with the MLEM algorithm by calculating the relative difference between the RPG for each reconstructed profile. In non-homogeneous targets, the spatial changes in the PG emission due to the different materials could not be fully resolved from the reconstructed profiles; however, the fall-off region still resembled the ground truth emission. For this scenario, the PG correlation (RD-RPG) varied from 0.1 mm to 4 mm, which is close to the ground truth correlation (3 mm). This work provides a framework for the evaluation of the range monitoring capabilities of a CC device for PG imaging. The two investigated image reconstruction algorithms showed a comparable and consistent performance for homogeneous and heterogeneous targets. |
| first_indexed | 2024-03-08T21:51:45Z |
| format | Article |
| id | doaj.art-22613bf0864a4dd18326d94cad7efd27 |
| institution | Directory Open Access Journal |
| issn | 0939-3889 |
| language | English |
| last_indexed | 2024-03-08T21:51:45Z |
| publishDate | 2023-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Zeitschrift für Medizinische Physik |
| spelling | doaj.art-22613bf0864a4dd18326d94cad7efd272023-12-20T07:33:19ZengElsevierZeitschrift für Medizinische Physik0939-38892023-05-01332124134Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoringIngrid Valencia Lozano0George Dedes1Steve Peterson2Dennis Mackin3Andreas Zoglauer4Sam Beddar5Stephen Avery6Jerimy Polf7Katia Parodi8Department of Medical Physics, Ludwig-Maximilians-Universität, Garching b. München, Germany; Corresponding author: Ingrid Valencia Lozano, Department of Radiation Oncology, Columbia University Irving Medical Center, New York, NY, USA.Department of Medical Physics, Ludwig-Maximilians-Universität, Garching b. München, GermanyDepartment of Physics, University of Cape Town, Rondebosch, Cape Town, South AfricaDepartment of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, USASpace Sciences Laboratory, University of California at Berkeley, Berkeley, CA, USADepartment of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, USADepartment of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USADepartment of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USADepartment of Medical Physics, Ludwig-Maximilians-Universität, Garching b. München, GermanyCompton-based prompt gamma (PG) imaging is being investigated by several groups as a potential solution for in vivo range monitoring in proton therapy. The performance of this technique depends on the detector system as well as the ability of the reconstruction method to obtain good spatial resolution to establish a quantitative correlation between the PG emission and the proton beam range in the patient. To evaluate the feasibility of PG imaging for range monitoring, we quantitatively evaluated the emission distributions reconstructed by a Maximum Likelihood Expectation Maximization (MLEM) and a Stochastic Origin Ensemble (SOE) algorithm. To this end, we exploit experimental and Monte Carlo (MC) simulation data acquired with the Polaris-J Compton Camera (CC) prototype. The differences between the proton beam range (RD) defined as the 80% distal dose fall-off and the PG range (RPG), obtained by fitting the distal end of the reconstructed profile with a sigmoid function, were quantified. A comparable performance of both reconstruction algorithms was found. For both experimental and simulated irradiation scenarios, the correlation between RD and RPG was within 5 mm. These values were consistent with the ground truth distance (RD-RPGg≈ 3 mm) calculated by using the expected PG emission available from MC simulation. Furthermore, shifts of 3 mm in the proton beam range were resolved with the MLEM algorithm by calculating the relative difference between the RPG for each reconstructed profile. In non-homogeneous targets, the spatial changes in the PG emission due to the different materials could not be fully resolved from the reconstructed profiles; however, the fall-off region still resembled the ground truth emission. For this scenario, the PG correlation (RD-RPG) varied from 0.1 mm to 4 mm, which is close to the ground truth correlation (3 mm). This work provides a framework for the evaluation of the range monitoring capabilities of a CC device for PG imaging. The two investigated image reconstruction algorithms showed a comparable and consistent performance for homogeneous and heterogeneous targets.http://www.sciencedirect.com/science/article/pii/S0939388922000605Proton therapyPrompt gamma imagingRange verificationCompton cameraMLEMSOE |
| spellingShingle | Ingrid Valencia Lozano George Dedes Steve Peterson Dennis Mackin Andreas Zoglauer Sam Beddar Stephen Avery Jerimy Polf Katia Parodi Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoring Zeitschrift für Medizinische Physik Proton therapy Prompt gamma imaging Range verification Compton camera MLEM SOE |
| title | Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoring |
| title_full | Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoring |
| title_fullStr | Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoring |
| title_full_unstemmed | Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoring |
| title_short | Comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a Compton camera system tailored to proton range monitoring |
| title_sort | comparison of reconstructed prompt gamma emissions using maximum likelihood estimation and origin ensemble algorithms for a compton camera system tailored to proton range monitoring |
| topic | Proton therapy Prompt gamma imaging Range verification Compton camera MLEM SOE |
| url | http://www.sciencedirect.com/science/article/pii/S0939388922000605 |
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