Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator
A Compton camera prototype for ion beam range monitoring via prompt (< 1 ns) gamma detection in hadron therapy is being developed and characterized at the Medical Physics Department of LMU Munich. The system consists of a large (50x50x30 mm3) monolithic LaBr3(Ce) scintillation crystal as absorber...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
De Gruyter
2017-09-01
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| Series: | Current Directions in Biomedical Engineering |
| Subjects: | |
| Online Access: | https://doi.org/10.1515/cdbme-2017-0138 |
| _version_ | 1797848699383054336 |
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| author | Liprandi Silvia Mayerhofer Michael Aldawood Saad Binder Tim Dedes George Miani Agnese Schaart Dennis R. Lozano Ingrid I. Valencia Parodi Katia Thirolf Peter G. |
| author_facet | Liprandi Silvia Mayerhofer Michael Aldawood Saad Binder Tim Dedes George Miani Agnese Schaart Dennis R. Lozano Ingrid I. Valencia Parodi Katia Thirolf Peter G. |
| author_sort | Liprandi Silvia |
| collection | DOAJ |
| description | A Compton camera prototype for ion beam range monitoring via prompt (< 1 ns) gamma detection in hadron therapy is being developed and characterized at the Medical Physics Department of LMU Munich. The system consists of a large (50x50x30 mm3) monolithic LaBr3(Ce) scintillation crystal as absorber component to detect the multi-MeV Compton scattered photons, together with a stack of 6 double-sided silicon strip detectors (DSSSD) acting as scatterer component. Key ingredient of the γ-source reconstruction is the determination of the γ-ray interaction position in the scintillator, which is read out by a 256-fold segmented multi-anode photomultiplier tube (PMT). From simulations an angular resolution of about 1.5o for the photon source reconstruction can be expected for the energy range around 3 – 5 MeV, provided that a spatial resolution of 3 mm can be reached in the absorbing scintillator [1]. Therefore, particular effort was dedicated to characterize this latter property as a function of the γ-ray energy. Intense, tightly collimated 137Cs and 60Co photon sources were used for 2D irradiation scans (step size 0.5 mm) as prerequisite for studying the performance of the “k-Nearest-Neighbors” algorithm developed at TU Delft [2] (together with its variant ”Categorical Average Pattern”, CAP) and extending its applicability into the energy range beyond the original 511 keV. In this paper we present our most recent interaction position analysis in the absorbing scintillator, leading to a considerably improved value for the spatial resolution: systematic studies were performed as a function of the k-NN parameters and the PMT segmentation. A trend of improving spatial resolution with increasing photon energy was confirmed, resulting in the realization of the presently optimum spatial resolution of 2.9(1) mm @1.3 MeV, thus reaching the design specifications of the Compton camera absorber. The specification goal was reached also for a reduced PMT segmentation of 8x8 anode segments (each with 6x6 mm2 active area), thus allowing to reduce the complexity of the signal processing while preserving the performance. |
| first_indexed | 2024-04-09T18:32:54Z |
| format | Article |
| id | doaj.art-4b44371c8117445783e3e59298d89716 |
| institution | Directory Open Access Journal |
| issn | 2364-5504 |
| language | English |
| last_indexed | 2024-04-09T18:32:54Z |
| publishDate | 2017-09-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Current Directions in Biomedical Engineering |
| spelling | doaj.art-4b44371c8117445783e3e59298d897162023-04-11T17:07:14ZengDe GruyterCurrent Directions in Biomedical Engineering2364-55042017-09-013265565910.1515/cdbme-2017-0138cdbme-2017-0138Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillatorLiprandi Silvia0Mayerhofer Michael1Aldawood Saad2Binder Tim3Dedes George4Miani Agnese5Schaart Dennis R.6Lozano Ingrid I. Valencia7Parodi Katia8Thirolf Peter G.9Ludwig Maximilians Universität (LMU) München, Medical Physics Department, Am Coulombwall 1, Garching, GermanyLMU München, Medical Physics Department, Germany LMU München, Department of Medical Physics, Germany LMU München, Medical Physics Department, Germany LMU München, Medical Physics Department, Germany LMU München, Medical Physics Department, Germany Delft University of Technology, Netherlands LMU München, Medical Physics Department, Germany LMU München, Medical Physics Department, Germany LMU München, Medical Physics Department, Germany A Compton camera prototype for ion beam range monitoring via prompt (< 1 ns) gamma detection in hadron therapy is being developed and characterized at the Medical Physics Department of LMU Munich. The system consists of a large (50x50x30 mm3) monolithic LaBr3(Ce) scintillation crystal as absorber component to detect the multi-MeV Compton scattered photons, together with a stack of 6 double-sided silicon strip detectors (DSSSD) acting as scatterer component. Key ingredient of the γ-source reconstruction is the determination of the γ-ray interaction position in the scintillator, which is read out by a 256-fold segmented multi-anode photomultiplier tube (PMT). From simulations an angular resolution of about 1.5o for the photon source reconstruction can be expected for the energy range around 3 – 5 MeV, provided that a spatial resolution of 3 mm can be reached in the absorbing scintillator [1]. Therefore, particular effort was dedicated to characterize this latter property as a function of the γ-ray energy. Intense, tightly collimated 137Cs and 60Co photon sources were used for 2D irradiation scans (step size 0.5 mm) as prerequisite for studying the performance of the “k-Nearest-Neighbors” algorithm developed at TU Delft [2] (together with its variant ”Categorical Average Pattern”, CAP) and extending its applicability into the energy range beyond the original 511 keV. In this paper we present our most recent interaction position analysis in the absorbing scintillator, leading to a considerably improved value for the spatial resolution: systematic studies were performed as a function of the k-NN parameters and the PMT segmentation. A trend of improving spatial resolution with increasing photon energy was confirmed, resulting in the realization of the presently optimum spatial resolution of 2.9(1) mm @1.3 MeV, thus reaching the design specifications of the Compton camera absorber. The specification goal was reached also for a reduced PMT segmentation of 8x8 anode segments (each with 6x6 mm2 active area), thus allowing to reduce the complexity of the signal processing while preserving the performance.https://doi.org/10.1515/cdbme-2017-0138hadron therapygamma-ray medical imagingcompton cameramonolithic scintillatorspatial resolution |
| spellingShingle | Liprandi Silvia Mayerhofer Michael Aldawood Saad Binder Tim Dedes George Miani Agnese Schaart Dennis R. Lozano Ingrid I. Valencia Parodi Katia Thirolf Peter G. Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator Current Directions in Biomedical Engineering hadron therapy gamma-ray medical imaging compton camera monolithic scintillator spatial resolution |
| title | Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator |
| title_full | Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator |
| title_fullStr | Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator |
| title_full_unstemmed | Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator |
| title_short | Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator |
| title_sort | sub 3mm spatial resolution from a large monolithic labr3 ce scintillator |
| topic | hadron therapy gamma-ray medical imaging compton camera monolithic scintillator spatial resolution |
| url | https://doi.org/10.1515/cdbme-2017-0138 |
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