Assessment of the axial resolution of a compact gamma camera with coded aperture collimator
Abstract Purpose Handheld gamma cameras with coded aperture collimators are under investigation for intraoperative imaging in nuclear medicine. Coded apertures are a promising collimation technique for applications such as lymph node localization due to their high sensitivity and the possibility of...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2024-03-01
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| Series: | EJNMMI Physics |
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| Online Access: | https://doi.org/10.1186/s40658-024-00631-5 |
| _version_ | 1797247015990591488 |
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| author | Tobias Meißner Laura Antonia Cerbone Paolo Russo Werner Nahm Jürgen Hesser |
| author_facet | Tobias Meißner Laura Antonia Cerbone Paolo Russo Werner Nahm Jürgen Hesser |
| author_sort | Tobias Meißner |
| collection | DOAJ |
| description | Abstract Purpose Handheld gamma cameras with coded aperture collimators are under investigation for intraoperative imaging in nuclear medicine. Coded apertures are a promising collimation technique for applications such as lymph node localization due to their high sensitivity and the possibility of 3D imaging. We evaluated the axial resolution and computational performance of two reconstruction methods. Methods An experimental gamma camera was set up consisting of the pixelated semiconductor detector Timepix3 and MURA mask of rank 31 with round holes of 0.08 mm in diameter in a 0.11 mm thick Tungsten sheet. A set of measurements was taken where a point-like gamma source was placed centrally at 21 different positions within the range of 12–100 mm. For each source position, the detector image was reconstructed in 0.5 mm steps around the true source position, resulting in an image stack. The axial resolution was assessed by the full width at half maximum (FWHM) of the contrast-to-noise ratio (CNR) profile along the z-axis of the stack. Two reconstruction methods were compared: MURA Decoding and a 3D maximum likelihood expectation maximization algorithm (3D-MLEM). Results While taking 4400 times longer in computation, 3D-MLEM yielded a smaller axial FWHM and a higher CNR. The axial resolution degraded from 5.3 mm and 1.8 mm at 12 mm to 42.2 mm and 13.5 mm at 100 mm for MURA Decoding and 3D-MLEM respectively. Conclusion Our results show that the coded aperture enables the depth estimation of single point-like sources in the near field. Here, 3D-MLEM offered a better axial resolution but was computationally much slower than MURA Decoding, whose reconstruction time is compatible with real-time imaging. |
| first_indexed | 2024-04-24T19:51:59Z |
| format | Article |
| id | doaj.art-adc9edd4133a4e839d2e31ba396314a1 |
| institution | Directory Open Access Journal |
| issn | 2197-7364 |
| language | English |
| last_indexed | 2024-04-24T19:51:59Z |
| publishDate | 2024-03-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | EJNMMI Physics |
| spelling | doaj.art-adc9edd4133a4e839d2e31ba396314a12024-03-24T12:34:23ZengSpringerOpenEJNMMI Physics2197-73642024-03-0111112110.1186/s40658-024-00631-5Assessment of the axial resolution of a compact gamma camera with coded aperture collimatorTobias Meißner0Laura Antonia Cerbone1Paolo Russo2Werner Nahm3Jürgen Hesser4Institute of Biomedical Engineering (IBT), Karlsruhe Institute of Technology (KIT)Scuola Superiore MeridionaleINFN Sezione di Napoli, Istituto Nazionale di Fisica NucleareInstitute of Biomedical Engineering (IBT), Karlsruhe Institute of Technology (KIT)Mannheim Institute for Intelligent Systems in Medicine (MIISM), Heidelberg UniversityAbstract Purpose Handheld gamma cameras with coded aperture collimators are under investigation for intraoperative imaging in nuclear medicine. Coded apertures are a promising collimation technique for applications such as lymph node localization due to their high sensitivity and the possibility of 3D imaging. We evaluated the axial resolution and computational performance of two reconstruction methods. Methods An experimental gamma camera was set up consisting of the pixelated semiconductor detector Timepix3 and MURA mask of rank 31 with round holes of 0.08 mm in diameter in a 0.11 mm thick Tungsten sheet. A set of measurements was taken where a point-like gamma source was placed centrally at 21 different positions within the range of 12–100 mm. For each source position, the detector image was reconstructed in 0.5 mm steps around the true source position, resulting in an image stack. The axial resolution was assessed by the full width at half maximum (FWHM) of the contrast-to-noise ratio (CNR) profile along the z-axis of the stack. Two reconstruction methods were compared: MURA Decoding and a 3D maximum likelihood expectation maximization algorithm (3D-MLEM). Results While taking 4400 times longer in computation, 3D-MLEM yielded a smaller axial FWHM and a higher CNR. The axial resolution degraded from 5.3 mm and 1.8 mm at 12 mm to 42.2 mm and 13.5 mm at 100 mm for MURA Decoding and 3D-MLEM respectively. Conclusion Our results show that the coded aperture enables the depth estimation of single point-like sources in the near field. Here, 3D-MLEM offered a better axial resolution but was computationally much slower than MURA Decoding, whose reconstruction time is compatible with real-time imaging.https://doi.org/10.1186/s40658-024-00631-5Compact gamma cameraCoded apertureAxial resolutionImage reconstructionIntraoperative imagingRadioguided surgery |
| spellingShingle | Tobias Meißner Laura Antonia Cerbone Paolo Russo Werner Nahm Jürgen Hesser Assessment of the axial resolution of a compact gamma camera with coded aperture collimator EJNMMI Physics Compact gamma camera Coded aperture Axial resolution Image reconstruction Intraoperative imaging Radioguided surgery |
| title | Assessment of the axial resolution of a compact gamma camera with coded aperture collimator |
| title_full | Assessment of the axial resolution of a compact gamma camera with coded aperture collimator |
| title_fullStr | Assessment of the axial resolution of a compact gamma camera with coded aperture collimator |
| title_full_unstemmed | Assessment of the axial resolution of a compact gamma camera with coded aperture collimator |
| title_short | Assessment of the axial resolution of a compact gamma camera with coded aperture collimator |
| title_sort | assessment of the axial resolution of a compact gamma camera with coded aperture collimator |
| topic | Compact gamma camera Coded aperture Axial resolution Image reconstruction Intraoperative imaging Radioguided surgery |
| url | https://doi.org/10.1186/s40658-024-00631-5 |
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