The CPLEAR experiment at CERN measured the CP and CPT violation parameters and determined in a di... more The CPLEAR experiment at CERN measured the CP and CPT violation parameters and determined in a direct way the T violation. The results allow the determination of the CPT violation parameters in the neutral kaon mixing with a precision better than a few 10-4. The mass equality between K0 and K~0 is tested down to the level of 10-19 GeV.
Medical Imaging 2011: Physics of Medical Imaging, 2011
A new silicon strip detector with sub-millimeter pixel size operated in single photon-counting mo... more A new silicon strip detector with sub-millimeter pixel size operated in single photon-counting mode has been developed for use in spectral computed tomography (CT). An ultra fast application specific integrated circuit (ASIC) specially designed for fast photon-counting application is ...
Medical Imaging 2014: Physics of Medical Imaging, 2014
ABSTRACT Purpose: Photon counting x-ray detectors (PCXD) may improve dose-efficiency but are hamp... more ABSTRACT Purpose: Photon counting x-ray detectors (PCXD) may improve dose-efficiency but are hampered by limited count rate. They generally have imperfect energy response. Multi-layer ("in-depth") detectors have been proposed to enable higher count rates but the potential benefit of the depth information has not been explored. We conducted a simulation study to compare in-depth detectors against single layer detectors composed of common materials. Both photon counting and energy integrating modes were studied. Methods: Polyenergetic transmissions were simulated through 25cm of water and 1cm of calcium. For PCXD composed of Si, GaAs or CdTe a 120kVp spectrum was used. For energy integrating x-ray detectors (EIXD) made from GaAs, CdTe or CsI, spectral imaging was done using 80 and 140kVp and matched dose. Semi-ideal and phenomenological energy response models were used. To compare these detectors, we computed the Cramér-Rao lower bound (CRLB) of the variance of basis material estimates. Results: For PCXDs with perfect energy response, depth data provides no additional information. For PCXDs with imperfect energy response and for EIXDs the improvement can be significant. E.g., for a CdTe PCXD with realistic energy response, depth information can reduce the variance by ~50%. The improvement depends on the x-ray spectrum. For a semi-ideal Si detector and a narrow x-ray spectrum the depth information has minimal advantage. For EIXD, the in-depth detector has consistent variance reduction (15% and 17%~19% for water and calcium, respectively). Conclusions: Depth information is beneficial to spectral imaging for both PCXD and EIXD. The improvement depends critically on the detector energy response.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2004
A new electronic portal imaging device, EPID, is under development at the Karolinska Institutet a... more A new electronic portal imaging device, EPID, is under development at the Karolinska Institutet and the Royal Institute of Technology. Due to considerable demands on radiation tolerance in the radiotherapy environment, a dedicated electronic readout system has been designed. ...
Medical Imaging 2011: Physics of Medical Imaging, 2011
Beam quality optimization in mammography traditionally considers detection of a target obscured b... more Beam quality optimization in mammography traditionally considers detection of a target obscured by quantum noise on a homogenous background. It can be argued that this scheme does not correspond well to the clinical imaging task because real mammographic images contain a complex superposition of anatomical structures, resulting in anatomical noise that may dominate over quantum noise. Using a newly developed
2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI), 2014
ABSTRACT The in-depth photon counting x-ray detector (PCXD) is a multi-layer detector arrangement... more ABSTRACT The in-depth photon counting x-ray detector (PCXD) is a multi-layer detector arrangement which has been introduced to tackle photon count rate limitations of current systems. The capability of resolving photon detections along the detector's depth direction enables multiple measurements in a single scan with energy information that could be potentially utilized for x-ray spectral imaging. The benefit of this depth information has not been explored. We conducted a simulation study to evaluate the performance of in-depth PCXDs for dual material decomposition and compared it against single layer detectors. Common semiconductor materials (Si, GaAs and CdTe) were assessed, with imperfect energy response modeled. We demonstrate that depth information is useful if spectral distortion is present. The benefits depend on how the detector is segmented in the depth direction.
... 5), W. FETSCHER (17), M. FIDECARO (4), A. FILIPCIC (10) D. FRANCIS (3), j. FRY (9), E. GABATH... more ... 5), W. FETSCHER (17), M. FIDECARO (4), A. FILIPCIC (10) D. FRANCIS (3), j. FRY (9), E. GABATHULER (9), R. GAMET (9), D. GARRETA (14) H.- J. GERBER (17), A. GO (15), C. GUYOT (14), A. HASELDEN (9), pj HAYMAN (9) F ... (8) Am = (0.5274 + 0.0029star + 0.0005~ 9 9 ...
I. INTRODUCTION In vivo imaging of molecular mechanism using SPECT and PET is increasingly import... more I. INTRODUCTION In vivo imaging of molecular mechanism using SPECT and PET is increasingly important in preclinical imaging. This has created the need for systems with higher resolution, especially in small animal imaging. PET resolution is limited to 1-3 mm by the ...
The CPLEAR experiment at CERN measured the CP and CPT violation parameters and determined in a di... more The CPLEAR experiment at CERN measured the CP and CPT violation parameters and determined in a direct way the T violation. The results allow the determination of the CPT violation parameters in the neutral kaon mixing with a precision better than a few 10-4. The mass equality between K0 and K~0 is tested down to the level of 10-19 GeV.
Medical Imaging 2011: Physics of Medical Imaging, 2011
A new silicon strip detector with sub-millimeter pixel size operated in single photon-counting mo... more A new silicon strip detector with sub-millimeter pixel size operated in single photon-counting mode has been developed for use in spectral computed tomography (CT). An ultra fast application specific integrated circuit (ASIC) specially designed for fast photon-counting application is ...
Medical Imaging 2014: Physics of Medical Imaging, 2014
ABSTRACT Purpose: Photon counting x-ray detectors (PCXD) may improve dose-efficiency but are hamp... more ABSTRACT Purpose: Photon counting x-ray detectors (PCXD) may improve dose-efficiency but are hampered by limited count rate. They generally have imperfect energy response. Multi-layer ("in-depth") detectors have been proposed to enable higher count rates but the potential benefit of the depth information has not been explored. We conducted a simulation study to compare in-depth detectors against single layer detectors composed of common materials. Both photon counting and energy integrating modes were studied. Methods: Polyenergetic transmissions were simulated through 25cm of water and 1cm of calcium. For PCXD composed of Si, GaAs or CdTe a 120kVp spectrum was used. For energy integrating x-ray detectors (EIXD) made from GaAs, CdTe or CsI, spectral imaging was done using 80 and 140kVp and matched dose. Semi-ideal and phenomenological energy response models were used. To compare these detectors, we computed the Cramér-Rao lower bound (CRLB) of the variance of basis material estimates. Results: For PCXDs with perfect energy response, depth data provides no additional information. For PCXDs with imperfect energy response and for EIXDs the improvement can be significant. E.g., for a CdTe PCXD with realistic energy response, depth information can reduce the variance by ~50%. The improvement depends on the x-ray spectrum. For a semi-ideal Si detector and a narrow x-ray spectrum the depth information has minimal advantage. For EIXD, the in-depth detector has consistent variance reduction (15% and 17%~19% for water and calcium, respectively). Conclusions: Depth information is beneficial to spectral imaging for both PCXD and EIXD. The improvement depends critically on the detector energy response.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2004
A new electronic portal imaging device, EPID, is under development at the Karolinska Institutet a... more A new electronic portal imaging device, EPID, is under development at the Karolinska Institutet and the Royal Institute of Technology. Due to considerable demands on radiation tolerance in the radiotherapy environment, a dedicated electronic readout system has been designed. ...
Medical Imaging 2011: Physics of Medical Imaging, 2011
Beam quality optimization in mammography traditionally considers detection of a target obscured b... more Beam quality optimization in mammography traditionally considers detection of a target obscured by quantum noise on a homogenous background. It can be argued that this scheme does not correspond well to the clinical imaging task because real mammographic images contain a complex superposition of anatomical structures, resulting in anatomical noise that may dominate over quantum noise. Using a newly developed
2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI), 2014
ABSTRACT The in-depth photon counting x-ray detector (PCXD) is a multi-layer detector arrangement... more ABSTRACT The in-depth photon counting x-ray detector (PCXD) is a multi-layer detector arrangement which has been introduced to tackle photon count rate limitations of current systems. The capability of resolving photon detections along the detector's depth direction enables multiple measurements in a single scan with energy information that could be potentially utilized for x-ray spectral imaging. The benefit of this depth information has not been explored. We conducted a simulation study to evaluate the performance of in-depth PCXDs for dual material decomposition and compared it against single layer detectors. Common semiconductor materials (Si, GaAs and CdTe) were assessed, with imperfect energy response modeled. We demonstrate that depth information is useful if spectral distortion is present. The benefits depend on how the detector is segmented in the depth direction.
... 5), W. FETSCHER (17), M. FIDECARO (4), A. FILIPCIC (10) D. FRANCIS (3), j. FRY (9), E. GABATH... more ... 5), W. FETSCHER (17), M. FIDECARO (4), A. FILIPCIC (10) D. FRANCIS (3), j. FRY (9), E. GABATHULER (9), R. GAMET (9), D. GARRETA (14) H.- J. GERBER (17), A. GO (15), C. GUYOT (14), A. HASELDEN (9), pj HAYMAN (9) F ... (8) Am = (0.5274 + 0.0029star + 0.0005~ 9 9 ...
I. INTRODUCTION In vivo imaging of molecular mechanism using SPECT and PET is increasingly import... more I. INTRODUCTION In vivo imaging of molecular mechanism using SPECT and PET is increasingly important in preclinical imaging. This has created the need for systems with higher resolution, especially in small animal imaging. PET resolution is limited to 1-3 mm by the ...
Uploads
Papers by M. Danielsson