6 results on '"Dulski, K."'
Search Results
2. Estimating relationship between the time over threshold and energy loss by photons in plastic scintillators used in the J-PET scanner
- Author
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Sharma, S., Chhokar, J., Curceanu, C., Czerwiński, E., Dadgar, M., Dulski, K., Gajewski, J., Gajos, A., Gorgol, M., Gupta-Sharma, N., Del Grande, R., Hiesmayr, B.C., Jasińska, B., Kacprzak, K., Kapłon, Ł., Karimi, H., Kisielewska, D., Klimaszewski, K., Korcyl, G., Kowalski, P., Kozik, T., Krawczyk, N., Krzemień, W., Kubicz, E., Mohammed, M., Niedzwiecki, Sz., Pałka, M., Pawlik-Niedźwiecka, M., Raczyński, L., Raj, J., Ruciński, A., Shivani, S., Shopa, R.Y., Silarski, M., Skurzok, M., Stępień, E.Ł., Wiślicki, W., Zgardzińska, B., and Moskal, P.
- Published
- 2020
- Full Text
- View/download PDF
3. Performance assessment of the 2 γpositronium imaging with the total-body PET scanners
- Author
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Moskal, P., Kisielewska, D., Y. Shopa, R., Bura, Z., Chhokar, J., Curceanu, C., Czerwiński, E., Dadgar, M., Dulski, K., Gajewski, J., Gajos, A., Gorgol, M., Del Grande, R., C. Hiesmayr, B., Jasińska, B., Kacprzak, K., Kamińska, A., Kapłon, Ł, Karimi, H., Korcyl, G., Kowalski, P., Krawczyk, N., Krzemień, W., Kozik, T., Kubicz, E., Małczak, P., Mohammed, M., Niedźwiecki, Sz., Pałka, M., Pawlik-Niedźwiecka, M., Pędziwiatr, M., Raczyński, L., Raj, J., Ruciński, A., Sharma, S., Shivani, S., Silarski, M., Skurzok, M., Stępień, E. Ł., Vandenberghe, S., Wiślicki, W., and Zgardzińska, B.
- Subjects
lcsh:Medical physics. Medical radiology. Nuclear medicine ,PET ,Total-body PET ,lcsh:R895-920 ,Medical imaging ,Positronium imaging ,Original Research - Abstract
Purpose In living organisms, the positron-electron annihilation (occurring during the PET imaging) proceeds in about 30% via creation of a metastable ortho-positronium atom. In the tissue, due to the pick-off and conversion processes, over 98% of ortho-positronia annihilate into two 511 keV photons. In this article, we assess the feasibility for reconstruction of the mean ortho-positronium lifetime image based on annihilations into two photons. The main objectives of this work include the (i) estimation of the sensitivity of the total-body PET scanners for the ortho-positronium mean lifetime imaging using 2γ annihilations and (ii) estimation of the spatial and time resolution of the ortho-positronium image as a function of the coincidence resolving time (CRT) of the scanner. Methods Simulations are conducted assuming that radiopharmaceutical is labeled with 44 S c isotope emitting one positron and one prompt gamma. The image is reconstructed on the basis of triple coincidence events. The ortho-positronium lifetime spectrum is determined for each voxel of the image. Calculations were performed for cases of total-body detectors build of (i) LYSO scintillators as used in the EXPLORER PET and (ii) plastic scintillators as anticipated for the cost-effective total-body J-PET scanner. To assess the spatial and time resolution, the four cases were considered assuming that CRT is equal to 500 ps, 140 ps, 50 ps, and 10 ps. Results The estimated total-body PET sensitivity for the registration and selection of image forming triple coincidences (2γ+γ prompt) is larger by a factor of 13.5 (for LYSO PET) and by factor of 5.2 (for plastic PET) with respect to the sensitivity for the standard 2γ imaging by LYSO PET scanners with AFOV = 20 cm. The spatial resolution of the ortho-positronium image is comparable with the resolution achievable when using TOF-FBP algorithms already for CRT = 50 ps. For the 20-min scan, the resolution better than 20 ps is expected for the mean ortho-positronium lifetime image determination. Conclusions Ortho-positronium mean lifetime imaging based on the annihilations into two photons and prompt gamma is shown to be feasible with the advent of the high sensitivity total-body PET systems and time resolution of the order of tens of picoseconds.
- Published
- 2020
4. Performance assessment of the 2 \gamma positronium imaging with the total-body PET scanners
- Author
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Moskal, P., Kisielewska, D., Shopa, R. Y., Bura, Z., Chhokar, J., Curceanu, C., Czerwinski, E., Dadgar, Meysam, Dulski, K., Gajewski, J., Gajos, A., Gorgol, M., Del Grande, R., Hiesmayr, B. C., Jasinska, B., Kacprzak, K., Kaminska, A., Kaplon, L., Karimi, H., Korcyl, G., Kowalski, P., Krawczyk, N., Krzemien, W., Kozik, T., Kubicz, E., Malczak, P., Mohammed, M., Niedzwiecki, Sz, Palka, M., Pawlik-Niedzwiecka, M., Pedziwiatr, M., Raczynski, L., Raj, J., Rucinski, A., Sharma, S., Shivani, S., Silarski, M., Skurzok, M., Stepien, E. L., Vandenberghe, Stefaan, Wislicki, W., and Zgardzinska, B.
- Subjects
POSITRON-ANNIHILATION SPECTROSCOPY ,Technology and Engineering ,PET ,RESOLUTION ,TOMOGRAPHY ,Total-body PET ,OF-FLIGHT RECONSTRUCTION ,Medical imaging ,FREE-VOLUME ,Positronium imaging ,TIME - Abstract
Purpose In living organisms, the positron-electron annihilation (occurring during the PET imaging) proceeds in about 30% via creation of a metastable ortho-positronium atom. In the tissue, due to the pick-off and conversion processes, over 98% of ortho-positronia annihilate into two 511 keV photons. In this article, we assess the feasibility for reconstruction of the mean ortho-positronium lifetime image based on annihilations into two photons. The main objectives of this work include the (i) estimation of the sensitivity of the total-body PET scanners for the ortho-positronium mean lifetime imaging using 2 gamma annihilations and (ii) estimation of the spatial and time resolution of the ortho-positronium image as a function of the coincidence resolving time (CRT) of the scanner. Methods Simulations are conducted assuming that radiopharmaceutical is labeled with(44)Scisotope emitting one positron and one prompt gamma. The image is reconstructed on the basis of triple coincidence events. The ortho-positronium lifetime spectrum is determined for each voxel of the image. Calculations were performed for cases of total-body detectors build of (i) LYSO scintillators as used in the EXPLORER PET and (ii) plastic scintillators as anticipated for the cost-effective total-body J-PET scanner. To assess the spatial and time resolution, the four cases were considered assuming that CRT is equal to 500 ps, 140 ps, 50 ps, and 10 ps. Results The estimated total-body PET sensitivity for the registration and selection of image forming triple coincidences (2 gamma+gamma(prompt)) is larger by a factor of 13.5 (for LYSO PET) and by factor of 5.2 (for plastic PET) with respect to the sensitivity for the standard 2 gamma imaging by LYSO PET scanners with AFOV = 20 cm. The spatial resolution of the ortho-positronium image is comparable with the resolution achievable when using TOF-FBP algorithms already for CRT = 50 ps. For the 20-min scan, the resolution better than 20 ps is expected for the mean ortho-positronium lifetime image determination. Conclusions Ortho-positronium mean lifetime imaging based on the annihilations into two photons and prompt gamma is shown to be feasible with the advent of the high sensitivity total-body PET systems and time resolution of the order of tens of picoseconds.
- Published
- 2020
5. 3D TOF-PET image reconstruction using total variation regularization.
- Author
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Raczyński, L., Wiślicki, W., Klimaszewski, K., Krzemień, W., Kopka, P., Kowalski, P., Shopa, R.Y., Bała, M., Chhokar, J., Curceanu, C., Czerwiński, E., Dulski, K., Gajewski, J., Gajos, A., Gorgol, M., Del Grande, R., Hiesmayr, B., Jasińska, B., Kacprzak, K., and Kapłon, L.
- Abstract
• TV regularization in image space is more efficient than usual iterative approaches. • The efficiency of proposed method comes from the one-time TOF backprojection step. • The overall operator can be modelled with a closed-form analytical formula. • The operator models TOF uncertainty and spatial detection uncertainty inside detector. In this paper we introduce a semi-analytic algorithm for 3-dimensional image reconstruction for positron emission tomography (PET). The method consists of the back-projection of the acquired data into the most likely image voxel according to time-of-flight (TOF) information, followed by the filtering step in the image space using an iterative optimization algorithm with a total variation (TV) regularization. TV regularization in image space is more computationally efficient than usual iterative optimization methods for PET reconstruction with full system matrix that use TV regularization. The efficiency comes from the one-time TOF back-projection step that might also be described as a reformatting of the acquired data. An important aspect of our work concerns the evaluation of the filter operator of the linear transform mapping an original radioactive tracer distribution into the TOF back-projected image. We obtain concise, closed-form analytical formula for the filter operator. The proposed method is validated with the Monte Carlo simulations of the NEMA IEC phantom using a one-layer, 50 cm-long cylindrical device called Jagiellonian PET scanner. The results show a better image quality compared with the reference TOF maximum likelihood expectation maximization algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
6. Comparative studies of plastic scintillator strips with high technical attenuation length for the total-body J-PET scanner.
- Author
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Kapłon, Ł., Baran, J., Chug, N., Coussat, A., Curceanu, C., Czerwiński, E., Dadgar, M., Dulski, K., Gajewski, J., Gajos, A., Hiesmayr, B., Valsan, E. Kavya, Klimaszewski, K., Korcyl, G., Kozik, T., Krzemień, W., Kumar, D., Moskal, G., Niedźwiecki, S., and Panek, D.
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SCINTILLATORS , *PHOTODETECTORS , *POSITRON emission tomography , *VISIBLE spectra , *PLASTICS , *ATTENUATION of light - Abstract
Plastic scintillator strips are considered as one of the promising solutions for the cost-effective construction of total-body positron emission tomography, (PET) system. The purpose of the performed measurements is to compare the transparency of long plastic scintillators with dimensions 6 mm × 24 mm × 1000 mm and with all surfaces polished. Six different types of commercial, general purpose, blue-emitting plastic scintillators with low attenuation of visible light were tested, namely: polyvinyl toluene-based BC-408, EJ-200, RP-408, and polystyrene-based Epic, SP32 and UPS-923A. For determination of the best type of plastic scintillator for total-body Jagiellonian positron emission tomograph (TB-J-PET) construction, emission and transmission spectra, and technical attenuation length (TAL) of blue light-emitting by the scintillators were measured and compared. The TAL values were determined with the use of UV lamp as excitation source, and photodiode as light detector. Emission spectra of investigated scintillators have maxima in the range from 420 nm to 429 nm. The BC-408 and EJ-200 have the highest transmittance values of about 90% at the maximum emission wavelength measured through a 6 mm thick scintillator strip and the highest technical attenuation length reaching about 2000 mm, allowing assembly of long detection modules for time-of-flight (TOF) J-PET scanners. Influence of the 6 mm × 6 mm, 12 mm × 6 mm, 24 mm × 6 mm cross-sections of the 1000 mm long EJ-200 plastic scintillator on the TAL and signal intensity was measured. The highest TAL value was determined for samples with 24 mm × 6 mm cross-section. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
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