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Sam Beddar - One of the best experts on this subject based on the ideXlab platform.

  • preliminary evaluation of the dosimetric accuracy of the in vivo plastic Scintillation Detector oartrac system for prostate cancer treatments
    Physics in Medicine and Biology, 2014
    Co-Authors: S Klawikowski, Clint Zeringue, Landon S Wootton, G Ibbott, Sam Beddar
    Abstract:

    A promising, new, in vivo prostate dosimetry system has been developed for clinical radiation therapy. This work outlines the preliminary end-to-end testing of the accuracy and precision of the new OARtrac Scintillation dosimetry system. We tested 94 calibrated plastic Scintillation Detector (PSD) probes before their final integration into endorectal balloon assemblies. These probes had been calibrated at The University of Texas MD Anderson Cancer Center Dosimetry Laboratory. We used a complete clinical OARtrac system including the PSD probes, charge coupled device camera monitoring system, and the manufacturer's integrated software package. The PSD probes were irradiated at 6 MV in a Solid Water® phantom. Irradiations were performed with a 6 MV linear accelerator using anterior–posterior/posterior–anterior matched fields to a maximum dose of 200 cGy in a 100 cm source-axis distance geometry. As a whole, the OARtrac system has good accuracy with a mean error of 0.01% and an error spread of ±5.4% at the 95% confidence interval. These results reflect the PSD probes' accuracy before their final insertion into endorectal balloons. Future work will test the dosimetric effects of mounting the PSD probes within the endorectal balloon assemblies.

  • On the use of a single-fiber multipoint plastic Scintillation Detector for 192Ir high-dose-rate brachytherapy
    Medical Physics, 2013
    Co-Authors: François Therriault-proulx, Sam Beddar, Luc Beaulieu
    Abstract:

    Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic Scintillation Detector (mPSD) as anin vivo verification tool during 192Ir high-dose-rate brachytherapy treatments. Methods: A three-point Detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-Detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the Detector, and with various integration times. Several strategies for improving the accuracy of the Detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the Detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the Detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the Detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This Detector shows great promise for development ofin vivo applications for real-time verification of treatment delivery.

  • On the use of a single-fiber multipoint plastic Scintillation Detector for 192 Ir high-dose-rate brachytherapy
    Medical Physics, 2013
    Co-Authors: François Therriault-proulx, Sam Beddar, Luc Beaulieu
    Abstract:

    Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic Scintillation Detector (mPSD) as an in vivo verification tool during 192 Ir high-dose-rate brachytherapy treatments. Methods: A three-point Detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-Detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the Detector, and with various integration times. Several strategies for improving the accuracy of the Detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the Detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the Detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the Detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This Detector shows great promise for development of in vivo applications for real-time verification of treatment delivery. © 2013 American Association of Physicists in Medicine.

  • development of a novel multi point plastic Scintillation Detector with a single optical transmission line for radiation dose measurement
    Physics in Medicine and Biology, 2012
    Co-Authors: F Therriaultproulx, L Archambault, L Beaulieu, Sam Beddar
    Abstract:

    The goal of this study was to develop a novel multi-point plastic Scintillation Detector (mPSD) capable of measuring the dose accurately at multiple positions simultaneously using a single optical transmission line. A 2-point mPSD used a band-pass approach that included splitters, color filters and an EMCCD camera. The 3-point mPSD was based on a new full-spectrum approach, in which a spectrograph was coupled to a CCD camera. Irradiations of the mPSDs and of an ion chamber were performed with a 6 MV photon beam at various depths and lateral positions in a water tank. For the 2-point mPSD, the average relative differences between mPSD and ion chamber measurements for the depth–dose were 2.4±1.6% and 1.3±0.8% for BCF-60 and BCF-12, respectively. For the 3-point mPSD, the average relative differences over all conditions were 2.3±1.1%, 1.6±0.4% and 0.32±0.19% for BCF-60, BCF-12 and BCF-10, respectively. This study demonstrates the practical feasibility of mPSDs. This type of Detector could be very useful for pre-treatment quality assurance applications as well as an accurate tool for real-time in vivo dosimetry.

Luc Beaulieu - One of the best experts on this subject based on the ideXlab platform.

  • On the use of a single-fiber multipoint plastic Scintillation Detector for 192Ir high-dose-rate brachytherapy
    Medical Physics, 2013
    Co-Authors: François Therriault-proulx, Sam Beddar, Luc Beaulieu
    Abstract:

    Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic Scintillation Detector (mPSD) as anin vivo verification tool during 192Ir high-dose-rate brachytherapy treatments. Methods: A three-point Detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-Detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the Detector, and with various integration times. Several strategies for improving the accuracy of the Detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the Detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the Detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the Detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This Detector shows great promise for development ofin vivo applications for real-time verification of treatment delivery.

  • On the use of a single-fiber multipoint plastic Scintillation Detector for 192 Ir high-dose-rate brachytherapy
    Medical Physics, 2013
    Co-Authors: François Therriault-proulx, Sam Beddar, Luc Beaulieu
    Abstract:

    Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic Scintillation Detector (mPSD) as an in vivo verification tool during 192 Ir high-dose-rate brachytherapy treatments. Methods: A three-point Detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-Detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the Detector, and with various integration times. Several strategies for improving the accuracy of the Detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the Detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the Detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the Detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This Detector shows great promise for development of in vivo applications for real-time verification of treatment delivery. © 2013 American Association of Physicists in Medicine.

François Therriault-proulx - One of the best experts on this subject based on the ideXlab platform.

  • On the use of a single-fiber multipoint plastic Scintillation Detector for 192Ir high-dose-rate brachytherapy
    Medical Physics, 2013
    Co-Authors: François Therriault-proulx, Sam Beddar, Luc Beaulieu
    Abstract:

    Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic Scintillation Detector (mPSD) as anin vivo verification tool during 192Ir high-dose-rate brachytherapy treatments. Methods: A three-point Detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-Detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the Detector, and with various integration times. Several strategies for improving the accuracy of the Detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the Detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the Detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the Detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This Detector shows great promise for development ofin vivo applications for real-time verification of treatment delivery.

  • On the use of a single-fiber multipoint plastic Scintillation Detector for 192 Ir high-dose-rate brachytherapy
    Medical Physics, 2013
    Co-Authors: François Therriault-proulx, Sam Beddar, Luc Beaulieu
    Abstract:

    Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic Scintillation Detector (mPSD) as an in vivo verification tool during 192 Ir high-dose-rate brachytherapy treatments. Methods: A three-point Detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-Detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the Detector, and with various integration times. Several strategies for improving the accuracy of the Detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the Detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the Detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the Detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This Detector shows great promise for development of in vivo applications for real-time verification of treatment delivery. © 2013 American Association of Physicists in Medicine.

Krasimir Mitev - One of the best experts on this subject based on the ideXlab platform.

Hongdi Li - One of the best experts on this subject based on the ideXlab platform.

  • A simulation study on optically decoding reflecting windows for PMT quadrant sharing Scintillation Detector block
    IEEE Symposium Conference Record Nuclear Science 2004., 2004
    Co-Authors: Hongdi Li, Wai-hoi Wong, R. Ramirez, Yu Wang, Tao Xing, J. Uribe, H. Baghaei, Yuxuan Zhang
    Abstract:

    A large number of decodable crystals per photomultiplier tube (PMT) can be achieved using the PMT-quadrant-sharing (PQS) technique with proper optically reflecting windows to channel light distribution in Scintillation Detector block. However, to develop brand new optically decoding reflecting windows for a Detector block with different crystal material, PMT size or decoding resolution, is still very time-consuming and also requires much experience. This study is to develop a computer software tool that can simulate an expected 2-dimensional crystal decoding map before implementing a real Detector block with a new set of decoding reflectors. After comparing the experimental decoding data to the simulated results with the same reflector set, data are feed to adjust the software parameters. More accurate decoding reflectors will then be created using the adjusted parameters. A 13times13 Detector block was evaluated and our preliminary study shows this simulation tool is very promising which can significantly reduce a new product developing time; only a few development cycles are needed to get to the final optimized decoding reflectors

  • a simulation study on optically decoding reflecting windows for pmt quadrant sharing Scintillation Detector block
    IEEE Nuclear Science Symposium, 2004
    Co-Authors: Hongdi Li, Wai-hoi Wong, R. Ramirez, Yu Wang, Tao Xing, J. Uribe, Soonseok Kim, Shitao Liu, Shuping Xie, H. Baghaei
    Abstract:

    A large number of decodable crystals per photomultiplier tube (PMT) can be achieved by using the PMT-quadrant-sharing (PQS) technique with proper optically reflecting windows to channel light distribution in Scintillation Detector block. However, to develop brand new optically decoding reflecting windows for a Detector block with different crystal material, PMT size or decoding resolution, is still very time-consuming and also requires much experience. This study is to develop a computer software tool that can simulate an expected two-dimensional (2-D) crystal decoding map before implementing a real Detector block with a new set of decoding reflectors. After comparing the experimental decoding data to the simulated results with the same reflector set on a block, data are feed to adjust the software parameters. More accurate decoding reflectors will then be created by the adjusted parameters. Our result shows the decoding simulation of a 10times10 BGO block can be finished within a few minutes, which is much faster than using the Monte Carlo simulation with "DETECT". This software has been evaluated by five different PQS blocks. Our preliminary study shows this simulation tool is very promising which can significantly reduce a new product developing time; only about two-three development cycles are needed to get to the final optimized decoding reflectors

  • An efficient Detector production method for position-sensitive Scintillation Detector arrays with 98% Detector packing fraction
    IEEE Transactions on Nuclear Science, 2003
    Co-Authors: J. Uribe, Hongdi Li, Wai-hoi Wong, Yu Wang, H. Baghaei, R. Farrell, M. Aykac, D. Bilgen, Tao Xing
    Abstract:

    Position-sensitive Scintillation-Detector arrays (PSSDAs) are used in nuclear-imaging methods such as PET. The kind of technique selected in producing the PSSDA determines the imaging resolution, sensitivity, labor/part cost, and reliability of the system. Production of PSSDA is especially challenging and costly for ultra-high-resolution systems that have large numbers of very small crystal needles, so we developed a new slab-sandwich-slice (SSS) production method. Instead of using individual crystal needles, the construction started with crystal slabs that are 15-crystal-needles wide and 1-needle thick. White-paint was deposited onto slab surfaces to form shaped optical windows. The painted slabs were grouped into two crystal-sandwich types. Each sandwich type consisted of a stack of seven slabs painted with a distinctive set of optical windows, held together with optical glue. For a 40 000-crystal system, only 192 type A and 144 type B sandwiches are needed. Sandwiches were crosscut into another slab formation ("slices"). Each slice was again 1-needle thick; each slice was basically a stack of needles glued together, optically coupled by the glue and the painted windows. After a second set of white-paint optical-windows was applied on the slices' surface, three slices of type B were grouped between four slices of type A to form a 7 /spl times/ 7 PSSDA. We used SSS production method to build 7 /spl times/ 7, 7 /spl times/ 8 and 8 /spl times/ 8 crystal blocks needed for a high-resolution 12-module prototype PET camera. The method reduced the more than 400 000 precision painting and gluing steps into 55 500 steps for a 40 000-BGO-crystal system, thus lowering the labor cost. The Detectors fabricated with the method were of high quality: 2.66 mm /spl times/ 2.66 mm crystals were separated by only a 0.06-mm gap for a 98% linear Detector packing fraction or 96% area packing fraction. Compared to 90% linear-packing (81% area) from conventional methods, the 20% increase in packing density translates into as much as a 1.2 to 1.4 coincidence sensitivity in PET. Crystal cost was halved, and production yield increased to 94%. It generated very small crystal-positioning errors (/spl sigma/=0.09mm), required for ultrahigh resolution Detectors.

  • an efficient Detector production method for position sensitive Scintillation Detector arrays with 98 Detector packing fraction
    IEEE Nuclear Science Symposium, 2002
    Co-Authors: J. Uribe, Hongdi Li, Wai-hoi Wong, Yu Wang, H. Baghaei, R. Farrell, M. Aykac, D. Bilgen, Tao Xing
    Abstract:

    Position-sensitive Scintillation-Detector arrays (PSSDAs) are used in nuclear-imaging methods such as PET. The kind of technique selected in producing the PSSDA determines the imaging resolution, sensitivity, labor/part cost, and reliability of the system. Production of PSSDA is especially challenging and costly for ultra-high-resolution systems that have large numbers of very small crystal needles, so we developed a new slab-sandwich-slice (SSS) production method. Instead of using individual crystal needles, the construction started with crystal slabs that are 15-crystal-needles wide and 1-needle thick. White-paint was deposited onto slab surfaces to form shaped optical windows. The painted slabs were grouped into two crystal-sandwich types. Each sandwich type consisted of a stack of seven slabs painted with a distinctive set of optical windows, held together with optical glue. For a 40 000-crystal system, only 192 type A and 144 type B sandwiches are needed. Sandwiches were crosscut into another slab formation ("slices"). Each slice was again 1-needle thick; each slice was basically a stack of needles glued together, optically coupled by the glue and the painted windows. After a second set of white-paint optical-windows was applied on the slices' surface, three slices of type B were grouped between four slices of type A to form a 7 /spl times/ 7 PSSDA. We used SSS production method to build 7 /spl times/ 7, 7 /spl times/ 8 and 8 /spl times/ 8 crystal blocks needed for a high-resolution 12-module prototype PET camera. The method reduced the more than 400 000 precision painting and gluing steps into 55 500 steps for a 40 000-BGO-crystal system, thus lowering the labor cost. The Detectors fabricated with the method were of high quality: 2.66 mm /spl times/ 2.66 mm crystals were separated by only a 0.06-mm gap for a 98% linear Detector packing fraction or 96% area packing fraction. Compared to 90% linear-packing (81% area) from conventional methods, the 20% increase in packing density translates into as much as a 1.2 to 1.4 coincidence sensitivity in PET. Crystal cost was halved, and production yield increased to 94%. It generated very small crystal-positioning errors (/spl sigma/=0.09mm), required for ultrahigh resolution Detectors.