Julia Brosch-Lenz, F. Yousefirizi, K. Zukotynski, J. Beauregard, Vincent C. Gaudet, B. Saboury, A. Rahmim, Carlos Uribe Department of Integrative Oncology, BC Cancer Research Institute, Vancouver., Bc, Canada, Department of Preventive Medicine, Radiology, Mcmaster University, Hamilton, on, D. Radiology, Nuclear Medicine, C. Centre, Universit'e Laval, Québec City, Qc, Department of Functional Imaging, Research Center, C. Laval, D. Electrical, Computer Engineering, U. Waterloo, Waterloo, Imaging Sciences, C. Center, N. Health, Bethesda., Md., Usa, Department of Materials Science, Electrical Engineering, U. M. County, Baltimore., Hospital of the University of Pennsylvania, Philadelphia., Pa, D. Physics, U. Columbia, Department of Functional Imaging, Bc Cancer
This work was in part supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grants RGPIN-2019- 06467 and RGPIN-2021-02965.
{"title":"Role of AI in Theranostics: Towards Routine Personalized Radiopharmaceutical Therapies","authors":"Julia Brosch-Lenz, F. Yousefirizi, K. Zukotynski, J. Beauregard, Vincent C. Gaudet, B. Saboury, A. Rahmim, Carlos Uribe Department of Integrative Oncology, BC Cancer Research Institute, Vancouver., Bc, Canada, Department of Preventive Medicine, Radiology, Mcmaster University, Hamilton, on, D. Radiology, Nuclear Medicine, C. Centre, Universit'e Laval, Québec City, Qc, Department of Functional Imaging, Research Center, C. Laval, D. Electrical, Computer Engineering, U. Waterloo, Waterloo, Imaging Sciences, C. Center, N. Health, Bethesda., Md., Usa, Department of Materials Science, Electrical Engineering, U. M. County, Baltimore., Hospital of the University of Pennsylvania, Philadelphia., Pa, D. Physics, U. Columbia, Department of Functional Imaging, Bc Cancer","doi":"10.13016/M2RLZU-F7Q9","DOIUrl":"https://doi.org/10.13016/M2RLZU-F7Q9","url":null,"abstract":"This work was in part supported by the Natural Sciences and \u0000Engineering Research Council of Canada (NSERC) Discovery Grants RGPIN-2019- \u000006467 and RGPIN-2021-02965.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76136843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-15DOI: 10.21203/RS.3.RS-289633/V1
Zohreh Hosseinaee, Nima Abbasi, Layla Khalili, Lyazzat Mukhangaliyeva, N. Pellegrino, P. H. Reza
Early diagnosis of ocular diseases improves the understanding of pathophysiology and helps with accurate monitoring and effective treatment. Advanced multimodal ocular imaging platforms play a crucial role in the visualization of the ocular components and provide clinicians with a valuable tool for evaluating different eye diseases. Here, for the first time, we present a non-contact, multimodal photoacoustic remote sensing (PARS) microscopy and swept-source optical coherence tomography (SS-OCT) for in-vivo functional and structural imaging of the eye. The system provides complementary imaging contrasts of optical absorption and optical scattering and is used for non-contact, in-vivo imaging of the murine eye. Results of vasculature and structural imaging as well as melanin content in the retinal pigment epithelium (RPE) layer are presented. Multiwavelength PARS microscopy using Stimulated Raman Scattering (SRS) is applied for the first time, to provide non-contact oxygen saturation estimation in the ocular tissue. The reported work may be a major step toward clinical translation of ophthalmic technologies and has the potential to advance the diagnosis and treatment of ocular diseases.
{"title":"Non-contact, in-vivo, functional, and structural ophthalmic imaging using multimodal photoacoustic remote sensing (PARS) microscopy and swept source optical coherence tomography (SS-OCT)","authors":"Zohreh Hosseinaee, Nima Abbasi, Layla Khalili, Lyazzat Mukhangaliyeva, N. Pellegrino, P. H. Reza","doi":"10.21203/RS.3.RS-289633/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-289633/V1","url":null,"abstract":"Early diagnosis of ocular diseases improves the understanding of pathophysiology and helps with accurate monitoring and effective treatment. Advanced multimodal ocular imaging platforms play a crucial role in the visualization of the ocular components and provide clinicians with a valuable tool for evaluating different eye diseases. Here, for the first time, we present a non-contact, multimodal photoacoustic remote sensing (PARS) microscopy and swept-source optical coherence tomography (SS-OCT) for in-vivo functional and structural imaging of the eye. The system provides complementary imaging contrasts of optical absorption and optical scattering and is used for non-contact, in-vivo imaging of the murine eye. Results of vasculature and structural imaging as well as melanin content in the retinal pigment epithelium (RPE) layer are presented. Multiwavelength PARS microscopy using Stimulated Raman Scattering (SRS) is applied for the first time, to provide non-contact oxygen saturation estimation in the ocular tissue. The reported work may be a major step toward clinical translation of ophthalmic technologies and has the potential to advance the diagnosis and treatment of ocular diseases.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87722522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-24DOI: 10.21203/RS.3.RS-225323/V1
L. Weishaupt, J. Torres, S. Camilleri-Broet, R. Rayes, J. Spicer, Sabrina Cot'e Maldonado, S. Unit, Department of Radiation Oncology, Faculty of Veterinary Medicine, M. University, Montr'eal, Qu'ebec, Canada, Departmentof Pathology, Cancer Research Program, the LD MacLean Surgical Research Laboratories, D. Surgery, GI DivisionofUpper, Thoracic Surgery, Research Center
The goal of this study was (i) to use artificial intelligence to automate the traditionally labor-intensive process of manual segmentation of tumor regions in pathology slides performed by a pathologist and (ii) to validate the use of a deep learning architecture. Automation will reduce the human error involved in the manual process, increase efficiency, and result in more accurate and reproducible segmentation. This advancement will alleviate the bottleneck in the workflow in clinical and research applications due to a lack of pathologist time. Our application is patient-specific microdosimetry and radiobiological modeling, which builds on the contoured pathology slides. A deep neural network named UNet was used to segment tumor regions in pathology core biopsies of lung tissue with adenocarcinoma stained using hematoxylin and eosin. A pathologist manually contoured the tumor regions in 56 images with binary masks for training. To overcome memory limitations overlapping and non-overlapping patch extraction with various patch sizes and image downsampling were investigated individually. Data augmentation was used to reduce overfitting and artificially create more data for training. Using this deep learning approach, the UNet achieved accuracy of 0.91±0.06, specificity of 0.90±0.08, sensitivity of 0.92±0.07, and precision of 0.8±0.1. The F1/DICE score was 0.85±0.07, with a segmentation time of 3.24±0.03 seconds per image, thus achieving a 370±3 times increased efficiency over manual segmentation, which took 20 minutes per image on average. In some cases, the neural network correctly delineated the tumor's stroma from its epithelial component in tumor regions that were classified as tumor by the pathologist. The UNet architecture can segment images with a level of efficiency and accuracy that makes it suitable for tumor segmentation of histopathological images in fields such as radiotherapy dosimetry, specifically in the subfields of microdosimetry.
{"title":"Deep learning-based tumor segmentation on digital images of histopathology slides for microdosimetry applications","authors":"L. Weishaupt, J. Torres, S. Camilleri-Broet, R. Rayes, J. Spicer, Sabrina Cot'e Maldonado, S. Unit, Department of Radiation Oncology, Faculty of Veterinary Medicine, M. University, Montr'eal, Qu'ebec, Canada, Departmentof Pathology, Cancer Research Program, the LD MacLean Surgical Research Laboratories, D. Surgery, GI DivisionofUpper, Thoracic Surgery, Research Center","doi":"10.21203/RS.3.RS-225323/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-225323/V1","url":null,"abstract":"\u0000 The goal of this study was (i) to use artificial intelligence to automate the traditionally labor-intensive process of manual segmentation of tumor regions in pathology slides performed by a pathologist and (ii) to validate the use of a deep learning architecture. Automation will reduce the human error involved in the manual process, increase efficiency, and result in more accurate and reproducible segmentation. This advancement will alleviate the bottleneck in the workflow in clinical and research applications due to a lack of pathologist time. Our application is patient-specific microdosimetry and radiobiological modeling, which builds on the contoured pathology slides. A deep neural network named UNet was used to segment tumor regions in pathology core biopsies of lung tissue with adenocarcinoma stained using hematoxylin and eosin. A pathologist manually contoured the tumor regions in 56 images with binary masks for training. To overcome memory limitations overlapping and non-overlapping patch extraction with various patch sizes and image downsampling were investigated individually. Data augmentation was used to reduce overfitting and artificially create more data for training. Using this deep learning approach, the UNet achieved accuracy of 0.91±0.06, specificity of 0.90±0.08, sensitivity of 0.92±0.07, and precision of 0.8±0.1. The F1/DICE score was 0.85±0.07, with a segmentation time of 3.24±0.03 seconds per image, thus achieving a 370±3 times increased efficiency over manual segmentation, which took 20 minutes per image on average. In some cases, the neural network correctly delineated the tumor's stroma from its epithelial component in tumor regions that were classified as tumor by the pathologist. The UNet architecture can segment images with a level of efficiency and accuracy that makes it suitable for tumor segmentation of histopathological images in fields such as radiotherapy dosimetry, specifically in the subfields of microdosimetry.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77532700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Chatelin, R. Pop, C. Giraudeau, K. Ambarki, N. Jin, Franccois Severac, E. Breton, J. Vappou
The invasive measurement of the hepatic venous pressure gradient is still considered as the reference method to assess the severity of portal hypertension. Even though previous studies have shown that the liver stiffness measured by elastography could predict portal hypertension in patients with chronic liver disease, the mechanisms behind remain today poorly understood. The main reason is that the liver stiffness is not specific to portal hypertension and is also influenced by concomitant pathologies, such as cirrhosis. Portal hypertension is also source of a vascular incidence, with a substantial diversion of portal venous blood to the systemic circulation, bypassing the liver. This study focuses on this vascular effect of portal hypertension. We propose to generate and control the portal venous flow (to isolate the modifications in the portal venous flow as single effect of portal hypertension) in an anesthetized pig and then to quantify its implications on liver stiffness by an original combination of MRE and 4D-Flow Magnetic Resonance Imaging (MRI). A catheter balloon is progressively inflated in the portal vein and the peak flow, peak velocity magnitude and liver stiffness are quantified in a 1.5T MRI scanner (AREA, Siemens Healthcare, Erlangen, Germany). A strong correlation is observed between the portal peak velocity magnitude, the portal peak flow or the liver stiffness and the portal vein intraluminal obstruction. Moreover, the comparison of mechanical and flow parameters highlights a correlation with the possibility of identifying linear relationships. These results give preliminary indications about how liver stiffness can be affected by portal venous flow and, by extension, by hypertension.
{"title":"Magnetic Resonance Elastography and Portal Hypertension: Influence of the Portal Venous Flow on the Liver Stiffness","authors":"S. Chatelin, R. Pop, C. Giraudeau, K. Ambarki, N. Jin, Franccois Severac, E. Breton, J. Vappou","doi":"10.3233/bhr210022","DOIUrl":"https://doi.org/10.3233/bhr210022","url":null,"abstract":"The invasive measurement of the hepatic venous pressure gradient is still considered as the reference method to assess the severity of portal hypertension. Even though previous studies have shown that the liver stiffness measured by elastography could predict portal hypertension in patients with chronic liver disease, the mechanisms behind remain today poorly understood. The main reason is that the liver stiffness is not specific to portal hypertension and is also influenced by concomitant pathologies, such as cirrhosis. Portal hypertension is also source of a vascular incidence, with a substantial diversion of portal venous blood to the systemic circulation, bypassing the liver. This study focuses on this vascular effect of portal hypertension. We propose to generate and control the portal venous flow (to isolate the modifications in the portal venous flow as single effect of portal hypertension) in an anesthetized pig and then to quantify its implications on liver stiffness by an original combination of MRE and 4D-Flow Magnetic Resonance Imaging (MRI). A catheter balloon is progressively inflated in the portal vein and the peak flow, peak velocity magnitude and liver stiffness are quantified in a 1.5T MRI scanner (AREA, Siemens Healthcare, Erlangen, Germany). A strong correlation is observed between the portal peak velocity magnitude, the portal peak flow or the liver stiffness and the portal vein intraluminal obstruction. Moreover, the comparison of mechanical and flow parameters highlights a correlation with the possibility of identifying linear relationships. These results give preliminary indications about how liver stiffness can be affected by portal venous flow and, by extension, by hypertension.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83450459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.21203/rs.3.rs-131073/v1
Wei-Tang Chang, Khoi Minh Huynh, P. Yap, Weili Lin
The ability to achieve submillimter isotropic resolution diffusion MR imaging (dMRI) is critically important to study fine-scale brain structures. One of the major challenges in submillimeter dMRI is the inherently low signal-to-noise ratio (SNR). While approaches capable of mitigating the low SNR have been proposed, namely simultaneous multi-slab (SMSlab) and generalized slice dithered enhanced resolution with simultaneous multislice (gSlider-SMS), limitations are associated with these approaches. The SMSlab sequences suffer from the slab boundary artifacts and require additional navigators for phase estimation. On the other hand, gSlider sequences require relatively high RF power and peak amplitude, which increase the SAR and complicate the RF excitation. In this work, we developed a navigator-free multishot-encoded simultaneous multi-slice (MUSIUM) imaging approach, achieving enhanced SNR, low RF power and peak amplitude, and being free from slab boundary artifacts. The dMRI with ultrahigh resolution (0.86 mm isotropic), whole brain coverage and ~12.5 minute acquisition time were achieved, revealing detailed structures at cortical and white matter areas. The simulated and in vivo results also demonstrated that the MUSIUM imaging was minimally affected by the motion. Taken together, the MUSIUM imaging is a promising approach to achieve submillimeter diffusion imaging on 3T scanner within clinically feasible scan time.
{"title":"Navigator-Free Submillimeter Diffusion Imaging Using Multishot-Encoded Simultaneous Multi-Slice (MUSIUM)","authors":"Wei-Tang Chang, Khoi Minh Huynh, P. Yap, Weili Lin","doi":"10.21203/rs.3.rs-131073/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-131073/v1","url":null,"abstract":"\u0000 The ability to achieve submillimter isotropic resolution diffusion MR imaging (dMRI) is critically important to study fine-scale brain structures. One of the major challenges in submillimeter dMRI is the inherently low signal-to-noise ratio (SNR). While approaches capable of mitigating the low SNR have been proposed, namely simultaneous multi-slab (SMSlab) and generalized slice dithered enhanced resolution with simultaneous multislice (gSlider-SMS), limitations are associated with these approaches. The SMSlab sequences suffer from the slab boundary artifacts and require additional navigators for phase estimation. On the other hand, gSlider sequences require relatively high RF power and peak amplitude, which increase the SAR and complicate the RF excitation. In this work, we developed a navigator-free multishot-encoded simultaneous multi-slice (MUSIUM) imaging approach, achieving enhanced SNR, low RF power and peak amplitude, and being free from slab boundary artifacts. The dMRI with ultrahigh resolution (0.86 mm isotropic), whole brain coverage and ~12.5 minute acquisition time were achieved, revealing detailed structures at cortical and white matter areas. The simulated and in vivo results also demonstrated that the MUSIUM imaging was minimally affected by the motion. Taken together, the MUSIUM imaging is a promising approach to achieve submillimeter diffusion imaging on 3T scanner within clinically feasible scan time.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75581885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose a novel solution for volumetric ultrasound imaging using single-side access 3-D synthetic-aperture scanning of a clinical linear array. This solution is based on an advanced scanning geometry and a software-based ultrasound platform. The rotate-translate scanning scheme increases the elevation angular aperture by pivoting the array [-45{textdegree} to 45{textdegree}] around its array axis (axis along the row of its elements) and then, scans the imaged object for each pivoted angle by translating the array perpendicularly to the rotation axis. A theoretical basis is presented so that the angular and translational scan sampling periods can be best adjusted for any linear transducer array. We experimentally implemented scanning with a 5-MHz array. In vitro characterization was performed with phantoms designed to test resolution and contrast. Spatial resolution assessed based on the full-width half-maximum of images from isolated microspheres was increased by a factor 3 along the translational direction from a simple translation scan of the array. Moreover, the resolution is uniform over a cross-sectional area of 4.5 cm 2. Angular sampling periods were optimized and tapered to decrease the scan duration while maintaining image contrast (contrast at the center of a 5 mm cyst on the order of-26 dB for 4{textdegree} angular period and a scan duration of 10 s for a 9cm 3 volume). We demonstrate that superior 3-D US imaging can be obtained with a clinical array using our scanning strategy. This technique offers a promising and flexible alternative to development of costly matrix arrays toward the development of sensitive volumetric ultrasonography.
我们提出了一种新的解决方案，体积超声成像使用单侧访问三维合成孔径扫描临床线性阵列。该解决方案基于先进的扫描几何结构和基于软件的超声平台。旋转平移扫描方案通过将阵列[-45{textdegree}到45{textdegree}]围绕其阵列轴(沿其元素行轴)旋转来增加仰角孔径，然后通过垂直于旋转轴平移阵列来扫描成像对象的每个旋转角度。为任意线性换能器阵列的角度和平移扫描采样周期的最佳调整提供了理论基础。我们通过实验实现了5mhz阵列的扫描。体外表征采用设计用于测试分辨率和对比度的模型进行。基于隔离微球图像的全宽度半最大值评估的空间分辨率从阵列的简单平移扫描沿平移方向增加了3倍。此外，在4.5 cm 2的横截面积上，分辨率是均匀的。在保持图像对比度的同时，对角采样周期进行了优化和变细，以减少扫描时间(5 mm囊肿中心的对比度为-26 dB，角采样周期为4{textdegree}，扫描时间为10 s，体积为9cm 3)。我们证明，使用我们的扫描策略，临床阵列可以获得优越的3-D超声成像。该技术为灵敏体积超声的发展提供了一个有前途和灵活的替代方案，以发展昂贵的矩阵阵列。
{"title":"High-Contrast and -Resolution 3-D Ultrasonography with a Clinical Linear Transducer Array Scanned in a Rotate-Translate Geometry","authors":"T. Lucas, I. Quidu, S. Bridal, J. Gateau","doi":"10.3390/app11020493","DOIUrl":"https://doi.org/10.3390/app11020493","url":null,"abstract":"We propose a novel solution for volumetric ultrasound imaging using single-side access 3-D synthetic-aperture scanning of a clinical linear array. This solution is based on an advanced scanning geometry and a software-based ultrasound platform. The rotate-translate scanning scheme increases the elevation angular aperture by pivoting the array [-45{textdegree} to 45{textdegree}] around its array axis (axis along the row of its elements) and then, scans the imaged object for each pivoted angle by translating the array perpendicularly to the rotation axis. A theoretical basis is presented so that the angular and translational scan sampling periods can be best adjusted for any linear transducer array. We experimentally implemented scanning with a 5-MHz array. In vitro characterization was performed with phantoms designed to test resolution and contrast. Spatial resolution assessed based on the full-width half-maximum of images from isolated microspheres was increased by a factor 3 along the translational direction from a simple translation scan of the array. Moreover, the resolution is uniform over a cross-sectional area of 4.5 cm 2. Angular sampling periods were optimized and tapered to decrease the scan duration while maintaining image contrast (contrast at the center of a 5 mm cyst on the order of-26 dB for 4{textdegree} angular period and a scan duration of 10 s for a 9cm 3 volume). We demonstrate that superior 3-D US imaging can be obtained with a clinical array using our scanning strategy. This technique offers a promising and flexible alternative to development of costly matrix arrays toward the development of sensitive volumetric ultrasonography.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81067135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-10DOI: 10.13140/RG.2.2.31966.46407
C. Altunbas, Y. Zhong, C. Shaw
Suppressing the effects of scattered radiation in flat panel detector, FPD, based CBCT still remains to be a challenge. To address the scatter problem, we have been investigating the feasibility of a two dimensional antiscatter grid (2D ASG) concept for FPDs. Although a 2D ASG can potentially provide high scatter rejection capability, primary transmission characteristics of a 2D ASG and its implications in image quality plays a more critical role in implementation of the 2D ASG concept. Thus, in this work, a computational model was developed to investigate the primary transmission properties of the 2D ASG for various grid and FPD pixel geometries, and the improvement in signal to noise ratio,SNR, was calculated analytically to demonstrate the impact of 2D ASG's transmission characteristics on image quality. Computational model showed that average primary transmission fraction (Tp) strongly depends on the septal thickness of 2D ASG, and 2D ASG can provide higher Tp than existing radiographic ASGs at a septal thickness of 0.1 mm. Due to the higher Tp, 2D ASG was also predicted to provide SNR improvements in projections in low to moderate scatter environments typically observed in CBCT imaging. On the other hand, the model also indicated that the shadow or footprint of the 2D ASG leads to spatially nonuniform variations in primary signal in FPD pixels. Reduction of septal thickness and optimization of 2D ASG's pitch may play an essential role in reducing such variations in primary image signal, and avoiding potential image artifacts associated with 2D ASG's footprint.
{"title":"Feasibility of 2D antiscatter grid concept for flat panel detectors: preliminary investigation of primary transmission properties.","authors":"C. Altunbas, Y. Zhong, C. Shaw","doi":"10.13140/RG.2.2.31966.46407","DOIUrl":"https://doi.org/10.13140/RG.2.2.31966.46407","url":null,"abstract":"Suppressing the effects of scattered radiation in flat panel detector, FPD, based CBCT still remains to be a challenge. To address the scatter problem, we have been investigating the feasibility of a two dimensional antiscatter grid (2D ASG) concept for FPDs. Although a 2D ASG can potentially provide high scatter rejection capability, primary transmission characteristics of a 2D ASG and its implications in image quality plays a more critical role in implementation of the 2D ASG concept. Thus, in this work, a computational model was developed to investigate the primary transmission properties of the 2D ASG for various grid and FPD pixel geometries, and the improvement in signal to noise ratio,SNR, was calculated analytically to demonstrate the impact of 2D ASG's transmission characteristics on image quality. Computational model showed that average primary transmission fraction (Tp) strongly depends on the septal thickness of 2D ASG, and 2D ASG can provide higher Tp than existing radiographic ASGs at a septal thickness of 0.1 mm. Due to the higher Tp, 2D ASG was also predicted to provide SNR improvements in projections in low to moderate scatter environments typically observed in CBCT imaging. On the other hand, the model also indicated that the shadow or footprint of the 2D ASG leads to spatially nonuniform variations in primary signal in FPD pixels. Reduction of septal thickness and optimization of 2D ASG's pitch may play an essential role in reducing such variations in primary image signal, and avoiding potential image artifacts associated with 2D ASG's footprint.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87941511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hyperthermia has been in use for many years; as a potential alternative modality for cancer treatment. In this paper, an experimental investigation of microwave assisted thermal heating (MWATH) of tissue phantom using a domestic microwave oven has been reported. Computer simulations using finite element method based tools was also carried out to support the experimental observations and probe insight on the thermal transport aspects deep within the tissue phantom. A good agreement between predicted and measured temperature were achieved. Furthermore, experiments were conducted to investigate the efficacy of dielectric nanoparticles viz. alumina (Al2O3) and titanium oxide (TiO2) during the MWATH of nanoparticle infused tumor phantoms. A deep seated tumor injected with nanoparticle solution was specifically mimicked in the experiments. Interesting results were obtained in terms of spatiotemporal thermal history of the nanoparticle infused tissue phantoms. An elevation in the temperature distribution was achieved in the vicinity of the targeted zone due to the presence of nanoparticles, and the spatial distribution of temperature was grossly morphed. We conclusively show, using experiments and simulations that unlike other nanoparticle mediated hyperthermia techniques, direct injection of the nanoparticles within the tumor leads to enhanced heat generation in the neighb oring healthy tissues. The inhomogeneity of the hyperthermia event is evident from the lo cal occurrence of hot spots and cold spots respectively. The present findings may have far reaching implications as a framework in predicting temperature distributions during MWA.
{"title":"Thermal Response of Dielectric Nanoparticle-Infused Tissue Phantoms During Microwave-Assisted Hyperthermia","authors":"Dhiraj Kumar, Purbarun Dhar, Anup K. Paul","doi":"10.1115/1.4050665","DOIUrl":"https://doi.org/10.1115/1.4050665","url":null,"abstract":"Hyperthermia has been in use for many years; as a potential alternative modality for cancer treatment. In this paper, an experimental investigation of microwave assisted thermal heating (MWATH) of tissue phantom using a domestic microwave oven has been reported. Computer simulations using finite element method based tools was also carried out to support the experimental observations and probe insight on the thermal transport aspects deep within the tissue phantom. A good agreement between predicted and measured temperature were achieved. Furthermore, experiments were conducted to investigate the efficacy of dielectric nanoparticles viz. alumina (Al2O3) and titanium oxide (TiO2) during the MWATH of nanoparticle infused tumor phantoms. A deep seated tumor injected with nanoparticle solution was specifically mimicked in the experiments. Interesting results were obtained in terms of spatiotemporal thermal history of the nanoparticle infused tissue phantoms. An elevation in the temperature distribution was achieved in the vicinity of the targeted zone due to the presence of nanoparticles, and the spatial distribution of temperature was grossly morphed. We conclusively show, using experiments and simulations that unlike other nanoparticle mediated hyperthermia techniques, direct injection of the nanoparticles within the tumor leads to enhanced heat generation in the neighb oring healthy tissues. The inhomogeneity of the hyperthermia event is evident from the lo cal occurrence of hot spots and cold spots respectively. The present findings may have far reaching implications as a framework in predicting temperature distributions during MWA.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85956201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-06DOI: 10.11648/J.AJIM.20200806.15
A. Floch, Samuel Henriat, Rosane Fourage, G. Ropars
Postural stability is linked to vision in everyone, since when the eyes are closed stability decreases by a factor of 2 or more. However, in persons with dyslexia postural stability is often deficient even when the eyes are open, since they show deficits in motor as well as specific cognitive functions. In dyslexics we have shown that abnormal symmetry between retinal Maxwell's centroid outlines occurs, perturbing the interhemispheric connections. We have also shown that pulse-width modulated lighting can compensate for this lack of asymmetry, improving the reading skills. As the postural stability and the vision are correlated, one may wonder if the excess of the postural instability recorded in a young adult with dyslexia can also be reduced by a pulse-width modulated light controlling the Hebbian synaptic plasticity. Using a force platform we compared the postural responses of an observer without dyslexia with the responses of a subject with dyslexia, by measuring their respective standing postures with eyes open looking at a target in a room with either continuous or pulse lighting. There was no effect of changing the lighting conditions on the postural control of the subject without dyslexia. However, we found that the postural stability of the subject with dyslexia which was actually impaired during continuous light, but was greatly improved when a 80 Hz pulsed light frequency was used. Importantly, the excursions of the surface area of the center of pressure on the force platform were reduced by a factor of 2.3.
{"title":"Postural Instability in a Young Dyslexic Adult Improved by Hebbian Pulse-width Modulated Lighting","authors":"A. Floch, Samuel Henriat, Rosane Fourage, G. Ropars","doi":"10.11648/J.AJIM.20200806.15","DOIUrl":"https://doi.org/10.11648/J.AJIM.20200806.15","url":null,"abstract":"Postural stability is linked to vision in everyone, since when the eyes are closed stability decreases by a factor of 2 or more. However, in persons with dyslexia postural stability is often deficient even when the eyes are open, since they show deficits in motor as well as specific cognitive functions. In dyslexics we have shown that abnormal symmetry between retinal Maxwell's centroid outlines occurs, perturbing the interhemispheric connections. We have also shown that pulse-width modulated lighting can compensate for this lack of asymmetry, improving the reading skills. As the postural stability and the vision are correlated, one may wonder if the excess of the postural instability recorded in a young adult with dyslexia can also be reduced by a pulse-width modulated light controlling the Hebbian synaptic plasticity. Using a force platform we compared the postural responses of an observer without dyslexia with the responses of a subject with dyslexia, by measuring their respective standing postures with eyes open looking at a target in a room with either continuous or pulse lighting. There was no effect of changing the lighting conditions on the postural control of the subject without dyslexia. However, we found that the postural stability of the subject with dyslexia which was actually impaired during continuous light, but was greatly improved when a 80 Hz pulsed light frequency was used. Importantly, the excursions of the surface area of the center of pressure on the force platform were reduced by a factor of 2.3.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72992535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-02-25DOI: 10.31390/gradschool_theses.4788
N. Bhusal
Single Photon Emission Computed Tomography (SPECT) is a non-invasive imaging modality, frequently used in myocardial perfusion imaging. The biggest challenges facing the majority of clinical SPECT systems are low sensitivity, poor resolution, and the relatively high radiation dose to the patient. New generation systems (GE Discovery, DSPECT) dedicated to cardiac imaging improve sensitivity by a factor of 5-8. The purpose of this work is to investigate a new gamma camera design with 21 hemi-ellipsoid detectors each with a pinhole collimator for Cardiac SPECT for further improvement in sensitivity, resolution, imaging time, and radiation dose. To evaluate the resolution of our hemi-ellipsoid system, GATE Monte-Carlo simulations were performed on point-sources, rod-sources, and NCAT phantoms. The purpose of point-source simulation is to obtain operating pinhole diameter by comparing the average FWHM (Full width half-maximum) of flat-detector system with curved hemi-ellipsoid detector system. The operating pinhole diameter for the curved hemi-ellipsoid detector was found to be 8.68mm. System resolution is evaluated using reconstructed rod-sources equally spaced within the region of interest. The results were compared with results of GE discovery system available in the literature. The system performance was also evaluated using the mathematical anthropomorphic NCAT (NURBSbased Cardiac Torso) phantom with a full (clinical) dose acquisition (25mCi) for 2 mins and an ultra-low-dose acquisition of 3mCi for 5.44mins.
{"title":"Third Generation Gamma Camera SPECT System","authors":"N. Bhusal","doi":"10.31390/gradschool_theses.4788","DOIUrl":"https://doi.org/10.31390/gradschool_theses.4788","url":null,"abstract":"Single Photon Emission Computed Tomography (SPECT) is a non-invasive imaging modality, frequently used in myocardial perfusion imaging. The biggest challenges facing the majority of clinical SPECT systems are low sensitivity, poor resolution, and the relatively high radiation dose to the patient. New generation systems (GE Discovery, DSPECT) dedicated to cardiac imaging improve sensitivity by a factor of 5-8. The purpose of this work is to investigate a new gamma camera design with 21 hemi-ellipsoid detectors each with a pinhole collimator for Cardiac SPECT for further improvement in sensitivity, resolution, imaging time, and radiation dose. To evaluate the resolution of our hemi-ellipsoid system, GATE Monte-Carlo simulations were performed on point-sources, rod-sources, and NCAT phantoms. The purpose of point-source simulation is to obtain operating pinhole diameter by comparing the average FWHM (Full width half-maximum) of flat-detector system with curved hemi-ellipsoid detector system. The operating pinhole diameter for the curved hemi-ellipsoid detector was found to be 8.68mm. System resolution is evaluated using reconstructed rod-sources equally spaced within the region of interest. The results were compared with results of GE discovery system available in the literature. The system performance was also evaluated using the mathematical anthropomorphic NCAT (NURBSbased Cardiac Torso) phantom with a full (clinical) dose acquisition (25mCi) for 2 mins and an ultra-low-dose acquisition of 3mCi for 5.44mins.","PeriodicalId":8462,"journal":{"name":"arXiv: Medical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80268106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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