The Circular Electron-Positron Collider (CEPC) can also work as a powerful and excellent synchrotron light source, which can generate high-quality synchrotron radiation. This synchrotron radiation has potential advantages in the medical field, with a broad spectrum, with energies ranging from visible light to x-rays used in conventional radiotherapy, up to several MeV. FLASH radiotherapy is one of the most advanced radiotherapy modalities. It is a radiotherapy method that uses ultra-high dose rate irradiation to achieve the treatment dose in an instant; the ultra-high dose rate used is generally greater than 40 Gy/s, and this type of radiotherapy can protect normal tissues well. In this paper, the treatment effect of CEPC synchrotron radiation for FLASH radiotherapy was evaluated by simulation. First, Geant4 simulation was used to build a synchrotron radiation radiotherapy beamline station, and then the dose rate that CEPC can produce was calculated. Then, a physicochemical model of radiotherapy response kinetics was established, and a large number of radiotherapy experimental data were comprehensively used to fit and determine the functional relationship between the treatment effect, dose rate and dose. Finally, the macroscopic treatment effect of FLASH radiotherapy was predicted using CEPC synchrotron radiation light through the dose rate and the above-mentioned functional relationship. The results show that CEPC synchrotron radiation beam is one of the best beams for FLASH radiotherapy.
{"title":"Prediction of the treatment effect of FLASH radiotherapy with Circular Electron-Positron Collider (CEPC) synchrotron radiation","authors":"Junyu Zhang, Xiangyu Wu, Pengyuan Qi, Jike Wang","doi":"arxiv-2407.15217","DOIUrl":"https://doi.org/arxiv-2407.15217","url":null,"abstract":"The Circular Electron-Positron Collider (CEPC) can also work as a powerful\u0000and excellent synchrotron light source, which can generate high-quality\u0000synchrotron radiation. This synchrotron radiation has potential advantages in\u0000the medical field, with a broad spectrum, with energies ranging from visible\u0000light to x-rays used in conventional radiotherapy, up to several MeV. FLASH\u0000radiotherapy is one of the most advanced radiotherapy modalities. It is a\u0000radiotherapy method that uses ultra-high dose rate irradiation to achieve the\u0000treatment dose in an instant; the ultra-high dose rate used is generally\u0000greater than 40 Gy/s, and this type of radiotherapy can protect normal tissues\u0000well. In this paper, the treatment effect of CEPC synchrotron radiation for\u0000FLASH radiotherapy was evaluated by simulation. First, Geant4 simulation was\u0000used to build a synchrotron radiation radiotherapy beamline station, and then\u0000the dose rate that CEPC can produce was calculated. Then, a physicochemical\u0000model of radiotherapy response kinetics was established, and a large number of\u0000radiotherapy experimental data were comprehensively used to fit and determine\u0000the functional relationship between the treatment effect, dose rate and dose.\u0000Finally, the macroscopic treatment effect of FLASH radiotherapy was predicted\u0000using CEPC synchrotron radiation light through the dose rate and the\u0000above-mentioned functional relationship. The results show that CEPC synchrotron\u0000radiation beam is one of the best beams for FLASH radiotherapy.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141774422","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}
Steady blood flow, or Poiseuille flow, through compressed or defective blood vessels is a critical issue in hemodynamics, particularly in cardiovascular studies. This research explores a tube with a bipolar cross-section, simulating the geometry of a bicuspid aortic valve (BAV) during an oval systolic opening. The BAV, typically featuring two cusps instead of the usual three found in normal tricuspid configurations, introduces unique hemodynamic challenges. As the most prevalent congenital heart defect, BAV increases the risk of aortic dilation and dissection. A bipolar cross-sectional analysis provides a more accurate geometric approximation for modeling flow through these atypical valve shapes, crucial for understanding the specific fluid dynamics associated with BAV. We derived an exact solution for the governing equations of Poiseuille flow within a bipolar cross-sectional tube, including velocity field, flow rate, and wall shear stress (WSS). The velocity profiles for BAV show remarkable agreement with previous studies using coherent multi-scale simulations, consistently demonstrating a jet-like flow structure absent in tricuspid aortic valve (TAV) scenarios. Analysis reveals that at the center of the entrance, BAV blood flow velocity is significantly higher than TAV but decreases more rapidly towards the vessel wall, creating a steeper vertical velocity gradient and resulting in higher WSS for BAV. Additionally, the WSS, inversely proportional to sin({xi}*), where {xi}* represents the bipolar coordinate at the wall boundary, exceeds that found in a circular cylindrical tube with an equivalent diameter. In cases of aortic valve stenosis, where {xi}* approaches {pi}, the WSS increases rapidly. This elevated WSS, commonly observed in BAV patients, may detrimentally impact the aortic wall in these structurally abnormal valves, particularly within the ascending aorta.
{"title":"Poiseuille Flow in Tubes of Bipolar Cross Sections: An exact hemodynamic analysis for potential mechanisms of aortopathy in bicuspid aortic valve","authors":"Doyeol AhnDavid","doi":"arxiv-2407.15035","DOIUrl":"https://doi.org/arxiv-2407.15035","url":null,"abstract":"Steady blood flow, or Poiseuille flow, through compressed or defective blood\u0000vessels is a critical issue in hemodynamics, particularly in cardiovascular\u0000studies. This research explores a tube with a bipolar cross-section, simulating\u0000the geometry of a bicuspid aortic valve (BAV) during an oval systolic opening.\u0000The BAV, typically featuring two cusps instead of the usual three found in\u0000normal tricuspid configurations, introduces unique hemodynamic challenges. As\u0000the most prevalent congenital heart defect, BAV increases the risk of aortic\u0000dilation and dissection. A bipolar cross-sectional analysis provides a more\u0000accurate geometric approximation for modeling flow through these atypical valve\u0000shapes, crucial for understanding the specific fluid dynamics associated with\u0000BAV. We derived an exact solution for the governing equations of Poiseuille\u0000flow within a bipolar cross-sectional tube, including velocity field, flow\u0000rate, and wall shear stress (WSS). The velocity profiles for BAV show\u0000remarkable agreement with previous studies using coherent multi-scale\u0000simulations, consistently demonstrating a jet-like flow structure absent in\u0000tricuspid aortic valve (TAV) scenarios. Analysis reveals that at the center of\u0000the entrance, BAV blood flow velocity is significantly higher than TAV but\u0000decreases more rapidly towards the vessel wall, creating a steeper vertical\u0000velocity gradient and resulting in higher WSS for BAV. Additionally, the WSS,\u0000inversely proportional to sin({xi}*), where {xi}* represents the bipolar\u0000coordinate at the wall boundary, exceeds that found in a circular cylindrical\u0000tube with an equivalent diameter. In cases of aortic valve stenosis, where\u0000{xi}* approaches {pi}, the WSS increases rapidly. This elevated WSS, commonly\u0000observed in BAV patients, may detrimentally impact the aortic wall in these\u0000structurally abnormal valves, particularly within the ascending aorta.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141774191","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}
In radiation oncology, inter-fractional dosimetry is often performed with luminescent dosimeters to verify the accurate delivery of a plan and ensure patient safety. Optically stimulated luminescent detectors (OSLDs) are the most commonly used detector type which offers good dose linearity and accuracy in the megavoltage energy range. Freiberg Instruments offer a dosimetry system under the brand name myOLSchip which consists of a BeO OSL dosimeter, reader, and eraser. A Varian Truebeam was used to characterize the detectors and calibrate their response in order to perform in-situ dosimetry during treatment. The OSLDs were tested with both photon and electron beams from 6-15 MV and 6-20 MV respectively. The dose signal to dose conversion in this investigation follows the recommendations of TG-191 in developing a dose response curve and creating a batch calibration factor for each dosimeter. The repeatability of this system is also investigated following successive erasing and re-irradiation cycles. The results of this data have been compared to the stated accuracy and precision of the BeO detectors by the manufacturer and shown to have good dose linearity and repeatability across multiple exposures and erasure cycles.
{"title":"Clinical Validation of myOSLchip system for Radiotherapy Dosimetry","authors":"H. Davis, J. Siebers, K. Wijesooriya, M. Mistro","doi":"arxiv-2407.15246","DOIUrl":"https://doi.org/arxiv-2407.15246","url":null,"abstract":"In radiation oncology, inter-fractional dosimetry is often performed with\u0000luminescent dosimeters to verify the accurate delivery of a plan and ensure\u0000patient safety. Optically stimulated luminescent detectors (OSLDs) are the most\u0000commonly used detector type which offers good dose linearity and accuracy in\u0000the megavoltage energy range. Freiberg Instruments offer a dosimetry system\u0000under the brand name myOLSchip which consists of a BeO OSL dosimeter, reader,\u0000and eraser. A Varian Truebeam was used to characterize the detectors and\u0000calibrate their response in order to perform in-situ dosimetry during\u0000treatment. The OSLDs were tested with both photon and electron beams from 6-15\u0000MV and 6-20 MV respectively. The dose signal to dose conversion in this\u0000investigation follows the recommendations of TG-191 in developing a dose\u0000response curve and creating a batch calibration factor for each dosimeter. The\u0000repeatability of this system is also investigated following successive erasing\u0000and re-irradiation cycles. The results of this data have been compared to the\u0000stated accuracy and precision of the BeO detectors by the manufacturer and\u0000shown to have good dose linearity and repeatability across multiple exposures\u0000and erasure cycles.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141774416","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}
Tam Atkins, Navid Freidoonimehr, John Beltrame, Christopher Zeitz, Maziar Arjomandi
The relationship between measures of stenosis and microvascular resistance is of importance due to medical decisions being based on these values. This research investigates the impact of varying microvascular resistance on fractional flow reserve (FFR) and hyperaemic stenosis resistance (hSR). Microvascular resistance is classified using hyperaemic microvascular resistance (hMR). Additionally, hMR using the upstream pressure value (hMRPa) has also been calculated and is compared to hMR measured conventionally. Tests were conducted at three different degrees of stenosis (quantified by percent area) in a coronary flow circuit with varying downstream resistance to simulate the microvasculature. Pressure and flow values are recorded across the stenosed section, allowing for calculation of the diagnostic indexes. Results indicate that for a constant degree of stenosis, FFR would increase with increasing microvascular resistance while hSR would remain almost constant. hMRPa was found to approach hMR as the stenosis severity decreased, and the pressure gradient decreased. In the results shown here, with sufficiently high downstream resistance, an 84% stenosis could produce an FFR value over 0.8. This result suggests that there is the potential for misdiagnosis of the severity of stenosis when combined with elevated microvascular resistance. Consequently, decisions on the clinical significance of a stenosis, classified by FFR, need to consider the effect of the microvascular resistance.
{"title":"The impact of the microvascular resistance on the measures of stenosis severity","authors":"Tam Atkins, Navid Freidoonimehr, John Beltrame, Christopher Zeitz, Maziar Arjomandi","doi":"arxiv-2407.14005","DOIUrl":"https://doi.org/arxiv-2407.14005","url":null,"abstract":"The relationship between measures of stenosis and microvascular resistance is\u0000of importance due to medical decisions being based on these values. This\u0000research investigates the impact of varying microvascular resistance on\u0000fractional flow reserve (FFR) and hyperaemic stenosis resistance (hSR).\u0000Microvascular resistance is classified using hyperaemic microvascular\u0000resistance (hMR). Additionally, hMR using the upstream pressure value (hMRPa)\u0000has also been calculated and is compared to hMR measured conventionally. Tests\u0000were conducted at three different degrees of stenosis (quantified by percent\u0000area) in a coronary flow circuit with varying downstream resistance to simulate\u0000the microvasculature. Pressure and flow values are recorded across the stenosed\u0000section, allowing for calculation of the diagnostic indexes. Results indicate\u0000that for a constant degree of stenosis, FFR would increase with increasing\u0000microvascular resistance while hSR would remain almost constant. hMRPa was\u0000found to approach hMR as the stenosis severity decreased, and the pressure\u0000gradient decreased. In the results shown here, with sufficiently high\u0000downstream resistance, an 84% stenosis could produce an FFR value over 0.8.\u0000This result suggests that there is the potential for misdiagnosis of the\u0000severity of stenosis when combined with elevated microvascular resistance.\u0000Consequently, decisions on the clinical significance of a stenosis, classified\u0000by FFR, need to consider the effect of the microvascular resistance.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738558","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}
The field of bio-inspired soft grippers has emerged as a transformative area of research with profound implications for biomedical applications. This book chapter provides a comprehensive overview of the principles, developments, challenges, and prospects of soft grippers that draw inspiration from biological systems. Bio-inspired soft grippers have gained prominence due to their unique characteristics, including compliance, adaptability, and biocompatibility. They have revolutionized the way we approach biomedical tasks, offering safer interactions with delicate tissues and enabling complex operations that were once inconceivable with rigid tools. The chapter delves into the fundamental importance of soft grippers in biomedical contexts. It outlines their significance in surgeries, diagnostics, tissue engineering, and various medical interventions. Soft grippers have the capacity to mimic the intricate movements of biological organisms, facilitating minimally invasive procedures and enhancing patient outcomes. A historical perspective traces the evolution of soft grippers in biomedical research, highlighting key milestones and breakthroughs. From early attempts to emulate the dexterity of octopus tentacles to the latest advancements in soft lithography and biomaterials, the journey has been marked by ingenuity and collaboration across multiple disciplines. Motivations for adopting soft grippers in biomedical applications are explored, emphasizing their ability to reduce invasiveness, increase precision, and provide adaptability to complex anatomical structures. The requirements and challenges in designing grippers fit for medical contexts are outlined, encompassing biocompatibility, sterilization, control, and integration.
{"title":"Bio-inspired Soft Grippers for Biological Applications","authors":"Rekha Raja, Ali Leylavi Shoushtari","doi":"arxiv-2407.14324","DOIUrl":"https://doi.org/arxiv-2407.14324","url":null,"abstract":"The field of bio-inspired soft grippers has emerged as a transformative area\u0000of research with profound implications for biomedical applications. This book\u0000chapter provides a comprehensive overview of the principles, developments,\u0000challenges, and prospects of soft grippers that draw inspiration from\u0000biological systems. Bio-inspired soft grippers have gained prominence due to\u0000their unique characteristics, including compliance, adaptability, and\u0000biocompatibility. They have revolutionized the way we approach biomedical\u0000tasks, offering safer interactions with delicate tissues and enabling complex\u0000operations that were once inconceivable with rigid tools. The chapter delves\u0000into the fundamental importance of soft grippers in biomedical contexts. It\u0000outlines their significance in surgeries, diagnostics, tissue engineering, and\u0000various medical interventions. Soft grippers have the capacity to mimic the\u0000intricate movements of biological organisms, facilitating minimally invasive\u0000procedures and enhancing patient outcomes. A historical perspective traces the\u0000evolution of soft grippers in biomedical research, highlighting key milestones\u0000and breakthroughs. From early attempts to emulate the dexterity of octopus\u0000tentacles to the latest advancements in soft lithography and biomaterials, the\u0000journey has been marked by ingenuity and collaboration across multiple\u0000disciplines. Motivations for adopting soft grippers in biomedical applications\u0000are explored, emphasizing their ability to reduce invasiveness, increase\u0000precision, and provide adaptability to complex anatomical structures. The\u0000requirements and challenges in designing grippers fit for medical contexts are\u0000outlined, encompassing biocompatibility, sterilization, control, and\u0000integration.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"81 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738559","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}
Maxime CalkaTIMC-BIOMÉCA, Pascal PerrierGIPSA-PPC, GIPSA-PCMD, Michel RochetteTIMC-BIOMÉCA, Yohan PayanTIMC-BIOMÉCA
The tongue is a crucial organ for performing basic biological functions, such as chewing, swallowing and phonation. Understanding how it behaves, its motor control and involvement in the execution of these different tasks is therefore an important issue for the management and therapeutic treatment of pathologies relating to these essential functions so that quality of life can be preserved. This chapter focuses on the biomechanical modeling of this organ, as one of the key steps towards this understanding. Such a modeling will be an important tool to predict and control the functional impact of lingual surgery in the field of computer-assisted medical interventions.
{"title":"Biomechanical modeling of the human tongue","authors":"Maxime CalkaTIMC-BIOMÉCA, Pascal PerrierGIPSA-PPC, GIPSA-PCMD, Michel RochetteTIMC-BIOMÉCA, Yohan PayanTIMC-BIOMÉCA","doi":"arxiv-2407.13259","DOIUrl":"https://doi.org/arxiv-2407.13259","url":null,"abstract":"The tongue is a crucial organ for performing basic biological functions, such\u0000as chewing, swallowing and phonation. Understanding how it behaves, its motor\u0000control and involvement in the execution of these different tasks is therefore\u0000an important issue for the management and therapeutic treatment of pathologies\u0000relating to these essential functions so that quality of life can be preserved.\u0000This chapter focuses on the biomechanical modeling of this organ, as one of the\u0000key steps towards this understanding. Such a modeling will be an important tool\u0000to predict and control the functional impact of lingual surgery in the field of\u0000computer-assisted medical interventions.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738560","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}
Victor Steiner, Aviv Malki, Tzafrir Ben Yehuda, Murray Moinester
This study aims to determine the protective concrete shielding thickness requirements in concrete walls of positron emission tomography (PET) and computed tomography (CT) facilities. Consider the most commonly used PET radiotracer, the radioisotope F18, which emits two back-to-back 511 keV photons. Photon transmission measurements were carried out through an Israeli B30 strength ordinary concrete wall (3 meter high, 20 cm thick) using photons emitted from an F18 source into a cone having a 24 degree FWHM dose aperture angle. The source, positioned 3 meters from the wall, yielded a 0.64 m beam disk radius on the wall. Our measurement setup roughly simulates radiation emitted from a patient injected with F18. Dose rates were measured by an Atomtex Radiation Survey Meter, positioned at distances 0.05 to 3 meters from the far side of the wall. For a wide-beam, thick-shielding setup, there is a buildup effect, as photons having reduced energies may reach the detector from Compton scattering in the wall. In concrete, the Compton scattering cross section accounts for 99% of the total interaction cross section. The buildup factor B accounts for the increase of observed radiation transmission through shielding material due to scattered radiation. We measured a narrow-beam transmission coefficient T=3.0 +- 0.9 %, consistent with the theoretical value 2% calculated from NIST photon attenuation data without buildup. We measured a wide-beam transmission coefficient of 8.6 +- 1.8%; in good agreement with two available wide-beam Monte Carlo (MC) simulations. We confirm by experiment, complementing MC simulations, that for a 20 cm thick concrete wall, due to buildup, about four times thicker shielding is required to achieve a designated level of radiation protection, compared to that calculated using narrow-beam, thin-shielding transmission coefficients.
{"title":"Concrete Shielding Requirements for PET Facilities","authors":"Victor Steiner, Aviv Malki, Tzafrir Ben Yehuda, Murray Moinester","doi":"arxiv-2407.12991","DOIUrl":"https://doi.org/arxiv-2407.12991","url":null,"abstract":"This study aims to determine the protective concrete shielding thickness\u0000requirements in concrete walls of positron emission tomography (PET) and\u0000computed tomography (CT) facilities. Consider the most commonly used PET\u0000radiotracer, the radioisotope F18, which emits two back-to-back 511 keV\u0000photons. Photon transmission measurements were carried out through an Israeli\u0000B30 strength ordinary concrete wall (3 meter high, 20 cm thick) using photons\u0000emitted from an F18 source into a cone having a 24 degree FWHM dose aperture\u0000angle. The source, positioned 3 meters from the wall, yielded a 0.64 m beam\u0000disk radius on the wall. Our measurement setup roughly simulates radiation\u0000emitted from a patient injected with F18. Dose rates were measured by an\u0000Atomtex Radiation Survey Meter, positioned at distances 0.05 to 3 meters from\u0000the far side of the wall. For a wide-beam, thick-shielding setup, there is a\u0000buildup effect, as photons having reduced energies may reach the detector from\u0000Compton scattering in the wall. In concrete, the Compton scattering cross\u0000section accounts for 99% of the total interaction cross section. The buildup\u0000factor B accounts for the increase of observed radiation transmission through\u0000shielding material due to scattered radiation. We measured a narrow-beam\u0000transmission coefficient T=3.0 +- 0.9 %, consistent with the theoretical value\u00002% calculated from NIST photon attenuation data without buildup. We measured a\u0000wide-beam transmission coefficient of 8.6 +- 1.8%; in good agreement with two\u0000available wide-beam Monte Carlo (MC) simulations. We confirm by experiment,\u0000complementing MC simulations, that for a 20 cm thick concrete wall, due to\u0000buildup, about four times thicker shielding is required to achieve a designated\u0000level of radiation protection, compared to that calculated using narrow-beam,\u0000thin-shielding transmission coefficients.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"245 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738561","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}
Background: X-ray dark-field imaging (XDFI) has been explored to provide superior performance over the conventional X-ray imaging for the diagnosis of many pathologic conditions. A simulation tool to reliably predict clinical XDFI images at a human scale, however, is currently missing. Purpose: In this paper, we demonstrate XDFI simulation at a human scale for the first time to the best of our knowledge. Using the developed simulation tool, we demonstrate the strengths and limitations of XDFI for the diagnosis of emphysema, fibrosis, atelectasis, edema, and pneumonia. Methods: We augment the XCAT phantom with Voronoi grids to simulate alveolar substructure, responsible for the dark-field signal from lungs, assign material properties to each tissue type, and simulate X-ray wave propagation through the augmented XCAT phantom using a multi-layer wave-optics propagation. Altering the density and thickness of the Voronoi grids as well as the material properties, we simulate XDFI images of normal and diseased lungs. Results: Our simulation framework can generate realistic XDFI images of a human chest with normal or diseased lungs. The simulation confirms that the normal, emphysematous, and fibrotic lungs show clearly distinct dark-field signals. It also shows that alveolar fluid accumulation in pneumonia, wall thickening in interstitial edema, and deflation in atelectasis result in a similar reduction in dark-field signal. Conclusions: It is feasible to augment XCAT with pulmonary substructure and generate realistic XDFI images using multi-layer wave optics. By providing the most realistic XDFI images of lung pathologies, the developed simulation framework will enable in-silico clinical trials and the optimization of both hardware and software for XDFI.
{"title":"Realistic wave-optics simulation of X-ray dark-field imaging at a human scale","authors":"Yongjin Sung, Brandon Nelson, Rajiv Gupta","doi":"arxiv-2407.12664","DOIUrl":"https://doi.org/arxiv-2407.12664","url":null,"abstract":"Background: X-ray dark-field imaging (XDFI) has been explored to provide\u0000superior performance over the conventional X-ray imaging for the diagnosis of\u0000many pathologic conditions. A simulation tool to reliably predict clinical XDFI\u0000images at a human scale, however, is currently missing. Purpose: In this paper,\u0000we demonstrate XDFI simulation at a human scale for the first time to the best\u0000of our knowledge. Using the developed simulation tool, we demonstrate the\u0000strengths and limitations of XDFI for the diagnosis of emphysema, fibrosis,\u0000atelectasis, edema, and pneumonia. Methods: We augment the XCAT phantom with Voronoi grids to simulate alveolar\u0000substructure, responsible for the dark-field signal from lungs, assign material\u0000properties to each tissue type, and simulate X-ray wave propagation through the\u0000augmented XCAT phantom using a multi-layer wave-optics propagation. Altering\u0000the density and thickness of the Voronoi grids as well as the material\u0000properties, we simulate XDFI images of normal and diseased lungs. Results: Our simulation framework can generate realistic XDFI images of a\u0000human chest with normal or diseased lungs. The simulation confirms that the\u0000normal, emphysematous, and fibrotic lungs show clearly distinct dark-field\u0000signals. It also shows that alveolar fluid accumulation in pneumonia, wall\u0000thickening in interstitial edema, and deflation in atelectasis result in a\u0000similar reduction in dark-field signal. Conclusions: It is feasible to augment XCAT with pulmonary substructure and\u0000generate realistic XDFI images using multi-layer wave optics. By providing the\u0000most realistic XDFI images of lung pathologies, the developed simulation\u0000framework will enable in-silico clinical trials and the optimization of both\u0000hardware and software for XDFI.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738562","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}
Alejandro Lopez-Montes, Thomas McSkimming, Anthony Skeats, Chris Delnooz, Brian Gonzales, Wojciech Zbijewski, Alejandro Sisniega
Diffusion Posterior Sampling (DPS) can be used in Computed Tomography (CT) reconstruction by leveraging diffusion-based generative models for unconditional image synthesis while matching the observations (data) of a CT scan. Of particular interest is its application in scenarios involving sparse or limited angular sampling, where conventional reconstruction algorithms are often insufficient. We developed a DPS algorithm for 3D reconstruction from a stationary CT (sCT) portable brain stroke imaging unit based on a multi-x-ray source array (MXA) of 31 x-ray tubes and a curved area detector. In this configuration, conventional reconstruction e.g., Penalized Weighted Least Squares (PWLS) with a Huber edge-preserving penalty, suffers from severe directional undersampling artifacts. The proposed DPS integrates a two-dimensional diffusion model, acting on image slices, coupled to sCT data consistency and volumetric regularization terms to enable 3D reconstruction robust to noise and incomplete sampling. To reduce the computational burden of DPS, stochastic contraction with PWLS initialization was used to decrease the number of diffusion steps. The validation studies involved simulations of anthropomorphic brain phantoms with synthetic bleeds and experimental data from an sCT bench. In simulations, DPS achieved ~130% reduction of directional artifacts compared to PWLS and 30% better recovery of lesion shape (DICE coefficient). Benchtop studies demonstrated enhanced visualization of brain features in a Kyoto Kagaku head phantom. The proposed DPS achieved improved visualization of intracranial hemorrhage and brain morphology compared to conventional model-based reconstruction for the highly undersampled sCT system.
{"title":"Stationary CT Imaging of Intracranial Hemorrhage with Diffusion Posterior Sampling Reconstruction","authors":"Alejandro Lopez-Montes, Thomas McSkimming, Anthony Skeats, Chris Delnooz, Brian Gonzales, Wojciech Zbijewski, Alejandro Sisniega","doi":"arxiv-2407.11196","DOIUrl":"https://doi.org/arxiv-2407.11196","url":null,"abstract":"Diffusion Posterior Sampling (DPS) can be used in Computed Tomography (CT)\u0000reconstruction by leveraging diffusion-based generative models for\u0000unconditional image synthesis while matching the observations (data) of a CT\u0000scan. Of particular interest is its application in scenarios involving sparse\u0000or limited angular sampling, where conventional reconstruction algorithms are\u0000often insufficient. We developed a DPS algorithm for 3D reconstruction from a\u0000stationary CT (sCT) portable brain stroke imaging unit based on a multi-x-ray\u0000source array (MXA) of 31 x-ray tubes and a curved area detector. In this\u0000configuration, conventional reconstruction e.g., Penalized Weighted Least\u0000Squares (PWLS) with a Huber edge-preserving penalty, suffers from severe\u0000directional undersampling artifacts. The proposed DPS integrates a\u0000two-dimensional diffusion model, acting on image slices, coupled to sCT data\u0000consistency and volumetric regularization terms to enable 3D reconstruction\u0000robust to noise and incomplete sampling. To reduce the computational burden of\u0000DPS, stochastic contraction with PWLS initialization was used to decrease the\u0000number of diffusion steps. The validation studies involved simulations of\u0000anthropomorphic brain phantoms with synthetic bleeds and experimental data from\u0000an sCT bench. In simulations, DPS achieved ~130% reduction of directional\u0000artifacts compared to PWLS and 30% better recovery of lesion shape (DICE\u0000coefficient). Benchtop studies demonstrated enhanced visualization of brain\u0000features in a Kyoto Kagaku head phantom. The proposed DPS achieved improved\u0000visualization of intracranial hemorrhage and brain morphology compared to\u0000conventional model-based reconstruction for the highly undersampled sCT system.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141722460","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}
Savva SavenkovInstitute for Nuclear Research of the Russian Academy of Sciences, Alexandr SvetlichnyiInstitute for Nuclear Research of the Russian Academy of Sciences, Igor PshenichnovInstitute for Nuclear Research of the Russian Academy of Sciences
Single minibeams of protons, $^{4}$He, $^{12}$C and $^{16}$O in water were modeled with Geant4, and their dose distributions were parameterized with double-Gauss-Rutherford (DGR) functions. Dose distributions from arrays of 16 parallel minibeams centered on a rectangular or hexagonal grid were constructed from the parameterized minibeam profiles to simulate the lateral convergence of the minibeams resulting in a homogeneous dose field in the target tumor volume. Peak-to-valley dose ratios (PVDR) and dose-volume histograms (DVH) were calculated for the parameterized dose distributions and compared with those obtained directly from Geant4 modeling of minibeam arrays. The similarity of the results obtained by these two methods suggests that the fast calculation of dose profiles of minibeam arrays based on the DGR parameterizations proposed for the first time in this work can replace the time-consuming MC modeling in future preclinical studies and also in the development of treatment planning systems for minibeam therapy.
{"title":"Parameterization of dose profiles of therapeutic minibeams of protons, $^{4}$He, $^{12}$C, and $^{16}$O","authors":"Savva SavenkovInstitute for Nuclear Research of the Russian Academy of Sciences, Alexandr SvetlichnyiInstitute for Nuclear Research of the Russian Academy of Sciences, Igor PshenichnovInstitute for Nuclear Research of the Russian Academy of Sciences","doi":"arxiv-2407.09851","DOIUrl":"https://doi.org/arxiv-2407.09851","url":null,"abstract":"Single minibeams of protons, $^{4}$He, $^{12}$C and $^{16}$O in water were\u0000modeled with Geant4, and their dose distributions were parameterized with\u0000double-Gauss-Rutherford (DGR) functions. Dose distributions from arrays of 16\u0000parallel minibeams centered on a rectangular or hexagonal grid were constructed\u0000from the parameterized minibeam profiles to simulate the lateral convergence of\u0000the minibeams resulting in a homogeneous dose field in the target tumor volume.\u0000Peak-to-valley dose ratios (PVDR) and dose-volume histograms (DVH) were\u0000calculated for the parameterized dose distributions and compared with those\u0000obtained directly from Geant4 modeling of minibeam arrays. The similarity of\u0000the results obtained by these two methods suggests that the fast calculation of\u0000dose profiles of minibeam arrays based on the DGR parameterizations proposed\u0000for the first time in this work can replace the time-consuming MC modeling in\u0000future preclinical studies and also in the development of treatment planning\u0000systems for minibeam therapy.","PeriodicalId":501378,"journal":{"name":"arXiv - PHYS - Medical Physics","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141721239","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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