Purpose: Modern radiotherapy delivers radiation doses to targets within a few minutes using intricate multiple-beam segments determined with multi-leaf collimators (MLC). Therefore, we propose a scintillator-based dosimetry system capable of assessing the dosimetric and mechanical performance of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in real time. Methods: The dosimeter was equipped with a scintillator plate and two digital cameras. The dose distribution was generated by applying deep learning-based signal processing to correct the intrinsic characteristics of the camera sensor and a tomographic image reconstruction technique to rectify the geometric distortion of the recorded video. Dosimetric evaluations were performed using a gamma analysis against a two-dimensional array and radiochromic film measurements for 20 clinical cases. The average difference in the MLC position measurements and machine log files was tested for the applicability of the mechanical quality assurance (QA) of MLCs. Results: The agreement of the dose distribution in the IMRT and VMAT plans was clinically acceptable between the proposed system and conventional dosimeters. The average differences in the MLC positions for the IMRT/VMAT plans were 1.7010/2.8107 mm and 1.4722/2.7713 mm in banks A and B, respectively. Conclusions In this study, we developed an instantaneously interpretable real-time dosimeter for QA in a medical linear accelerator using a scintillator plate and digital cameras. The feasibility of the proposed system was investigated using dosimetric and mechanical evaluations in the IMRT and VMAT plans. The developed system has clinically acceptable accuracy in both the dosimetric and mechanical QAs of the IMRT and VMAT plans.

Purpose: Modern radiotherapy delivers radiation doses to targets within a few minutes using intricate multiple-beam segments determined with multi-leaf collimators (MLC). Therefore, we propose a scintillator-based dosimetry system capable of assessing the dosimetric and mechanical performance of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in real time. Methods: The dosimeter was equipped with a scintillator plate and two digital cameras. The dose distribution was generated by applying deep learning-based signal processing to correct the intrinsic characteristics of the camera sensor and a tomographic image reconstruction technique to rectify the geometric distortion of the recorded video. Dosimetric evaluations were performed using a gamma analysis against a two-dimensional array and radiochromic film measurements for 20 clinical cases. The average difference in the MLC position measurements and machine log files was tested for the applicability of the mechanical quality assurance (QA) of MLCs. Results: The agreement of the dose distribution in the IMRT and VMAT plans was clinically acceptable between the proposed system and conventional dosimeters. The average differences in the MLC positions for the IMRT/VMAT plans were 1.7010/2.8107 mm and 1.4722/2.7713 mm in banks A and B, respectively. Conclusions In this study, we developed an instantaneously interpretable real-time dosimeter for QA in a medical linear accelerator using a scintillator plate and digital cameras. The feasibility of the proposed system was investigated using dosimetric and mechanical evaluations in the IMRT and VMAT plans. The developed system has clinically acceptable accuracy in both the dosimetric and mechanical QAs of the IMRT and VMAT plans.

Purpose: Modern radiotherapy delivers radiation doses to targets within a few minutes using intricate multiple-beam segments determined with multi-leaf collimators (MLC). Therefore, we propose a scintillator-based dosimetry system capable of assessing the dosimetric and mechanical performance of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in real time. Methods: The dosimeter was equipped with a scintillator plate and two digital cameras. The dose distribution was generated by applying deep learning-based signal processing to correct the intrinsic characteristics of the camera sensor and a tomographic image reconstruction technique to rectify the geometric distortion of the recorded video. Dosimetric evaluations were performed using a gamma analysis against a two-dimensional array and radiochromic film measurements for 20 clinical cases. The average difference in the MLC position measurements and machine log files was tested for the applicability of the mechanical quality assurance (QA) of MLCs. Results: The agreement of the dose distribution in the IMRT and VMAT plans was clinically acceptable between the proposed system and conventional dosimeters. The average differences in the MLC positions for the IMRT/VMAT plans were 1.7010/2.8107 mm and 1.4722/2.7713 mm in banks A and B, respectively. Conclusions In this study, we developed an instantaneously interpretable real-time dosimeter for QA in a medical linear accelerator using a scintillator plate and digital cameras. The feasibility of the proposed system was investigated using dosimetric and mechanical evaluations in the IMRT and VMAT plans. The developed system has clinically acceptable accuracy in both the dosimetric and mechanical QAs of the IMRT and VMAT plans.

Purpose: Modern radiotherapy delivers radiation doses to targets within a few minutes using intricate multiple-beam segments determined with multi-leaf collimators (MLC). Therefore, we propose a scintillator-based dosimetry system capable of assessing the dosimetric and mechanical performance of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in real time. Methods: The dosimeter was equipped with a scintillator plate and two digital cameras. The dose distribution was generated by applying deep learning-based signal processing to correct the intrinsic characteristics of the camera sensor and a tomographic image reconstruction technique to rectify the geometric distortion of the recorded video. Dosimetric evaluations were performed using a gamma analysis against a two-dimensional array and radiochromic film measurements for 20 clinical cases. The average difference in the MLC position measurements and machine log files was tested for the applicability of the mechanical quality assurance (QA) of MLCs. Results: The agreement of the dose distribution in the IMRT and VMAT plans was clinically acceptable between the proposed system and conventional dosimeters. The average differences in the MLC positions for the IMRT/VMAT plans were 1.7010/2.8107 mm and 1.4722/2.7713 mm in banks A and B, respectively. Conclusions In this study, we developed an instantaneously interpretable real-time dosimeter for QA in a medical linear accelerator using a scintillator plate and digital cameras. The feasibility of the proposed system was investigated using dosimetric and mechanical evaluations in the IMRT and VMAT plans. The developed system has clinically acceptable accuracy in both the dosimetric and mechanical QAs of the IMRT and VMAT plans.

Purpose: Modern radiotherapy delivers radiation doses to targets within a few minutes using intricate multiple-beam segments determined with multi-leaf collimators (MLC). Therefore, we propose a scintillator-based dosimetry system capable of assessing the dosimetric and mechanical performance of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in real time. Methods: The dosimeter was equipped with a scintillator plate and two digital cameras. The dose distribution was generated by applying deep learning-based signal processing to correct the intrinsic characteristics of the camera sensor and a tomographic image reconstruction technique to rectify the geometric distortion of the recorded video. Dosimetric evaluations were performed using a gamma analysis against a two-dimensional array and radiochromic film measurements for 20 clinical cases. The average difference in the MLC position measurements and machine log files was tested for the applicability of the mechanical quality assurance (QA) of MLCs. Results: The agreement of the dose distribution in the IMRT and VMAT plans was clinically acceptable between the proposed system and conventional dosimeters. The average differences in the MLC positions for the IMRT/VMAT plans were 1.7010/2.8107 mm and 1.4722/2.7713 mm in banks A and B, respectively. Conclusions In this study, we developed an instantaneously interpretable real-time dosimeter for QA in a medical linear accelerator using a scintillator plate and digital cameras. The feasibility of the proposed system was investigated using dosimetric and mechanical evaluations in the IMRT and VMAT plans. The developed system has clinically acceptable accuracy in both the dosimetric and mechanical QAs of the IMRT and VMAT plans.

Purpose: High-dose radiotherapy (RT) for localized prostate cancer requires careful consideration of target position changes and adjacent organs-at-risk (OARs), such as the rectum and bladder. Therefore, daily monitoring of target position and OAR changes is crucial in minimizing interfractional dosimetric uncertainties. For efficient monitoring of the internal condition of patients, we assessed the feasibility of an auto-segmentation of OARs on the daily acquired images, such as megavoltage computed tomography (MVCT), via a commercial artificial intelligence (AI)-based solution in this study. Materials and Methods: We collected MVCT images weekly during the entire course of RT for 100 prostate cancer patients treated with the helical TomoTherapy system. Based on the manually contoured body outline, the bladder including prostate area, and rectal balloon regions for the 100 MVCT images, we trained the commercially available fully convolutional (FC)-DenseNet model and tested its auto-contouring performance. Results: Based on the optimally determined hyperparameters, the FC-DenseNet model successfully auto-contoured all regions of interest showing high dice similarity coefficient (DSC) over 0.8 and a small mean surface distance (MSD) within 1.43 mm in reference to the manually contoured data. With this well-trained AI model, we have efficiently monitored the patient's internal condition through six MVCT scans, analyzing DSC, MSD, centroid, and volume differences. Conclusion We have verified the feasibility of utilizing a commercial AI-based model for auto-segmentation with low-quality daily MVCT images. In the future, we will establish a fast and accurate auto-segmentation and internal organ monitoring system for efficiently determining the time for adaptive replanning.

BACKGROUND: The present study was done to elucidate the effects of acute normovolemic hemodilution (ANH) on intrapulmonary shunt (Qs/Qt) and systemic oxygen delivery balance during one lung ventilation (OLV). METHODS: To induce one lung ventilation, an atelectasis of the right lung was produced in anesthetized mongrel dogs. In 6 dogs with OLV, ANH was produced by sequential hemodilution with hydroxyethyl starch. ANH was divided into 3 stages (ANH0: no hemodilition, ANH1: first hemodilution, ANH2: second hemodilution). Qs/Qt was measured by using blood gas analysis. Various hemodynamic parameters, oxygen delivery, and consumption were measured or calculated indirectly. RESULTS: After hemodilution, hemoglobin levels at each stage were 9.9 +/- 1.3 g/dl (ANH0), 7.0 +/- 1.0 g/dl (ANH1), and 5.2 +/- 0.7 g/dl (ANH2). The Qs/Qt of ANH2 stage increased from 25.0 11.4% of ANH0 to 35.4 9.2% (P < 0.05). Cardiac output of ANH2 increased from 2.4 +/- 0.8 ml/min of ANH0 to 3.2 +/- 0.8 ml/min (P < 0.05). Pulmonary and systemic vascular resistance measurements in ANH2 were lower than those of ANH0 (P < 0.05). The changes in pH and carbon dioxide tension and mixed venous oxygen tension by ANH were not significant in comparison with ANH0 (P > 0.05). Global oxygen delivery was markedly decreased by hemodilution in OLV (P < 0.05), whereas global oxygen consumption was maintained. CONCLUSIONS: We conclude that global oxygen delivery balance is preserved by ANH in this study. However, extreme ANH has a deleterious effect on pulmonary gas exchange, possibly through the attenuation of hypoxic pulmonary vasoconstriction during one-lung ventilation. On the basis of this study, increased cardiac output generated by ANH might be the cause of inhibition or blunting of hypoxic pulmonary vasoconstriction.
Animals ; Blood Gas Analysis ; Carbon Dioxide ; Cardiac Output ; Dogs* ; Hemodilution* ; Hemodynamics ; Hydrogen-Ion Concentration ; Lung ; One-Lung Ventilation* ; Oxygen Consumption ; Oxygen* ; Pulmonary Atelectasis ; Pulmonary Gas Exchange ; Starch ; Vascular Resistance ; Vasoconstriction

BACKGROUND: As one of the etiologies of acute respiratory distress syndrome (ARDS), sepsis is one of the morbid causes of this cryptogenic malady. Even though many documents on the role of endotoxin (ETX) in the pathogenesis of ARDS have been issued, still the underlying mechanism associated with oxidative stress and activation of PLA2 has been a controversy controversial . In the present study, the role of phospholipase A2 (PLA2) in the neutrophilic respiratory burst(,) which is presumed to cause acute lung injury during sepsis(,) was probed. METHOD: In glutathione (-)depleted Sprague-Dawley rats, lung leak, infiltration of neutrophils, PLA2 activity and lipid peroxidation in the lung were measured after intratracheal instillation of endotoxin intratracheally (delete). In addition, gamma glutamyl transferase (GGT) activity and the amount of pulmonary surfactant were measured. Morphologically, changes of the changes in ultrastructure and cytochemical demonstration of oxidants were presented to confirm the neutrophilic oxidative stress and to elucidate the effects of the activation of PLA2 activation on the (delete) oxidative stress. RESULTS: Instillation of ETX to glutathione (-) depleted rats intensified lung leak and lipid peroxidation when compared with non-glutathione depleted rats treated with the endotoxin. Moreover, oxidative stress was confirmed by the assay of GGT and malondialdehyde. Functionally, the depletion of glutathione altered the secretion of pulmonary surfactant from alveolar type II cells. Ultrastructurally and cytochemically, oxidative stress was also confirmed after treatment of with ETX and diethylmaleate (DEM). CONCLUSION: The endotoxin-induced acute lung injury was mediated by oxidative stress(,) which in turn was provoked by the neutrophilic respiratory burst. The activation of PLA2 in the lung seems to play the a pivotal role in the oxidative stress of the lung.
Acute Lung Injury ; Animals ; Glutathione* ; Lipid Peroxidation ; Lung* ; Malondialdehyde ; Neutrophils ; Oxidants ; Oxidative Stress* ; Phospholipases A2 ; Pulmonary Surfactants ; Rats* ; Rats, Sprague-Dawley ; Respiratory Burst ; Respiratory Distress Syndrome, Adult ; Sepsis ; Transferases

BACKGROUND: As the clinical application of non-invasive shunt estimation to operation under one-lung ventilation has not been reported, this study was carried out to evaluate the validity and accuracy of the non-invasive shunt estimations in one-lung ventilation with hemodilution. METHODS: Following general anesthesia with enflurane 0.5 1 vol.% and 100% oxygen in ten Mongrel dogs (B.W. around 16 kg), tracheostomy and insertion of left-side endobronchial tube and one-lung ventilation were performed. Acute normovolemic hemodilution was produced by sequential hemodilution with hydroxyethyl starch. The intrapulmonary shunt (QS/QT) was calculated by the classic shunt equation, by the oxygen contents-based estimated shunt equation, and by oxygen tension-based estimations such as alveolar to arterial oxygen difference (P(A-a)O2), respiratory index (RI, P(A-a)O2/PaO2), arterial oxygen tension to alveolar oxygen ratio (PaO2/PAO2), and PaO2 to FiO2 ratio. To assess the quantitative accuracy of the estimated shunt, the data were divided arbitrarily into two groups on the basis of the mean arteriovenous oxygen content difference (C(a-v)O2) being 3.6 ml/dl or greater (group 1) and less than 3.6 ml/dl (group 2). Relationships to QS/QT were analyzed by simple linear regression. RESULTS: In 104 measurements, the correlation between QS/QT and non-invasive shunt were poor (r = 0.66 - 0.76). However, in group 1 (n = 45), the correlation between QS/QT and the estimated shunt were very good (r = 0.93) and good for P(A-a)O2 (r = 0.83), RI (r = 0.87), PaO2/PAO2 (r = - 0.84), and PaO2/FiO2 (r = - 0.85). In group 2 (n = 58), the correlation between QS/QT and non-invasive shunt were worse than in group 1. Group 2 had lower hematocrit (20.6% vs 26.7 %, P < 0.001), higher cardiac output, and lower pulmonary and systemic vascular resistance than group 1 (P < 0.05). The difference between the estimated shunt and the classic shunt in group 1 remained constant when the classic shunt was increased further. However, the difference in group 2 was enhanced by the increment of the classic shunt. CONCLUSIONS: We conclude that even if the non-invasive shunt estimation might be affected by hemoglobin and cardiac output, it is a viable method in mild hemodiluted patients with good cardiovascular reserve.
Anesthesia, General ; Animals ; Cardiac Output ; Dogs* ; Enflurane ; Hematocrit ; Hemodilution ; Humans ; Linear Models ; One-Lung Ventilation ; Oxygen ; Starch ; Tracheostomy ; Vascular Resistance

PURPOSE: To evaluate the MR imaging findings of intraosseous lipoma. MATERIALS AND METHODS: The MR imaging findings of 12 cases of intraosseous lipoma were retrospectively analyzed with regard to internal signal intensity, enhancement patterns, the presence of calcification and the status of the margin. The findings relating to these last two features were compared with those of plain films and CT. RESULTS: Six tumors were located in the calcaneus, three in the tibia, two in the ilium, and one in the carpal lunate. A fat component was clearly identified in all cases, but no lesion was purely fatty. Cyst formation was noted in four cases, and hyperintense portions different from the cystic area were seen on T2WI in ten. Contrast enhancement was observed in four patients, and although plain film and CT images revealed, in all cases, the presence of calcification, in two cases this was not demonstrated by MRI. In all cases, however, MRI showed well-defined tumoral margins. CONCLUSION: MRI clearly depicts fat and other components related to the involutional changes occurring in cases of intraosseous lipoma. The information these images provide is useful for the diagnosis and histologic classification of intraosseous lipoma.
Bone Neoplasms ; Calcaneus ; Classification ; Diagnosis ; Humans ; Ilium ; Lipoma* ; Magnetic Resonance Imaging* ; Retrospective Studies ; Tibia