1.Development of an Instantaneously Interpretable Real-Time Dosimeter System for Quality Assurance of a Medical Linear Accelerator
Dongyeon LEE ; Sung Jin KIM ; Wonjoong CHEON ; Hyosung CHO ; Youngyih HAN
Progress in Medical Physics 2024;35(4):178-204
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.
2.Development of an Instantaneously Interpretable Real-Time Dosimeter System for Quality Assurance of a Medical Linear Accelerator
Dongyeon LEE ; Sung Jin KIM ; Wonjoong CHEON ; Hyosung CHO ; Youngyih HAN
Progress in Medical Physics 2024;35(4):178-204
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.
3.Development of an Instantaneously Interpretable Real-Time Dosimeter System for Quality Assurance of a Medical Linear Accelerator
Dongyeon LEE ; Sung Jin KIM ; Wonjoong CHEON ; Hyosung CHO ; Youngyih HAN
Progress in Medical Physics 2024;35(4):178-204
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.
4.Development of an Instantaneously Interpretable Real-Time Dosimeter System for Quality Assurance of a Medical Linear Accelerator
Dongyeon LEE ; Sung Jin KIM ; Wonjoong CHEON ; Hyosung CHO ; Youngyih HAN
Progress in Medical Physics 2024;35(4):178-204
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.
5.Development of an Instantaneously Interpretable Real-Time Dosimeter System for Quality Assurance of a Medical Linear Accelerator
Dongyeon LEE ; Sung Jin KIM ; Wonjoong CHEON ; Hyosung CHO ; Youngyih HAN
Progress in Medical Physics 2024;35(4):178-204
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.
6.Feasibility of artificial intelligence-driven interfractional monitoring of organ changes by mega-voltage computed tomography in intensity-modulated radiotherapy of prostate cancer
Yohan LEE ; Hyun Joon CHOI ; Hyemi KIM ; Sunghyun KIM ; Mi Sun KIM ; Hyejung CHA ; Young Ju EUM ; Hyosung CHO ; Jeong Eun PARK ; Sei Hwan YOU
Radiation Oncology Journal 2023;41(3):186-198
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.
7.Effect of the inhibition of PLA2 on the oxidative stress in the lungs of glutathione depleted rats given endotoxin intratracheally.
Hyun Gug CHO ; Hye Jung MOON ; Won Hark PARK ; Te Oan KIM ; Young Man LEE
Tuberculosis and Respiratory Diseases 2000;48(2):246-259
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
8.Two Cases of Rhabdomyolysis Complicated with Doxylamine Overdose.
Sun Joo CHO ; Jeong Ki PARK ; Dong Geun YEO ; Ye Dal JEONG ; Jung Yoon CHEO ; Ki Sung AHN ; Jee Hyen LEE ; Ho Sang SOHN
Korean Journal of Nephrology 2000;19(3):542-546
Doxylamine succinate is common over-the-counter sleep medication that is frequently involved in accidental poisonings and suicide attempts. Doxylamine overdose is generally directed at the anticholinergic effect including autonomic,and central nervous system effect and direct cardiac toxicity. Rarely, rhabdomyolysis has been reported with doxylamine overdose. We experienced two cases of rhabdomyolysis with overdose of doxylamine in 17-year-old and 31-year-old male. They were diagnosed with high levels of creatine phosphokinase in serum, myoglobin in serum and urine, and increased radionuclide uptake of muscles in (99m)Tc-MDP bone scan. Patients recovered without any complications with hydration and diuresis. Clinicians should be aware of the possibility of rhabdomyolysis in patients with doxylamine overdose.
Acute Kidney Injury
;
Adolescent
;
Adult
;
Central Nervous System
;
Creatine Kinase
;
Diuresis
;
Doxylamine*
;
Humans
;
Male
;
Muscles
;
Myoglobin
;
Poisoning
;
Rhabdomyolysis*
;
Succinic Acid
;
Suicide
9.A Case of Rhabdomyolysis, Acute Renal Failure, and Acute Hepatitis Due to Carp Bile Ingestion.
Dong Geun YEO ; Jeong Ki PARK ; Wern Chan YOON ; Ye Dal JUNG ; Hak Jun KIM ; Sun Joo CHO ; In Hee LEE ; Ki Sung AHN ; Yong Jin KIM
Korean Journal of Nephrology 2000;19(5):972-976
Sevral cases of acute renal failure and acute hepatitis after ingestion of raw carp gall bladder have been reported. We experienced for the first time 1 case of acute renal failure and acute hepatitis associated with rhabdomyolysis, which has not been seen in previous studies, after ingestion of the raw carp gall bladder. Serum creatine phosphokinase, myoglobin and urine myoglobin were increased and 99mTc-MDP bone scan showed diffusely increased uptake of isotope in soft tissue of whole body. The other laboratory data corresponded to acute tubular necrosis and acute toxic hepatitis. The kidney pathology showed the recovery phase of acute tubular necrosis. Etiologic factor for rhabdomyolysis was not found except carp gall bladder. We considered that carp gall bladder was etiologic factor for rhabdomyolysis and that rhabdomyolysis acted as agravatting factor for developing acute tubular necrosis due to carp bile toxicity in this case.
Acute Kidney Injury*
;
Bile*
;
Carps*
;
Creatine Kinase
;
Drug-Induced Liver Injury
;
Eating*
;
Hepatitis*
;
Kidney
;
Myoglobin
;
Necrosis
;
Pathology
;
Rhabdomyolysis*
;
Technetium Tc 99m Medronate
;
Urinary Bladder
10.Comparisons between Classic Shunt and Non-Invasive Shunt in One-Lung Ventilated and Hemodiluted Dogs.
Woon Seok ROH ; Hyun Chul JOO ; Chan Hong PARK ; Bong Il KIM ; Soung Kyung CHO ; Sang Hwa LEE
Korean Journal of Anesthesiology 2000;38(3):537-545
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

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