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Jeon, Hosang,Kim, Dong Woon,Joo, Ji Hyeon,Ki, Yongkan,Kim, Wontaek,Park, Dahl,Nam, Jiho,Kim, Dong Hyeon Korean Society of Medical Physics 2021 의학물리 Vol.32 No.1
Purpose: Kilovoltage computed tomography (kV-CT) is essential for radiation treatment planning. However, kV-CT images are significantly distorted by artifacts when a metallic prosthesis is present in the patient's body. Thus, the accuracies of target delineation and treatment dose calculation are inevitably lowered. We evaluated the accuracy of the calculated doses using an image restoration method with hybrid CT, which was introduced in our previous study. Methods: A cylindrical phantom containing four metals, namely, silver, copper, tin, and tungsten, was scanned using kV-CT and megavoltage CT to produce hybrid CT images. We created six verification plans for three head and neck patients on kV-CT and hybrid CT images of the phantom and calculated their doses. The actual doses were measured with film patches during beam delivery using tomotherapy. We used the gamma evaluation method to compare dose distribution between kV-CT and hybrid CT with three gamma criteria, namely, 3%/3 mm, 2%/2 mm, and 1%/1 mm. Results: The gamma pass rates decreased as the gamma criteria were strengthened, and the pass rate of hybrid CT was higher than that of kV-CT in all cases. When the 1%/1 mm criterion was used, the difference in gamma pass rates between them was up to 13%p. Conclusions: According to our findings, we expect that the use of hybrid CT can be a suitable approach to avoid the effect of severe metal artifacts on the accuracy of dose calculation and contouring.
Experimental Study of In-vivo Dosimetry Using Glass Rod Dosimeters to Minimize the Initialization
Jeon, Hosang,Nam, Jiho,Lee, Jayoung,Lee, Juhye,Park, Dahl,Kim, Wontaek,Ki, Yongkan,Kim, Donghyun 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.5
<P>In-vivo dosimetry, in which small detector elements are attached to a patient's body, is an important technique for directly evaluating radiation treatment doses. The glass rod dosimeter (GRD) possesses several advantages over alternatives, which makes it one of the most useful detectors for in-vivo dosimetry. However, because the GRD initialization process requires a prolonged exposure at very high temperatures, as well as subsequent gradual quenching, each measurement takes approximately a day to complete. Therefore, we investigated the reliability of a GRD used repeatedly without initialization processes to improve efficiency. Ten doses of 0.5 Gy were delivered and read using three GRD elements. Then, the same procedure was performed for doses of 1.0 Gy. A readout error of less than 2% was maintained for up to three irradiation doses. However, the fluctuations in the readout data increased significantly as the number of irradiation doses increased. In addition, we discovered that the combined uncertainty of the readouts was influenced more heavily by the cumulative amount of irradiation than it was by the number of doses. Our results should provide guidance for accurate and efficient GRD use.</P>
Jeon Hosang,Kim Dong Woon,Joo Ji Hyeon,Ki Yongkan,Kim Wontaek,Park Dahl,Nam Jiho,Kim Dong Hyeon 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.1
Image-guided radiation treatment (IGRT) is essential for verifying patient positioning during modern radiotherapy. Although megavoltage digital radiographs (MV-DR) are available on most therapeutic linear accelerators and can be used for checking treatment beam shapes, they are much inferior to kilovoltage digital radiographs (KV-DR) in terms of image quality. As it is generally challenging to obtain a well-aligned MV−KV training dataset of patients in clinical scenarios, there is a lack of sufcient information on the accuracy of KV-DR synthesized using supervised training. Therefore, we aimed to synthesize pseudo KV-DR (pKV-DR) from MV-DR using a training dataset developed with a single anthropomorphic chest phantom. The phantom was adopted to obtain MV−KV image pairs at various gantry angles because these image pairs of patients are highly difcult to acquire and exactly align with each other. A deep-learning model based on U-net architecture was trained with the phantom image pairs using the mean absolute error (MAE) and structure similarity (SSIM) indices as loss functions. The mean MAEs of MV-DR and pKV-DR against KV-DR as the ground truth were 0.1152 and 0.0169, respectively, and their mean SSIM values were 0.9693 and 0.9942, respectively. Finally, pKV-DR showed a relatively high image similarity to that of KV-DR with smaller MAE (14.7%) and higher SSIM (2.5%), compared with MV-DR. The image contrast was also improved by 37.1% in clinical cases. The proposed method is expected to enable the implementation of improved IGRT with high image quality of KV-DR level, even in clinics where MV-DR is only available.
Jeon, Hosang,Kim, Dong Woon,Joo, Ji Hyeon,Ki, Yongkan,Kim, Wontaek,Park, Dahl,Nam, Jiho,Kim, Dong Hyeon Korean Society of Medical Physics 2020 의학물리 Vol.31 No.4
Purpose: Radiation oncology information systems (ROIS) have evolved toward connecting and integrating information between radiation treatment procedures. ROIS can play an important role in utilizing modern radiotherapy techniques that have high complexity and require a large amount of information. Methods: Using Access<sup>TM</sup> software, we have developed a relational database that is highly optimized for a radiotherapeutic workflow. Results: The prescription table was chosen as the core table to which the other tables were connected, and three types of forms-charts, worklists, and calendars- were suggested. A fast and reliable channel for delivering orders and remarks according to changes in the situation was also designed. Conclusions: We expect our ROIS design to inspire those who need to develop and manage an individual ROIS suitable for their radiation oncology departments at a low cost.
A metallic buildup cap for glass rod dosimeters in radiotherapeutic in vivo dosimetry
Jeon Hosang,Lee Ho Jeong,Kim Dong Woon,Joo Ji Hyeon,Baek Cheol-Ha,Ki Yongkan,Kim Wontaek,Park Dahl,Nam Jiho,Kim Dong Hyeon 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.9
In vivo measurement of radiotherapeutic doses is an important procedure for ensuring the accuracy of radiation treatments. The glass rod dosimeter is a known dosimeter for in vivo dosimetry, which has high reproducibility and low dependencies with respect to major radiotherapeutic conditions. A hemispherical buildup cap made of brass was fabricated to avoid a large measurement error owing to the partial lack of buildup effect during the measurement on the patient’s skin. The correction factors (CFs) were experimentally obtained and verified using a Monte Carlo simulation. A clinical trial was performed with 117 patients. As a result, the measured CF was consistent with the simulation by a 2.3% error, and the mean errors of each site were within 2%. The total mean error was 1.84%, with a standard deviation of 1.39%. To conclude, this methodology can provide high accuracy and convenience in radiotherapeutic in vivo measurements.
Hosang Oh,Hwa-Kyung Shin,Myoungouk Park,Han-Seoung Choe,Jeon-Il Moon,Joonwoo Son 대한인간공학회 2012 대한인간공학회 학술대회논문집 Vol.2012 No.11
Objective: The aim of this study is to develop the upper limb training and assessment systems for stroke patient rehabilitation using a driving simulator. Background: About 795,000 people experience a new or recurrent stroke in the United States each year, and lots of researchers are suggesting effective rehabilitation methods. In most of their studies, however, pre- and post-assessments tool using some clinical scales were used for the assessment tool of the recovery through upper limb rehabilitation. In some studies, physiological measure was considered as important factor for rehabilitation process from earlier studies. Method: The experiment for the assessment is conducted at a fixed-based driving simulator. The proposed rehabilitation assessment system consists of quantitative assessment using driving simulator, motion analysis system, EMG (Electromyograph), ECG (Electrocardiograph), EEG (Electroencephalograph), gaze tracker, body pressure sensor and myotonometer and subjective assessment using clinical scale such as CNT (Computerized Neurocognitive Function Test) and UFOV(Useful Field of View). In order to quantitatively compare the upper limb function during assessment, the driving performance measures (speed, steering activity, and etc.), upper limb function (muscle activity, kinematics and etc.) and physiological measures (EEG, ECG and etc.) were collected from each subsystem. Results: This driving simulator based rehabilitation system can be utilized as training method for stroke patient, because the training using the steering activity can affect skeletomuscular system positively. The proposed system can offer objective method for assessing a training effect by using driving performance, upper limb function and physiological measures. In addition, the system can measure the driving performance that can be used for evaluating the driving ability of stroke drivers. Conclusion: The proposed upper limb rehabilitation system can be used as a combined system for quantitative and subjective assessment through driving simulator.
Jeon, Eonju,Kwon, Hyojung,Shin, Imhee,Kang, Seokbong,Shon, Hosang BMJ Publishing Group Ltd 2014 ACUPUNCTURE IN MEDICINE Vol.32 No.4
<P><B>Background</B></P><P>Diabetic neuropathic pain can severely influence quality of life, and patients may be dissatisfied with treatment.</P><P><B>Objective</B></P><P>To carry out an observational study of the effects of acupuncture for the treatment of diabetic neuropathic pain, in preparation for a full study.</P><P><B>Methods</B></P><P>Nine patients with diabetic neuropathic pain were recruited from a Korean diabetic clinic and given 12 sessions of acupuncture over 4 weeks. Their symptoms were evaluated using the Total Symptom Score (TSS) and Michigan Neuropathy Screening Instrument (MNSI) at baseline and 4 weeks after the last treatment.</P><P><B>Results</B></P><P>Mean TSS scores reduced from 7.99 (SD 3.55) at baseline to 4.95 (SD 4.41), at the 8-week follow-up—a statistically non-significant change (p=0.057). The MNSI scores improved from 6.33 (SD 1.31) before treatment to 4.33 (SD 3.00) after acupuncture treatment—a significant improvement (p=0.010). One participant experienced an exacerbation of diabetic neuropathy symptoms, but two patients gained complete relief of their diabetic peripheral neuropathy (DPN) symptoms.</P><P><B>Conclusions</B></P><P>The results of this study justify further investigations into the effects of acupuncture on DPN.</P>
김동운,Jeon Hosang,Joo Ji Hyeon,기용간,김원택,김동현,Park Dahl,Nam Jiho 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.1
A deep-inspiration breath-hold (DIBH) is a useful technique that can reduce the risk of radiation-related toxicity to major organs during radiation treatment (RT) of breast cancer. A laser sensor-based position monitoring system was developed to measure the absolute position of the object and to realize high accuracy and reproducibility during DIBH. A laser distance sensor (LDS) was manufactured to be mounted on a commercial breast board and to measure the absolute distance between the sensor and the patient’s sternum. The absolute distance measured by using the LDS was evaluated for the movement generated by the motorized jack system. The respiration of five volunteers was measured by using the LDS and commercial real-time position management (RPM) to evaluate the correlation of the signals. The data measured by using the LDS for the input to the motorized jack had a relative error of 0.2%. At DIBH, the average correlation coefficient between the LDS and RPM was 0.98, and at FB, it was 0.84. The LDS and RPM showed almost similar timings for the rising and the falling portions, but the magnitudes of amplitudes were slightly different from each other. The LDS proposed in this study can easily reproduce patient setup and monitor DIBH without any disturbance from the treatment beam. The measuring accuracy of the LDS for the quantitative motion of a motorized jack system was successfully verified. The performance of the LDS compared to RPM in the FB and the DIBH of five volunteers was also clinically acceptable.