https://scholar.korea.ac.kr/handle/2021.sw.korea/2535 2026-04-05T15:56:17Z 2026-04-05T15:56:17Z Han, Suchul Lee, Boram Shin, Gwisoon Choi, Jonghak Kim, Jungmin Park, Changseo Park, Hyok Lee, Kisung Kim, Youhyun https://scholar.korea.ac.kr/handle/2021.sw.korea/107988 2024-11-15T11:41:48Z 2012-07-01T00:00:00Z

Title: Dose area product measurement for diagnostic reference levels and analysis of patient dose in dental radiography Authors: Han, Suchul; Lee, Boram; Shin, Gwisoon; Choi, Jonghak; Kim, Jungmin; Park, Changseo; Park, Hyok; Lee, Kisung; Kim, Youhyun Abstract: In this study, diagnostic reference levels (DRLs) were suggested and patient doses were analysed through the dosearea product value in dental radiography. In intraoral radiography, at three sites, i.e. molar, premolar and incisor on the maxilla and acquired third quartile values: 55.5, 46 and 36.5 mGy cm(2), respectively, were measured. In panoramic, cephalometric and cone beam computed tomography, the values were 120.3, 146 and 3203 mGy cm(2) (16 18 cm), respectively. It has been shown that, in intraoral radiography, the patient dose changes proportionally to the value of mA s, but the change in extraoral radiography in response to mA s could not be confirmed. The authors could confirm, however, the difference in dose according to the manufacturer in all dental radiography examinations, except for panoramic radiography. Depending on the size of hospital, there were some differences in patient dose in intraoral radiography, but no difference in patient dose in extraoral radiography.

2012-07-01T00:00:00Z Lee, Boram Shin, Gwisoon Kang, Sunjung Shin, Boram Back, Ilhong Park, Hyok Park, Changseo Lee, Jeongwoo Lee, Wonho Choi, Jonghak Park, Ryeonghwang Kim, Youhyun https://scholar.korea.ac.kr/handle/2021.sw.korea/106276 2024-11-15T11:41:50Z 2012-01-01T00:00:00Z

Title: DOSE EVALUATION OF SELECTIVE COLLIMATION EFFECT IN CEPHALOGRAPHY BY MEASUREMENT AND MONTE CARLO SIMULATION Authors: Lee, Boram; Shin, Gwisoon; Kang, Sunjung; Shin, Boram; Back, Ilhong; Park, Hyok; Park, Changseo; Lee, Jeongwoo; Lee, Wonho; Choi, Jonghak; Park, Ryeonghwang; Kim, Youhyun Abstract: Recently, simulations based on the Monte Carlo code have been increasingly applied for physics phenomena, patient dose and quality assurance of radiation systems. The objective of this study was to use Monte Carlo simulation and measurement to verify dose and dose reduction in cephalography. The collimator was constructed with 3-mm thick lead plate, and attached to the tube head to remove regions of disinterest in the radiation field. A digital phantom patient was constructed to evaluate patient dose. In addition, detectors of pixel size 1 x 1 cm(2) and 0.1 x 0.1 cm(2) were constructed to check collimator location. The effective dose according to International Commission on Radiological Protection 103 was calculated with and without collimation. The effective doses for simulation with and without collimation were 5.09 and 11.32 mu Sv, respectively. The results of the calculated effective dose show 61.7% reduction of field area and 55%, of effective dose. The Monte Carlo simulation is a good evaluation tool for patient dose.

2012-01-01T00:00:00Z Park, Ji-Yeon Lee, Jeong-Woo Choi, Kyoung-Sik Lee, Jung Seok Kim, You-Hyun Hong, Semie Suh, Tae-Suk https://scholar.korea.ac.kr/handle/2021.sw.korea/111025 2024-11-15T15:02:47Z 2011-12-01T00:00:00Z

Title: Development of a novel quality assurance system based on rolled-up and rolled-out radiochromic films in volumetric modulated arc therapy Authors: Park, Ji-Yeon; Lee, Jeong-Woo; Choi, Kyoung-Sik; Lee, Jung Seok; Kim, You-Hyun; Hong, Semie; Suh, Tae-Suk Abstract: Purpose: To develop a cylindrical phantom with rolled-up radiochromic films and dose analysis software in the rolled-out plane for quality assurance (QA) in volumetric modulated arc therapy (VMAT). Methods: The phantom consists of an acrylic cylindrical body wrapped with radiochromic film inserted into an outer cylindrical shell of 5 cm thickness. The rolled-up films with high spatial resolution enable detection of specific dose errors along the arc trajectory of continuously irradiated and modulated beams in VMAT. The developed dose analysis software facilitates dosimetric evaluation in the rolled-up and rolled-out planes of the film; the calculated doses on the corresponding points where the rolled-up film was placed were reconstructed into a rectangular dose matrix equivalent to that of the rolled-out plane of the film. The VMAT QA system was implemented in 3 clinical cases of prostate, nasopharynx, and pelvic metastasis. Each calculated dose on the rolled-out plane was compared with measurement values by modified gamma evaluation. Detected positions of dose disagreement on the rolled-out plane were also distinguished in cylindrical coordinates. The frequency of error occurrence and error distribution were summarized in a histogram and in an axial view of rolled-up plane to intuitively identify the corresponding positions of detected errors according to the gantry angle. Results: The dose matrix reconstructed from the developed VMAT QA system was used to verify the measured dose distribution along the arc trajectory. Dose discrepancies were detected on the rolled-out plane and visualized on the calculated dose matrix in cylindrical coordinates. The error histogram obtained by gamma evaluation enabled identification of the specific error frequency at each gantry angular position. The total dose error occurring on the cylindrical surface was in the range of 5%-8% for the 3 cases. Conclusions: The developed system provides a practical and reliable QA method to detect dosimetric errors according to the gantry angle. Film dosimetry based on rolled-up and rolled-out techniques leads to dose verification in the subspaces of the 3D dose volume. The system can be employed as an alternative tool to detect the pitfalls of planar dose verification. VC 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3659706]

2011-12-01T00:00:00Z Jin, Hosang Palta, Jatinder R. Kim, You-Hyun Kim, Siyong https://scholar.korea.ac.kr/handle/2021.sw.korea/115351 2024-11-15T06:50:59Z 2010-11-01T00:00:00Z

Title: APPLICATION OF A NOVEL DOSE-UNCERTAINTY MODEL FOR DOSE-UNCERTAINTY ANALYSIS IN PROSTATE INTENSITY-MODULATED RADIOTHERAPY Authors: Jin, Hosang; Palta, Jatinder R.; Kim, You-Hyun; Kim, Siyong Abstract: Purpose: To analyze dose uncertainty using a previously published dose-uncertainty model, and to assess potential dosimetric risks existing in prostate intensity-modulated radiotherapy (IMRT). Methods and Materials: The dose-uncertainty model provides a three-dimensional (3D) dose-uncertainty distribution in a given confidence level. For 8 retrospectively selected patients, dose-uncertainty maps were constructed using the dose-uncertainty model at the 95% CL. In addition to uncertainties inherent to the radiation treatment planning system, four scenarios of spatial errors were considered: machine only (S1), S1 + intrafraction, S1 + interfraction, and S1 + both intrafraction and interfraction errors. To evaluate the potential risks of the IMRT plans, three dose-uncertainty based plan evaluation tools were introduced: confidence-weighted dose volume histogram, confidence-weighted dose distribution, and dose-uncertainty volume histogram. Results: Dose uncertainty caused by interfraction setup error was more significant than that of intrafraction motion error. The maximum dose uncertainty (95% confidence) of the clinical target volume (CTV) was smaller than 5% of the prescribed dose in all but two cases (13.9% and 10.2%). The dose uncertainty for 95% of the CTV volume ranged from 1.3% to 2.9% of the prescribed dose. Conclusions: The dose uncertainty in prostate IMRT could be evaluated using the dose-uncertainty model. Prostate IMRT plans satisfying the same plan objectives could generate a significantly different dose uncertainty because a complex interplay of many uncertainty sources. The uncertainty-based plan evaluation contributes to generating reliable and error-resistant treatment plans. (C) 2010 Elsevier Inc.

2010-11-01T00:00:00Z