• Progress in Medical Physics
• /
• v.33 no.4
• /
• pp.72-79
• /
• 2022

Purpose: The proficiency test was conducted to assess the performance of the dosimetry audit service provider in the readout practice of the dose delivered to patients in medical institutions. Methods: A certain amount of the absorbed dose to water for the high-energy X-ray from the medical linear accelerator (LINAC) installed in the Korea Research Institute of Standards and Science (KRISS) was delivered to the postal dose audit package given by the dosimetry audit service provider, in which the radio-photoluminescence (RPL) glass dosimeters were mounted. The dosimetry audit service provider read the RPL glass dosimeters and sent the readout dose value with its uncertainty to KRISS. The performance of the dosimetry audit service provider was evaluated based on the E_n number given in ISO/IEC 17043:2010. Results: The evaluated E_n number was -0.954. Based on the ISO/IEC 17043, the performance of the dosimetry service provider is "satisfactory." Conclusions: As part of the conformity assessment, the KRISS performed the proficiency test over the postal dose audit practice run by the dosimetry audit service provider. The proficiency test is in line with confirming the traceability of the medical institutions to the primary standard of absorbed dose to the water of the KRISS and ensuring the confidence of the dosimetry audit service provider.

• Progress in Medical Physics
• /
• v.29 no.4
• /
• pp.164-172
• /
• 2018

We evaluated the performance of various detectors for small-field dosimetry with field sizes defined by a high-definition (HD) multileaf collimator (MLC) system. For small-field dosimetry, diodes referred to as "RAZOR detectors," MOSFET detectors, and Gafchromic EBT3 films were used in this study. For field sizes less than $1{\times}1cm^2$, percent depth doses (PDDs) and lateral profiles were measured by diodes, MOSFET detectors, and films, and absolute dosimetry measurements were conducted with MOSFET detectors. For comparison purposes, the same measurements were carried out with a field size of $10{\times}10cm^2$. The dose distributions were calculated by the treatment planning system Eclipse. A comparison of the measurements with calculations yielded the percentage differences. With field sizes less than $1{\times}1cm^2$, it was shown that most of the percentage difference values were within 5% for 6-MV and 15-MV photon beams with the use of diodes. The measured lateral profiles were well matched with those calculated by Eclipse as the field sizes increased. Except for the depths of 0.5 cm and 20 cm, there was agreement in terms of the absolute dosimetry within 10% when MOSFET detectors were used. There was good agreement between the calculations and measurements conducted using diodes and EBT films. Both diode detectors and EBT3 films were found to be appropriate options for relative measurements of PDDs and for lateral profiles.

• Progress in Medical Physics
• /
• v.20 no.4
• /
• pp.253-259
• /
• 2009

We have developed standards based on international criterions for the quality control of dose tested by the measurement institutions of individual exposure doses through improving the reliability of data on the exposure dose of individuals working in radioactive environment and securing the accuracy and reliability of individual dose measurements. Laws related to radiation dose applied to domestic institutions refer to ANSI N13.11.1993, but currently, in U.S. and some other countries the measurement of radiation doses is based on ANSI N13.11.2001 that reduced test categories and tightened the standards. We made efforts to simplify the standards and to reduce the number of dosimeters required in experiment, and avoided preventing or hindering the use of future technologies not approved under the current law such as glass dosimeter and optical stimulation dosimeter. The Quality Management Manual of Radiation Dosimetry Service, Assessment Manual of Radiation Dosimetry Service Accreditation Program, and the Personnel Dosimetry Performance. Criteria for Testing are documents applicable in supervising laboratories.

• Korean Journal of Digital Imaging in Medicine
• /
• v.13 no.1
• /
• pp.7-11
• /
• 2011

As applications of radiation grow wider from use in the early detection of lesions and preventive diagnosis purposes to the treatment of diseases, the possibilities for patients and working professionals to be exposed to radiation are becoming greater than ever. This can not only directly bring about an increase in patient's individual radiation exposure, but also brings about an increase in the annual radiation dose of working professionals. Therefore, research and countermeasures to reduce radiation dosage are required. In this study, space dosimetry has been divided into two separate measuments with an understanding of the increasing number of angiography procedures: front perspective and side perspective. According to the results of the isodose curve, a way to minimize radiation exposure in working professionals has been suggested. This was made possible by workers through awareness of suitable working positions.

• Progress in Medical Physics
• /
• v.33 no.4
• /
• pp.158-163
• /
• 2022

Purpose: We subjected scanning electron microscopic (SEM) images of the active layer of EBT3 film to texture analysis to determine the dose-response curve. Methods: Uncoated Gafchromic EBT3 films were prepared for direct surface SEM scanning. Absorbed doses of 0-20 Gy were delivered to the film's surface using a 6 MV TrueBeam STx photon beam. The film's surface was scanned using a SEM under 100× and 3,000× magnification. Four textural features (Homogeneity, Correlation, Contrast, and Energy) were calculated based on the gray level co-occurrence matrix (GLCM) using the SEM images corresponding to each dose. We used R-square to evaluate the linear relationship between delivered doses and textural features of the film's surface. Results: Correlation resulted in higher linearity and dose-response curve sensitivity than Homogeneity, Contrast, or Energy. The R-square value was 0.964 for correlation using 3,000× magnified SEM images with 9-pixel offsets. Dose verification was used to determine the difference between the prescribed and measured doses for 0, 5, 10, 15, and 20 Gy as 0.09, 1.96, -2.29, 0.17, and 0.08 Gy, respectively. Conclusions: Texture analysis can be used to accurately convert microscopic structural changes to the EBT3 film's surface into absorbed doses. Our proposed method is feasible and may improve the accuracy of film dosimetry used to protect patients from excess radiation exposure.

• Journal of Radiation Protection and Research
• /
• v.29 no.1
• /
• pp.9-15
• /
• 2004

Firstly, we compared the two staining techniques, Giemsa and Acridine orange, to determine micronuclei on samples of cultures of five healthy human peripheral blood lymphocytes after ${\gamma}-irradiation\;(^{137}Cs)$ in dose ranges of 0 to 800cGy. It was found that the Acridine orange staining method gives more reliable results than the usual Giemsa staining method in micronucleus tests. Moreover, the frequency of micronuclei in cytokinesis-blocked human B-lymphocytes was studied after in vitro irradiation in dose ranges of 0 to 50cGy. After setting and separating the B-lymphocytes, the frequency of radiation-induced micronuclei were observed as the end-point markers for the low-dose radiation dosimetry after staining with Giemsa and Acridine orange dyes. The micronuclei frequency in B-lymphocytes was significantly elevated from 10 to 30cGy ${\gamma}-irradiation$. The determination of micronuclei in B-lymphocytes after staining with Acridine orange was higher than that of Giemsa. The frequency of micronuclei in B-lymphocytes was observed to be at least two times higher than those of T-lymphocytes Giemsa in dose increasing. Therefore, the determination of low-dose radiation-induced micronuclei in B-lymphocytes after staining with Acridine orange is likely to have the greatest potential in the estimation of low dose radiation exposure.

• Journal of radiological science and technology
• /
• v.43 no.5
• /
• pp.343-351
• /
• 2020

This study analyzed dose reduction and quality of images through dose reduction tools and shielding board to protect sensitive eye lens in radiation during orbit CT examinations for clinical data use. During CT scans of the phantom, surface dose (CT scanner dosimetry phantom, ion chamber-3 times) and quality of image (radiosurgery head phantom, visual assessment-2 times, HU standard deviation) were evaluated using X-care which is dose reduction tools and bismuth shielding board. The results of experiments of eight conditions showed a relatively reduced dose in all other conditions compared to when no conditions were set. In particular, the area corresponding to the ophthalmic part reduced the surface dose by up to 45.7 %. The visual evaluation of images by specialists and the quality evaluation of images analyzed by HU standard deviation were clinically closest to the use of X-care and shielding board (1 cm in height). Therefore, it is believed that the use of shielding board in a suitable location with dose reduction tools while investigating the optimal radiation dose will reduce the exposure dose of sensitive lens at radiation while maintaining the quality of the images with high diagnostic value.

• Journal of radiological science and technology
• /
• v.47 no.2
• /
• pp.107-116
• /
• 2024

In this study, we analyzed the use of general radiography imaging and effective dose in inpatients. Our aim is to help reduce national medical radiation exposure doses and develop rational health-care financial policies. The effective dose for each general radiography was calculated using the ALARA-GR program for 53 types (total: 260 codes) general radiography codes selected from 'National Health Insurance Care Benefit Cost'. The usage of general radiography was analyzed in the 2018 inpatient patient data of the Health Insurance Review and Assessment Service, and the effective dose for each general radiography was analyzed. 89.00% of inpatients undergo general radiography imaging at least once, with an average of 12.63 scans per person and an effective dose of 1.00 mSv. Those who received support from Medical Aid showed a higher value compared to those who were insured by National Health Insurance, with 17.39 cases and 1.43 mSv (p<.001). Chest had the highest usage rate at 23.12% for general radiography imaging, while L-spine had the highest effective dose at 24.53%. It is estimated that 420 inpatients patients undergo 121 to 820 general radiography imaging procedures per year, and 233 inpatients are estimated to have an annual effective dose of >20.00~58.25 mSv. Rational use of health-care finances and the practice of medical radiation safety management are essential for the well-being of individuals, the enhancement of quality of life, and the improvement of health-care quality.

• Progress in Medical Physics
• /
• v.21 no.1
• /
• pp.60-69
• /
• 2010

For treatment of Total Skin Electron beam Therapy (TSET), measurement of dose at various conditions is need on the contrary to usual radiotherapy. When treating TSET with modified Stanford technique based on linear accelerator, the energy of treatment electron beam, the spatial dose distribution and the actual doses deposited on the surface of the patient were measured by using EBT2. The measured energy of the electron beam was agreed with the value that measured by ionization chamber, and the spatial dose distribution at the patient position and the doses at several point on the patient's skin could be easily measured by EBT2 film. The dose on the patient that was measured by EBT2 film showed good agreement with the data measured simultaneously by TLD. With the results of this study, it was proven that the EBT2 film can be one of the useful dosimeter for TSET.

• Journal of radiological science and technology
• /
• v.44 no.5
• /
• pp.495-502
• /
• 2021

This study aims to provide basic data for elderly health insurance policy and medical radiation safety management by analyzing the general radiography usage and exposure dose of the elderly in Korea. The effective dose for each general radiography was calculated using the ALARA-GR program for 260 general radiography codes selected from 'National Health Insurance Care Benefit Cost'. The usage of general radiography was analyzed in the 2016 elderly patient data of the Health Insurance Review and Assessment Service, and the effective dose for each general radiography was applied. The general radiography usage and exposure dose per person aged 65 years and over was 6.47 cases and 0.56 mSv. Females showed higher value than males as 7.15 cases and 0.66 mSv(p<.001). By age, those between 75 and 79 showed the highest number as 6.97 cases and 0.62 mSv(p<.001). Those who were supported by Medical Aid showed higher value than those who were insured by National Health Insurance as 8.82 cases and 0.76 mSv(p<.001). In addition, the ratio by radiography was in the order of Chest 20.85%, Knee Joint 15.58%, and L-spine 14.67%, and the exposure dose was L-spine 29.40%, Chest 15.82%, Abdomen 7.97%, and Entire Spine 7.20%. General radiography, which is widely used due to the high frequency of diseases in the elderly population should be taken into consideration when establishing health insurance policies. In addition, it is necessary to check whether the general radiography with high exposure dose is performed as a routine examination without considering medical necessity.