• Journal of Radiation Protection and Research
• /
• v.35 no.1
• /
• pp.1-5
• /
• 2010

This study concerning the surface dose of eye and thyroid from panoramagraphy used thermoluminescent dosimeter (TLD) and photoluminescent dosimeter (PLD) to take measurements at ten hospitals in the Gwangju metropolitan area. The recommendations from ICRP 60 and ICRP 73 on the allowance standard for eye are 15 mSv and for thyroid is 1 mSv. The left eye TLD and PLD values are 0.19 mSv and 0.24 mSv respectively. The right eye TLD and PLD values are 0.23 mSv and 0.25 mSv respectively. Thyroid TLD and PLD values are 0.08 mSv and 0.25 mSv respectively and did not exceed the allowance standards(p<0.001). Also comparisons are made between TLD and PLD for each organ and PLD has higher dose measurements than TLD. There are statistically significant differences in left eye measurements and thyroid measurements (p<0.01). There is no significant difference in measurements for the right eye (p>0.05). The TLD and PLD measured dose from panoramagraphy instruments on eyes and thyroid from each hospital did not exceed the recommended dose from ICRP 60 for surface dose measurements. However, due to the probability of influence, consideration should be made for all levels of dose.

• Journal of radiological science and technology
• /
• v.44 no.5
• /
• pp.451-457
• /
• 2021

Recently, the number of interventional procedures has increased dramatically as an alternative of invasive surgical procedure and patient radiation exposure is also increasing accordingly. In this study, we evaluated the patient dose of major interventional procedures nationwide and we established our Korean database. With these results, we tried to suggest the reference dose level for major interventional procedures. We evaluated patent dose data in the field of interventional radiology from foreign countries. Measurement of radiation dose exposure for 11 major interventional procedures was conducted using embedded DAP meters in 10,006 patients from 47 hospitals, and reference level of each interventional procedure was suggested. The DRLs of each intervenional procedure are as follows: TACE 206(Gy·cm²), AVF 12(Gy·cm²), LE intervention 43(Gy·cm²), TFCA 122(Gy·cm²), Cerebral aneurysm coil embolization 214(Gy·cm²), PTBD 22(Gy·cm²), Biliary stent 60(Gy·cm²), PCN 7(Gy·cm²), Hickman catheter 2.1(Gy·cm²), Chemoport 1.4(Gy·cm²), BAE 104(Gy·cm²). Compared with the previously established DRL in 2012, the radiation dose decreased in all 10 interventional procedures. In the future, continuous publicity and education on the radiation dose reduction will be needed.

• Journal of Radiation Protection and Research
• /
• v.47 no.1
• /
• pp.30-38
• /
• 2022

Background: Residential areas have some factors on the external exposure of residents, who usually spend a long time in these areas. Although various survey has been carried out by the government or the research institutions after the Fukushima Daiichi Nuclear Power Plant accident, the mechanism of radiocesium inventory in the terrestrial zone has not been cleared. To better evaluate the radiation environment, this study investigated the temporal changes in air dose rate and ¹³⁷Cs inventories (Bq/m²) in residential areas and agricultural fields. Materials and Methods: Air dose rate and ¹³⁷Cs inventories were investigated in residential areas located in an evacuation zone at 5-8 km from the Fukushima Daiichi Nuclear Power Plant. From December 2014 to September 2018, the air dose rate distribution was investigated through a walking survey (backpack survey), which was conducted by operators carrying a γ-ray detector on their backs. Additionally, from December 2014 to January 2021, the ¹³⁷Cs inventories on paved and permeable grounds were also measured using a portable γ-ray detector. Results and Discussion: In the areas where decontamination was not performed, the air dose rate decreased faster in residential areas than in agricultural fields. Moreover, the ¹³⁷Cs inventory on paved surfaces decreased with time owing to the horizontal wash-off, while the ¹³⁷Cs inventory on permeable surfaces decreased dramatically owing to the decontamination activities. Conclusion: These findings suggest that the horizontal wash-off of ¹³⁷Cs on paved surfaces facilitated the air dose rate decrease in residential areas to a greater extent compared with agricultural fields, in which the air dose rate decreased because of the vertical migration of ¹³⁷Cs. Results of this study can explain the faster environmental restoration in a residential environment reported by previous studies.

• The Journal of Korean Society for Radiation Therapy
• /
• v.18 no.1
• /
• pp.1-5
• /
• 2006

Purpose: IMRT quality assurance(Q.A) is consist of the absolute dosimetry using ionization chamber and relative dosimetry using the film. We have in general used 0.015 cc ionization chamber, because small size and measure the point dose. But this ionization chamber is too small to give an accurate measurement value. In this study, we have examined the degree of calculated to measured dose difference in intensity modulated radiotherapy(IMRT) based on the observed/expected ratio using various kinds of ion chambers, which were used for absolute dosimetry. Materials and Methods: we peformed the 6 cases of IMRT sliding-window method for head and neck cases. Radiation was delivered by using a Clinac 21EX unit(Varian, USA) generating a 6 MV x-ray beam, which is equipped with an integrated multileaf collimator. The dose rate for IMRT treatment is set to 300 MU/min. The ion chamber was located 5cm below the surface of phantom giving 100cm as a source-axis distance(SAD). The various types of ion chambers were used including 0.015cc(pin point type 31014, PTW. Germany), 0.125 cc(micro type 31002, PTW, Germany) and 0.6 cc(famer type 30002, PTW, Germany). The measurement point was carefully chosen to be located at low-gradient area. Results: The experimental results show that the average differences between plan value and measured value are ${\pm}0.91%$ for 0.015 cc pin point chamber, ${\pm}0.52%$ for 0.125 cc micro type chamber and ${\pm}0.76%$ for farmer type 0.6cc chamber. The 0.125 cc micro type chamber is appropriate size for dose measure in IMRT. Conclusion: IMRT Q.A is the important procedure. Based on the various types of ion chamber measurements, we have demonstrated that the dose discrepancy between calculated dose distribution and measured dose distribution for IMRT plans is dependent on the size of ion chambers. The reason is small size ionization chamber have the high signal-to-noise ratio and big size ionization chamber is not located accurate measurement point. Therefore our results suggest the 0.125 cc farmer type chamber is appropriate size for dose measure in IMRT.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2017.05a
• /
• pp.377-378
• /
• 2017

• Korean Journal of Radiology
• /
• v.23 no.2
• /
• pp.256-263
• /
• 2022

Objective: This study aimed to evaluate the image quality and dose reduction of low-dose three-dimensional (3D) rotational angiography (RA) for evaluating intracranial aneurysms. Materials and Methods: We retrospectively evaluated the clinical data and 3D RA datasets obtained from 146 prospectively registered patients (male:female, 46:100; median age, 58 years; range, 19-81 years). The subjective image quality of 79 examinations obtained from a conventional method and 67 examinations obtained from a low-dose (5-seconds and 0.10-μGy/frame) method was assessed by two neurointerventionists using a 3-point scale for four evaluation criteria. The total image quality score was then obtained as the average of the four scores. The image quality scores were compared between the two methods using a noninferiority statistical testing, with a margin of -0.2 (i.e., score of low-dose group - score of conventional group). For the evaluation of dose reduction, dose-area product (DAP) and air kerma (AK) were analyzed and compared between the two groups. Results: The mean total image quality score ± standard deviation of the 3D RA was 2.97 ± 0.17 by reader 1 and 2.95 ± 0.20 by reader 2 for conventional group and 2.92 ± 0.30 and 2.95 ± 0.22, respectively, for low-dose group. The image quality of the 3D RA in the low-dose group was not inferior to that of the conventional group according to the total image quality score as well as individual scores for the four criteria in both readers. The mean DAP and AK per rotation were 5.87 Gy-cm² and 0.56 Gy, respectively, in the conventional group, and 1.32 Gy-cm² (p < 0.001) and 0.17 Gy (p < 0.001), respectively, in the low-dose group. Conclusion: Low-dose 3D RA was not inferior in image quality and reduced the radiation dose by 70%-77% compared to the conventional 3D RA in evaluating intracranial aneurysms.

• Journal of radiological science and technology
• /
• v.32 no.3
• /
• pp.299-306
• /
• 2009

Purpose : To compare radiation dose for coronary CT angiography (CTA) obtained with 6 examination protocols such as a retrospectively ECG gated helical scan, a prospectively ECG gated sequential scan, low kVp technique, and cardiac dose modulation technique. Materials and Methods : Coronary CTA was performed by using 6 current clinical protocols to evaluate effective dose and organ dose in primary beam area with anthropomorphic female phantom and glass dosimetric system in 64 channel multi-detector CT. After acquiring topograms of frontal and lateral projection with 80 kVp and 10 mA, main coronary scan was done with 0.35 sec tube rotation time, 40 mm collimation ($0.625\;mm{\times}64\;ea$), small scan field of view (32 cm diameter), 105 mm scan length. Heart beat rate of phantom was maintained 60 bpm in ECG gating. In constant mAs technique 120 kVp, 600 mA was used, and 100 kVp for low kVp technique. In a retrospectively ECG gated helical CT technique 0.22 pitch was used, peak mA (600 mA) was adopted in range of $40{\sim}80%$ of R-R interval and 120mA(80% reduction) in others with cardiac dose modulation. And 210 mAs was used without cardiac dose modulation. In a prospectively ECG gated sequential CT technique data were acquired at 75% R-R interval (middle diastolic phase in cardiac cycle), and 120 msec additional padding of the tube-on time was used. For effective dose calculation region specific conversion factor of dose length product in thorax was used, which was recommended by EUR 16262. Results : The mean effective dose for conventional coronary CTA without cardiac dose modulation in a retrospectively ECG gated helical scan was 17.8 mSv, and mean organ dose of heart was 103.8 mGy. With low kVp and cardiac dose modulation the mean effective dose showed 54.5% reduction, and heart dose showed 52.3% reduction, compared with that of conventional coronary CTA. And at the sequential scan(SnapShot pulse mode) under prospective ECG gating the mean effective dose was 4.9 mSv, this represents an 72.5% reduction compared with that of conventional coronary CTA. And heart dose was 33.8 mGy, this represents 67.4% reduction. In the sequential scan technique under prospective ECG gating with low kVp the mean effective dose was 3.0 mSv, this represents an 83.2% reduction compared with that of conventional coronary CTA. And heart dose was 17.7 mGy, this represents an 82.9% reduction. Conclusion : In coronary CTA at retrospectively ECG gated helical scan, cardiac dose modulation technique using low kVp reduced dose to 50% above compared with the conventional helical scan. And the prospectively ECG gated sequential scan offers substantially reduced dose compared with the traditional retrospectively ECG gated helical scan.

• Journal of Information Technology Services
• /
• v.8 no.2
• /
• pp.147-156
• /
• 2009

As the result of the rapid development of IT technology, an on-line diagnostic system using the field bus communication network coupled with a smart sensor module will be widely used at the nuclear power plant in the near future. The smart sensor system is very useful for the prompt understanding of abnormal state of the key equipments installed in the nuclear power plant. In this paper, it is assumed that a smart sensor system based on the fieldbus communication network for the surveillance and diagnostics of safety-critical equipments will be installed in the harsh-environment of the nuclear power plant. It means that the key components of fieldbus communication system including microprocessor, FPGA, and ASIC devices, are to be installed in the RPV (reactor pressure vessel) and the RCS (reactor coolant system) area, which is the area of a high dose-rate gamma irradiation fields. Gamma radiation constraints for the DBA (design basis accident) qualification of the RTD sensor installed in the harsh environment of nuclear power plant, are typically on the order of 4 kGy/h. In order to use a field bus communication network as an ad-hoc diagnostics sensor network in the vicinity of the RCS pump area of the nuclear power plant, the robust survivability of IT-based micro-electronic components in such intense gamma-radiation fields therefore should be verified. An intelligent CCD camera system, which are composed of advanced micro-electronics devices based on IT technology, have been gamma irradiated at the dose rate of about 4.2kGy/h during an hour UP to a total dose of 4kGy. The degradation performance of the gamma irradiated CCD camera system is explained.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.16 no.5
• /
• pp.893-898
• /
• 2002

Citri Reticulatae Viride Pericarpium extract(CRVP) have been used in oriental medicine for many centuries as a therapeutic agent for smoothing the liver and regulating the circulation of qi, and promoting digestion and removing stagnated food. The effects of CRVP on the inhibition of brain damage in cerebral ischemia is not known. Therefore, this Study was designed to investigate the cerebral protective effects of CRVP on the transient cerebral ischemia using modern techniques, and further to provide the possibility of scientification of oriental medicine. The size of cerebral infarct size was measured by morphometry, and brain edema was measured by morphometry and brain water content determination. The results were a$ follows ; 1. Water fraction of CRVP was reduced infect area of rats brain slices which were subjected to a transient cerebral ischemia in a dose-dependent manner. 2. Methylene chloride fraction and hexane fraction of CRVP was significantly reduced infarct area of rats brain slices which were subjected to a transient cerebral ischemia in a dose-dependent manner. 3. Methylene chloride fraction and hexane fraction of CRVP was significantly reduced infarct volume of rats brain which was subjected to a transient cerebral ischemia in a dose-dependent manner. 4. Methylene Chloride fraction and hexane fraction of CRVP was significantly decreased brain edema induced by a transient cerebral ischemia in a dose-dependent manner. 5. Methylene chloride fraction and hexane fraction of CRVP was significantly decreased brain water content of rats which were subjected to a transient cerebral ischemia. It is suggested that CRVP has an anti-ischemic effect through the inhibition of brain damage in a transient cerebral ischemia, and that in future further development of main effective constituent in CRVP can provide a novel therapeutic strategy for cerebral ischemia.

• Korean Journal of Digital Imaging in Medicine
• /
• v.14 no.1
• /
• pp.37-42
• /
• 2012

Pediatric head and neck phantom, using the rate by focusing distance and grid images, Image J using the Quality Assessment and Dose Area Product compared. X-ray laboratory equipment due to the Philips Digital DIAGNOST a 110 cm FFD set and using ACE Non-grid, focusing distance 110 cm (12 : 1), 140 cm (12 : 1), 180 cm (8 : 1) Focused grid, Acryl Phantom (Fluke Model 76-2 Series Phantom) 15.24 cm, by resolution chart image acquisition, image evaluation program (Image J Ver. 1.4.3.67, USA) imaging experiments were analyzed using. Dose Area Product in the Non Grid 0.028 $mGy{\cdot}cm^2$, focusing distance 110 cm (12 : 1), the 0.129 $mGy{\cdot}cm^2$, 140 cm (12 : 1), the 0.135 $mGy{\cdot}cm^2$, 180 cm (8 : 1) was measured with a 0.110 $mGy{\cdot}cm^2$ Non Grid, focusing distance 110 cm (12 : 1), 140 cm (12 : 1), 180 cm (8 : 1) Image obtained when grid using the image J program focusing distance 110 cm with grid based on the measured SNR and PSNR Non Grid if the SNR the 17.307 dB, PSNR of the 20.002 dB, if the SNR 28.755 dB, PSNR was measured by the 31.451 dB. Image J image analysis through the streets, rather than focusing on grid by the rate that could see an increase in dose. Select the grid by a small dose rate reduction is possible.