• Journal of radiological science and technology
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• v.26 no.2
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• pp.37-42
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• 2003

Purpose : Computed tomographic equipment is essential for diagnosis by means of radiation. With passage of time and development of science computed tomographic was developed time and again and in future examination by means of this equipment is expected to increase. In this connection these authors measured rate of scatter ray generation at front of lead glass for patients within control room of computed tomographic equipment room and outside of entrance door for exit and entrance of patients and attempted to ind out method for minimizing exposure to scatter ray. Material and Method : From November 2001 twenty five units of computed tomographic equipments which were already installed and operation by 13 general hospitals and university hospitals in Seoul were subjected to this study. As condition of photographing those recommended by manufacturer for measuring exposure to sauter ray was use. At the time objects used DALI CT Radiation Dose Test Phantom fot Head (${\oint}16\;cm$ Plexglas) and Phantom for Stomache(${\oint}32\;cm$ Plexglas) were used. For measurement of scatter ray Reader (Radiation Monitor Controller Model 2026) and G-M Survey were used to Survey Meter of Radical Corporation, model $20{\times}5-1800$, Electrometer/Ion Chamber, S/N 21740. Spots for measurement of scatter ray included front of lead glass for patients within control room of computed tomographic equipment room which is place where most of work by gradiographic personnel are carried out and is outside of entrance door for exit and entrance of patients and their guardians and at spot 100 cm off from isocenter at the time of scanning the object. The results : Work environment within computed tomography room which was installed and under operation by each hospital showed considerable difference depending on circumstances of pertinent hospitals and status of scatter ray was as follows. 1) From isocenter of computed tomographic equipment to lead glass for patients within control room average distance was 377 cm. At that time scatter ray showed diverse distribution from spot where no presence was detected to spot where about 100 mR/week was detected. But it met requirement of weekly tolerance $2.58{\times}10^{-5}\;C/kg$(100 mR/week). 2) From isocenter of computed tomographic equipment to outside of entrance door where patients and their guardians exit and enter was 439 cm in average, At that time scatter ray showed diverse distribution from spot where almost no presence was detected to spot with different level but in most of cases it satisfied requirement of weekly tolerance of $2.58{\times}10^{-6}\;C/kg$(100 mR/week). 3) At the time of scanning object amount of scatter ray at spot with 100 cm distance from isocenter showed considerable difference depending on equipments. Conclusion : Use of computed tomographic equipment as one for generation of radiation for diagnosis is increasing daily. Compared to other general X-ray photographing field of diagnosis is very high but there is a high possibility of exposure to radiation and scatter ray. To be free from scatter ray at computed tomographic equipment room even by slight degree it is essential to secure sufficient space and more effort should be exerted for development of variety of skills to enable maximum photographic image at minimum cost.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.289-295
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• 2018

Most diagnostic devices in the medical field use X-ray sources, which emit energy spectra. In radiological diagnosis, the quantitative and qualitative analyses of X-rays are essential for maintaining the image quality and minimizing the radiation dose to patients. This work aims to obtain the X-ray energy spectra used in diagnostic imaging by Monte Carlo simulation. Various X-ray spectra are simulated using a Monte Carlo simulation tool. These spectra are then compared to the reference data obtained with a tungsten anode spectral model using the interpolating polynomial (TASMIP) code. The X-ray tube voltages used are 50, 60, 80, 100, and 110 kV, respectively. CdTe and a-Se detector are used as the detectors for obtaining the X-ray spectra. Simulation results demonstrate that the various X-ray spectra are well matched with the reference data. Based on the simulation results, an appropriate X-ray spectrum, in accordance with the tube voltage, can be selected when generating an image for diagnostic imaging. The dose to be delivered to the patient can be predicted prior to examination in the diagnostic field.

• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.389-395
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• 2013

This study intended to investigate the optimum conditions for lumbar test that has the highest level of irradiation conditions among general test sites. To to this, the most widely used irradiation conditions in terms of statistics were set as standards; test groups applied with DMF were selected; tests groups suitable for clinical trials were selected by using suggested patient dose. Blind tests were conducted by 10 specialists and radiologists. The results suggested that under the optimum conditions, the radiation dose reduction of 2.09 mGy, 4.42 mGy and 3.65 mGy can be achieved in forward-backward test, lateral test and 4-direction test, respectively. There is a need of further studies on the optimization of irradiation conditions in accordance with the conditions of patients.

• Journal of Yeungnam Medical Science
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• v.8 no.1
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• pp.166-177
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• 1991

Uterine cervical cancer is the most common malignancy in korean women. In spite of recent development of early diagnostic and therapeutic modalities, about 40% of treated patient will develop relapse. So more aggressive local treatment such as more extensive surgery and higher radiation dose and administration of systemic chemotherapy will promote the curability but treatment related complications can not be avoidable. We used 22 cases of early cervical cancer, treated with surgery and post-operative radiotherapy, clinical data of these patients were analized to determine relationship between clinical parameters and final outcome. Three out of 22 cases revealed relapse and one patient showed rectovaginal fistula and another patient showed small bowel obstruction and the other patient showed rectal obstruction. Two out of three recurrence were stage IIa and the other one case was stage Ib adenocarcinoma with lymphovascular involvement. Nineteen out of 22 cases were followed without remarkable side effect or treatment related complication or sequelae. We concluded that our treatment policy was safe and effective to eradicate high risk postoperative cervical cancer with acceptable side effects or complication.

• Progress in Medical Physics
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• v.26 no.3
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• pp.168-177
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• 2015

For evaluating the treatment planning accurately, the quality assurance for treatment planning is recommended when patients were treated with IMRT which is complex and delicate. To realize this purpose, treatment plan quality assurance software can be used to verify the delivered dose accurately before and after of treatment. The purpose of this study is to evaluate the accuracy of treatment plan quality assurance software for each IMRT plan according to MLC DLG (dosimetric leaf gap). Novalis Tx with a built-in HD120 MLC was used in this study to acquire the MLC dynalog file be imported in MobiusFx. To establish IMRT plan, Eclipse RTP system was used and target and organ structures (multi-target, mock prostate, mock head/neck, C-shape case) were contoured in I'mRT phantom. To verify the difference of dose distribution according to DLG, MLC dynalog files were imported to MobiusFx software and changed the DLG (0.5, 0.7, 1.0, 1.3, 1.6 mm) values in MobiusFx. For evaluation dose, dose distribution was evaluated by using 3D gamma index for the gamma criteria 3% and distance to agreement 3 mm, and the point dose was acquired by using the CC13 ionization chamber in isocenter of I'mRT phantom. In the result for point dose, the mock head/neck and multi-target had difference about 4% and 3% in DLG 0.5 and 0.7 mm respectively, and the other DLGs had difference less than 3%. The gamma index passing-rate of mock head/neck were below 81% for PTV and cord, and multi-target were below 30% for center and superior target in DLGs 0.5, 0.7 mm, however, inferior target of multi-target case and parotid of mock head/neck case had 100.0% passing rate in all DLGs. The point dose of mock prostate showed difference below 3.0% in all DLGs, however, the passing rate of PTV were below 95% in 0.5, 0.7 mm DLGs, and the other DLGs were above 98%. The rectum and bladder had 100.0% passing rate in all DLGs. As the difference of point dose in C-shape were 3~9% except for 1.3 mm DLG, the passing rate of PTV in 1.0 1.3 mm were 96.7, 93.0% respectively. However, passing rate of the other DLGs were below 86% and core was 100.0% passing rate in all DLGs. In this study, we verified that the accuracy of treatment planning QA system can be affected by DLG values. For precise quality assurance for treatment technique using the MLC motion like IMRT and VMAT, we should use appropriate DLG value in linear accelerator and RTP system.

• Journal of the Korean Society of Radiology
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• v.83 no.3
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• pp.669-679
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• 2022

Purpose To evaluate the feasibility of pediatric low-dose facial CT reconstructed with filtered back projection (FBP) using adequate kernels. Materials and Methods We retrospectively reviewed the clinical and imaging data of children aged < 10 years who underwent facial CT at our emergency department. The patients were divided into two groups: low-dose CT (LDCT; Group A, n = 73) with a fixed 80-kVp tube potential and automatic tube current modulation (ATCM) and standard-dose CT (SDCT; Group B, n = 40) with a fixed 120-kVp tube potential and ATCM. All images were reconstructed with FBP using bone and soft tissue kernels in Group A and only bone kernel in Group B. The groups were compared in terms of image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Two radiologists subjectively scored the overall image quality of bony and soft tissue structures. The CT dose index volume and dose-length product were recorded. Results Image noise was higher in Group A than in Group B in bone kernel images (p < 0.001). Group A using a soft tissue kernel showed the highest SNR and CNR for all soft tissue structures (all p < 0.001). In the qualitative analysis of bony structures, Group A scores were found to be similar to or higher than Group B scores on comparing bone kernel images. In the qualitative analysis of soft tissue structures, there was no significant difference between Group A using a soft tissue kernel and Group B using a bone kernel with a soft tissue window setting (p > 0.05). Group A showed a 76.9% reduction in radiation dose compared to Group B (3.2 ± 0.2 mGy vs. 13.9 ± 1.5 mGy; p < 0.001). Conclusion The addition of a soft tissue kernel image to conventional CT reconstructed with FBP enables the use of pediatric low-dose facial CT protocol while maintaining image quality.

• Molecular & Cellular Toxicology
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• v.1 no.2
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• pp.124-129
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• 2005

Pro-inflammatory cytokines, such as tumor necrosis factor $(TNF)-{\alpha}$, interleukin-12 (IL-12) and interleukin $(IL-1)-{\beta}$, play a key role in causing inflammatory diseases, which are rheumatoid arthritis, Crohn's disease and sepsis. Accumulating evidences suggest that low level laser irradiation (LLLI) may have an anti-inflammatory action. However, there are few data regarding down regulation of Th1 immune response by using the diod typed laser emitting device for human patients. As a fundamental step in order to address this issue, we investigated immunological impact of the low level laser irradiation (10 mw laser diode with a wavelength of 630 nm) on expression of pro-inflammatory cytokines in murine immunocytes (splenocytes and peritoneal macrophages) in vitro. The LLLI on lipopolysaccharide (LPS 100 ng/ml)-stimulated murine splenocytes and macrophages, clearly down regulated mRNA expression of $TNF-{\alpha}$ and IL-12 in dose-dependent manner. In addition, LLLI significantly inhibits the NO production in the LPS-stimulated murine macrophages. This data suggests that LLLI (wavelength of 630 nm) may exert an anti-inflammatory action via modulation of pro-inflammatory cytokine and NO production pathway.

• Journal of radiological science and technology
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• v.19 no.1
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• pp.81-87
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• 1996

When high energy photon beam is incident upon an air cavity interface the effect of ionization build-up observed. This phenomenon is resulting from the surface layers of the lesions are significant deficiency of electrons reaching the layers because of the replacement of solid scattering material by the air cavity, that is lack of electronic equilibrium. Measurement have been made in an acrylic phantom with a parallel plate chamber and high energy Photon beams, CO-60, 4MV, 6MV and 10MV X-rays have been investigated. The result of our study show that a significant effect was measured and was determined to be very dependent on field size, air cavity dimension and photon energy. The reductions were much larger for 10MV beam, underdosage at the interface was 12, 12.2, 16.9 and 20.6% for the CO-60, 4 MV, 6MV and 10MV, respectively. It was found that this non-equilibrium effect at the interface is more severe for the higher energy beams than that of lower energy beams and the larger cavity dimensions it is, the larger beam reductions we have. This problem is of clinical concern when lesions such as carcinoma beyond air cavities are irradiated, such as larynx, glottic and the patients with maxillectomy and ethmoidectomy and so forth.

• The Korean Journal of Nuclear Medicine
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• v.24 no.2
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• pp.307-316
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• 1990

Irradiation is widely used for the treatment of malignant diseases, and possibly cause the osteoporosis. The densitometry and bone scintigraphy are valuable when used to monitor the patients longitudinally to access the progression of osteoporosis and risk of osteoradionecrosis. To evaluate the osteoporosis after irradiation of Cobalt-60 gamma ray on the lumbar spines of New Zealand white rabbits, bone densitometry by dual photon absorptiometry and bone scintigraphy were performed weekly. The decrease of bone density began at the first week after irradiation, and were in the nadir at 4-6th week. The osteoblastic activity measured by bone scintigraphy decreased in the first week, and was in the nadir at 4-6th week. The severity of these changes were related to the radiation dose. In conclusion, the osteoporosis before the presentation of the osteoradionecrosis can be diagnosed early with the dual photon absorptionmetry and bone scintigraphy.

• Korean Journal of Head & Neck Oncology
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• v.4 no.1
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• pp.13-19
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• 1988

Brachytherapy is known to be a good modality to achieve local control as a boost treatment following limited external irradiation, which may reduce the external beam related acute radiation sickness, particularly in head and neck cancer. The authors developed iridium-192 ribbons recently to replace the radium needles. Total of 13 head and neck cancer patients had been treated with Ir-192 ribbons during last one year from October 1986 to September 1987, and the results were analysed to assess the applicability of the fabricated sources. The conclusion is as follows; 1) Iridium implant achieved 54% (7/13) of complete response and 69% (9/13) of overall response rate in head and neck cancer. 2) Iridium is superior to radium and cecium in brachytherapy because of easier to use and lesser exposure to the personnel. 3) Afterloading technique is useful to modify dose distribution, to expand treatment site and method, and to develop interstitial hyperthermia.