• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.294-297
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• 2002

For the quality control procedure of diagnostic x ray units, a method for simultaneous measurement of air kerma, half value layer and tube potential was developed utilizing a computed radiography system for intraoral radiography and film badge case. The response of average pixel values under the windows were calibrated by x rays generated at tube potentials from 40 to 140 kV with filtration from 1.5 to 3.7 mmAl. The calibration curves for half value layer and tube potential were derived as functions of attenuation factors by the 1.4 mmAl filter and the 0.2 mmCu filter. The energy dependency of the open window response was corrected by the calibration factor as a function of the attenuation factor by the 1.4 mmAl filter. The uncertainty of the estimated half value layer, tube potential and air kerma were 0.2 mmAl, 3.6 % and 5 %, respectively. It was thus suggested that this system could be applied to quality control program to detect the variation of working condition of x ray units in clinical use.

• Journal of Korean Neurosurgical Society
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• v.29 no.3
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• pp.317-323
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• 2000

Objective : To evaluate the role of stereotactic LINAC radiosurgery in treatment of meningiomas, the authors retrospectively analyzed the result of radiosurgery in our institute. Method: During last ten years, twenty patients underwent stereotactic LINAC radiosurgery(LINAC SRS) for meningiomas. The mean age of the patients was 51 years(22-78 years). The most common tumor location for radiosurgery was parasagittal, sphenoid wing and tentorial area. With regards to indications of radiosurgery for meningiomas, LINAC radiosurgery was done for primary treatment in six patients, for postoperative residual tumors in eleven patients, for postoperative regrowth in three patients. Mean tumor volume was $5.14cm^3$($0.28-15.1cm^3$), mean field diameter was 2.01cm(1.2-3cm). The mean marginal dose was 20.55Gy(13-30Gy). The follow-up evaluation was done annually with radiologic findings and clinical status. The mean follow-up period was 46.8(24-120) months. Result : In the radiologic response, the tumor volume was reduced in five(25%) of twenty patients, fourteen showed arrested growth(70%), but one patient showed increased growth(5%). In the clinical response, nine patients improved clinically(45%), ten patients was stable(50%) and one patient worsened during follow-up period. With regards to correlation with radiologic and clinical response, in nineteen patients who showed radiologic response to radiosurgery(decreased and arrested growth after radiosurgery), nine patients(47.4%) improved and ten patients (52.6%) showed no change, one patient(5%) had symptomatic radiation necrosis at four years after SRS, which needed craniotomy. Conclusion : The overall control rate of meningiomas with LINAC radiosurgery was 95% in radiologic follow up and 95% clinically. The radiation complication rate was 5%. These results indicate that LINAC radiosurgery can be considered as safe and effective method for meningiomas.

• Journal of radiological science and technology
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• v.25 no.1
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• pp.73-76
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• 2002

In order to evaluate the exposure to the radiologic technologists from patients who had been administrated with radiopharmaceuticals, we measured the spatial dose rates at 5 cm, 50 cm, and 100 cm from skin surface of patients using an proportional digital surveymeter, both 5 min after injection and right before the studies. In results, the exposure to the technologists in each procedure was small, compared nth the dose limits of the medical workers. However, the dose-response relationships in cancer and hereditary effects, referred to as the stochastic effects, have been assumed linear and no threshold models ; therefore, the exposure should be minimized. For this purpose, the measurements of spatial dose rate distributions were thought to be useful.

• Korean Journal of Digital Imaging in Medicine
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• v.11 no.2
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• pp.93-99
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• 2009

This conclusion was from the 3rd grade students of radiologic technology of Daegu Health College who already taken the hospital practice. 231 students answer our question and this study used sampling method. The contents of Questionnaire consisted of normal facts of respondent, Training satisfaction, Training Methods, Practice Environment of Hospital, Problem in Practice Hospital, Before and after views, etc. The statistical program SPSS/Win 10.0 version was used to see the results of the survey data used in. The response contents of brief question were separetely checked and clean.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.5
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• pp.2003-2007
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• 2015

Background: Elevated serum alpha-fetoprotein (AFP) levels in adults are considered abnormal. This parameter is used mostly in the diagnosis and follow-up of hepatocellular carcinomas and yolk sac tumors. Among the other rare tumors accompanied with elevated serum AFP levels, gastric cancer is the most common. In this study, we evaluated the follow-up and comparison of the treatment and marker response of patients with metastatic gastric cancer who had elevated serum AFP levels. Materials and Methods: We performed a retrospective study, including all consecutive patients with advanced gastric cancer, who received systemic chemotherapy with elevated AFP level. Results: Seventeen metastatic gastric cancer patients with elevated AFP levels at the time of diagnosis were evaluated. Fourteen (82.4%) were males and three (17.6%) were females. The primary tumor localization was the gastric body in 8 (76.4%), cardia in 7 (41.2%), and antrum in 2 (11.8%). Hepatic metastasis was observed in 13 (76.4%) at the time of diagnosis. When the relationship of AFP levels and carcinoembryonic antigen (CEA) response of the patients with their radiologic responses was evaluated, it was found that the radiologic response was compatible with AFP response in 16 (94.1%) patients and with CEA response in 12 (70.6%); however, in 5 (29.4%) patients no accordance was observed between radiological and CEA responses. Conclusions: Follow-up of AFP levels in metastatic gastric cancer patients with elevated AFP levels may allow prediction of early treatment response and could be more useful than the CEA marker for follow-up in response evaluation.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.463-470
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• 2015

The angular dependence of active dosimeters, EPD, is analysed and compared with that of passive dosimeters, OSLD, after evaluating their relative response and uncertainty of measurement, where it is known that the personal use of them has been increased recently. There appeared a minor variation for average relative response of OSLD in the horizontal and vertical directions within the range $0^{\circ}{\sim}{\pm}90^{\circ}$, which are 0.97 and 0.95 respectively. The variations of angular dependence in the same situations with OSLD are 0.65 and 0.62, respectively, which also reveals a negligible effect on the overall uncertainty. EPDs within the interval $0^{\circ}{\sim}{\pm}60^{\circ}$ for horizontal and vertical directions are 0.94 and 0.97, respectively. These satisfy the requirements of IEC 61526. Uncertainties about the dependence of direction from horizontal and vertical directions are 0.44, 0.40, respectively. The impact of these uncertainties on the overall uncertainty was negligible. However, we observed a significant change in reactivity: the relative reactivities for $+90^{\circ}$ and $-90^{\circ}$ from the horizontal direction are 0.60, 0.37, while that form vertical direction is 0.06. The direction dependence of OSLD was superior to EPD in the range of $0^{\circ}{\sim}{\pm}90^{\circ}$. There appeared a rapidly changing structural features in EPD response for a certain direction. Therefore, we conclude that concurrent use of passive dosimeters and auxiliary dosimeter provides accurate data for personal dose measurements.

• Korean Journal of Radiology
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• v.25 no.6
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• pp.550-558
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• 2024

Hepatocellular carcinoma (HCC) is a biologically heterogeneous tumor characterized by varying degrees of aggressiveness. The current treatment strategy for HCC is predominantly determined by the overall tumor burden, and does not address the diverse prognoses of patients with HCC owing to its heterogeneity. Therefore, the prognostication of HCC using imaging data is crucial for optimizing patient management. Although some radiologic features have been demonstrated to be indicative of the biologic behavior of HCC, traditional radiologic methods for HCC prognostication are based on visually-assessed prognostic findings, and are limited by subjectivity and inter-observer variability. Consequently, artificial intelligence has emerged as a promising method for image-based prognostication of HCC. Unlike traditional radiologic image analysis, artificial intelligence based on radiomics or deep learning utilizes numerous image-derived quantitative features, potentially offering an objective, detailed, and comprehensive analysis of the tumor phenotypes. Artificial intelligence, particularly radiomics has displayed potential in a variety of applications, including the prediction of microvascular invasion, recurrence risk after locoregional treatment, and response to systemic therapy. This review highlights the potential value of artificial intelligence in the prognostication of HCC as well as its limitations and future prospects.

• The Korean Journal of Pain
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• v.2 no.2
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• pp.198-202
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• 1989

The Tolosa-Hunt syndrome is one of the rare disease with facial, especially peri-orbital pain, and ophthalomoplegia associated mostly with granulomatous lesions in cavernous sinus or superior orbital fissure. In addition to ophthalmoplegia by multiple cranial nerve involvement, the sympathetic nervous system may also be involved leading to Horner's syndrome. A typical Tolosa-Hunt syndrome has a neuro-radiologic finding of an increased density in the involved region, and a laboratory finding of an elevated ESR, as well as a dramatic response to systemic corticosteroid therapy. An unusual case of the Tolosa-Hunt syndrome with normal radiologic and laboratory findings, unresponsive to systemic corticosteroid, and some response of pain relief to a stellate ganglion block, is presented.

• Journal of radiological science and technology
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• v.35 no.4
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• pp.309-314
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• 2012

Nowadays, digital Radiography (DR) systems are widely used in clinical sites and substitute the analog-film x-ray imaging systems. The resolution of DR images depends on several factors such as characteristic contrast and motion of the object, the focal spot size and the quality of x-ray beam, x-ray scattering, the performance of the DR detector (x-ray conversion efficiency, the intrinsic resolution). The DR detector is composed of an x-ray capturing element, a coupling element and a collecting element, which systematically affect the system resolution. Generally speaking, the resolution of a medical imaging system is the discrimination ability of anatomical structures. Modulation transfer function (MTF) is widely used for the quantification of the resolution performance for an imaging system. MTF is defined as the frequency response of the imaging system to the input of a point spread function and can be obtained by doing Fourier transform of a line spread function, which is extracted from a test image. In clinic, radiologic technologists, who are in charge of system maintenance and quality control, have to evaluate or make routine check on their imaging system. However, it is not an easy task for the radiologic technologists to measure MTF accurately due to lack of their engineering and mathematical backgrounds. The objective of this study is to develop and provide for radiologic technologists a medical system imaging evaluation tool, so that they can measure and quantify system performance easily.

• Journal of Korean Neurosurgical Society
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• v.55 no.1
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• pp.5-11
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• 2014

Objective : We evaluated pseudoprogression (PsPD) following radiation therapy combined with concurrent temozolomide (TMZ), and we assessed pseudoresponse following anti-angiogenic therapy for patients with recurrent disease using the Response Assessment of the Neuro-Oncology Working Group. Methods : Patients who were pathologically confirmed as having high-grade glioma received radiotherapy with concurrent TMZ followed by adjuvant TMZ. Bevacizumab (Avastin) with CPT-11 were used as a salvage option for cases of radiologic progression. Magnetic resonance imaging (MRI) was routinely performed 1 month after concurrent radiochemotherapy (CRT) and every 3 months thereafter. For cases treated with the bevacizumab-containing regimen for progressive disease, MRI was performed every 2 months. Results : Of 55 patients, 21 (38%) showed radiologic progression within 4 weeks after CRT. Of these patients, 16 (29%) showed progression at second post-CRT MRI (etPD) and five (9%) showed improvement (PsPD). Seven of thirty-four initially non-progressed patients showed progression at the second post-CRT MRI (ltPD). No difference in survival was observed between the etPD and ltPD groups (p=0.595). Five (50%) of ten patients showed a radiological response after salvage bevacizumab therapy. Four of those patients exhibited rapid progression immediately after discontinuation of the drug (drug holiday). Conclusion : Twelve weeks following treatment could be the optimal timing to determine PsPD or true progression. MRI with gadolinium enhancement alone is not sufficient to characterize tumor response or growth. Clinical correlation with adequate follow-up duration and histopathologic validation may be helpful in discriminating PsPD from true progression.