• Radiation Oncology Journal
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• v.21 no.2
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• pp.158-166
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• 2003

Purpose: To propose a conceptual design of a novel source for intensity modulated brachytherapy. Materials and Methods: The source design incorporates both radioactive and shielding materials (stainless steel or tungsten), to provide an asymmetric dose intensity in the azimuthal direction. The intensity modulated intravascular brachytherapy was performed by combining a series of dwell positions and times, distributed along the azimuthal coordinates. Two simple designs for the beta-emitting sources, with similar physical dimensions to a $^{90}Sr/Y$ Novoste Beat-Cath source, were considered in the dosimetric feasibility study. In the first design, the radioactive and materials each occupy half of the cylinder and in the second, the radioactive material occupies only a quater of the cylinder. The radial and azimuthal dose distributions around each source were calculated using the MCNP Monte Carlo code. Results: The preliminary hypothetical simulation and optimization results demonstrated the 87$\%$ difference between the maximum and minimum doses to the lumen wall, due to off-centering of the radiation source, could be reduced to less than 7$\%$ by optimizing the azimuthal dwell positions and times of the partially shielded intravascular brachytherapy sources. Conclusion: The novel brachytherapy source design, and conceptual source delivery system, proposed in this study show promising dosimetric characteristics for the realization of intensity modulated brachytherapy in intravascular treatment. Further development of this concept will center on building a delivery system that can precisely control the angular motion of a radiation source in a small-diameter catheter.

• Journal of the Korean Society of Radiology
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• v.82 no.3
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• pp.512-526
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• 2021

Peripheral arterial disease is an occlusive condition commonly involving the lower extremity vessels. When the aortoiliac region is affected by this disease, conventional management involves surgical bypass and endovascular treatment has been mainly recommended for patients with focal and simple lesions. It has been common strategy to perform endovascular treatment for selected patients with high surgical risk due to its minimally invasive nature. However, recent advances in the devices and techniques for endovascular treatment have resulted in its utilization for treating patients with various disease status and its clinical outcomes are comparable to those of conventional surgery. This review discusses the current diagnostic strategies for peripheral artery disease in the aortoiliac region, followed by the introduction of techniques and devices, and the role of endovascular treatment.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.1
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• pp.25-31
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• 2009

Purpose: Evaluate the mold we have made to improve the reproducibility of the patient position and make homogeneous dose distribution to the treatment volume effectively when treating the patient who has hypervascular ulcer on her tongue caused by paraneoplastic autoimmune multiorgan syndrome by mold brachytherapy. Materials and Methods: The mold is consisted of upper and lower parts. We inserted 2 mm of lead sheet on the gums toward the oral cavity to protect them from unnecessary irradiation during the treatment. We had planned on orthogonal images obtained the patient. 200 cGy was delivered in every fraction with a total dose of 3000 cGy. To evaluate the effect of the lead sheet, we made a measurement with a phantom that has gums and tongue made of tissue with an equivalent material (bolus). Five of TLDs were placed on the interesting points of gums to measure the dose during irradiation with lead sheet and without lead sheet for three times respectively. Results: The result of the measurement without lead sheet are A: 33.9 cGy, B: 30.1 cGy, C: 31.8 cGy, D: 23.3 cGy, E: 24.1 cGy. The results of measurement with lead sheet are A: 20.6 cGy, B: 18.8 cGy, C: 19.6 cGy, D: 14.7 cGy, E: 15.1 cGy. Conclusion: Since we are using the mold made in our department during the treatment of the patient with hypervascular ulcer on tongue, we could deliver a proper dose to the treatment volume. In addition, the mold provided highly accurate and reproducible treatment and reduced the dose to the gums and teeth. Therefore, the possibility of side effects could be decreased significantly.

• Radiation Oncology Journal
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• v.17 no.1
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• pp.43-51
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• 1999

Purpose : To discuss the technical aspect of interstitial brachytherapy including method of implant, insertion time of radioactive source, total radiation dose, and complication, we reviewed patients who had diagnoses of soft tissue sarcoma and were treated by conservative surgery, interstitial implant and external beam radiation therapy Materials and Methods : Between May 1995 and Dec. 1997, ten patients with primary or recurrent soft tissue sarcoma underwent surgical resection (wide margin excision) and received radiotherapy including interstitial brachytherapy. Catheters were placed with regular intervals of 1 ~l.5 cm immediately after tumor removal and covering the critical structures, such as neurovascular bundle or bone, with gelform, muscle, or tissue expander in the cases where the tumors were close to those structures. Brachytherapy consisted of high dose rate, iridium-192 implant which delivered 12~15 Gy to 1 cm distance from the center of source axis with 2~2.5 Gy/fraction, twice a day, starting on 6th day after the surgery, Within one month after the surgery, total dose of 50~55 Gy was delivered to the tumor bed with wide margin by the external beam radiotherapy. Results : All patients completed planned interstitial brachytherapy without acute side effects directly related with catheter implantation such as infection or bleeding. With median follow up duration of 25 months (range 12~41 months), no local recurrences were observed. And there was no severe form of chronic complication (RTOGIEORTC grade 3 or 4). Conclusion : The high dose rate interstitial brachytherapy is easy and safe way to minimize the radiation dose delivered to the adjacent normal tissue and to decrease radiation induced chronic morbidity such as fibrosis by reducing the total dose of external radiotherapy in the management of soft tissue sarcoma with conservative surgery.

• 대한핵의학회:학술대회논문집
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• 1999.05a
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• pp.209-221
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• 1999

Coronary restenosis is still regarded as Achilles' Hill of interventional cardiology despite relentless efforts of many investigators. Recent experimental and clinical studies have suggested that both gamma and beta radiation can reduce restenosis after angioplasty. Currently, intracoronary brachytherapy for the prevention of restenosis has become a new evolving treatment modality in interventional cardiology. This report discusses a physical aspect of gamma and beta radiation, initial clinical results and delivery systems used in intracoronary brachytherapy. We shall take a brief overview of methods and their advantages in intra-coronary brachytherapy. Future work should provide further insight for the best way of treating restenosis.

• 대한핵의학회:학술대회논문집
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• 2001.05a
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• pp.24-34
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• 2001

Restenosis remains a major limitation of percutaneous coronary interventions. Numerous studios including pharmacological approaches and new devices failed to reduce the restenosis rate except coronary stenting. Since the results of $BENESTENT^{1)}\;and\;STRESS^{2)}$ studies came out, coronary stenting has been the most popular interventional strategy in the various kinds of coronary stenotic lesions, although the efficacy of stenting was shown only in the discrete lesion of the large coronary artery. The widespread use of coronary stenting has improved the early and late outcomes after coronary intervention, but it has also led to a new and serious problem, e.g., in-stent restenosis. Intravascular radiation for prevention of restenosis is a new technology in the field of percutaneous coronary intervention. Recent animal experiments and human trials have demonstrated that local irradiation, in conjunction with coronary interventions, substantially diminished the rate of restenosis. This paper reviews basic radiation biology of intracoronary radiation and its role in the inhibition of restenosis. The current status of intracoronary radiation therapy using Re-188 liquid balloon is also discussed.

• Pediatric Infection and Vaccine
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• v.10 no.2
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• pp.186-192
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• 2003

Purposes : Recently, acute gastroenteritis broke out among the neonates transferred from postpartum care centers located in Seoul, and Gyeounggi area. Thus, we researched the cause, progress and characters of the disease by analyzing the cases from 9 hospitals in Seoul and Gyeounggi area. Methods : We conducted retrospective study of 33 neonates transferred from postpartum care centers from October 2001 to July 2002 : we divided the neonates into 2 groups. The severe group had any of following 5 conditions : blood pH <7.20, respiratory difficulty, mechanical ventilation, shock, and disseminated intravascular coagulation. And the rest were classified into the moderate group. Results : The severe group was significantly more aged than the moderate group(P= 0.005). Weight loss was significantly severe in the severe group(P=0.0512). In blood gas analysis, bicarbonate was less in the severe group than the moderate group(P=0.032). In the virus examination, rotavirus was detected in 7 cases, and astrovirus was detected in 1 case. In the severe group, 4 neonates were dead. Conclusion : In acute gastroenteritis of neonates, early diagnosis and treatment are important. Thus, the legislation of postpartum care center is needed, and the medical specialists should be stationed in postpartum care center. We assume that the severe group had severe conditions because they were treated comparatively late. However, to find out the cause of the disease and to cope with it, the nationwide epidemiologic study on acute gastrenteritis of neonates is needed.

• Progress in Medical Physics
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• v.14 no.3
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• pp.167-174
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• 2003

In the radiation treatment planning (RTP) process, especially for stereotactic radiosurgery (SRS), knowing the exact volume and shape and the precise position of a lesion is very important. Sometimes X-ray projection images, such as angiograms, become the best choice for lesion identification. However, while the exact target position can be acquired by bi-projection images, 3D target reconstruction from bi-projection images is considered to be impossible. The aim of this study was to reconstruct the 3D target volume from multiple projection images. It was assumed that we knew the exact target position in advance, and all processes were performed in Target Coordinates, where the origin was the center of the target. We used six projections: two projections were used to make a Reconstruction Box and four projections were for image acquisition. The Reconstruction Box was made up of voxels of 3D matrices. Projection images were transformed into 3D in this virtual box using a geometric back-projection method. The resolution and the accuracy of the reconstructed target volume were dependent on the target size. An algorithm was applied to an ellipsoid model and a horseshoe-shaped model. Projection images were created geometrically using C program language, and reconstruction was also performed using C program language and Matlab ver. 6(The Mathwork Inc., USA). For the ellipsoid model, the reconstructed volume was slightly overestimated, but the target shape and position proved to be correct. For the horseshoe-shaped model, reconstructed volume was somewhat different from the original target model, but there was a considerable improvement in determining the target volume.

• Journal of Chest Surgery
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• v.32 no.4
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• pp.388-393
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• 1999

Background: Correct preoperative staging of esophageal cancer is a prerequisite for adequate treatment. We prospectively compared the accuracy of positron emission tomography (PET) with [fluorine-18]FDG in the staging of esophageal cancer to that of computed tomography (CT). Material and Method: The findings of FDG PET and of chest CT including lower neck and the upper abdomen of 20 biopsy-proven squamous cell carcinoma patients (male, 19; female, 1; mean age, 61) were compared with the pathologic findings obtained from a curative esophagectomy with lymph node dissection. Result: The sensitivities of FDG PET and CT for diagnosis of primary tumor were the same, 90.0% (18/20). Both FDG PET and CT failed to show the primary tumor in 2 of 20 patients; one had a 1cm sized carcinoma in situ and the other had T1 stage cancer. By using the results of the pathologic examinations of 193 removed lymph node groups, we calculated the diagnostic sensitivities, specificities and accuracies of PET and CT (*$\chi$2 p < 0.005). Sensitivity** Specificity Accuracy* PET 55.6%(30/54) 97.1%(135/139) 85.5%(165/193) CT 13.0%(7/54) 98.6%(137/139) 74.6%(144/193) One of four patients with a false-positive for PEThad had active pulmonary tuberculosis. Among the 24 tumor involved lymph node groups, PET failed to show tumor metastasis in 5 lymph node groups abutting the tumor and in 14 lymph node groups located where the decay correction was not performed. Conclusion: Based on the above findings, it is suggested that [F-18]FDG-PET is superior to CT in the detection of nodal metastases and in the staging of patients with esophageal cancer.