• Radiation Oncology Journal
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• v.19 no.1
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• pp.53-65
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• 2001

Purpose : To improve the local control of patients with nasopharyngeal cancer, we have implemented 3-D conformal radiotherapy and forward intensity modulated radiation therapy (IMRT) to used of compensating filters. Three dimension conformal radiotherapy with intensity modulation is a new modality for cancer treatments. We designed 3-D treatment planning with 3-D RTP (radiation treatment planning system) and evaluation dose distribution with tumor control probability (TCP) and normal tissue complication probability (NTCP). Material and Methods : We have developed a treatment plan consisting four intensity modulated photon fields that are delivered through the compensating tilters and block transmission for critical organs. We get a full size CT imaging including head and neck as 3 mm slices, and delineating PTV (planning target volume) and surrounding critical organs, and reconstructed 3D imaging on the computer windows. In the planning stage, the planner specifies the number of beams and their directions including non-coplanar, and the prescribed doses for the target volume and the permissible dose of normal organs and the overlap regions. We designed compensating filter according to tissue deficit and PTV volume shape also dose weighting for each field to obtain adequate dose distribution, and shielding blocks weighting for transmission. Therapeutic gains were evaluated by numerical equation of tumor control probability and normal tissue complication probability. The TCP and NTCP by DVH (dose volume histogram) were compared with the 3-D conformal radiotherapy and forward intensity modulated conformal radiotherapy by compensator and blocks weighting. Optimization for the weight distribution was peformed iteration with initial guess weight or the even weight distribution. The TCP and NTCP by DVH were compared with the 3-D conformal radiotherapy and intensitiy modulated conformal radiotherapy by compensator and blocks weighting. Results : Using a four field IMRT plan, we have customized dose distribution to conform and deliver sufficient dose to the PTV. In addition, in the overlap regions between the PTV and the normal organs (spinal cord, salivary grand, pituitary, optic nerves), the dose is kept within the tolerance of the respective organs. We evaluated to obtain sufficient TCP value and acceptable NTCP using compensating filters. Quality assurance checks show acceptable agreement between the planned and the implemented MLC(multi-leaf collimator). Conclusion : IMRT provides a powerful and efficient solution for complex planning problems where the surrounding normal tissues place severe constraints on the prescription dose. The intensity modulated fields can be efficaciously and accurately delivered using compensating filters.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.41-52
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• 2002

Purpose : 3D conformal radiotherapy, the optimum dose delivered to the tumor and provided the risk of normal tissue unless marginal miss, was restricted by organ motion. For tumors in the thorax and abdomen, the planning target volume (PTV) is decided including the margin for movement of tumor volumes during treatment due to patients breathing. We designed the respiratory gating radiotherapy device (RGRD) for using during CT simulation, dose planning and beam delivery at identical breathing period conditions. Using RGRD, reducing the treatment margin for organ (thorax or abdomen) motion due to breathing and improve dose distribution for 3D conformal radiotherapy. Materials and Methods : The internal organ motion data for lung cancer patients were obtained by examining the diaphragm in the supine position to find the position dependency. We made a respiratory gating radiotherapy device (RGRD) that is composed of a strip band, drug sensor, micro switch, and a connected on-off switch in a LINAC control box. During same breathing period by RGRD, spiral CT scan, virtual simulation, and 3D dose planing for lung cancer patients were peformed, without an extended PTV margin for free breathing, and then the dose was delivered at the same positions. We calculated effective volumes and normal tissue complication probabilities (NTCP) using dose volume histograms for normal lung, and analyzed changes in doses associated with selected NTCP levels and tumor control probabilities (TCP) at these new dose levels. The effects of 3D conformal radiotherapy by RGRD were evaluated with DVH (Dose Volume Histogram), TCP, NTCP and dose statistics. Results : The average movement of a diaphragm was 1.5 cm in the supine position when patients breathed freely. Depending on the location of the tumor, the magnitude of the PTV margin needs to be extended from 1 cm to 3 cm, which can greatly increase normal tissue irradiation, and hence, results in increase of the normal tissue complications probabiliy. Simple and precise RGRD is very easy to setup on patients and is sensitive to length variation (+2 mm), it also delivers on-off information to patients and the LINAC machine. We evaluated the treatment plans of patients who had received conformal partial organ lung irradiation for the treatment of thorax malignancies. Using RGRD, the PTV margin by free breathing can be reduced about 2 cm for moving organs by breathing. TCP values are almost the same values $(4\~5\%\;increased)$ for lung cancer regardless of increasing the PTV margin to 2.0 cm but NTCP values are rapidly increased $(50\~70\%\;increased)$ for upon extending PTV margins by 2.0 cm. Conclusion : Internal organ motion due to breathing can be reduced effectively using our simple RGRD. This method can be used in clinical treatments to reduce organ motion induced margin, thereby reducing normal tissue irradiation. Using treatment planning software, the dose to normal tissues was analyzed by comparing dose statistics with and without RGRD. Potential benefits of radiotherapy derived from reduction or elimination of planning target volume (PTV) margins associated with patient breathing through the evaluation of the lung cancer patients treated with 3D conformal radiotherapy.

• Radiation Oncology Journal
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• v.21 no.3
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• pp.238-244
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• 2003

Purpose: The Planning of High-Dose-Rate (HDR) brachytherapy treatments are becoming individualized and more dependent on the treatment planning system. Therefore, computer software has been developed to perform independent point dose calculations with the integration of an isodose distribution curve display into the patient anatomy images. Meterials and Methods: As primary input data, the program takes patients'planning data including the source dwell positions, dwell times and the doses at reference points, computed by an HDR treatment planning system (TPS). Dosimetric calculations were peformed in a $10\times12\times10\;Cm^3$ grid space using the Interstitial Collaborative Working Group (ICWG) formalism and an anisotropy table for the HDR Iridium-192 source. The computed doses at the reference points were automatically compared with the relevant results of the TPS. The MR and simulation film images were then imported and the isodose distributions on the axial, sagittal and coronal planes intersecting the point selected by a user were superimposed on the imported images and then displayed. The accuracy of the software was tested in three benchmark plans peformed by Gamma-Med 12i TPS (MDS Nordion, Germany). Nine patients'plans generated by Plato (Nucletron Corporation, The Netherlands) were verified by the developed software. Results: The absolute doses computed by the developed software agreed with the commercial TPS results within an accuracy of $2.8\%$ in the benchmark plans. The isodose distribution plots showed excellent agreements with the exception of the tip legion of the source's longitudinal axis where a slight deviation was observed. In clinical plans, the secondary dose calculations had, on average, about a $3.4\%$ deviation from the TPS plans. Conclusion: The accurate validation of complicate treatment plans is possible with the developed software and the qualify of the HDR treatment plan can be improved with the isodose display integrated into the patient anatomy information.

• The Korean Journal of Nuclear Medicine
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• v.35 no.3
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• pp.131-141
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• 2001

Purpose: We evaluated the sensitivity of the F-18 FDG PET by visual assessment and statistical parametric mapping (SPM) analysis for the localization of the epileptogenic zones in frontal lobe epilepsy. Materials and Methods: Twenty-four patients with frontal lobe epilepsy were examined. All patients exhibited improvements after surgical resection (Engel class I or II). Upon pathological examination, 18 patients revealed cortical dysplasia, 4 patients revealed tumor, and 2 patients revealed cortical scar. The hypometabolic lesions were found in F-18 FDG PET by visual assessment and SPM analysis. On SPM analysis, cutoff threshold was changed. Results: MRI showed structural lesions in 12 patients and normal results in the remaining 12. F-18 FDG PET correctly localized epileptogenic zones in 13 patients (54%) by visual assessment. Sensitivity of F-18 FDG PET in MR-negative patients (50%) was similar to that in MR-positive patients (67%). On SPM analysis, sensitivity decreased according to the decrease of p value. Using uncorrected p value of 0.05 as threshold, sensitivity of SPM analysis was 53%, which was not statistically different from that of visual assessment. Conclusion: F-18 FDG PET was sensitive in finding epileptogenic zones by revealing hypometabolic areas even in MR-negative patients with frontal lobe epilepsy as well as in MR-positive patients. SPM analysis showed comparable sensitivity to visual assessment and could be used as an aid in the diagnosis of epileptogenic zones in frontal lobe epilepsy.

• Clinical and Experimental Pediatrics
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• v.48 no.8
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• pp.865-870
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• 2005

Purpose : The use of growth hormone(GH) to promote growth in normal short children without classical GH deficiency is controversial. Numerous foreign studies have shown the effects of GH therapy in children with idiopathic short stature(ISS) whereas few has been interested in Korea. Therefore, this study is designed to investigate the effects of GH therapy on ISS by observing correlations and changes among various growth parameters such as, insulin-like growth factor-I(IGF-I) and insulin-like growth factor binding protein-3(IGFBP-3). Methods : This study was conducted retrospectively with 15 children with ISS in Chungbuk National University Hospital in Korea. Mean age was $11.44{\pm}2.81$ and the children were treated with 0.66 IU/kg/wk dosage of GH for 1 or 2 years. Also, the growth parameters before and after the GH therapy were observed. Results : Height standard deviation score(HT-SDS) was increased from $-1.85{\pm}0.70$ to $-1.58{\pm}0.56$ at 1 year and to $-1.21{\pm}0.37$ at 2 years after GH therapy. Predicted adult height standard deviation score(PAH-SDS) was also increased from $-2.10{\pm}0.52$ to $-1.67{\pm}0.59$ at 1 year, and to $-0.96{\pm}0.60$ at 2 years. Serum IGF-I and IGFBP-3 levels were significantly increased after 1 year and marginally increased after 2 years of GH therapy. Conclusion : It is concluded that GH therapy has growth promoting effect. The significant increase in IGF-I and IGFBP-3 levels during the GH therapy suggests that IGF-I and IGFBP-3 are useful predictors of response to the use of GH therapy. It is expected that larger patient samples would provide more reliable information about the effect of GH therapy.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.135-142
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• 2003

Purpose: The purpose of this study was to investigate the positional change of the uterus during radiotherapy. Materials and Methods: Between 1997 and 2001, 47 patients received definitive radiotherapy for cervical cancer at the Samsung Medical Center. For each patient, two MRI scans were taken; one before and the other 3$\~$4 weeks after the radiotherapy treatment. In T2 weighted MRI images, the positional change of the uterine was quantified by measuring six quantities; the distance from the cervix os to the isthmus of the uterus (Dcx), the maximum length from the isthmus of the uterus to the uterine fundus (Dco), the maximum vertical distance of the uterine body (Dco-per), the angle between the vertical line and the cervical canal in the sagittal images (Acx), the angle of the uterine corpus from the vertical line in the sagittal plan (Aco-ap), and the relative angle of the uterine corpus from a fixed anatomical landmark in the axial images (Aco-axi). Results: The mean Dcx values, before and during the treatment, were 36.7 and 27.8 mm, respectively. The Dco deviated by more than 10 mm in 14 cases (29.8$\%$). The change in the Acx ranged from 0.1 to 67.8$^{\circ}$ (mean 13.2$^{\circ}$). The Aco-ap changed by a maximum of 84.8$^{\circ}$ (mean 16.9$^{\circ}$). The differences in the Dcx plus the Dco in the smaller (<4 cm) and larger ($geq$4 cm) tumors were 5.3 and 19.4 mm, respectively. With patients less than 60 years old, or with a tumor size larger than 4 cm, the difference in the Acx was statistically significant. Conclusion: The positional changes of the uterus, during radiation treatment, should be considered in the 3DCRT or IMRT treatment planning, particularly in patients under 60 years of age or in those with a tumor size greater than 4 cm in maximum diameter.

• The Korean Journal of Nuclear Medicine
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• v.33 no.4
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• pp.422-429
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• 1999

Purpose: The measurement of radiation absorbed dose is useful to predict the response after I-131 labeled metaiodobenzylguanidine (MIBG) therapy and determine therapy dose in patients with unresectable or malignant pheochromocytoma. We estimated the absorbed dose in tumor tissue after high dose I-131 MIBG in a patient with pheochromocytoma using a gamma camera and Medical Internal Radiation Dose (MIRD) formula. Materials and Methods: A 64-year old female patient with pheochromocytoma who had multiple metastases of mediastinum, right kidney and periaortic lymph nodes, received 74 GBq (200 mCi) of I-131 MIBG. We obtained anterior and posterior images at 0.5, 16, 24, 64 and 145 hours after treatment. Two standard sources of 37 and 74 MBq of I-131 were imaged simultaneously. Cummulated I-131 MIBG uptake in tumor tissue was calculated after the correction of background activity, attenuation, system sensitivity and count loss at a high count rate. Results: The calculated absorbed radiation dose was 32-63 Gy/ 74 GBq, which was lower than the known dose for tumor remission (150-200 Gy). follow-up studies at 1 month showed minimally reduced tumor size on computed tomography, and mildly reduced I-131 MIBG uptake. Conclusion: We estimated radiation absorbed dose after therapeutic I-131 MIBG using a gamma camera and MIRD formula, which can be peformed in a clinical nuclear medicine laboratory. Our results suggest that the measurement of radiation absorbed dose in I-131 MIBG therapy is feasible as a routine clinical practice that can guide further treatment plan. The accuracy of dose measurement and correlation with clinical outcome should be evaluated further.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1207-1217
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• 2021

Purpose To evaluate the safety and efficacy of ultrasound-guided percutaneous core needle biopsy (USPCB) of pancreatic and peripancreatic lesions adjacent to critical vessels. Materials and Methods Data were collected retrospectively from 162 patients who underwent USPCB of the pancreas (n = 98), the peripancreatic area adjacent to the portal vein, the paraaortic area adjacent to pancreatic uncinate (n = 34), and lesions on the third duodenal portion (n = 30) during a 10-year period. An automated biopsy gun with an 18-gauge needle was used for biopsies under US guidance. The USPCB results were compared with those of the final follow-up imaging performed postoperatively. The diagnostic accuracy and major complication rate of the USPCB were calculated. Multiple factors were evaluated for the prediction of successful biopsies using univariate and multivariate analyses. Results The histopathologic diagnosis from USPCB was correct in 149 (92%) patients. The major complication rate was 3%. Four cases of mesenteric hematomas and one intramural hematoma of the duodenum occurred during the study period. The following factors were significantly associated with successful biopsies: a transmesenteric biopsy route rather than a transgastric or transenteric route; good visualization of targets; and evaluation of the entire US pathway. In addition, the number of biopsies required was less when the biopsy was successful. Conclusion USPCB demonstrated high diagnostic accuracy and a low complication rate for the histopathologic diagnosis of pancreatic and peripancreatic lesions adjacent to critical vessels.