• Progress in Medical Physics
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• v.3 no.1
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• pp.53-62
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• 1992

Stereotactic implantation of intracranial lesions, and the development of stereotactic convergent irradiation, radiosurgery, techniques have to obtain the accurate coordinates of the tumor locations and that of critical organ. Computed tomography(CT) provides relatively precise imformations of tumor localization and surround the normal organs for conventional radiotherapy. This CT image use to extend for stereotactic radiosurgery procedures. Since the convergent irradiation technique in linear accelerator requires the target center coincident with gantry isocenter or radosurgery frame, the target coordinates must be described in accurately. We used the BRW stereotactic system for describing the target position in CT images This algorithm provides the coordinate conversions for orthogonal or non-orthogonal CT scan image. In this experiments, the target positions have shown the small discripancy within :to.3mm uncertanty in several known target positions in the phantom through the provided programs and it compared to that of BRW stereotactic systems.

• Progress in Medical Physics
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• v.8 no.1
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• pp.17-24
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• 1997

We developed PC-based planning system for linear accelerator based stereotactic radiosurgery. The system was developed under Windows 95 on Pentium Pro$\^$(R) 200 ㎒ IBM PC with 128 MB RAM. It was programed using IDL$\^$(R)/ of Research Systems, Inc. as a programing tool. CT image data obtained with BRW stereotactic frame is transferred to PC through magnetoptical disk. As loading the image, the system automatically recognizes the location of rods and establishes stereotactic coordinates. It accurately calculates and corrects the coordinates, degree of tilting, and magnification rate of axial images. After the coordinates is defined we can delineate and edit the contours of target and organs of interest on axial images. Upon delineating contours of target, isocenter is determined automatically and we can set up the beam configuration for radiosurgery. The system provides beam's eye view and room's eye view for efficient confuguring of beams. The system calculates dose distribution 3-dimensionally. It takes 1 to 2 minutes to calculate dose distribution for 5 arcs. We can verify the dose distribution on serial axial images. We can analyze the dose distribution quantitatively by evaluation of dose-volume histogram of target and organ of interest. This system, PC-based radiosurgery planning system, includes the basic features for radiosurgery planning and calculates dose distribution within reasonable time for clinical application.

• Journal of Veterinary Clinics
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• v.40 no.2
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• pp.139-146
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• 2023

Three dogs were referred with epistaxis and facial deformity. Computed tomography (CT) scan identified masses in the bilateral nasal cavity with soft tissue attenuation and contrast enhancement. These masses had caused adjacent bones lysis, especially lysis of cribriform plate that extended to the intracranial region. Base on histopathology and CT imaging results, tumors were diagnosed as nasal carcinomas at stage 4. Three dogs were treated with stereotactic radiation therapy (SRT). These dogs received 30-35 Gy from 3-5 daily treatments (7-10 Gy per treatment). The sizes of tumors decreased the most on follow-up CT images at one month after treatment. Recurrence was confirmed between 3 and 5 months after completing SRT. The survival time of dogs treated with SRT were 110, 190, and 210 days, respectively. This study confirmed that SRT could treat canine nasal carcinomas with cribriform plate lysis without causing serious radiation toxicities. Follow-up CT examination is considered at 1 month and 3 to 6 months after SRT to accurately evaluate the prognosis and the timing of recurrence.

• Radiation Oncology Journal
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• v.31 no.4
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• pp.247-251
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• 2013

Purpose: This study aimed to investigate efficient approaches for determining internal target volume (ITV) from four-dimensional computed tomography (4D CT) images used in stereotactic body radiotherapy (SBRT) for patients with early-stage non-small cell lung cancer (NSCLC). Materials and Methods: 4D CT images were analyzed for 15 patients who received SBRT for stage I NSCLC. Three different ITVs were determined as follows: combining clinical target volume (CTV) from all 10 respiratory phases ($ITV_{10Phases}$); combining CTV from four respiratory phases, including two extreme phases (0% and 50%) plus two intermediate phases (20% and 70%) ($ITV_{4Phases}$); and combining CTV from two extreme phases ($ITV_{2Phases}$). The matching index (MI) of $ITV_{4Phases}$ and $ITV_{2Phases}$ was defined as the ratio of $ITV_{4Phases}$ and $ITV_{2Phases}$, respectively, to the $ITV_{10Phases}$. The tumor motion index (TMI) was defined as the ratio of $ITV_{10Phases}$ to $CTV_{mean}$, which was the mean of 10 CTVs delineated on 10 respiratory phases. Results: The ITVs were significantly different in the order of $ITV_{10Phases}$, $ITV_{4Phases}$, and $ITV_{2Phases}$ (all p < 0.05). The MI of $ITV_{4Phases}$ was significantly higher than that of $ITV_{2Phases}$ (p < 0.001). The MI of $ITV_{4Phases}$ was inversely related to TMI (r = -0.569, p = 0.034). In a subgroup with low TMI (n = 7), $ITV_{4Phases}$ was not statistically different from $ITV_{10Phases}$ (p = 0.192) and its MI was significantly higher than that of $ITV_{2Phases}$ (p = 0.016). Conclusion: The $ITV_{4Phases}$ may be an efficient approach alternative to optimal $ITV_{10Phases}$ in SBRT for early-stage NSCLC with less tumor motion.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.85-87
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• 1994

In this paper, we present an object-oriented stereotactic radiosurgery planning system, which accepts medical images such as CT and angiography, transforms the coordinates to a reference frame coordinate, calculates dose distributions, and finally displays isodose curves over the images. The user finds an adequate one for radiosurgeries after performing computer simulations on different treatment parameter sets. The object-oriented design concept was fully applied to the system composed of seven manager objects of different classes: a patient information manager, a user-interface manager, a coordinate transformation manager, a blackboard manager, a dose calculation manager, an isodose curve display manager, and a report manager. All the user interactions are carried out through the use of mouse buttons. The performance of the system was verified by four physicians and two medical physicists, and now is being used in two clinical sites.

• Journal of Korean Neurosurgical Society
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• v.57 no.6
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• pp.469-472
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• 2015

Undifferentiated sarcomas are rarely identified in the intracranial region. A 23-year-old man was admitted with a chief complaint of headache. Initial magnetic resonance images showed signs of low-grade glioma in the frontal lobe. Stereotactic biopsy was performed, and a diagnosis of diffuse astrocytoma was confirmed. Three months later, the patient presented with a high-grade tumor as seen on imaging studies. He underwent total resection of the tumor and histopathological tests identified an undifferentiated sarcoma. The patient died eight months later due to massive tumor bleeding. To the best of our knowledge, this is the first report of undifferentiated sarcoma arising from low-grade glioma without any chemotherapy or radiotherapy.

• Journal of Korean Neurosurgical Society
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• v.41 no.6
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• pp.391-396
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• 2007

Objective : This study was performed to review the clinical characteristics and operative results of brain abscess in order to define the therapeutic strategy for this disease. Methods : We reviewed the medical records and radiology images of brain abscess patients treated in our hospital during the last 16 years. A total of 35 cases included 23 males and 12 females, with the mean age of 48 years old. We excluded cases of postoperative, post traumatic, and fungal abscess. All patient underwent at least one surgical treatment such as stereotactic aspiration or craniotomy with excision. Results : Twenty seven [77.1%] patients presented with symptoms of increased intracranial pressure. The frontal lobe was the most common anatomical place, and streptococcal species were the most frequently encountered pathogens. The chronic pulmonary diseases and chronic otitis media are common underlying condition. Eighteen patients underwent stereotactic aspiration and 17 patients had excision of their abscess as an initial treatment. Seven patients had a repeated surgery, 6 of them had been treated with aspiration initially. At discharge, 60.0% patients showed a favorable outcome. Conclusion : The stereotactic drainage would be more suitable for the brain abscess located in deep and eloquent area. A large, solitary, and well-encapsulated lesion of superficial location could be best treated with complete excision, and this procedure was more definite because it is associated with less repeated surgery and showed more favorable outcome compared to aspiration surgery.

• Progress in Medical Physics
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• v.7 no.1
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• pp.3-7
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• 1996

The accuracy in target localization of CT, MR, and digital angiography were investigated for stereotactic radiosurgery. The images using CT and MR were obtained out of geometrical phantom which was designed to produce exact coordinates of several points within a 0.lmm error range. The slice interval was 3mm and FOV was 35cm for CT and 28cm for MR. These images were transferred to treatment planning computer using TCP/IP in forms of GE format. Measured 3-D coordinates of these images from planning computer were compared to known values by geometrical phantom. Anterior-posterior and lateral films were taken by digital angiography for measurement of spatial accuracy. Target localization errors were 1.2${\pm}$0.5mm with CT images, 1.7${\pm}$0.4mm with MR-coronal images, and 2.1${\pm}$0.7mm with MR-sagittal images. But, in case of MR-axial images, the target localization error was 4.7${\pm}$0.9mm. Finally, the target localization error of digital angiography was 0.9${\pm}$0.4mm. The accuracy of diagnostic machines such as CT, MR, and angiography depended on their resolutions and distortions. The target localization error mainly depended on the resolution due to slice interval with CT and the image distortion as well as the resolution with MR However, in case of digital angiography, the target localization error was closely related to the distortion of fiducial markers. The results of our study should be considered when PTV (Planning Target Volume) was determined.

• Radiation Oncology Journal
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• v.10 no.2
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• pp.137-145
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• 1992

Three-dimensional dose calculations based on CT images are fundamental to stereotactic radiosurgery for small intracranial tumor. In our stereotactic radiosurgery program, irradiations have been performed using the 6 MV photon beam of linear accelerator after stereotactic CT investigations of the target center through the beam's-eye view and the coordinates of BRW frame converted to that of radiosurgery. Also we can describe the tumor diameter and the shape in three dimensional configuration. Non-coplanar irradiation technique was developed that it consists of a combination of a moving field with a gantry angle of $140^{\circ}$, and a horizontal couch angle of $200^{\circ}C$ around the isocenter. In this radiosurgery technique, we provide the patient head setup in the base-ring holder and rotate around body axis. The total gantry moving range shows angle of 2520 degrees via two different types of gantry movement in a plane perpendicular to the axis of patient. The 3-D isodose curves overlapped to the tumor contours in screen and analytic dose profiles in calculation area were provided to calculate the thickness of $80\%$ of tumor center dose to $20\%$ of that. Furtheremore we provided the 3-D dose profiles in entire calculation plane. In this experiments, measured isodose curves in phantom irradiation have shown very similiar to that of computer generations.

• Journal of Korean Neurosurgical Society
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• v.58 no.4
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• pp.334-340
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• 2015

Objective : Pineal parenchymal tumors (PPTs) in adults are rare, and knowledge regarding their optimal management and treatment outcome is limited. Herein, we present the clinical results of our series of PPTs other than pineoblastomas managed by stereotactic radiosurgery (SRS) at upfront setting. Methods : Between 1997 and 2014, nine consecutive adult patients with the diagnosis of PPTs, either pineocytoma or pineal parenchymal tumor of intermediate differentiation, were treated with SRS. There were 6 men and 3 women. The median age was 39 years (range, 31-53 years). All of the patients presented with symptoms of hydrocephalus. Endoscopic third ventriculostomy and biopsy was done for initial management. After histologic diagnosis, patients were treated with Gamma Knife with the mean dose of 13.3 Gy (n=3) or fractionated Cyberknife with 32 Gy (n=6). Results : After a mean follow-up of 78.6 months (range, 14-223 months), all patients were alive and all of their tumors were locally controlled except for one instance of cerebrospinal fluid seeding metastasis. On magnetic resonance images, tumor size decreased in all patients, resulting in complete response in 3 patients and partial response in 6. One patient had experienced temporary memory impairment after SRS, which improved spontaneously. Conclusion : SRS is effective and safe for PPTs in adults and can be considered as a useful alternative to surgical resection at upfront setting.