• 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.17 no.1
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• pp.84-88
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• 1999

Purpose :To develop a method for verifying a treatment setup in stereotactic radiotherapy by ma- tching portal images to DRRs. Materials and Methods : Four pairs of orthogonal portal images of one patient immobilized by a thermoplastic mask frame for fractionated stereotactic radiotherapy were compared with DRRs. Portal images are obtained in AP (anteriorfposterior) and lateral directions with a target localizer box containing fiducial markers attached to a stereotactic frame. DRRs superimposed over a planned iso-center and fiducial markers are printed out on transparent films. And then, they were overlaid over onhogonal penal images by matching anatomical structures. From three different kind of objects (isgcenter, fiducial markers, anatomical structure) on DRRs and portal images, the displacement error between anatomical structure and isocenters (overall setup error), the displacement error between anatomical structure and fiducial markers (irnrnobiliBation error), and the displacement error between fiducial markers and isocenters (localization error) were measured. Results : Localization error were 1.5$\pm$0.3 mm (AP), 0.9$\pm$0.3 mm (lateral), and immobilization errors were 1.9$\pm$0.5 mm (AP), 1.9$\pm$0.4 mm (lateral). In addition, overall setup errors were 1.0$\pm$0.9 mm (AP), 1.3$\pm$0.4 mm (lateral). From these orthogonal displacement errors, maximum 3D displacement errors($\sqrt{(\DeltaAP)^{2}+(\DeltaLat)^{2}$)) were found to be 1.7$\pm$0.4 mm for localization, 2.0$\pm$0.6 mm for immobilization, and 2.3$\pm$0.7 mm for overall treatment setup. Conclusion : By comparing orthogonal portal images with DRRs, we find out that it is possible to verify treatment setup directly in stereotactic radiotherapy.

• Journal of Korean Neurosurgical Society
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• v.38 no.5
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• pp.359-365
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• 2005

Objective : The study investigates the extent of brain shift and its effect on the accuracy of the stereotaxic procedure. Methods : Thirty-five patients underwent 40stereotactic procedures between June 2002 and March 2004. There were 26 males, mean age 59years old. There were 34procedures for Parkinson's disease, 2 for essential tremor, 3 for cerebral palsy, 1 for dystonia. Patients were divided in four groups based on postoperative pneumocephalus : under 5cc [9 procedures], between $5{\sim}10cc$ [13procedures], between $10{\sim}15cc$ [11 procedures] and more than 15cc [7procedures]. The coordinates of the anterior commissure[AC], posterior commissure[PC], and target were defined in pre-and intraoperative magnetic resonance image scans and the amount of air volume was measured with @Target (BrainLab, Heimstetten, Germany]. Results : The mean AC-PC was 26.5mm for patients with less than 5cc, 26.9mm for $5{\sim}10cc$, 25.8mm for $10{\sim}15cc$ and 26.2mm for more than 15cc. The length of AC-PC line and coordinates of AC, PC was also not statistically different, Euclidean distance as well as ${\Delta}x$, ${\Delta}y$, ${\Delta}z$ of AC, PC, and target were also not statistically different among the groups [p>,1]. There was a variance in target of $0.7{\sim}7.6mm$, Euclidean distance of 2.5mm, related to electrophysiology but not to brain-shift. Conclusion : The amount of air accumulated in the intracranial space and compressing the cortical surface has no effect on the localization of subcortical stereotactic target and landmarks.

• Progress in Medical Physics
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• v.3 no.1
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• pp.63-69
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• 1992

Recently, stereotactic radiosurgery plan is required with the information of 3-D image and dose distribution. The purpose of this research is to develop 3-D radiosurgery planning system using personal computer. The procedure of this research is based on three steps. The first step is to input the image information of the patient obtained from CT or MR scan into personal computer through on-line or digitizer. The position and shape of target are also transferred into computer using Angio or CT localization. The second step is to compute dose distribution on image plane, which is transformed into stereotactic frame coordinate. and to optimize dose distribution through the selection of optimal treatment parameters. The third step is to display both isodose distribution and patient image simultaneously using superimpose technique. This prototype of radiosurgery planning system was applied recently for several clinical cases. It was shown that our planning system is fast, accurate and efficient while making it possible to handle various kinds of image modelities such as angio, CT and MRI. It is also possible to develop 3-D planning system in radiation therapy using beam's eye view or CT simulation in future.

• Journal of the Korean Society of Radiology
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• v.84 no.2
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• pp.345-360
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• 2023

In Korea, the number of institutions providing breast MRI, as well as the number of breast MRIs, has recently increased. However, MRI-guided procedures, including biopsy and needle localization, are rarely performed compared to ultrasound-guided or stereotactic biopsy. As breast MRI has high sensitivity but limited specificity, lesions detected only on MRI require pathologic confirmation through MRI-guided biopsy or surgical excision with MRI-guided needle localization. Thus, we aimed to review MRI-guided procedures, including their indications, techniques, procedural considerations, and limitations.

• Radiation Oncology Journal
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• v.33 no.1
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• pp.1-11
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• 2015

With the progress of image-guided localization, body immobilization system, and computerized delivery of intensity-modulated radiation delivery, it became possible to perform spine radiosurgery. The next question is how to translate the high technology treatment to the clinical application. Clinical trials have been performed to demonstrate the feasibility of spine radiosurgery and efficacy of the treatment in the setting of spine metastasis, leading to the randomized trials by a cooperative group. Radiosurgery has also demonstrated its efficacy to decompress the spinal cord compression in selected group of patients. The experience indicates that spine radiosurgery has a potential to change the clinical practice in the management of spine metastasis and spinal cord compression.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.365-373
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• 2002

Accurate localization of target lesion is required to protect normal peripheral tissue and irradiate exactly to tumors in stereotactic radiosurgery(SRS). Digital angiography is one of the most effective diagnostic tools to detect and identify the target tumors. However, it shows pincushion distortion due to the characteristics of the image intensifier. We have implemented a simulation study for the correction of distortion using the geometric transformation. Phantom images were produced transformation. In conclusion, the geometric transformation could effectively be used for the pincushion distortion of image intensifier and there was no significant different between two methods indicating 2% correction error from the ideal image in all cases.

• Radiation Oncology Journal
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• v.6 no.2
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• pp.269-276
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• 1988

Eight patients with intracranial tumors or arteriovenous malformation (AVM)s which were less than 3 cm in diameter were treated by a technique of stereotactic radiotherapy during the 4months period from July 1988 through October 1988 at the Division of Radiation Therapy, Kang-Nam St. Mary's Hospital, Catholic University Medical College. The patients were diagnosed as AVMs in 3 cases, acoustic neurinoma, craniopharyngiom (recurrent), hemangioblastoma, pineocytoma, and pituitary microadenoma in each case. There are several important factors in this procedure, such as localization system, portal, field size, radiation dose, and perioperative supportive care. It is suggested that stereotactic radiotherapy may be peformed safely with a radiation dose of 12-30 Gy. So this nonivasive procedure can be used to treat unresectable intracranial tumors or AVMs. Of these, clinical symptoms had been regressed in AVMs in 2 cases at 3 months and 2 months after Stereotactic radiotherapy, one of whom was confirmed slightly regressed on the follow-up angiogram. And also craniopharyngioma and pineocytoma was minimally regressed on 3 month follow-up CT.

• Progress in Medical Physics
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• v.7 no.2
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• pp.67-77
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• 1996

Purpose: To get a 3-D coordinates of intracranial target position was investicated in axial, sagittal and coronal magnetic resonance imaging with a preliminary experimented target localizer. Material and methods : In preliminal experiments, the localizer is made of engineering plastic to avoid the distrubance of magnetic field during the MR image scan. The MR localizer displayed the 9 points in three different axial tomogram. The bright signal of localizer was obtjained from 0.1～0.3％ of paramagnetic gadolinium/DTPA solution in T1WI or T2WI. In this study, the 3-D position of virtual targets were examined from three different axial MR images and the streotactic position was compared to that of BRW stereotactic system in CT scan with same targets. Results: This study provided the actual target position could be obtained from single scan with MRI localizer which has inverse N-typed 9 bars. This experiment was accomplished with shimming test for detection of image distortion in MR image. However we have not found the image distortion in axial scan. The maximum error of target positions showed 1.0 mm in axial, 1.3 mm for sagittal and 1.7 mm for coronal image, respectivelly. The target localization in MR localizer was investicated with spherical virtual target in skull cadaver. Furthermore, the target position was confirmed with CRW stereotactic system showed a 1.3 mm in discrepancy. Summary : The intracranial target position was determined within 1.7 mm of discrepancy with designed MR localizer. We found the target position from axial image has more small discrepancy than that of sagittal and coronal image.

• Progress in Medical Physics
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• v.15 no.1
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• pp.30-38
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• 2004

Purpose: To develop a whole body frame for the purpose of reducing patient motion and minimizing setup error for extra-cranial stereotactic radiotherapy, and to evaluate the repositioning setup error of a patient in the frame. Materials and Methods: The developed whole body frame is composed of a base plate, immobilizer, vacuum cushion, ruler and belts. The dimension of the base plate is 130 cm in length, 50 cm in width and 1 cm in thickness. The material used in the base plate of the frame was bakelite and the immobilizer was made of acetal. In addition, Radiopaque angio-catheter wires were engraved on the base plate for a coordinate system to determine the target localization. The measurement for radiation transmission and target localization is peformed in order to test the utilization of the frame. Also, a Matlab program analyzed the patients setup error by using the patient's setup images obtained from a CCTV camera and digital record recorder (DVR). Results: A frame that is useful for CT simulation and radiation treatment was fabricated. The frame structure was designed to minimize collisions from the changes in the rotation angle of the gantry and to maximize the transmission rate of the Incident radiation at the lateral or posterior oblique direction. The lightening belts may be used for the further reduction of the patient motion, and the belts can be adjusted so that they are not in the way of beam direction. The radiation transmission rates of this frame were measured as 95% and 96% at 10 and 21 MV, respectively. The position of a test target on the skin of a volunteer is accurately determined by CT simulation using the coordinate system in the frame. The estimated setup errors by Matlab program are shown 3.69$\pm$1.60, 2.14$\pm$0.78 mm at the lateral and central chest, and 7.11 $\pm$2.10, 6.54$\pm$2.22 mm at lateral and central abdomen, respectively. The setup error due to the lateral motion of breast is shown as 6.33$\pm$ 1.55 mm. Conclusion: The development and test of a whole body frame has proven very useful and practical in the radiosurgery for extra-cranial cancers. It may be used in determining target localization, and it can be used as a patient immobilization tool. More experimental data should be obtained in order to improve and confirm the results of the patient setup error.