• Progress in Medical Physics
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• v.26 no.3
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• pp.153-159
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• 2015

This study is to evaluate thedosiemtric leaf gap (DLG) at different depths for dynamic intensity-modulated radiation therapy (IMRT) in order to evaluate the absolute dose and dose distribution according to the different positions of tumors and compare the measured and planned the multileaf collimator (MLC) transmission factor (T.F.) and DLG values. We used the 6 MV and 15 MV photon beam from linear accelerator with a Millenium 120 MLC system. After the import the DICOM RT files, we measured the absolute dose at different depths (2 cm, 5 cm, 10 cm, and 15 cm) to calculate the MLC T. F. and DLG. For 6 MV photon beam, the measured both MLC T. F. and DLG were increased with the increase the measured depths. When applying to treatment planning systemas fixed transmission factor with its value measured under the reference condition at depth of 5 cm, although the difference fixed and varied transmission factor is not significant, the dosiemtric effect could be presented according to the depth that the tumor is placed. Therefore, we are planning to investigate the treatment planning system whichthe T. F. and DLG factor according to at the different depths can be applied in the patient-specific treatment plan.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.171-181
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• 2009

The objective of this study was to analyse stress distribution of maxillary complex by use of face mask. The construction of the three-dimensional FEM model was based on the computed tomography(CT) scans of 13.5 years-old male subject. The CT image were digitized and converted to the finite element model by using the mimics program, with PATRAN. An anteriorly directed force of 500g was applied at the first premolar 45 degrees downwards to the FH plane and at the first molar 20 degrees downwards to the FH plane. When 45 degrees force was applied at maxillary first premolar, there were observed expansion at molar part and constriction at premolar part. The largest displacement was 0.00011mm in the x-axis. In the y-axis, anterior displacement observed generally 0.00030mm at maximum. In the z-axis, maxillary complex was displaced 0.00036 mm forward and downward. When 20 degrees force was applied at maxilla first molar, there were observed expansion at lateral nasal wall and constriction at molar part. The largest displacement was 0.001mm in the X-axis. In the Y-axis, anterior displacement observed generally 0.004mm at maximum. In the Z-axis, ANS was displaced upward and pterygoid complex was displaced downward. The largest displacement was 0.002mm.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.42-51
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• 2022

Esthetic restoration of maxillary anterior implant heavily depends on the direction of installation of implant fixture. In patients with malpositioned implant, it is crucial to communicate the limitations of prosthetic outcome with the patient before starting on a restoration. To facilitate the communication, three-dimensional virtual representation by superimposing facial and intraoral digital scans with Computed Tomography (CT, dicom file) was used for visualization of the limitations of prosthesis. Through digital diagnostic wax-up, the profile of right maxillary anterior incisor implant was expected to be protrusive, which the patient was not satisfied with. Since the patient already had done root canal treatment on left maxillary anterior incisor due to previous trauma, a new prosthetic design including both right and left maxillary anterior incisors was presented to the patient. The second design was chosen and his comments were delivered to dental lab. The patient was satisfied with the new prosthesis, aesthetically and functionally.

• Progress in Medical Physics
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• v.21 no.2
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• pp.153-164
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• 2010

To determine the clinical target volumes considering vascularity and cellularity of tumors, the software was developed for mapping of the analyzed biological clinical target volumes on anatomical images using regional cerebral blood volume (rCBV) maps and apparent diffusion coefficient (ADC) maps. The program provides the functions for integrated registrations using mutual information, affine transform and non-rigid registration. The registration accuracy is evaluated by the calculation of the overlapped ratio of segmented bone regions and average distance difference of contours between reference and registered images. The performance of the developed software was tested using multimodal images of a patient who has the residual tumor of high grade gliomas. Registration accuracy of about 74% and average 2.3 mm distance difference were calculated by the evaluation method of bone segmentation and contour extraction. The registration accuracy can be improved as higher as 4% by the manual adjustment functions. Advanced MR images are analyzed using color maps for rCBV maps and quantitative calculation based on region of interest (ROI) for ADC maps. Then, multi-parameters on the same voxels are plotted on plane and constitute the multi-functional parametric maps of which x and y axis representing rCBV and ADC values. According to the distributions of functional parameters, tumor regions showing the higher vascularity and cellularity are categorized according to the criteria corresponding malignant gliomas. Determined volumes reflecting pathological and physiological characteristics of tumors are marked on anatomical images. By applying the multi-functional images, errors arising from using one type of image would be reduced and local regions representing higher probability as tumor cells would be determined for radiation treatment plan. Biological tumor characteristics can be expressed using image registration and multi-functional parametric maps in the developed software. The software can be considered to delineate clinical target volumes using advanced MR images with anatomical images.

• Journal of radiological science and technology
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• v.33 no.2
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• pp.97-107
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• 2010

The objectives of this study is to figure out the unknown image processing methods of commercial CR system. We have implemented the processing curve of each Look up table(LUT) in REGIUS 150 CR system by using virtual digital test pattern method. The characteristic of Dry Imager was measured also. First of all, we have generated the virtual digital test pattern file with binary file editor. This file was used as an input data of CR system (REGIUS 150 CR system, KONICA MINOLTA). The DICOM files which were automatically generated output files by the CR system, were used to figure out the processing curves of each LUT modes (THX, ST, STM, LUM, BONE, LIN). The gradation curves of Dry Imager were also measured to figure out the characteristics of hard copy image. According to the results of each parameters, we identified the characteristics of image processing parameter in CR system. The processing curves which were measured by this proposed method showed the characteristics of CR system. And we found the linearity of Dry Imager in the middle area of processing curves. With these results, we found that the relationships between the curves and each parameters. The G value is related to the slope and the S value is related to the shift in x-axis of processing curves. In conclusion, the image processing method of the each commercial CR systems are different, and they are concealed. This proposed method which uses virtual digital test pattern can measure the characteristics of parameters for the image processing patterns in the CR system. We expect that the proposed method is useful to analogize the image processing means not only for this CR system, but also for the other commercial CR systems.