• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.595-598
• /
• 2002

Laser scanners are getting used more and more in reverse engineering and inspection. For CNC-driven laser scanners, it is important to automate the scanning operations to improve the accuracy of capture point data and to reduce scanning time in industry. However, there are few research works on laser scan planning system. In addition, it is difficult to directly analyze multi-patched freeform models. In this paper, we propose an STL (Stereolithography) mesh based laser scan planning system for complex freeform surfaces. The scan planning system consists of three steps and it is assumed that the CAD model of the part exists. Firstly, the surface model is approximated into STL meshes. From the mesh model, normal vector of each node point is estimated. Second, scan directions and regions are determined through the region growing method. Also, scan paths are generated by calculating the minimum-bounding rectangle of points that can be scanned in each scan direction. Finally, the generated scan directions and paths are validated by checking optical constraints and the collision between the laser probe and the part to be scanned.

• Radiation Oncology Journal
• /
• v.22 no.1
• /
• pp.55-63
• /
• 2004

Purpose : To evaluate the reflection of tumor motion according to the planning CT scan time. Material and Methods : A model of N-shape, which moved aiong the longitudinal axis during the ventilation caused by a mechanical ventilator, was produced. The model was scanned by planning CT, while setting the relative CT scan time (T: CT scan time/ventilatory period) to 0.33, 0.50, 0.67, 0.75, 1.00, 1.337, and 1.537. In addition, three patients with non-small cell lung cancer who received stereotactic radiosurgery In the Department of Radiation Oncology, Asan Medical Center from 03/19/2002 to 05/21/2002 were scanned. Slow (10 Premier, Picker, scan time 2.0 seconds per slice) and fast CT scans (Lightspeed, GE Medical Systems, with a scan time of 0.8 second per slice) were peformed for each patient. The magnitude of reflected movement of the N-shaped model was evaluated by measuring the transverse length, which reflected the movement of the declined bar of the model at each slice. For patients' scans, all CT data sets were registered using a stereotactic body frame scale with the gross tumor volumes delineated in one CT image set. The volume and three-dimensional diameter of the gross tumor volume were measured and analyzed between the slow and fast CT scans. Results : The reflection degree of longitudinal movement of the model increased in proportion to the relative CT scan times below 1.00 7, but remained constant above 1.00 T Assuming the mean value of scanned transverse lengths with CT scan time 1.00 T to be $100\%$, CT scans with scan times of 0.33, 0.50, 0.57, and 0.75 T missed the tumor motion by 30, 27, 20, and $7.0\%$ respectively, Slow (scan time 2.0 sec) and Fast (scan time 0.8 sec) CT scans of three patients with longitudinal movement of 3, 5, and 10 mm measured by fluoroscopy revealed the increases in the diameter along the longitudinal axis Increased by 6.3, 17, and $23\%$ in the slow CT scans. Conculsion : As the relative CT scan time increased, the reflection of the respiratory tumor movement on planning CT also Increased, but remained constant with relative CT scan times above 1.00 T When setting the planning CT scan time above one respiration period (>1.00 T), only the set-up margin is needed to delineate the planning target volume. Therefore, therapeutic ratio can be increased by reducing the radiation dose delivered to normal lung tissue.

• Proceedings of the KIEE Conference
• /
• 2007.10a
• /
• pp.333-334
• /
• 2007

We propose a path planning method to decrease a inspection lead time of line scan camera in SMT(surface mount technology) in-line system. The inspection window area of printed circuit board should be minimized to consider the FOV(field of view) of line scan camera so that line scan inspector is going to find a optimal solution of path planning. We propose one of the hierarchical clustrering algorithm for a given board. Comparative simulation results are presented to verify the usefulness of proposed method.

• Progress in Medical Physics
• /
• v.24 no.4
• /
• pp.265-270
• /
• 2013

Correct target volume delineation is an important part of radiosurgery treatment planning process. We designed head phantom and performed target delineation to evaluate the volume differences due to radiosurgery treatment planning systems and image acquisition system, CT/MR. Delineated mean target volume from CT scan images was $2.23{\pm}0.08cm^3$ on BrainSCAN (NOVALS), $2.13{\pm}0.07cm^3$ on Leksell gamma plan (Gamma Knife) and $2.24{\pm}0.10cm^3$ on Multi plan (Cyber Knife). For MR images, $2.08{\pm}0.06cm^3$ on BrainSCAN, $1.94{\pm}0.05cm^3$ on Leksell gamma plan and $2.15{\pm}0.06cm^3$ on Multi plan. As a result, Differences of delineated mean target volume due to radiotherapy planning system was 3% to 6%. And overall mean target volume from CT scan images was 6.36% larger than those of MR scan images.

• The Journal of Korean Society for Radiation Therapy
• /
• v.2 no.1
• /
• pp.81-85
• /
• 1987

It has been evident since 1972 that computed tomography(CT) can play an important role in treatment and managment of the cancer patients as four steps; diagnosis, satging Treatment and follow-up. In this paper, we intended to investigate the availability of CT scan and treatment planning computer in 700 cancer patients who have undergone radiation therapy at the division of radiation therapy, Kangnam St. Mary's Hospital, Catholic Medical College between Mar. 1983 and Dec. 1985. The result were as follow; 1. Of 700 irradiated cancer patients, 342 patients ($48.9\%$) were performed CT scan prior to radiation therapy. 2. The distribution of lesions in 342 patients having CT scans was like this; CNS (83 of 104 patients, $79.8\%$), abdomen (44 of 76 patients, $57.9\%$), pelvis (100 of 188 patients, $53.2\%$) etc. in order. 3. The treatment planning computer were used in 280 cancer patients ($40\%$). 4. Of the 280 cancer patients using treatment planning computer, 167 patients ($59.6\%$) applied diagnostic CT scan and remaining 113 patients ($40.4\%$) were made body contour to be used for radiation therapy planning by the treatment planning computer. Authors also made some magnification devices used for small multiformat CT images to magnify into life size, consisting of overhead projector (3M) I.V. stand and mirror. These enabled us to make less errors in tracing the small-sized CT images during input of the anatomical data into the treatment planning computer.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.134-139
• /
• 2001

Laser scanners are widely used for reverse engineering and inspection of freeform parts in industry such as motors, electronic products, dies and molds. Due to the lack of measuring software and positioning device, the laser scanning processes have been erroneous and inconsistent. In order to automate measuring processes, an automated scan plan generation software and a proprietary hardware are developed. In this paper, an automated laser scanning system using a 3-axis motorized stage is proposed. In the scan planning step, scan directions, paths, and the number of scans are generated considering optical and mechanical parameters. In the scanning step, the generated scan plan is downloaded into the laser scanner and the motorized stage and the points on the surface are captured automatically. Finally, the point data set is analyzed to evaluate the performance of the system.

• Journal of Korea Multimedia Society
• /
• v.18 no.10
• /
• pp.1157-1163
• /
• 2015

In this paper, we propose a registration method of 3d facial scan data and CBCT data using voxelization and distance map. First, two data sets are initially aligned by exploiting the voxelization of 3D facial scan data and the information of the center of mass. Second, a skin surface is extracted from 3D CBCT data by segmenting air and skin regions. Third, the positional and rotational differences between two images are accurately aligned by performing the rigid registration for the distance minimization of two skin surfaces. Experimental results showed that proposed registration method correctly aligned 3D facial scan data and CBCT data for ten patients. Our registration method might give useful clinical information for the oral surgery planning and the diagnosis of the treatment effects after an oral surgery.

• Radiation Oncology Journal
• /
• v.1 no.1
• /
• pp.47-53
• /
• 1983

CT scans obtained on 15 patients of head and neck malignant tumors were evaluated for their utility in ratiotherapy treatment planning. To evaluate the advantage of incorporating CT scans in radiotherapy treatment planning of head and neck malignant tumors, the dose distributions of treatment plan with and without CT scan were compared in 15 patients. And then the dose distributions of the first and second treatment plan were compared. 1. Tumor extend and localization were clearly delineated on CT scan in 12 of 15 cases (80%), suggestive in 2 (13.3%), and not seen in only one (6.7%) which had been in the postoperative state. 2. Tumor coverage after CT scan was adequate in 14 of 15 cases (93.3%) and not in only one. In one case of inadequate tumor coverage the target volume lay inside the field but reached within 0.5cm of the field margin (marginal miss). 3. The volume of normal tissue irradiated was reduced after CT scan in 12 of 15 cases (80%), increased in 1 (6.7%) and not changed in 2 (13.3%). 4. We could maximize the local control of disease and minimize unnecessary morbidity by delineating the location and extent of tumor and normal tissue with CT for treatment plannings.

• Imaging Science in Dentistry
• /
• v.40 no.2
• /
• pp.93-97
• /
• 2010

This report was to show the radiographic appearances of the fungus ball in a paranasal sinus and to emphasize the scan area of cone beam computed tomography (CBCT) to detect the calcification in the paranasal sinus. A seventyfour-year-old woman visited our department for the implant rehabilitation at both maxillary posterior edentulous region. Pre-operative radiographic examinations including the panoramic, CBCT, and multidector CT images were taken. An opacification in the right maxillary sinus was observed on the multiplanar image of CBCT, however the pre-determined scan area of CBCT in this report hardly showed the calcifications at the central portion of the maxillary sinus. The opacification in the maxillary sinus could be misdiagnosed as chronic maxillary sinusitis if the calcification of fungus ball was not simultaneously detected. The scan area of pre-operative CBCT needs to be enough to scan the paranasal sinus from top to bottom.

• Imaging Science in Dentistry
• /
• v.51 no.1
• /
• pp.87-90
• /
• 2021

The increased use of cone-beam computed tomographic (CBCT) scans has made it increasingly necessary to evaluate incidental findings on CBCT scans. This report describes the case of a 66-year-old female patient who presented to the Department of Oral and Maxillofacial Pathology, Radiology and Medicine at the College of Dentistry of the author's institution and underwent a CBCT scan for maxillary alveolar process implant planning. Upon evaluation of the CBCT scan, a radiopaque (soft tissue attenuation) mass in the left superior aspect of the nasal cavity and left locule of the sphenoid sinus with opacification of the left locule of the sphenoid sinus was incidentally noted. These radiographic findings were suggestive of a space-occupying mass with a high possibility of malignancy. A further medical evaluation confirmed renal cell cancer metastasis to the sphenoid sinus. This study shows the significance of reviewing the entire CBCT scan for incidental findings.