• Imaging Science in Dentistry
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• 제37권2호
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• pp.69-77
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• 2007

Purpose: To evaluate the accuracy of the imaging reformation of cone beam computed tomography for the assessment of bone defect healing in rat model. Materials and Methods: Sprague-Dawley strain rats weighing about 350 gms were selected. Then critical size bone defects were done at parietal bone with implantation of collagen sponge. The rats were divided into seven groups of 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, and 8 weeks. The healing of surgical defect was assessed by multi planar reconstruction (MPR) images and three-dimensional (3-D) images of cone beam computed tomography, compared with soft X-ray radiograph and histopathologic examination. Results: MPR images and 3-D images showed similar reformation of the healing amount at 3 days, 1 week, 2 weeks, and 8 weeks, however, lower reformation at 3 weeks, 4 weeks, and 6 weeks. According to imaging-based methodologies, MPR image revealed similar reformation of the healing amount than 3-D images compare with soft X-ray image. Among the four threshold values for 3-D images, 400-500 HU revealed similar reformation of the healing amount. Histopathologic examination confirmed the newly formed trabeculation correspond with imaging-based methologies. Conclusion: MPR images revealed higher accuracy of the imaging reformation of cone beam computed tomography and cone beam computed tomography is a clinically useful diagnostic tool for the assessment of bone defect healing.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2341-2347
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• 2021

Because single-photon emission computed tomography (SPECT) is one of the widely used nuclear medicine imaging systems, it is extremely important to acquire high-quality images for diagnosis. In this study, we designed a super-resolution (SR) technique using dense block-based deep convolutional neural network (CNN) and evaluated the algorithm on real SPECT phantom images. To acquire the phantom images, a real SPECT system using a^99mTc source and two physical phantoms was used. To confirm the image quality, the noise properties and visual quality metric evaluation parameters were calculated. The results demonstrate that our proposed method delivers a more valid SR improvement by using dense block-based deep CNNs as compared to conventional reconstruction techniques. In particular, when the proposed method was used, the quantitative performance was improved from 1.2 to 5.0 times compared to the result of using the conventional iterative reconstruction. Here, we confirmed the effects on the image quality of the resulting SR image, and our proposed technique was shown to be effective for nuclear medicine imaging.

• Journal of Multimedia Information System
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• 제5권1호
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• pp.35-42
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• 2018

Direct volume rendering (DVR) is an important 3D visualization method for medical images as it depicts the full volumetric data. However, because DVR renders the whole volume, regions of interests (ROIs) such as a tumor that are embedded within the volume maybe occluded from view. Thus, conventional 2D cross-sectional views are still widely used, while the advantages of the DVR are often neglected. In this study, we propose a new visualization algorithm where we augment the 2D slice of interest (SOI) from an image volume with volumetric information derived from the DVR of the same volume. Our occlusion-based DVR augmentation for SOI (ODAS) uses the occlusion information derived from the voxels in front of the SOI to calculate a depth parameter that controls the amount of DVR visibility which is used to provide 3D spatial cues while not impairing the visibility of the SOI. We outline the capabilities of our ODAS and through a variety of computer tomography (CT) medical image examples, compare it to a conventional fusion of the SOI and the clipped DVR.

• 한국방사선학회논문지
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• 제14권3호
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• pp.221-233
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• 2020

컴퓨터단층촬영장치(computed tomography, CT)을 이용한 검사는 영상의학과에서 인체 내 정보를 파악하기 위한 가장 유용한 진단장비 중 하나로 신뢰도가 매우 높다. CT검사에 대한 신뢰성이 높아 최근에는 CT를 이용한 검사 건수도 매년 증가하고 있다. 검사 건수 증가는 CT장치의 노화를 촉진하게 되고, 이로 인해 CT장치에 대한 품질관리(quality management, QM)의 중요성이 대두된다. 특히, CT검사에서 품질관리란 임상영상에서 영상의 질(image quality, IQ) 저하로 진단영역 축소를 초래할 수 있는 발생가능한 모든 문제점을 사전에 파악하여 교정함으로써 항상 일정 수준의 영상의 질을 유지하고 영상을 획득할 수 있게 하는 행위를 의미한다. 이에 본 연구진은 CT검사의 품질관리에 대한 일반적인 내용을 요약하여 보고 한다.

• Journal of Magnetics
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• 제20권3호
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• pp.302-307
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• 2015

The purpose of the study was to identify how isotope and magnetic resonance imaging (MRI) contrast media impact on noise to computed tomography (CT) examination. For the study, divide the phantoms to two groups: 1) saline, saline + different kinds of contrast agent without $^{99m}Tc$ administration; 2) $^{99m}Tc$ administration: saline, saline + different kinds of contrast agent with $^{99m}Tc$ administration. CT contrast agent was used for Iopamidol$^{(R)}$ and Dotarem. And MRI contrast agent was used for Primovist$^{(R)}$ and Gadovist$^{(R)}$. To obtain an image, we used CT scanner. With an obtained image, we set the $1cm^2$ region of interest in the middle of bottle to measure the noise and CT number. As a result, there was no difference in CT number before and after inserting $^{99m}Tc$ into all contrast media including Normal Saline. However, when it comes to Noise, there was a difference before and after inserting $^{99m}Tc$ into every contrast media except MRI contrast media such as Primovist$^{(R)}$ and Gadovist$^{(R)}$.

• Journal of Information Technology Applications and Management
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• 제29권6호
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• pp.13-21
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• 2022

In this study, we presented a method to inspect the mechanical defects of 4680 type lithium-ion batteries through image processing method. The raw X-ray images are filtered with CLAHE, then Radon inverse transformations are calculated to reconstruct 3D computed tomography of the battery. Using Haar-cascade, the ROI is targeted automatically, and the template matchings are applied twice. The variations of contrast between template and background show the appropriate values for detecting tabs. It was shown that the proposed algorithm can detect all the tab inside the battery and the distances between tabs. Finally, we successfully found the geometrical defects of battery.

• 한국임상수의학회지
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• 제20권4호
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• pp.523-526
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• 2003

Three dimensional computed tomographic images were obtained in two cases with trauma. The first case of a 3 year-old male Maltese, with ataxia and head tilting due to head trauma was referred to veterinary medical teaching hospital, Seoul National University. Remarkable findings were not found on survey radiographs. With the help of three-dimensional reconstruction computed tomographic imaging, parietal and occipital bone fracture was identified. The second case of 4 month-old female Yorkshire terrier with left forelimb lameness was referred right after trauma. Survey radiography showed obvious incongruity of the elbow joint. Lateral and medial condyle of the left humerus fracture and lateral displacement of the left ulna were apparent in three-dimensional computed tomographic image. It was considered that three-dimensional computed tomography could be used as an aid modality for the exact evaluation of extends and degree of fracture as well as planning of orthopedic surgery.

• Imaging Science in Dentistry
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• 제36권3호
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• pp.123-129
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• 2006

The use of computed tomography for dental procedures has increased recently. Cone beam computed tomography (CBCT) systems have been designed for imaging hard tissues of the dentomaxillofacial region. CBCT is capable of providing high resolution in images of high diagnostic quality. This technology allows for 3-dimensional representation of the dentomaxillofacial skeleton with minimal distortion, but at lower equipment cost, simpler image acquisition and lower patient dose. Because this technology produces images with isotropic sub-millimeter spatial resolution, it is ideally suited for dedicated dentomaxillofacial imaging. In this paper, we provide a brief overview of cone beam scanning technology and compare it with the fan beam scanning used in conventional CT and the basic principles of currently available CBCT systems.

• Imaging Science in Dentistry
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• 제49권3호
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• pp.179-190
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• 2019

Panoramic radiographs and computed tomography (CT) play a paramount role in the accurate diagnosis, treatment planning, and prognostic evaluation of various complex dental pathologies. The advent of cone-beam computed tomography (CBCT) has revolutionized the practice of dentistry, and this technique is now considered the gold standard for imaging the oral and maxillofacial area due to its numerous advantages, including reductions in exposure time, radiation dose, and cost in comparison to other imaging modalities. This review highlights the broad use of CBCT in the dentomaxillofacial region, and also focuses on future software advancements that can further optimize CBCT imaging.

• Journal of Radiation Protection and Research
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• 제46권4호
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• pp.151-159
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• 2021

Background: Computed tomography (CT) is one of the crucial diagnostic tools in modern medicine. However, careful monitoring of radiation dose for CT patients is essential since the procedure involves ionizing radiation, a known carcinogen. Materials and Methods: The most desirable CT dose descriptor for risk analysis is the organ absorbed dose. A variety of CT organ dose calculators currently available were reviewed in this article. Results and Discussion: Key common elements included in CT dose calculators were discussed and compared, such as computational human phantoms, CT scanner models, organ dose database, effective dose calculation methods, tube current modulation modeling, and user interface platforms. Conclusion: It is envisioned that more research needs to be conducted to more accurately map CT coverage on computational human phantoms, to automatically segment organs and tissues for patient-specific dose calculations, and to accurately estimate radiation dose in the cone beam computed tomography process during image-guided radiation therapy.