• 한국의학물리학회지:의학물리
• /
• 제19권3호
• /
• pp.178-185
• /
• 2008

간경변 및간암 환자의 증가로 간이식술의 필요성이 점점 증가되고 있고, 특히 공여자의 생체 간이식은 간이식술의 주된 분야를 차지하고 있으며 간이식 수술 전 공여자에서 간체적의 정확한 측정은 수술 후 공여자와 수여자의 간기능을 예측하는데 있어 중요한 자료가 되며, 성공적인 수술과 환자의 예후에 밀접한 영향을 미친다. 그러나 현재 환자의 간체적을 구하는 과정은 환자의 모든 CT 영상위의 간을 수작업을 통해 영상분할한 후에 3차원 간체적을 구하고 있으며 많은 시간과 노력이 필요한 작업이다. 이러한 문제를 해결하기 위해서 본 논문에서는 자동으로 간과 비장을 문턱값처리, 형태학적 영상처리, 3차원 영역확장법등의 기법을 이용하여 분할하는 알고리즘을 개발하여 체적을 구하는 시간을 단축하였다. 이러한 알고리즘의 정확성을 평가하기 위해서 동물의 실제 간과 비장을 팬텀으로 제작하여 실제 측정한 체적과 알고리즘으로 분할된 영상의 결과를 비교 평가하였다. 문턱치값의 설정에 따라 다른 결과를 보이는 특성이 있지만 자동으로 문턱치를 결정했을 때 비장과 간의 체적측정 오차는 9.27%, -4.52%이었으며, 수동으로 문턱치를 결정했을 때 최소 오차가 각각 0.2%, 0.17%의 결과를 보였다. 이러한 팬텀 연구를 통해 자동 분할 알고리즘으로 얻은 체적의 결과가 정확성과 재현성을 보여주어 추후 간체적을 구하는 보조수단으로 활용될 수 있을 것이라 예상된다.

• 한국지반공학회논문집
• /
• 제32권6호
• /
• pp.41-48
• /
• 2016

본 연구에서는 영상처리 기법을 이용해 총 9개의 모래 시료의 형상을 정량화하여 전단강도와의 상관관계를 분석하였다. 분석 시료는 6개의 자연모래 시료와 3개의 부순모래 시료이며 이를 고해상도 3차원 X-ray CT 촬영하여 그로부터 개별 입자 영상을 분리하고 구형도(Sphericity) 및 이완도(Elongation)와 같은 형상 계수를 통해 모래 시편의 형상을 정량화 하였다. 또한 시료의 상대밀도를 다르게 조성하여 직접전단시험을 수행해 첨두내부마찰각(Peak friction angle)과 극한내부마찰각(Critical state friction angle)을 획득하였다. 시료의 구형도가 감소하고 이완도가 증가할수록, 첨두내부마찰각과 극한내부마찰각은 유사한 기울기를 보이며 증가함을 확인하였으며 두 내부마찰각 사이 절댓값 차이는 입자 형상보다는 상대밀도 차이로부터 기인함을 확인하였다.

• 대한방사선기술학회지:방사선기술과학
• /
• 제41권2호
• /
• pp.123-128
• /
• 2018

Recently, the use of contrast agents has been increasing as a broader range of tests and dynamic tests have become common due to the development of equipment and imaging techniques such as Multi-Detector CT. However, the side effects of using contrast agents have been reduced by the development of non-ionic contrast agents, but they are still occurring often. The purpose of this study was to propose a method to minimize the side effect of contrast agent by using the amount of contrast agent injected to the brain angiography test to suppress excessive use of contrast agent and analyze the amount of contrast agent. Patients who were prescribed Brain Angiography due to cerebrovascular disease, According to the results of the comparison of the results obtained by dividing into 4 groups of 10ml each according to the amount of contrast medium injected with contrast agent according to the BMI of the patient, BA and SNR were not different between groups, and even if the amount of contrast injection was reduced, there was no problem in the evaluation of CT angiography through 3D reconstruction. This result shows that even if the contrast medium is injected into the blood vessels of the patient first and then the contrast medium is used as the physiological saline solution, the contrast medium is reduced by 40% it can be expected to minimize.

• 대한의용생체공학회:의공학회지
• /
• 제16권4호
• /
• pp.425-430
• /
• 1995

핵자기 공명 뇌기능 영상에서 상관관계를 이용한 데이터 해석기법이 많이 사용되고 있다. 이 논문에서 새롭게 제안된 CLT 기법은 상관관계(CCT)를 이용한 기법을 변화시켜서, 이 CCT기법의 단점을 보완하고자 하였다. CLT기법은 다음의 두 단계로 이루어진다. 첫째, 잡음을 포함한 CCT기법의 상관계수결과로 부터 잡음은 제거하고 실제 자극반응 픽셀들은 추출한다. 둘째, 이산적인 분포를 가지는 반응 픽셀들을 두 가지의 선별법으로 군집을 이루도록 한다. 이 CLT기법을 이용해서 실제 자극에 반응하는 픽셀들은 서로 모이게 하였고, 잡음에 기인한 오류의 픽셀들은 제거 되어질 수 있었다. 본 논문에서 제안된 CLT기법은 기존의 다른 기법에 비해 여러 잇점이 있고, 특히 잡음에 강한 특성이 있다.

• Imaging Science in Dentistry
• /
• 제43권4호
• /
• pp.261-266
• /
• 2013

Purpose: This study was performed to investigate the bone thickness of the infrazygomatic crest area by computed tomography (CT) for placement of a miniplate as skeletal anchorage for maxillary protraction in skeletal Class III children. Materials and Methods: CT images of skeletal Class III children (7 boys, 9 girls, mean age: 11.4 years) were taken parallel to the Frankfurt horizontal plane. The bone thickness of the infrazygomatic crest area was measured at 35 locations on the right and left sides, perpendicular to the bone surface. Results: The bone was thickest (5.0 mm) in the upper zygomatic bone and thinnest (1.1 mm) in the anterior wall of the maxillary sinus. Generally, there was a tendency for the bone to be thicker at the superior and lateral area of the zygomatic process of the maxilla. There was no clinically significant difference in bone thickness between the right and left sides; however, it was thicker in male than in female subjects. Conclusion: In the infrazygomatic crest area, the superior and lateral area of the zygomatic process of the maxilla had the most appropriate thickness for placement of a miniplate in growing skeletal Class III children with a retruded maxilla.

• Imaging Science in Dentistry
• /
• 제46권2호
• /
• pp.87-92
• /
• 2016

Purpose: The aim of this study was to assess and compare the diagnostic performance of panoramic and occlusal radiographs in detecting submandibular sialoliths. Materials and Methods: A total of 40 patients (20 cases and 20 controls) were included in this retrospective study. Cases were defined as subjects with a submandibular sialolith confirmed by computed tomography (CT), whereas controls did not have any submandibular calcifications. Three observers with different expertise levels assessed panoramic and occlusal radiographs of all subjects for the presence of sialoliths. Intraobserver and interobserver agreement were assessed using the kappa test. Sensitivity, specificity, accuracy, positive and negative predictive values, and the diagnostic odds ratio of panoramic and occlusal radiographs in screening for submandibular sialoliths were calculated for each observer. Results: The sensitivity and specificity values for occlusal and panoramic radiographs all ranged from 80% to 100%. The lowest values of sensitivity and specificity observed among the observers were 82.6% and 80%, respectively (P=0.001). Intraobserver and interobserver agreement were higher for occlusal radiographs than for panoramic radiographs, although panoramic radiographs demonstrated a higher overall accuracy. Conclusion: Both panoramic and occlusal radiographic techniques displayed satisfactory diagnostic performance and should be considered before using a CT scan to detect submandibular sialoliths.

• Journal of Veterinary Science
• /
• 제22권2호
• /
• pp.22.1-22.9
• /
• 2021

Background: Standing surgery in horses combining intravenous sedatives, analgesics and local anaesthesia is becoming more popular. Ultrasound guided (USG) peribulbar nerve block (PB) has been described in dogs and humans for facial and ocular surgery, reducing the risk of complications versus retrobulbar nerve block (RB). Objective: To describe a technique for USG PB in horse cadavers. Methods: Landmarks and PB technique were described in two equine cadaver heads (Phase 1), with computed tomography (CT) imaging confirming contrast location and spread. In Phase 2, ten equine cadaver heads were randomised to two operators naive to the USG PB, with moderate experience with ultrasonography and conventional "blind" RB. Both techniques were demonstrated once. Subsequently, operators performed five USG PB and five RB each, unassisted. Contrast location and spread were evaluated by CT. Injection site success was defined for USG PB as extraconal contrast, and for RB intraconal contrast. Results: Success was 10/10 for USG PB and 0/10 for RB (p < 0.001). Of the RB injections, eight resulted in extraconal contrast and two in the masseter muscle (p = 0.47). Conclusions: The USG PB had a high injection site success rate compared with the RB technique; however, we cannot comment on clinical effect. The USG technique was easily learnt, and no potential complications were seen. The USG PB nerve block could have a wide application for use in horses for ocular surgeries (enucleations, eyelid, corneal, cataract surgeries, and ocular analgesia) due to reduced risk of iatrogenic damage. Further clinical studies are needed.

• The Korean Journal of Pain
• /
• 제35권4호
• /
• pp.403-412
• /
• 2022

Background: Most pain management techniques for challenging procedures are still performed under the guidance of the C-arm fluoroscope although it is sometimes difficult for even experienced clinicians to understand the modified three-dimensional anatomy as a two-dimensional X-ray image. To overcome these difficulties, the development of a virtual simulator may be helpful. Therefore, in this study, the authors developed a virtual simulator and presented its clinical application cases. Methods: We developed a computer program to simulate the actual environment of the procedure. Computed tomography (CT) Digital Imaging and Communications in Medicine (DICOM) data were used for the simulations. Virtual needle placement was simulated at the most appropriate position for a successful block. Using a virtual C-arm, the authors searched for the position of the C-arm at which the needle was visualized as a point. The positional relationships between the anatomy of the patient and the needle were identified. Results: For the simulations, the CT DICOM data of patients who visited the outpatient clinic was used. When the patients revisited the clinic, images similar to the simulated images were obtained by manipulating the C-arm. Transforaminal epidural injection, which was difficult to perform due to severe spinal deformity, and the challenging procedures of the superior hypogastric plexus block and Gasserian ganglion block, were successfully performed with the help of the simulation. Conclusions: We created a pre-procedural virtual simulation and demonstrated its successful application in patients who are expected to undergo challenging procedures.

• 한국의학물리학회지:의학물리
• /
• 제31권3호
• /
• pp.81-98
• /
• 2020

This review aims to provide a brief, comprehensive overview of advanced technologies of nuclear medicine physics, with a focus on recent developments from both hardware and software perspectives. Developments in image acquisition/reconstruction, especially the time-of-flight and point spread function, have potential advantages in the image signal-to-noise ratio and spatial resolution. Modern detector materials and devices (including lutetium oxyorthosilicate, cadmium zinc tellurium, and silicon photomultiplier) as well as modern nuclear medicine imaging systems (including positron emission tomography [PET]/computerized tomography [CT], whole-body PET, PET/magnetic resonance [MR], and digital PET) enable not only high-quality digital image acquisition, but also subsequent image processing, including image reconstruction and post-reconstruction methods. Moreover, theranostics in nuclear medicine extend the usefulness of nuclear medicine physics far more than quantitative image-based diagnosis, playing a key role in personalized/precision medicine by raising the importance of internal radiation dosimetry in nuclear medicine. Now that deep-learning-based image processing can be incorporated in nuclear medicine image acquisition/processing, the aforementioned fields of nuclear medicine physics face the new era of Industry 4.0. Ongoing technological developments in nuclear medicine physics are leading to enhanced image quality and decreased radiation exposure as well as quantitative and personalized healthcare.

• 대한인간공학회:학술대회논문집
• /
• 대한인간공학회 1996년도 추계학술대회논문집
• /
• pp.21-25
• /
• 1996

The Electomyographic (EMG) signals of flexor-extensor muscle pairs were investigated to identify the neural excitation pattern of low-back pain (LBP) patients during a repetitive bending motion. New parameters and EMG normalization technique were developed to quantitatively represent the difference of temporal EMG patterns between ten healthy subjects and ten LBP patients. Flexor-extensor muscle pairs such as rectus abdominis(RA)-erector spinae (ES at LS), external oblique(EO)-internal oblique(IO), rectus femois (quadriceps: QUD)-biceps femoris(hamstrings:HAM), and tibialis anterior(TA)-gastrocnemius(GAS) pairs of muscles were selected in this study. Results indicated that the temporal EMG pattern such as the peak timing difference of QUD-HAM muscle pair and the duration of coexcitation of ES-RA muscle pair showed a statistically isgnificant difference between healthy subjects and LBP patients. These results indicated that the new technique and parameters could be used as a diagnostic tool especially for LBP patients with soft tissue injuries that are rarely dentified by traditional imaging techniques such as X-ray, CT scan or MRI. Improtantly, the new EMG technique did not require the maximal volutary contraction(MVC) measure for normalization that helped patients minimize the pain experience during and after the session. Further study needs to be made to validate and refine this method for clinical application.