• 대한방사선기술학회지:방사선기술과학
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• 제41권1호
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• pp.33-38
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• 2018

There are limits to check the lesion as inserting a breast implant patients. So the application of BSGI based on Nuclear Medicine examination has increased. In this study, therefore we confirmed the effect of the image applying to breast implants in Breast Specific Gamma Imaging. We utilized Dilon 6800 BSGI scanner and developed the phantom. The self-development phantom was a rectangular shape of $230{\times}190{\times}80mm$ size and had 5 spheres which consisted of diameters of 10, 13, 17, 22, 28 mm in central part. We injected $^{99m}TcO_4$ into the self-development phantom in the proportion of four to one and made each additional phantom filled with 0.9 % sodium chloride, silicon and paraffin. Each additional phantom was placed between detector and self-development phantom. Each image was acquired five times depending on the type and thickness of the additional phantom. Statistical analysis with SPSS ver.18 was applied. In the test of variation according to the thickness of all additional phantoms, as the phantoms which 0.9% sodium chloride, silicon and paraffin increased, the attenuation variation was higher(P<0.005). There was no significant difference in the attenuation variation and the quality of image for type of the additional phantom. Therefore, if the effect of the image applying to breast implants in Breast Specific Gamma Imaging is confirmed, the higher diagnostic value can be achieved.

• The Korean Journal of Pain
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• 제32권4호
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• pp.271-279
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• 2019

Background: We utilized diffusion tensor imaging (DTI) to evaluate the cerebral white matter changes that are associated with phantom limb pain in patients with unilateral arm amputation. It was anticipated that this would complement previous research in which we had shown that changes in cerebral blood volume were associated with the cerebral pain network. Methods: Ten patients with phantom limb pain due to unilateral arm amputation and sixteen healthy age-matched controls were enrolled. The intensity of phantom limb pain was measured by the visual analogue scale (VAS) and depressive mood was assessed by the Hamilton depression rating scale. Diffusion tensor-derived parameters, including fractional anisotropy, mean diffusivity, axial diffusivity (AD), and radial diffusivity (RD), were computed from the DTI. Results: Compared with controls, the cases had alterations in the cerebral white matter as a consequence of phantom limb pain, manifesting a higher AD of white matter in both hemispheres symmetrically after adjusting for individual depressive moods. In addition, there were associations between the RD of white matter and VAS scores primarily in the hemispheres related to the missing hand and in the corpus callosum. Conclusions: The phantom limb pain after unilateral arm amputation induced plasticity in the white matter. We conclude that loss of white matter integrity, particularly in the hemisphere connected with the missing hand, is significantly correlated with phantom limb pain.

• 한국임상수의학회지
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• 제39권3호
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• pp.114-120
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• 2022

The purpose of this study is to examine the status of quality control using multipurpose phantom of ultrasound equipment used in hospital of veterinary college in South Korea by using ATS-539 multipurpose phantom so as to examine quantitative and objective new image evaluation method. Specialists discussed and analyzed multipurpose phantom images acquired by using convex transducer of 10 ultrasound imaging devices, currently used in 9 veterinary colleges, at 4.0-6.0 MHz. Total 8 items that can be measured with ATS-539 multipurpose phantom including dead zone, vertical and horizontal measurement, axial/lateral resolution, sensitivity, focal zone, functional resolution and gray scale/dynamic range were evaluated. For qualitative evaluation, valid decisions were made based on dead zone, axial/lateral resolution, and gray scale/dynamic range which are resolution index, and coefficient of variation (COV) and blind referenceless image spatial quality evaluator (BRISQUE) were found to increase objectivity. As a result of experiment, all the targeted ultrasonic devices were found appropriate from qualitative evaluation items of dead zone, axial/lateral resolution, and gray scale/dynamic range. In other evaluation items, they were found to be appropriate from focal zone and vertical measurement of quantitative evaluation while inappropriate from horizontal measurement, sensitivity, and functional resolution. COV value was 0.12 ± 0.04, and BRISQUE value was 47.77 ± 2.77, both analysis results show that the noise level of all ultrasonic devices was located within tolerance range. Upon image examination using ATS-539 multipurpose phantom, they were 100% appropriate with inspection standards of dead zone, axial/lateral resolution, and gray scale/dynamic range, and besides, focal zone and functional resolution can be used as evaluation items. In the field of veterinary medicine, 8 standard items using ATS-539 multipurpose phantom and image evaluation items using COV and BRISQUE can be used as standards for quality control of ultrasonography machine.

• 대한방사선기술학회지:방사선기술과학
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• 제45권2호
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• pp.103-109
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• 2022

To maintain improved image quality in mammography, the quality control process is performed using the ACR (American college of radiology) phantom. In addition, many studied were performed by fabricating the customized breast phantom to provide more information in mammography. Thus, the purpose of this study was to evaluate the image quality by designing the modified ACR phantoms. The five modified acrlylic ACR phantoms were designed by considering insert position and phantom thickness. The phantoms were consisted of 4.5, 3.0, and 1.5 cm in terms of phantom thickness, and 3.0, 2.0, and 0.5 cm in terms of insert position, respectively. The acquired images were evaluated by PSNR (peak signal to noise ratio), RMSE (root mean square error), CC (correlation coefficient), CNR (contrast to noise ratio), and COV (coefficient of variation). Based on the similarity analysis, the result is suitable between conventional and new designed phantoms. In addition, the CNR and COV results in terms of insert position showed that image quality for 0.5 cm was 2.3 and 27.4% improved compared with 2 and 3 cm, respectively. According to phantom thickness results, the CNR result for 1.5 cm and COV result for 4.5 cm were 50.1 and 62.7% improved compared with that those conditions. In conclusion, we confirmed that the image quality depends on the breast size and thickness through modified ACR phantom study.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.322-323
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• 2002

Partial volume averaging effect of PET data influences on the accuracy of quantitative measurements of regional brain metabolism because spatial resolution of PET is limited. The purpose of this study was to evaluate the accuracy of partial volume correction carried out on $^{18}$ F-PET images using Hoffman brain phantom. $^{18}$ F-PET Hoffman phantom images were co-registered to MR slices of the same phantom. All the MR slices of the phantom were then segmented to be binary images. Each of these binary images was convolved in 2 dimensions with the spatial resolution of the PET. The original PET images were then divided by the smoothed binary images in slice-by-slice, voxel-by-voxel basis resulting in larger PET image volume in size. This enlarged partial volume corrected PET image volume was multiplied by original binary image volume to exclude extracortical region. The evaluation of partial volume corrected PET image volume was performed by region of interests (ROI) analysis applying ROIs, which were drawn on cortical regions of the original MR image slices, to corrected and original PET image volume. From the ROI analysis, range of regional mean values increases of partial volume corrected PET images was 4 to 14%, and average increase for all the ROIs was about 10% in this phantom study. Hoffman brain phantom study was useful for the objective evaluation of the partial volume correction method. This MR-based correction method would be applicable to patients in the. quantitative analysis of FDG-PET studies.

• Restorative Dentistry and Endodontics
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• 제45권4호
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• pp.45.1-45.8
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• 2020

Objective: The aim of this study was to introduce a gelatin/bovine serum albumin (BSA) tissue standard, which provides dissolution properties identical to those of biological tissues. Further, the study evaluated whether the utilization of endodontic activating devices led to enhanced phantom dissolution rates. Materials and Methods: Bovine pulp tissue was obtained to determine a benchmark of tissue dissolution. The surface area and mass of samples were held constant while the ratio of gelatin and BSA were varied, ranging from 7.5% to 10% gelatin and 5% BSA. Each sample was placed in an individual test tube that was filled with an appropriate sodium hypochlorite solution for 1, 3, and 5 minutes, and then removed from the solution, blotted dry, and weighed again. The remaining tissue was calculated as the percent of initial tissue to determine the tissue dissolution rate. A radiopaque agent (sodium diatrizoate) and a fluorescent dye (methylene blue) were added to the phantom to allow easy quantification of phantom dissolution in a canal block model when activated using ultrasonic (EndoUltra) or sonic (EndoActivator) energy. Results: The 9% gelatin + 5% BSA phantom showed statistically equivalent dissolution to bovine pulp tissue at all time intervals. Furthermore, the EndoUltra yielded significantly more phantom dissolution in the canal block than the EndoActivator or syringe irrigation. Conclusions: Our phantom is comparable to biological tissue in terms of tissue dissolution and could be utilized for in vitro tests due to its injectability and detectability.

• 한국방사선학회논문지
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• 제17권6호
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• pp.809-817
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• 2023

뇌출혈 진단 방법 중 CT는 비침습적으로 피사체의 3차원 영상을 제공할 수 있다. 그래서 응급실에서 급성인 환자 상대로 많이 사용되고 중요한 역할을 담당하고 있다. 뇌혈관 CT는 다른 혈관 CT에 비해 비교적 촬영 빈도가 높으며 뇌혈관 CT 검사 시 적절한 SNR, 합리적인 유효선량으로 검사를 해야한다. 뇌혈관 CT 검사 시 이중에너지와 단일에너지를 이용하였을 때 실질적으로 어느 것이 유효선량이 적으며, SNR이 차이가 없는지 환자영상과 Phantom영상을 같이 비교하였다. SNR과 CNR의 P값이 0.05이상일 때 통계적으로 차이가 없다고 보았고, 유효선량은 0.05미만일 경우 통계적으로 차이가 있다고 보았다. 실험에서는 병원영상의 환자선량을 비교하였을 때 이중에너지의 유효선량이 53.53% 적게, Phantom의 OLSD 이중에너지 유효선량이 57.94% 적게, Phantom의 Dose Report의 이중에너지 유효선량이 56.04% 적었다. 그래서 뇌혈관조영 CT는 이중에너지를 권장한다.

• 핵의학기술
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• 제17권2호
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• pp.78-83
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• 2013

SPECT/CT는 SPECT와 CT를 결합하여 감약에 의한 왜곡된 영상을 CT의 감쇠보정을 이용하여 구현할 수 있는 장점이 있다. 감쇠보정을 이용한 SPECT/CT 영상은 우수한 의료 영상 정보를 제공하며 정확한 영상을 비교 및 판독할 수 있어서 영상의 진단적 가치가 높은 것으로 평가된다. 이 연구에서는 phantom 실험 및 환자의 영상을 이용하여 CT 감쇠보정 전후의 차이를 살펴보고자 한다. 2012년 7월부터 9월까지 본원 핵의학과에서 검사를 시행한 환자와 phantom을 이용하여 영상의 대조도와 공간분해능, 심근의 관류 점수를 연구하였다. NEMA IEC, Jaszczak phantom으로 영상의 대조도, triple line phantom으로 영상의 공간분해능, anthropomorphic torso phantom을 사용하여 심근의 관류 점수를 평가하였다. 또한 환자들의 검사 영상을 통하여 CT 감쇠보정 전후를 핵의학 전공의 3명, 5년 이상 근무한 방사선사 5명의 blind test를 통하여 영상을 평가해 보았다. IEC phantom에서 각 구별로 CT 감쇠보정 전후의 대조도 분석 결과 감쇠보정 전보다 최소 33.6%, 최대 89.8% 향상되었고, Jaszczak phantom의 경우 대조도가 최소 9.9%, 최대 27.8%, triple line phantom에서 수평의 경우 분해능이 4.4%, 수직의 경우 분해능이 4.6%로 평균 약 4.5%, anthropomorphic torso phantom의 경우 심근 하벽에서의 관류 점수가 29.4%로 향상된 것을 알 수 있었다. 그리고 환자를 대상으로 한 실험에서는 $^{131}I$, bone SPECT/CT의 blind test 결과 감쇠보정 후 영상의 질이 향상되었음을 알 수 있었다. CT 감쇠보정을 통한 SPECT/CT 영상의 질을 평가한 결과 SPECT 영상에서 대조도와 공간분해능이 향상됨을 알 수 있었다. 따라서 CT를 이용한 감쇠보정은 병소의 해부학적 위치를 정확히 검출할 수 있고, 보다 나은 영상을 기대할 수 있을 것으로 사료된다.

• 대한디지털의료영상학회논문지
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• 제12권1호
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• pp.59-64
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• 2010

We examined the accuracy and efficiency of phantom by applying the designed phantom in order to check daily quality assurance easily by objective criteria and to confirm daily quality assurance of linear accelerator, simulator, and CT-simulator. The results of 10 weeks of linear accelerator output dose using American Association of Physicists in Medicine(AAPM) daily quality assurance guide were measured within ${\pm}1%$ of error. Mechanical check of laser alignment, optical distance indicator(ODI), CT scanner laser and alignment of gantry lasers with the center of imaging plane were measured within ${\pm}1mm$. Daily average working time for daily quality assurance of radiation therapy equipments was 38 minutes. The designed phantom was easy to install and daily quality assurance was possible with only one installation. The aspects reproducibility and efficiency as well as accuracy of quality assurance were excellent.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 추계학술대회
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• pp.153-156
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• 1994

An in vitro steady flow experiment was performed in order to test the accuracy of velocity measurement obtained through a pulsed Doppler echocardiography. A flow phantom was designed for the use in a wide velocity range at a given flow rate. The results showed that the pulsed Doppler velocity measurement obtained in this flow phantom is accurate at low flow rates. However, ultrasound velocity measurement should be performed under a careful considerations of PRF and Doppler gain settings, especially at higher flow rates.