http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Aowlad Hossain, A.B.M. (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
-
A.B.M. Aowlad Hossain,이수열,조민형 대한의용생체공학회 2012 Biomedical Engineering Letters (BMEL) Vol.2 No.1
Purpose Ultrasound transient elastography takes images of shear modulus that is strongly associated with pathological and physiological states of biological tissues. Propagating shear wave velocity in the tissue is related to its shear modulus. In this paper, we propose an iterative shear velocity image reconstruction method for ultrasound transient elastography which is robust to the noise and fast in computation. Methods We reconstruct shear velocity images by iteratively finding the solution of the forward problem that best matches to the measured displacement data. We solve the forward problem of the shear wave propagation, governed by the Helmholtz equation, using the finite difference time domain (FDTD) method. To reduce the computation time in finding the gradient of the cost function, we use the Born approximation that considers the tissue heterogeneity as secondary virtual sources to cause displacement perturbations. We use the steepest descent method to solve the inverse problem. Results For the simulated noisy displacement data, we have reconstructed shear velocity images using the proposed method and the direct inversion technique. The proposed method shows more robust behavior to the noise than the direct inversion method whilst the computation time is about 60~100 times longer depending on the number of frames used in the direct inversion. Conclusions The proposed method can be used as a fast solver of the inverse problem of ultrasound transient elastography with less noise vulnerability than the direct inversion method.
-
Compression Induced Contrast Change in X-ray Mammograms: A Simulation Study
A.B.M. Aowlad Hossain,조민형,이수열 대한의용생체공학회 2011 Biomedical Engineering Letters (BMEL) Vol.1 No.1
Purpose X-ray mammograms are taken with compressing the breast to mitigate the x-ray scatter effect. When the breast is compressed by the compressing plate, the breast tissues are deformed according to the elasticity distribution inside the breast and the pressure distribution between the compressing plate and the breast surface. If multiple mammograms are taken with varying the compressing force,the projection images of the compressed breast will be also changing with respect to the compressing force. Tumor tissues, which are known to be much stiffer than normal breast tissues, would have smaller deformation as compared to the normal background tissues, hence, the x-ray image intensity at the tumor region would change less than the background tissues. In this study, we try to find out elasticity related contrast from multiple mammography images taken with different compression levels. Methods We have developed FEM models of a breast and a compressing device, and calculated breast deformation for different degrees of breast compression. We have calculated x-ray projection images of deformed breasts and we have compared pixel intensity changes at the tumor mimicking regions and the normal background regions. Results We have found that the x-ray image intensity changes at the tumor region are less than those at the nearby background region by factor of 0.66~0.84, which could induce detectable contrast change. Conclusions We expect the compression induced contrast change may be used for the development of x-ray elastography methods.
-
Calculation of strain images of a breast-mimicking phantom from 3D CT image data.
Kim, Jae G,Aowlad Hossain, A B M,Shin, Jong H,Lee, Soo Y The American Association of Physicists in Medicine 2012 Medical physics Vol.39 No.9
<P>Elastography is a medical imaging modality to visualize the elasticity of soft tissues. Ultrasound and MRI have been exclusively used for elastography of soft tissues since they can sensitize the tissues' minute displacements of an order of 관m. It is known that ultrasound and MRI elastography show cancerous tissues with much higher contrast than conventional ultrasound and MRI. To evaluate possibility of combining elastography with x-ray imaging, we have calculated strain images of a breast-mimicking phantom from its 3D CT image data.</P>
-
김효근,이수열,조민형,Kim, Hyo-Geun,Aowlad Hossain, A.B.M.,Lee, Soo-Yeol,Cho, Min-Hyoung 대한의용생체공학회 2011 의공학회지 Vol.32 No.2
Breast cancer is the most frequently appearing cancer in women, these days. To reduce mortality of breast cancer, periodic check-up is strongly recommended. X-ray mammography is one of powerful diagnostic imaging systems to detect 50~100 um micro-calcification which is the early sign of breast cancer. Although x-ray mammography has very high spatial resolution, it is not easy yet to distinguish cancerous tissue from normal tissues in mammograms and new tissue characterizing methods are required. Recently ultrasound elastography technique has been developed, which uses the phenomenon that cancerous tissue is harder than normal tissues. However its spatial resolution is not enough to detect breast cancer. In order to develop a new elastography system with high resolution we are developing x-ray elasticity imaging technique. It uses the small differences of tissue positions with and without external breast compression and requires an algorithm to detect tissue displacement. In this paper, computer simulation is done for preliminary study of x-ray elasticity imaging. First, 3D x-ray breast phantom for modeling woman's breast is created and its elastic model for FEM (finite element method) is generated. After then, FEM experiment is performed under the compression of the breast phantom. Using the obtained displacement data, 3D x-ray phantom is deformed and the final mammogram under the compression is generated. The simulation result shows the feasibility of x-ray elasticity imaging. We think that this preliminary study is helpful for developing and verifying a new algorithm of x-ray elasticity imaging.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
