| 1. |
- Achilles, Silvio, et al.
(författare)
-
GPU-Accelerated Coupled Ptychographic Tomography
- 2022
-
Ingår i: Developments in X-Ray Tomography XIV. - : SPIE. - 1996-756X .- 0277-786X. - 9781510654686 ; 12242
-
Konferensbidrag (refereegranskat)abstract
- Scanning coherent X-ray microscopy (ptychography) has gained considerable interest during the last decade since the performance of this indirect imaging technique does not necessarily rely on the quality of the X-ray optics and, in principle, can achieve highest spatial resolution in X-ray imaging. The method can be easily extended to 3D by adding standard tomographic reconstruction schemes. However, the tomographic reconstruction is often applied in a subsequent step using a sequence of aligned ptychographic 2D projections. In this contribution, we outline current developments of a GPU-accelerated framework for direct 3D ptychography, coupling 2D ptychography and tomography. The program utilizes a custom GPU-accelerated framework for ptychography that offers three distinct ptychographic reconstruction algorithms. The tomographic reconstruction runs simultaneously and uses numerical routines of the ASTRA Toolbox. This parallel-computing approach results in a high performance increase considerably reducing the reconstruction time of 3D ptychographic datasets.
|
|
| 2. |
- Ogbodum, Molly, et al.
(författare)
-
Sexual health and rights advocacy among marginalized young women during the COVID-19 pandemic in the Global South
- 2023
-
Ingår i: IAS 2023 Abstract Book. ; , s. 603-604
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Young women and adolescent girls (15-30years) are disproportionately affected by discrimination, sexual violence, unplanned pregnancy, and gender-based violence; even more so when they are at the intersection of multiple stigmatized identities. Nevertheless, sexual and reproductive health rights (SRH-R) services are often inaccessible due to costs, as well as lack of awareness and sensitivity by service providers. This study explored the impact of the COVID-19 pandemic and how civil society organizations and communities adapted to provide SRHR services to young women in Lebanon, Guatemala, Mozambique, Uganda and Nigeria.Methods: Data was collected electronically by a team of 11 young female researchers and advocates from 5 different countries using the KoboCollect toolkit between October and December, 2022. A mixed methods approach with surveys and interviews was used to investigate the lived experiences and perspectives of 227 young women identified primarily from existing networks and through chain-referral sampling. Targeted populations were young women and girls: living with HIV; identifying as lesbian, bisexual, transgender, and/or intersex (LBTI); affected by displacement; and/or living with disabilities. Both in-person and virtual interviews due to COVID-19 disruptions were conducted.Results: Several respondents (35%) were directly involved in implementing SRHR advocacy actions in their communities. A third (33%) of respondents described barriers inaccessing SRHR services, including stigmatization for being sexually active. In particular, young women with disabilities and young LBTI women faced discriminatory attitudes from health care professionals. The fear of contracting COVID-19 coupled with lockdown measures (including lack of transportation and diversion of resources) kept young women away from seeking SRHR services and left nearly half (46%) feeling the pandemic worsened accessing healthcare. Difficulty access-ing contraceptives during the pandemic and associated unplanned pregnancies was identified as a key barrier among 65% of respondents. Notably, sensitive counselling and cervical cancer screening was the least accessed SRHR services in all the included countries.Conclusions: Our findings show that there is an ongoing need for joint initiatives to address a range of issues surrounding the current advocacy efforts around SRHR in order to attain high standards of health, and ensure equality, non-discrimination, privacy, and confidentiality for young women and girls.
|
|
| 3. |
- West, Jay B., et al.
(författare)
-
Comparison and evaluation of retrospective intermodality image registration techniques
- 1997
-
Ingår i: SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. ; , s. 332-347
-
Konferensbidrag (refereegranskat)abstract
- All retrospective image registration methods have attached to them some intrinsic estimate of registration error. However, this estimate of accuracy may not always be a good indicator of the distance between actual and estimated positions of targets within the cranial cavity. This paper describes a project whose principal goal is to use a prospective method based on fiducial markers as a ’gold standard’ to perform an objective, blinded evaluation of the accuracy of several retrospective image-to-image registration techniques. Image volumes of three modalities – CT, MR, and PET – were taken of patients undergoing neurosurgery at Vanderbilt University Medical Center. These volumes had all traces of the fiducial markers removed, and were provided to project collaborators outside Vanderbilt, who then performed retrospective registrations on the volumes, calculating transformations from CT to MR and/or from PET to MR, and communicated their transformations to Vanderbilt where the accuracy of each registration was evaluated. In this evaluation the accuracy is measured at multiple ’regions of interest,’ i.e. areas in the brain which would commonly be areas of neurological interest. A region is defined in the MR image and its centroid C is determined. Then the prospective registration is used to obtain the corresponding point C’ in CT or PET. To this point the retrospective registration is then applied, producing C’ in MR. Statistics are gathered on the target registration error (TRE), which is the disparity between the original point C and its corresponding point C’. A second goal of the project is to evaluate the importance of correcting geometrical distortion in MR images, by comparing the retrospective TRE in the rectified images, i.e., those which have had the distortion correction applied, with that of the same images before rectification. This paper presents preliminary results of this study along with a brief description of each registration technique and an estimate of both preparation and execution time needed to perform the registration.
|
|
