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Belcher AH, Liu X, Grelewicz Z, Pearson E, Wiersma RD. Development of a 6DOF robotic motion phantom for radiation therapy. Med Phys 2015; 41:121704. [PMID: 25471951 DOI: 10.1118/1.4900828] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The use of medical technology capable of tracking patient motion or positioning patients along 6 degree-of-freedom (6DOF) has steadily increased in the field of radiation therapy. However, due to the complex nature of tracking and performing 6DOF motion, it is critical that such technology is properly verified to be operating within specifications in order to ensure patient safety. In this study, a robotic motion phantom is presented that can be programmed to perform highly accurate motion along any X (left-right), Y (superior-inferior), Z (anterior-posterior), pitch (around X), roll (around Y), and yaw (around Z) axes. In addition, highly synchronized motion along all axes can be performed in order to simulate the dynamic motion of a tumor in 6D. The accuracy and reproducibility of this 6D motion were characterized. METHODS An in-house designed and built 6D robotic motion phantom was constructed following the Stewart-Gough parallel kinematics platform archetype. The device was controlled using an inverse kinematics formulation, and precise movements in all 6 degrees-of-freedom (X, Y, Z, pitch, roll, and yaw) were performed, both simultaneously and separately for each degree-of-freedom. Additionally, previously recorded 6D cranial and prostate motions were effectively executed. The robotic phantom movements were verified using a 15 fps 6D infrared marker tracking system and the measured trajectories were compared quantitatively to the intended input trajectories. The workspace, maximum 6D velocity, backlash, and weight load capabilities of the system were also established. RESULTS Evaluation of the 6D platform demonstrated translational root mean square error (RMSE) values of 0.14, 0.22, and 0.08 mm over 20 mm in X and Y and 10 mm in Z, respectively, and rotational RMSE values of 0.16°, 0.06°, and 0.08° over 10° of pitch, roll, and yaw, respectively. The robotic stage also effectively performed controlled 6D motions, as well as reproduced cranial trajectories over 15 min, with a maximal RMSE of 0.04 mm translationally and 0.04° rotationally, and a prostate trajectory over 2 min, with a maximal RMSE of 0.06 mm translationally and 0.04° rotationally. CONCLUSIONS This 6D robotic phantom has proven to be accurate under clinical standards and capable of reproducing tumor motion in 6D. Such functionality makes the robotic phantom usable for either quality assurance or research purposes.
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Davis A, Pearson E, Pan X, Pelizzari C. SU-E-I-02: Characterizing Low-Contrast Resolution for Non-Circular CBCT Trajectories. Med Phys 2015. [DOI: 10.1118/1.4923999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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de Baere T, Tselikas L, Pearson E, Yevitch S, Boige V, Malka D, Ducreux M, Goere D, Elias D, Nguyen F, Deschamps F. Interventional oncology for liver and lung metastases from colorectal cancer: The current state of the art. Diagn Interv Imaging 2015; 96:647-54. [DOI: 10.1016/j.diii.2015.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 04/08/2015] [Indexed: 02/07/2023]
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Han X, Pearson E, Pelizzari C, Al-Hallaq H, Sidky EY, Bian J, Pan X. Algorithm-enabled exploration of image-quality potential of cone-beam CT in image-guided radiation therapy. Phys Med Biol 2015; 60:4601-33. [PMID: 26020490 DOI: 10.1088/0031-9155/60/12/4601] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Kilo-voltage (KV) cone-beam computed tomography (CBCT) unit mounted onto a linear accelerator treatment system, often referred to as on-board imager (OBI), plays an increasingly important role in image-guided radiation therapy. While the FDK algorithm is currently used for reconstructing images from clinical OBI data, optimization-based reconstruction has also been investigated for OBI CBCT. An optimization-based reconstruction involves numerous parameters, which can significantly impact reconstruction properties (or utility). The success of an optimization-based reconstruction for a particular class of practical applications thus relies strongly on appropriate selection of parameter values. In the work, we focus on tailoring the constrained-TV-minimization-based reconstruction, an optimization-based reconstruction previously shown of some potential for CBCT imaging conditions of practical interest, to OBI imaging through appropriate selection of parameter values. In particular, for given real data of phantoms and patient collected with OBI CBCT, we first devise utility metrics specific to OBI-quality-assurance tasks and then apply them to guiding the selection of parameter values in constrained-TV-minimization-based reconstruction. The study results show that the reconstructions are with improvement, relative to clinical FDK reconstruction, in both visualization and quantitative assessments in terms of the devised utility metrics.
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Pearson E, Pan X, Pelizzari C. TH-A-18C-10: Dynamic Intensity Weighted Region of Interest Imaging. Med Phys 2014. [DOI: 10.1118/1.4889569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Sensakovic W, Pearson E, Letter H. SU-E-J-262: Segmentation in Therapy: Impact of Display. Med Phys 2014. [DOI: 10.1118/1.4888316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Davis A, Pearson E, Pan X, Pelizzari C. WE-G-BRF-07: Non-Circular Scanning Trajectories with Varian Developer Mode. Med Phys 2014. [DOI: 10.1118/1.4889500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Pearson E. RD Lawrence lecture 2013. Stratified approaches to the management of diabetes. Diabet Med 2014; 31:393-8. [PMID: 24344913 DOI: 10.1111/dme.12391] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 12/12/2013] [Indexed: 11/28/2022]
Abstract
A stratified approach to medicine aims to identify subgroups of patients who should be managed differently from others. Diabetes is a condition that offers considerable potential for stratification, in areas of drug response, complication risk and rate of progression amongst others. Approaches to stratification can be simple, using clinical phenotyping, or more complex involving genomic and other '-omic' technologies. In this review, I will highlight the utility of measuring endogenous insulin production to aid in diagnosis and appropriate treatment; outline key advances in monogenic diabetes where determining genetic aetiology can result in dramatic changes in treatment, and describe the developments in the field of pharmacogenetics in Type 2 diabetes.
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Genu A, Koch G, Colin D, Aho S, Pearson E, Ben Salem D. Factors influencing the occurrence of a T2-STIR hypersignal in the lumbosacral adipose tissue. Diagn Interv Imaging 2014; 95:283-8. [DOI: 10.1016/j.diii.2013.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Pearson E, Belcher A, Grelewicz Z, Wiersma R, Pelizzari C. WE-G-141-04: Use of a Dynamic KV X-Ray Collimator for Reduced-Dose Fluoroscopic Fiducial Tracking. Med Phys 2013. [DOI: 10.1118/1.4815655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Colhoun HM, Livingstone SJ, Looker HC, Morris AD, Wild SH, Lindsay RS, Reed C, Donnan PT, Guthrie B, Leese GP, McKnight J, Pearson DWM, Pearson E, Petrie JR, Philip S, Sattar N, Sullivan FM, McKeigue P. Hospitalised hip fracture risk with rosiglitazone and pioglitazone use compared with other glucose-lowering drugs. Diabetologia 2012; 55:2929-37. [PMID: 22945303 PMCID: PMC3464390 DOI: 10.1007/s00125-012-2668-0] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 06/25/2012] [Indexed: 01/12/2023]
Abstract
AIMS/HYPOTHESIS Current drug labels for thiazolidinediones (TZDs) warn of increased fractures, predominantly for distal fractures in women. We examined whether exposure to TZDs affects hip fracture in women and men and compared the risk to that found with other drugs used in diabetes. METHODS Using a nationwide database of prescriptions, hospital admissions and deaths in those with type 2 diabetes in Scotland we calculated TZD exposure among 206,672 individuals. Discrete-time failure analysis was used to model the effect of cumulative drug exposure on hip fracture during 1999-2008. RESULTS There were 176 hip fractures among 37,479 exposed individuals. Hip fracture risk increased with cumulative exposure to TZD: OR per year of exposure 1.18 (95% CI 1.09, 1.28; p = 3 × 10(-5)), adjusted for age, sex and calendar month. Hip fracture increased with cumulative exposure in both men (OR 1.20; 95% CI 1.03, 1.41) and women (OR 1.18; 95% CI 1.07, 1.29) and risks were similar for pioglitazone (OR 1.18) and rosiglitazone (OR 1.16). The association was similar when adjusted for exposure to other drugs for diabetes and for other potential confounders. There was no association of hip fracture with cumulative exposure to sulfonylureas, metformin or insulin in this analysis. The 90-day mortality associated with hip fractures was similar in ever-users of TZD (15%) and in never-users (13%). CONCLUSIONS/INTERPRETATION Hip fracture is a severe adverse effect with TZDs, affecting both sexes; labels should be changed to warn of this. The excess mortality is at least as much as expected from the reported association of pioglitazone with bladder cancer.
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Elder DHJ, Donnelly L, Wong A, Szwejkowski BR, Pauriah M, Lim TK, Pringle SD, Choy A, Pearson E, Morris A, George J, Struthers A, Palmer C, Doney A, Lang CC. 011 HbA1c and mortality in diabetic individuals with heart failure: an observational cohort study. BRITISH HEART JOURNAL 2012. [DOI: 10.1136/heartjnl-2012-301877b.11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Basnett I, Shrestha MK, Shah M, Pearson E, Thapa K, Andersen KL. Evaluation of nurse providers of comprehensive abortion care using MVA in Nepal. JOURNAL OF NEPAL HEALTH RESEARCH COUNCIL 2012; 10:5-9. [PMID: 22929628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
BACKGROUND Although Nepal's maternal mortality ratio has fallen over the past decade, unsafe abortion remains a leading cause of maternal morbidity and mortality. A key strategy for improving access to safe abortion services is to train mid-level providers such as nurses in comprehensive abortion care (CAC). The Family Health Division of the Nepal Ministry of Health trained an initial cohort of 96 nurses to provide first trimester CAC services using manual vacuum aspiration (MVA) between September 2006 and July 2009. This study evaluates the acceptability and quality of CAC services provided by trained nurses in Nepal. METHODS Five assessments were used to evaluate post-training service provision on CAC: facility logbooks registry, nurse provider interviews, facility assessments, facility manager interviews and procedure observation checklists. Ninety-two nurses from 50 facilities participated in the evaluation. Descriptive statistics are reported. RESULTS Overall, 5,600 women received CAC services from 42 facilities where nurses were providing services between June 2009 and April 2010. Complications were experienced by 68 surgical abortion clients (1.6%) and 12 medical abortion clients (1.2%). All nurses reported that clients were happy to receive care from them, and 67% of facility managers reported that clients preferred nurse providers over physicians or had no preference. Facility managers and nurses reported a need for additional support, including further training and improved drug and equipment supply. CONCLUSIONS Trained nurses provide high quality CAC services in Nepal. Additional support in the form of facilitative supervision and training should be considered to strengthen CAC service provision.
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Pavone M, Dyson M, Pearson E, Kakinuma T, Bulun S. Alterations in retinoid signaling in endometriosis may lead to differences in decidualization. Fertil Steril 2011. [DOI: 10.1016/j.fertnstert.2011.07.379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Zhang Z, Han X, Pearson E, Bian J, Sidky E, Pelizzari C, Pan X. SU-E-J-07: A Preliminary Study on Optimal Dose-Allocation Parameters for Low-Dose Cone-Beam CT. Med Phys 2011. [DOI: 10.1118/1.3611775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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41
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Grelewicz Z, Pearson E, Alaei P, Pelizzari C, Wiersma R. Investigation of a Dynamical kV Aperture together with Combined MV-kV Dose Planning for Implementing Real-time 3D MV-kV Prostate Motion Tracking. Int J Radiat Oncol Biol Phys 2010. [DOI: 10.1016/j.ijrobp.2010.07.1564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Grelewicz Z, Pearson E, Alaei P, Pelizzari C, Wiersma R. SU-GG-J-78: Investigation of Combined MV-KV Prostate Treatment Dose Planning for Real-Time MV-KV IGRT. Med Phys 2010. [DOI: 10.1118/1.3468302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Han X, Pearson E, Bian J, Cho S, Sidky E, Pelizzari C, Pan X. SU-GG-I-32: Preliminary Performance Evaluation of CBCT Image Reconstruction from Reduced Projection Data by TV-Minimization. Med Phys 2010. [DOI: 10.1118/1.3468065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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44
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Pearson E. What are the practical implications of developments in genetics? J R Coll Physicians Edinb 2010. [DOI: 10.4997/jrcpe.2010.s02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Wiersma R, Pearson E, Pellizarri C. Development of a Dynamic kV Collimator for Low Diagnostic Dose Real-time 3D Motion Tracking during Radiation Therapy by Combined MV-kV Imaging. Int J Radiat Oncol Biol Phys 2009. [DOI: 10.1016/j.ijrobp.2009.07.1330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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46
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Pavone M, Pearson E, Milad M, Cheng Y, Bulun S. Endometriotic stromal cells express a molecular pattern consistent with decreased retinoid uptake, metabolism and action. Fertil Steril 2009. [DOI: 10.1016/j.fertnstert.2009.07.118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Tong Z, Yang Z, Meyer JJ, McInnes AW, Xue L, Azimi AM, Baird J, Zhao Y, Pearson E, Wang C, Chen Y, Zhang K. A Novel Locus for X-linked Retinitis Pigmentosa. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2009. [DOI: 10.47102/annals-acadmedsg.v35n7p476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Introduction: Retinitis pigmentosa (RP) is the most prevalent group of inherited retinopathies and demonstrates considerable clinical and genetic heterogeneity, with wide variations in disease severity, progression, and gene involvement. We studied a large family with RP to determine the pattern of inheritance and to identify the disease-causing gene/locus.
Materials and Methods: Ophthalmic examination was performed on 35 family members to identify affected individuals and carriers and to characterise the disease phenotype. Genetic linkage analysis was performed using short tandem repeat (STR) polymorphic markers encompassing the known loci for X-linked RP (xlRP) including RP2, RP3, RP6, RP23, and RP24. Mutation screening was performed by direct sequencing of PCR-amplified genomic DNA of the RP2 and RPGR genes of the affected individuals.
Results: A highly penetrant, X-linked form of RP was observed in this family. Age of onset was from 5 to 8 years and visual acuity ranged from 20/25 in children to light perception in older adults. Linkage analysis and direct sequencing showed that no known loci/genes were associated with the phenotype in this kindred.
Conclusion: A novel disease gene locus/loci is responsible for the xlRP phenotype in this family.
Key words: Genetic linkage, Mutation screening, Retinopathy
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Cho S, Pearson E, Pelizzari CA, Pan X. Region-of-interest image reconstruction with intensity weighting in circular cone-beam CT for image-guided radiation therapy. Med Phys 2009; 36:1184-92. [PMID: 19472624 DOI: 10.1118/1.3085825] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Imaging plays a vital role in radiation therapy and with recent advances in technology considerable emphasis has been placed on cone-beam CT (CBCT). Attaching a kV x-ray source and a flat panel detector directly to the linear accelerator gantry has enabled progress in target localization techniques, which can include daily CBCT setup scans for some treatments. However, with an increasing number of CT scans there is also an increasing concern for patient exposure. An intensity-weighted region-of-interest (IWROI) technique, which has the potential to greatly reduce CBCT dose, in conjunction with the chord-based backprojection-filtration (BPF) reconstruction algorithm, has been developed and its feasibility in clinical use is demonstrated in this article. A nonuniform filter is placed in the x-ray beam to create regions of two different beam intensities. In this manner, regions outside the target area can be given a reduced dose but still visualized with a lower contrast to noise ratio. Image artifacts due to transverse data truncation, which would have occurred in conventional reconstruction algorithms, are avoided and image noise levels of the low- and high-intensity regions are well controlled by use of the chord-based BPF reconstruction algorithm. The proposed IWROI technique can play an important role in image-guided radiation therapy.
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Wiersma R, Pearson E, Pelizzari C. TH-C-303A-05: Development of a Dynamic KV Collimator for Low Diagnostic Dose Real-Time 3D Motion Tracking During Radiation Therapy by Combined MV-KV Imaging. Med Phys 2009. [DOI: 10.1118/1.3182630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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50
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Han X, Bian J, Cho S, Sidky E, Pearson E, Pelizzari C, Pan X. SU-FF-I-46: Accurate Image Reconstruction From Incomplete Kilovoltage Cone-Beam CT Data in Radiation Therapy. Med Phys 2009. [DOI: 10.1118/1.3181165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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