Dr. Tong Xu

mhu — Mon, 22 Aug 2016 19:06:50 +0000

Dr. Tong Xu mhu Mon, 08/22/2016 - 15:06

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Research Summary

Real-time motion tracking for medical procedures

Real-time motion tracking of a target (patient body, organ, tumour, endoscope, catheter etc.) has very wideapplications in medical care. For example, during external beam radiation therapy on pulmonary and abdominaltumours, delivering accurate radiation therapy is limited by the motion of the tumour as the patient breathes. Thesolution is to track the tumour’s location during radiotherapy, then compensate for the motion through respiratorygating or even adjust the beam to follow the tumour in real-time. We proposed to use implanted positron emissionmarkers for real-time tumor tracking (PeTrack). By implanting positron emission markers into the tumor, and usingpairs of position-sensitive detectors to detect the resulting annihilation gamma rays, the position of the tumor can betracked in real-time with high accuracy. We are also applying this technique to image guided surgery. By integratingthe PeTrack with surgical x-ray c-arm, we will be able to provide real-time feed-back of the position of the surgicalinstruments without constant x-ray imaging, thus reduce the radiation dose to patient and surgeons.

Dynamic Dual-energy x-ray imaging (dDEXI)

While x-ray fluoroscopy can be used to observe internal organ motion, automatic and accurate evaluation of themotion is usually hindered by the interference between bone and soft tissue signals. For example, during breathing,the regional lung density variation can be observed on the x-ray images, which may be used to diagnosisemphysema and chronic obstructive pulmonary diseases. However, due to the overlapping rib signal in the image,the accuracy of these analyses is questionable. Dual-Energy x-ray imaging can overcome this issue by separatingbone and soft-tissue images, taking advantage of their different attenuation coefficients as a function of x-ray energy.We have developed the dDEXI technique that acquires two image sequences simultaneously, thus, it is free ofmotion artifacts. We also propose using dDEXI for lung tumour motion assessment. The oncologist can use thisinformation to determine whether motion management is required during radiotherapy. dDEXI can be a faster,cheaper, low dose alternative to current motion assessment methods, such as MRI or 4D CT.

Publications/Presentations

T. Xu, J.T. Wong, S. Molloi., “Method and apparatus for real-time tumor tracking by detecting annihilationgamma rays from low activity position isotope fiducial markers”, U.S. Patent # 8447387. 2013
C. Mennessier, B. Spencer, R. Clackdoyle, and T. Xu. Distortion correction, geometric calibration, andvolume reconstruction for an isocentric c-arm x-ray system. In Conference Proceedings of the 2011 IEEENuclear Science Symposium and Medical Imaging Conference, 2011. p2943-2947
M Chamberland, R Wassenaar, B Spencer, and T Xu. "Performance evaluation of real-time motion trackingusing positron emission fiducial markers", Medical Physics 38 (2), 810-819 (2011).
T. Xu, JL Ducote, JT Wong, and S Molloi. “Dynamic dual-energy chest radiography: a potential tool for lungtissue motion monitoring and kinetic study” Phys. Med. Biol. 56 (2011) 1–15
Churchill NW, Chamberland M, Xu T. Algorithm and simulation for real-time positron emission basedtumor tracking using a linear fiducial marker. Med Phys. 2009 May;36(5):1576-86.
T. Xu, J.T. Wong, P.M. Shikhaliev, J.L. Ducote, M.S. Al-Ghazi, and S. Molloi, "Real-time tumor tracking usingimplanted positron emission markers: concept and simulation study", Med Phys, 33, 2598-609 (2006).
T. Xu, J.L. Ducote, J.T. Wong, and S. Molloi, "Feasibility of real time dual-energy imaging based on a flatpanel detector for coronary artery calcium quantification", Med Phys, 33, 1612-22(2006).
J.T. Wong, J.L. Ducote, T. Xu, M.T. Hassanein, and S. Molloi, "Automated technique for angiographicdetermination of coronary blood flow and lumen volume", Acad Radiol, 13, 186-94,(2006).
P.M. Shikhaliev, T. Xu, J.L. Ducote, B. Easwaramoorthy, J. Mukherjee, and S. Molloi, "Positronautoradiography for intravascular imaging: feasibility evaluation", Phys Med Biol,51, 963-79,(2006).
J.L. Ducote, T. Xu, and S. Molloi, "Optimization of a flat-panel based real time dual-energy system forcardiac imaging". Med Phys, 33, 1562-8,(2006).P.M. Shikhaliev, J.L. Ducote, T. Xu, and S. Molloi, Q"uantum efficiency of the MCP detector: Monte Carlo calculation", IEEE Transactions on Nuclear Science, 52, 1257-1262,(2005).
P.M. Shikhaliev, T. Xu, and S. Molloi, "Photon counting computed tomography: Concept and initial results",Medical Physics 32, 427-436,(2005).
T. Xu, P.M. Shikhaliev, G.R. Berenji, J. Tehranzadeh, F. Saremi, and S. Molloi, "Area beam equalization:optimization and performance of an automated prototype system for chest radiography", Acad. Radiol., 11,377-89(2004).
T. Xu, M.S. Al-Ghazi, and S. Molloi, "Treatment planning considerations of reshapeable automatic intensitymodulator for intensity modulated radiation therapy", Med Phys 31, 2344-55(2004).
J.T. Wong, T. Xu, A. Husain, H. Le, and S. Molloi, "Effect of area x-ray beam equalization on image qualityand dose in digital mammography", Phys Med Biol 49, 3539-57 (2004).

txu@physics.carleton.ca

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(613) 520 - 2600 Ext. 8794

Office

3318 HP

Website

http://people.physics.carleton.ca/~txu/

Position

Associate Professor, Medical Physics

Dr. Elsayed Ali

mhu — Tue, 16 Aug 2016 19:13:04 +0000

Dr. Elsayed Ali mhu Tue, 08/16/2016 - 15:13

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Dr. Ali received his MSc and PhD in Medical Physics from Carleton University. He then joined The Ottawa Hospital Cancer Centre for a two-year residency in radiation Oncology Physics, and transitioned into a staff medical physicist in 2015. He is a member of the Canadian College of Physicist in Medicine (MCCPM) and holds academic appointments as an Assistant Professor at the Department of Radiology, University of Ottawa, and as an Adjunct Research Professor at the Department of Physics, Carleton University. He is a member of the Carleton Laboratory for Radiotherapy Physics (CLRP, http://www.physics.carleton.ca/clrp) and a Clinician Investigator with the Ottawa Hospital Research Institute (OHRI).

Current research: (a) Development and validation of different rapid-access palliative radiation therapy models. (b) Developments in cone beam CT for better geometric patient positioning, reduced imaging dose, and cone-beam-based radiation treatment planning. (c) Accurate dosimetric markers for radiation-induced early symptoms. (d) Auto-segmentation of the bowel bag using mathematical modelling and/or machine- and deep-learning methods. (e) Development and validation of Monte Carlo radiation transport methods for radiation measurements and dose calculations. This research is carried out primarily at The Ottawa Hospital Cancer Centre, with collaborators at Carleton University, the National Research Council Canada, and at Le Laboratoire TIMC-IMAG in France. Dr. Ali’s research group includes radiation oncology physics residents, graduate students at the MSc and PhD levels, as well as undergraduate and coop students. He served as a member of Task Group 195 of the American Association of Physicists in Medicine (AAPM) on Monte Carlo reference datasets for imaging research, and he is currently a member of the AAPM Working Group for Imaging in Treatment Planning. His publication list on Google Scholar can be accessed here:

https://scholar.google.com/citations?user=pNrEKz0AAAAJ&hl=en

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elali@toh.on.ca

Office

The Ottawa Hospital - Cancer Centre

Position

Adjunct Research Professor

Medicial Physics

Dr. Tong Xu

Research Summary

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Dr. Elsayed Ali

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