Geordi Pang

Assistant Professor

PhD, University of Toronto

Sunnybrook Health Sciences Centre
2075 Bayview Avenue, T-Wing, Room TG 217
Toronto, Ontario M4N 3M5

Phone: 416-480-4622
Lab Phone: (416) 480-6100
Email Dr. Geordi Pang


Image-Guided Radiation Therapy

The "cancer problem" is the most significant health problem in Canada. Approximately half of cancer patients receive radiation therapy treatments. It uses radiation, such as X rays generated by a linear accelerator (Linac), to kill cancer cells. The geometrical and dosimetrical accuracy of such treatments is crucial for their success. Currently, we are still unable to see exactly what we are treating in the treatment room due to the inability to image soft tissue targets with current megavoltage (MV) X-ray imaging systems that were developed for radiation therapy. There is also a lack of tools to verify the dose delivered to the patient during the treatment. Our overall goal is to develop a novel MV X-ray imaging system on a Linac to solve these problems (see Fig. 1). One of the main components in the system being developed is a high quantum efficiency (QE) flat panel detector with a QE of more than an order of magnitude higher than that of current flat panel detectors for MV X rays. This system can be used to perform (1) megavoltage cone beam computed tomography (MVCT) and megavoltage digital tomosynthesis (MVDT) to locate soft tissue targets in the treatment room; and (2) on-line dose verification during the treatment. The use of a high QE detector here is necessary for imaging soft tissue targets, such as the prostate, with a low dose so that image guided radiation therapy using MVCT or MVDT could be realized.

Some specific on-going research projects:
(1) Design and construction of a prototype high QE, flat panel, MV X-ray detector and investigation of its fundamental imaging and dosimetrical properties;
(2) Investigation of the feasibility of using digital tomosynthesis as a rapid approach to soft- tissue imaging in the treatment room for image-guided radiation therapy.

These research projects are supported by the Department of Defence Prostate Cancer Research Program, National Sciences and Engineering Research Council of Canada (NSERC), and Siemens Medical Solutions USA, Inc.


List of Key Publications:

Link to Pubmed Publications
  • X. Mei and G. Pang, “Development of high quantum efficiency, flat panel, thick detectors for megavoltage x-ray imaging: An experimental study of a single-pixel prototype,” Medical Physics 32, 3379-3388 (2005).

  • G. Pang and J. A. Rowlands, “Just-in-time tomography (JiTT): a new concept for image- guided radiation therapy,” Physics in Medicine and Biology 50, N323-N330 (2005).


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