Research at University Health Network
Technology Transfer
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David A Jaffray, PhD
Senior Scientist, Princess Margaret Cancer Centre
Executive VP Technology and Innovation, University Health Network
Director, Techna Institute, Techna Institute for the Advancement of Technology for Health (Techna)
Keywords: image-guidance, radiation therapy, cone-beam CT, X-ray imaging 

Research Interests

Radiation therapy, a proven cancer treatment, is employed to treat fifty percent of all cancer patients. Recent advances in the techniques of radiation delivery have highlighted the advantages of increasing the precision with which the radiotherapeutic dose distribution can be applied within the body.

The vast majority of work in Dr. Jaffray's laboratory focuses on the development of novel imaging systems and concepts to improve the precision of therapy by generating images at the time of therapy for the purpose of guiding the treatment delivery.

Recent developments have included the construction of megavoltage and kilovoltage imaging systems based upon high-performance charged coupled device cameras, prototyping, and evaluation of amorphous-silicon based large-area detectors for megavoltage work. In addition, a kilovoltage cone-beam computed tomography (CT) system has been developed.

These systems have been integrated with the megavoltage treatment devices to improve the precision with which the therapy could be executed without the interference of mechanical immobilization systems. The cone-beam CT approach has also been extended to a mobile C-arm for intra-operative imaging and therapy guidance.

A direct by-product of these investigations is the development of clinical processes that can use the images generated by these systems in a sensible and robust fashion. The development of such image-guidance processes is an active area of ongoing research in the program.

This area has been broadened through the use of cinematographic magnetic resonance imaging (MR) sequences that permit the spatial instabilities that are inherent in the human body to be assessed. These assessments describe a lower limit on the precision with which non-invasive therapy can be applied and they must be considered in the development of robust treatment regimens.

Areas of Investigation and Development:

  • Physics of x-ray imaging systems: cone-beam CT; x-ray scatter; innovative imaging geometries.
  • Contrast agents for image-guided therapy.
  • Advanced processes for image-guided procedures.
  • Integration of functional imaging data into the radiation therapy process.

Additional Appointments

  • Head, Radiation Physics Department, Princess Margaret Hospital

  • Principal, Image-Guided Therapy (IGTx) Group, Ontario Cancer Institute

  • Fidani Chair in Radiation Therapy Physics, Princess Margaret Hospital and the University Health Network

  • Associate Professor, Department of Medical Biophysics, University of Toronto

  • Site Leader, Medical Technology Innovation Priority Platform (OCI)

Pubmed Publications
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Selected Publications

  • 1. Siewerdsen JH, Cunningham IA, Jaffray DA. A framework for noise-power spectrum analysis of multidimensional images. Med Phys. 2002 Nov; 29(11):2655-71.

  • 2. Jaffray DA, Siewerdsen JH, Wong JW, Martinez AA. Flat-panel cone-beam computed tomography for image-guided radiation therapy. Int J Radiat Oncol Biol Phys. 2002 Aug 1; 53(5):1337-49.

  • 3. Groh BA, Siewerdsen JH, Drake DG, Wong JW, Jaffray DA. A performance comparison of flat-panel imager-based MV and kV cone-beam CT. Med Phys. 2002 Jun; 29(6):967-75.

  • 4. Oldham M, Siewerdsen JH, Shetty A, Jaffray DA. High resolution gel-dosimetry by optical-CT and MR scanning. Med Phys. 2001 Jul; 28(7):1436-45.

  • 5. Siewerdsen JH, Jaffray DA. Cone-beam computed tomography with a flat-panel imager: magnitude and effects of x-ray scatter. Med Phys. 2001 Feb; 28(2):220-31.

  • 6. Siewerdsen JH, Jaffray DA. Optimization of x-ray imaging geometry (with specific application to flat-panel cone-beam computed tomography). Med Phys. 2000 Aug; 27(8):1903-14.

  • 7. Jaffray DA and Siewerdsen JH, Cone-beam computed tomography with a flat-panel imager: initial performance characterization, Med. Phys. 2000 27(6) 1311-23.
Laboratory and Research Photographs

Flat-panel cone-beam CT (C-arm):  Multi-mode R/F/CT, open geometry, sub-mm 3-D spatial resolution, and soft-tissue visibility. Pelvis axial image of the first patient scanned using the integrated linear accelerator and flat-panel cone-beam CT system (0.5x0.5x2 mm voxels). 
Medical linear accelerator equipped with integration flat-panel cone-beam CT system 

  David  A Jaffray


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