Image-Guided Radiation Therapy
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 highperformance 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; imaging geometries.
- Contrast agents for image-guided therapy.
- Advanced processes for image-guided procedures.
- Integration of functional imaging data into the radiation therapy process.
Grant Funding Sources
- NIA/NIH – High Precision Radiation Therapy of the Prostate.
- NCI/NIH – Flat-panel Cone-Beam CT for Image-Guided Radiotherapy.
- Elekta – On-line Guidance Technologies for Precision Radiation Therapy.
- Varian – MR-based Simulation Process for Advanced Radiation Therapy.
- Premier Research Excellence Award – Multimodality Contrast Agents
- Siemens Medical Systems – Mobile 3-Dimensional Cone-Beam CT Imaging
As head of the Radiation Physics Department at Princess Margaret Hospital, Dr. Jaffray oversees and directs the physics aspects of the radiation medicine program. Dr. Jaffray is also a Principal in the Image-Guided Therapy (IGTx) Group at the Ontario Cancer Institute and holds the Fidani Chair in Radiation Therapy Physics at Princess Margaret Hospital and the University Health Network.
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- Ghilezan M., Siewerdsen JH, Sharpe MB, van Herk M, Brabbins D, Vicini F, Matter R, Jaffray, DA. Cine-MR for Characterization of Intrafraction Mobility of the Prostate, Int J Radiat Oncol Biol Phys. (in press)
- Oldham M, Siewerdsen JH, Kumar S, Wong J, Jaffray DA., Optical-CT gel-dosimetry I: basic investigations. Med Phys. 2003 Apr;30(4):623-34.
- Siewerdsen JH, Cunningham IA, Jaffray DA. A framework for noise-power spectrum analysis of multidimensional images. Med Phys. 2002 Nov; 29(11):2655-71.
- 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.
- 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.
- 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.
- 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.
- 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.
- Jaffray DA and Siewerdsen JH, "Cone-beam computed tomography with a flat-panel imager: initial performance characterization," Med. Phys. 2000 27(6) 1311-23.