Jennifer G. Dy

• Clustering

• SVM

• Radiotherapy

• Skin Cancer

Tumor Tracking for Radiotherapy Treatment of Lung Cancer:

Precise target localization in real time is particularly important for gated radiotherapy. In an idealized gated treatment, tumor position should be directly detected and the delivery of radiation is only allowed when the tumor is at the right position. However, direct detection of the tumor mass in real-time during the treatment is often difficult. Various surrogates, both external and internal, are used to identify the tumor position. Depending on the surrogates used, we categorized the respiratory gating into external gating and internal gating. During gated treatment, the internal or external surrogate signal is continuously compared against a pre-specified range of values, called the gating window. When the surrogate signal is within the gating window, a gating signal is sent to turn on the radiation beam. External gating techniques rely on the correlation between tumor location and the external surrogates, such as markers placed on the patient’s abdomen. The major weakness in external gating is the uncertainty in the correlation between the external marker position and internal target position. Current internal gating uses internal tumor motion surrogates such as implanted fiducial markers. However, due to the risk of pneumothorax, the implantations of radiopaque markers in patients’ lungs will unlikely become a widely accepted clinical procedure. Therefore, it is crucial to be able to perform accurately gated treatment of lung cancer without implanted markers. The goal of this project is to perform lung tumor tracking without radio-opaque markers, so as to identify the tumor location in 4DCT fluoroscopic images. The project involves developing a variety of image tracking techniques. The algorithms include feature extraction, dimensionality reduction, contrast enhancement, template generation and matching, classification, clustering, prediction, and other methods needed for automated image tracking.

This research is in collaboration with Prof. Steve B. Jiang medical physicist, from the University of California San Diego, Department of Radiation Oncology, and Dr. Greg Sharp (whose area of expertise is in computer vision and medical physics) from MGH.

Publications in Algorithms for Radiotherapy:

F. Azmandian, D. Kaeli, J. Dy, E. Hutchinson, M. Ancukiewicz, A. Niemierko, and S. B. Jiang, "Towards the Development of an Error Checker for Radiotherapy Treatment Plans: A Preliminary Study," Physics in Medicine and Biology, to appear.

Y. Cui, J. G. Dy, G. C. Sharp, B. Alexander, and S. B. Jiang, "Multiple Template Based Fluoroscopic Tracking of Lung Tumor Mass without Implanted Fiducial Markers," Physics in Medicine and Biology, Vol. 52, pp. 6229-6242, 2007. (journal).

Y. Cui, J. G. Dy, G. C. Sharp, B. Alexander and S. B. Jiang, "Robust Fluoroscopic Respiratory Gating for Lung Cancer Radiotherapy without Implanted Fiducial Markers," Physics in Medicine and Biology, Vol. 52, Number 3, February 2007, pp. 741-755. (journal).

Y. Cui, J. G. Dy, G. C. Sharp, B. Alexander, and S. B. Jiang, "Fluoroscopic Tracking of Lung Tumor Mass without Implanted Fiducial Markers," American Association of Physicists in Medicine (AAPM) 48th Annual Meeting, vol. 33, p. 2244, Orlando, FL, July 30-August 3, 2006.

Y. Cui, J. G. Dy, G. C. Sharp, B. Alexander, and S. B. Jiang, "Correlation Score Based Respiratory Gating for Lung Cancer Radiotherapy without Implanted Fiducial Markers," American Association of Physicists in Medicine (AAPM) 48th Annual Meeting, vol. 33, p. 2162, Orlando, FL, July 30-August 3, 2006.

The student working on this project is:

• Ying Cui