Anand P. Santhanam, Joint Research Scientist, MD Anderson Cancer Center Orlando & UCF

A team science project funded by James and Esther King grant foundation & I-4 Research Corridor Technology matching grant.

Virtual Dynamic Lung Anatomy

Lung tumors move during breathing depending on patient’s patho-physiological condition and orientation, thereby compromising the accurate deposition of radiation dose during radiotherapy. To date, real-time lung radiotherapy monitoring applications has not been investigated or developed because of the knowledge gap involved in simulating and visualizing radiation dose delivery.

Our Vision Imagine a clinician initiating external beam radiation therapy treatment for a human subject and being able to visually monitor where the tumor is and where the radiation dose is being delivered inside the subject’s body and control the treatment. Our vision to attain such a monitoring using physics and physiology based computational lung models and GPU based dose calculations.

4D Lung motion When a patient walks-in for therapy, a 4DCT imaging is performed along with spirometry measurements. The 4DCT image gives the 3D anatomy and its shape changes during breathing. The spirometry measurements provides the airflow inside the lungs and the alveolar pressure. The 3D shape changes which vary inside the lung are measured using a multi-level optical flow method.

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Lung ElasticityThe measurement of lung elasticity enables us to develop physics and physiology based lung models. An estimation of the lung elasticity takes into account the spirometry measurement and the 4D lung motion and estimates the physical property (Young’s Modulus) for each voxel (3D cube) inside the lung. The local variations in the elasticity also represent the patient’s patho-physical condition.

Image Gallery: I. A patient getting CT scanned with spirometry measurements being done in real-time. II. A 3D lung anatomy with airways (blue), tissues (green), and capillaries (red). The anatomy is generated from Phillips 16 slice CT.

III. 3D Displacement map of a human lung at 100% tidal volume. (0-1 cm as red), (1-2 cm as yellow), (2-3 cm as green) and (3-4 cm as blue). IV. 3D Young’s Modulus map of a human lung at 100% tidal volume. (0 - 0.1 KPa as black), (0.1-0.5 KPa asRed) (0.5-1 KPa as yellow), (1-1.2 KPa as green) and (1.2 - 1.5 KPa as white)

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Model based Lung Radiotherapy We present a collaborative effort in developing a Graphics Processing Unit (GPU) based simulation framework to calculate in real-time the delivered dose to 3D lung tumor and its surrounding normal tissues, which are undergoing model-based subject-specific lung deformations. Such a framework facilitates enabling applications for real-time monitoring of radiation dose delivered to a lung during treatment and retrospective analyses of the radiation delivery.

3D Stereoscopic VisualizationThe usage of 3D Augmented Reality Center (ARC) display system aims to enhance a clinician’s understanding by enhancing the 3D depth perception of the dose accumula-tion in lung tumors. Thus the framework and its visualization acts as a tool for presenting both real-time monitoring studies and retrospective treatment efficacy analysis when coupled with a real-time respiration monitor. A Clinical evaluation showed that physicists were able to perceive the formation of the hotspots and their 3D location at an average time of 1.2 seconds using the ARC system as compared to 13 seconds using a 2D display. The depth perception enabled by the usage of Head Mounted Displays facilitate the viewer to identify sensitive regions and their proximity to hotspots.

Image Gallery: I. A 3D dynamic lung anatomy with the external body, the airways, the left and right lung with a tumor on the right lung is receiving radiation dose using a conformal beam. The radiation beam is shown with green (99-100%), light blue (98-99%), blue (97-98%), and red (95-97%). II. A Radiation physicist at M.D. Anderson Cancer Center Orlando is monitoring in 3D the dose accumulated inside a deforming lung tumor. The dose is shown in White (95-100%), green (90-95%) and blue (85-90%).

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Virtual Dynamic Lung Anatomy

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CollaboratorsDr. Jannick P. Rolland PhD (University of Rochester)Dr. Patrick A. Kupelian MD (M.D. Anderson C.C.O.)Dr. Eric A. Hoffman PhD (University of Iowa) Dr. Paul Davenport PhD (University of Florida)Dr. Celina Imielinska PhD (Columbia U.)Dr. Raj Karunakara MD (Ocala Regional Healthcare)Dr. Bari H Ruddy PhD (UCF, Public Health)

ReferencesSanthanam, A.P., T. Willoughby, S.L.Meeks, and P. Kupelian. Modeling simulation and visualization of 3D lung conformal dosimetry. Physics in Medicine and Biology 54 6165-80.Santhanam, A.P., T. Willoughby, I. Kaya, A. Shah, S.L. Meeks, J.P.Rolland, and P. Kupelian. 2008. A Display Framework for Visualizing Real-time 3D Lung Tumor Radiotherapy. IEEE Journal of Display Technology “Special issue on Medical Displays” 4 (4) 473-482 (invited paper).Santhanam, A.P., C. Imielinska, P. Davenport, P. Kupelian, and J.P. Rolland. 2008. Modeling and simulation of Real-time 3D lung dynamics. IEEE Transactions on Information Technology and Biomedicine 12 (2) 257-270.Santhanam, A.P., F. Hamza-Lup, and J.P. Rolland. 2007. Simulating 3D lung dynamics in a programmable graphics processing unit. IEEE Transactions on Information Technology and Biomedicine 11 (5) 497-506.

ISMAR 20092009

ISMAR MELTING THE BOUNDARIES BETWEEN DREAMS AND REALITY2009