4D eXtended CArdiac-Torso (XCAT) Phantoms Simulated Real The 4D XCAT phantoms were developed as virtual patient models for imaging research. They are based on segmented human imaging data and use spline surfaces to realistically model the anatomy of various types of people (male, female, different ages, heights, and weights). The phantoms include realistic models for the cardiac and respiratory motions. The phantoms can be combined with computerized models that accurately simulate the physics of the imaging process of different scanners. With that, they can produce imaging data as if the phantom was a live patient. They can be used as virtual test subjects to evaluate and improve medical imaging devices and techniques. Based on Segmented Human Imaging Data, Detailed Anatomy defined with Spline Surfaces Combined with algorithms that mimic modern imaging devices, can produce realistic imaging data

Developing a population of XCAT phantoms XCAT previously limited to a pair of adult models (male and female) Modeling patient variability is essential to mimic clinical trials (what works for one person may not work for others) Number of phantoms is limited due to time to segment patient data (takes months to a year/model)

Population of 4D XCAT Phantoms Currently creating a population of hundreds of detailed phantoms to represent the public at large from infancy to adulthood for use in imaging research Each model is based on patient CT data Include cardiac and respiratory motions for 4D simulations Library of 4D phantoms 3

Phantom Construction Segment patient CT data (bones and major organs) to create an initial model Fit arms/legs to patient model using XCAT models scaled to patient size Utilize MC-LDDMM mapping algorithm to morph one complete template XCAT phantom (including cardiac & respiratory motions) to the target model Defines unsegmented structures (vessels, muscles, tendons, ligaments) No need to segment all structures Using this technique, a phantom can now be completed in days instead of months Template XCAT Patient XCAT Patient Target Tward el al, Patient Specific Dosimetry Phantoms Using Multichannel LDDMM of the Whole Body, International Journal of Biomedical Imaging, vol. 2011, Article 481064 4

New XCAT Phantoms Here are some example phantoms created at the different ages. Each includes the same amount of detail as the original XCAT templates. Segars el al, Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization, Med Phys, 40, (2013). Norris el al, A set of 4D Pediatric XCAT Reference Phantoms for Multimodality Research, Med Phys, 41, (2014). Segars el al, The development of a population of 4D pediatric XCAT phantoms for imaging research and optimization, Med Phys, (2015). 5

New XCAT Phantoms Each phantom also includes parameterized models for the cardiac and respiratory motions as transformed from the original XCAT templates. Segars el al, Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization, Med Phys, 40, (2013). Norris el al, A set of 4D Pediatric XCAT Reference Phantoms for Multimodality Research, Med Phys, 41, (2014). Segars el al, The development of a population of 4D pediatric XCAT phantoms for imaging research and optimization, Med Phys, (2015). 6

XCAT Population of Models With 4D modeling, our phantoms have pushed the envelope in what we can do with simulations. 7

Application to Imaging Research Population of models to simulate imaging data from varying body types under different protocols

Accurate Dose Estimation from Imaging Protocols In addition to being able to simulate medical images, the phantoms can be used to estimate the radiation dose from different imaging protocols. The above images show the radiation dose experienced by 5 year old phantoms undergoing standard chest and abdomen CT scan protocols. With the ability to simulate medical images as well as calculate the dose deposited in the body, the population of XCAT phantoms provide a nice tool to develop patient-specific imaging protocols so as to achieve a diagnostic image quality at the lowest possible radiation dose to the patient. This creates more personalized imaging techniques, moving away from the one size fits all mentality. Chest Scan Abdomen Scan Li et. al., Med Phys, 38(1), 397-407 (2011). Li et. al., Med Phys, 38(1), 408-419 (2011).