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Anatomical Phantoms

Paper List

For further information on the phantoms and download instructions see: Zubal Phantom.

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Papers

o Two dedicated software, voxel-based, anthropomorphic (torso and head) phantoms.

I. George Zubal, Ph. D., Charles R. Harrell, Eileen O. Smith, B.S., Amy L. Smith

Imaging Processing and Analysis Group
Department of Diagnostic Radiology
333 Cedar Street
Yale University School of Medicine, New Haven, CT 06510

Abstract

We have segmented CT torso+head and MRI head slices of two living human males. The manually segmented 129 x-ray CT transverse slices were used to create a computerized 3-dimensional volume array modeling all major internal structures of the body. The original x-ray CT images were reconstructed in a 512x512 matrix with a resolution of 1 millimeter in the x,y plane. The z-axis resolution is 1 centimeter from neck to mid-thigh and 0.5 centimeter from neck to crown of the head. Each voxel of the volume contains an index number designating it as belonging to a given organ or internal structure; 68 such index numbers are assigned. The final torso+head phantom is interpolated to create a 128x128x243 byte volume with isotropic voxel dimensions of 2.5 mms. Secondly, a dedicated head phantom was created by similar processing in which 124 transverse MRI were outlined. The transverse T2 slices, recorded in a 256x256 matrix have isotropic voxel dimensions of 1.5mm. This dedicated head phantom contains 62 index numbers designating neurological and taxonomical structures in the brain, as well as anatomical regions. The final volume is contained within a 256x256x128 byte array. Both of these volume arrays represent high resolution models of the human anatomy and can serve as a voxel-based anthropomorphic phantom suitable for many computer-based modeling and simulation calculations. We have applied them to Monte Carlo simulations from which realistic image projection data has been generated.

o High Resolution, MRI-Based, Segmented, Computerized Head Phantom.

I. George Zubal, Charles R. Harrell, Eileen O. Smith, Amy L. Smith, Paul Krischlunas.

Image Processing and Analysis Group,
Dept. of Diagnostic Radiology,
Yale University, New Haven, CT, 06510 USA

Abstract

Purpose: We have created a high resolution software phantom of the human brain which is applicable to voxel-based radiation transport calculations yielding nuclear medicine simulated images and/or internal dose estimates. Results: A software head phantom was created from 124 transverse MRI images of a healthy normal. The transverse T2 slices, recorded in a 256x256 matrix from a GE Signa 2 scanner, have isotropic voxel dimensions of 1.5 mm and were manually segmented by our clinical staff. Each voxel of the phantom contains one of 62 index numbers designating anatomical, neurological, and taxonomical structures. The result is stored as a 256x256x128 byte array. Internal volumes compare favorably to those described in the ICRP Reference Man. Conclusion: The computerized array represents a high resolution model of a typical human brain and serves as a voxel-based anthropomorphic head phantom suitable for computer based modeling and simulation calculations. It offers an improved realism over previous mathematically described software brain phantoms, and creates a reference standard for comparing results of newly emerging voxel-based computations. Such voxel-based computations lead the way to developing diagnostic and dosimetry calculations which can utilize patient specific diagnostic images. However, such individualized approaches lack fast, automatic segmentation schemes for routine use; therefore, our high resolution, typical head geometry gives the most realistic patient model currently available.

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