EXACT TM CT Scanner EXACT: The heart of an FAA-certified Explosives Detection Scanner 3-D Image

System Block Diagram Automatic Explosives Detection 4 processors 3D Image Display Image Reconstruction 1.5 GOp/s, 50 processors Helical Cone Beam Data X-ray CT scanner

Reconstruction Engine Requirements Nutating Slice Image Reconstruction 1.5 GOp/s Dual-energy Helical Cone- beam data Control and Status (RS232) Images (SCSI) 6064 samples/view 1080 views/s 450 3D bags /hr  90 2D slices/s

Reconstruction Algorithm Nutating Slice Reconstruction Prerequisite: cone beam data corrected for detector imperfections

Nutating Slice Reconstruction HELICAL CONE-BEAM

SKYpack* Computer Application-specific repackaging of standard 6U VME product –originally developed for DARPA SAST program Dual use in commercial applications –explosives detection –medical CT image reconstruction * SKY Computers, Chelmsford, MA

SKYpack Components 1 RISC processor for I/O control 12 RISC processors for compute processing – Labeled AP0-11 in diagram 6 SHARC processors 6 ASIC processors Shared Bus: SKYchannel

SKYpack Partitioning High and low energy images reconstructed on different SKYpacks Processes are data driven and asynchronous ProcessorMemory

AP 2 64 MB 4 MB Platform 0 Platform 1 Platform 2 SKY-CT Control Processor SKYchannel SKYpack RS232 SKYburst Data Entry Point SCSI 64 MB AP 3 AP 1 AP 0 AP 4 AP 5 AP 6 AP 7 AP 8 AP 9 AP 10 AP 11 SHARCS ASICS 4 MB

SKYpack Partitioning AP 0 o/p 0 SHARC 0 AP 7 AP 8 AP 9 o/p 21 i/p i/o 0 i/o 1 RS232 Correction Cone Fan Fan Hybrid Hybrid Parallel Filtering Input Data SHARC 5

SKYpack Partitioning cont’d ASIC 0 ASIC 5 L Video Memory AP 10 AP 11 R Video Memory i/p i/o 0 i/o 13 o/p 0 o/p 249 Backprojection Untilt Image Formatting And Transfer (SCSI)

SKYpack Partitioning System processor distributes cone beam data to AP 0-7 AP 0 does RS232 communication and controls other processors AP 0-7 correct and convert cone to hybrid data Each cone view contributes to 22 slices, every 12th view a new slice is created

SKYpack Partitioning AP 8-9 convert hybrid data to parallel SHARCs high pass filter parallel data using FFT ASICs backproject filtered data into tilted slices AP 10 untilts tilted slices into parallel AP 11 formats images and carries out SCSI communication

Verification and Validation Offline, single process software was implemented Simulations to verify offline software Intermediate results from offline software matched with online software

Automatic Detection Subsystem Consists of four processors Does image analysis, archiving and display Image data is propagated along two paths that search for two classes of explosives Each path uses detection and discrimination algorithms

References “Nutating Slices CT Image Reconstruction Apparatus and Method” United States Patent: 5,802,134, September 1998 “Parallel Processing Architecture for Computed Tomography Scanning System using Non-Parallel Slices” United States Patent: 5,887,047, March 23, 1999 “Computed Tomography Apparatus and Method for Classifying Objects” United States Patent: 6,317,508, November 13, 2001