Computed Tomography (CT) Scanner

1 STATEMENT OF WORK 1. Objective/Requirements The National Aeronautics and Space Administration (NASA), Marshall Space Flight Center (MSFC) Damage Tolerance Assessment Branch (EM21) is acquiring a next- generation computed tomography (CT) inspection system to restore and enhance essential nondestructive evaluation capabilities. This investment replaces a 17-year- old legacy system that has encountered considerable reliability challenges, including over 50% downtime in the past 18 months. The new CT platform will offer advanced imaging and analysis capabilities to support ongoing and future initiatives in additive manufacturing development, composite material evaluation—including composite overwrap pressure vessels—and detailed failure investigations. This upgrade will ensure the continuation of mission-critical inspection functions while significantly improving system performance, reliability, and analytical accuracy. 2. Characteristics, Scope, and Specs a. This document sets forth the minimum requirements for fabrication, testing, delivery and installation of a new computed tomography and digital radiography (CT/DR) system at NASA MSFC in Huntsville, AL. i. The CT/DR system shall be capable of inspecting objects in a 60” diameter by 60” height envelope with maximum weight of 3000 pounds. ii. The CT/DR system shall be capable of inspecting objects using a digital detector array (DDA) panel and using a linear detector array (LDA). CT/DR SYSTEM MECHANICAL AND HARDWARE COMPONENTS The CT/DR system mechanical and hardware subsystem shall be comprised of the following components: 3. X-Ray Source a. One dual-energy linear accelerator that produces x-rays at peak energies of both 2 MeV and 3 MeV (Varex Linatron M3A dual-energy model, Super Low Leakage, Focal spot size ≤ 2.0 mm) with thermal control unit (TCU), and including the following items: i. One imaging control unit to provide interface and synchronization with the 4343HE detector and with the LDA detector, including all required power and signal cables necessary for operation. ii. One motorized independent jaw external collimator. The jaws shall open asymmetrically to produce a field size from 1° to 24° in cone beam mode and to produce a fan beam with adjustable horizontal slice width from 1 mm to 6 mm as measured at the isocenter of the turntable. iii. One mechanically stowable laser alignment system. -- 1 of 17 -- 2 1. The laser wavelength shall be 532 nm, Class II, <1mW. 2. The laser alignment shall be capable of producing a crosshair indicator and a line indicator, each centered on the DDA (crosshair) and the LDA (line) active window/length. iv. The linear accelerator shall be fitted with one external bracket for tungsten filter plates, co-operable with the external collimator. v. One set of tungsten filter plates, one each at thicknesses of 0.0625”, 0.125”, 0.25”, 0.5” and 1”, shall be included with each of sufficient length and height to fit the filter bracket and completely cover the radiation output cone of the accelerator at its maximum 24° field size. vi. Two extended spare parts kits for the Linatron M3A shall be included. vii. Interconnecting cables with sufficient lengths to allow assembly and placement of all components shall be included. viii. Interconnecting hoses with sufficient lengths to allow assembly and placement of all components shall be included. ix. An internally mounted single spot laser to align the X-ray beam to an object being radiographed. Laser is 532 nm, Class II, 0.5 mW. x. A remote customer user interface with cabling to install in control room 136 adjacent to CT cell room 137 shall be included. xi. Operator manuals, drawings, schematics, and all supporting documentation in printed and electronic forms in English language shall be provided. 4. X-Ray Detectors a. Two DDA panels designed for high energy x-ray exposure, same make and model with pixel pitch no larger than 139 microns x 139 microns (Varex 4343HE) shall be included. i. DDA panels shall be fully compliant with the requirements of the latest versions of ASTM specifications E2597, E2698, E2736, E2737 and E3375. ii. One DDA panel shall be installed in the CT/DR system upon system assembly and the other shall be retained as a spare for installation upon end of serviceable life of the original DDA panel. iii. The DDA shall be capable of operating in native width, helical and mosaic scan modes. iv. One shielded enclosure for DDA panel to minimize radiation exposure of detector internal electronics shall be included. v. All cables, connectors, power supplies and accessories needed for operation in DR and CT modes shall be included. -- 2 of 17 -- 3 vi. All cables, connectors and accessories needed to support operation of the detector from control room 136 adjacent to CT cell room 137 shall be included. vii. The system shall be configured so that the DDA detector can be used with minimum x-ray exposure on the LDA detector. viii. Operator manuals, drawings, schematics, and all supporting documentation in printed and electronic forms in English language shall be provided. b. One LDA capable of high energy operation up to the 3 MeV Linatron x-ray output shall be included. i. The LDA pitch shall be 400 microns. ii. The LDA shall incorporate cadmium tungstate (CdWO4) or better capability detector crystals. iii. The LDA shall include a collimator that can support slice thicknesses of 1 mm to 6 mm (as measured at isocenter) in 1 mm increments. iv. The LDA detection length shall be between 30” and 36” (762 mm and 915 mm). v. The system shall be configured so that the LDA detector can be used with minimum x-ray exposure on the DDA panel. This requirement can be satisfied by any of three configurations: 1. A shield capable of blocking radiation from the DDA panel during LDA use shall be included; or 2. The DDA housing shall be constructed such that the DDA panel can be easily removed from the system during LDA operations; or 3. Detector mounting system can be…