Multisource inverse-geometry CT. Part I. System concept and development

• Published in: Medical physics (Lancaster) 2016-08, Vol.43 (8), p.4607-4616
• Main Authors: De Man, Bruno, Uribe, Jorge, Baek, Jongduk, Harrison, Dan, Yin, Zhye, Longtin, Randy, Roy, Jaydeep, Waters, Bill, Wilson, Colin, Short, Jonathan, Inzinna, Lou, Reynolds, Joseph, Neculaes, V. Bogdan, Frutschy, Kristopher, Senzig, Bob, Pelc, Norbert
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Algorithms; ANIMALS; Biological material, e.g. blood, urine; Haemocytometers; Calibrating of instruments or apparatus; Calibration; Computed tomography; Computerised tomographs; computerised tomography; COMPUTERIZED TOMOGRAPHY; DESIGN; DIAGNOSTIC IMAGING (IONIZING AND NON-IONIZING); Digital computing or data processing equipment or methods, specially adapted for specific applications; ELECTRIC POTENTIAL; Equipment Design; Image data processing or generation, in general; image denoising; Image enhancement or restoration, e.g. from bit‐mapped to bit‐mapped creating a similar image; image reconstruction; image resolution; Image scanners; Image sensors; inverse‐geometry CT; medical image processing; Medical image reconstruction; Medical X‐ray imaging; multisource CT; Noise; PHANTOMS; Phantoms, Imaging; Polymethyl Methacrylate; Rabbits; Radiation Dosage; RADIATION PROTECTION AND DOSIMETRY; Rats; Reconstruction; Scattering, Radiation; SPATIAL RESOLUTION; Standards and calibration; Testing or calibrating of apparatus or arrangements provided for in groups G01D1/00 to G01D15/00; Tomography Scanners, X-Ray Computed; Tomography, X-Ray Computed - instrumentation; Tomography, X-Ray Computed - methods; Water; X RADIATION; X-RAY SOURCES; X-Rays; X‐ray detectors; X‐ray imaging
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4954846

Purpose: This paper presents an overview of multisource inverse-geometry computed tomography (IGCT) as well as the development of a gantry-based research prototype system. The development of the distributed x-ray source is covered in a companion paper [V. B. Neculaes et al., “Multisource inverse-geometry CT. Part II. X-ray source design and prototype,” Med. Phys. 43, 4617–4627 (2016)]. While progress updates of this development have been presented at conferences and in journal papers, this paper is the first comprehensive overview of the multisource inverse-geometry CT concept and prototype. The authors also provide a review of all previous IGCT related publications. Methods: The authors designed and implemented a gantry-based 32-source IGCT scanner with 22 cm field-of-view, 16 cm z-coverage, 1 s rotation time, 1.09 × 1.024 mm detector cell size, as low as 0.4 × 0.8 mm focal spot size and 80–140 kVp x-ray source voltage. The system is built using commercially available CT components and a custom made distributed x-ray source. The authors developed dedicated controls, calibrations, and reconstruction algorithms and evaluated the system performance using phantoms and small animals. Results: The authors performed IGCT system experiments and demonstrated tube current up to 125 mA with up to 32 focal spots. The authors measured a spatial resolution of 13 lp/cm at 5% cutoff. The scatter-to-primary ratio is estimated 62% for a 32 cm water phantom at 140 kVp. The authors scanned several phantoms and small animals. The initial images have relatively high noise due to the low x-ray flux levels but minimal artifacts. Conclusions: IGCT has unique benefits in terms of dose-efficiency and cone-beam artifacts, but comes with challenges in terms of scattered radiation and x-ray flux limits. To the authors’ knowledge, their prototype is the first gantry-based IGCT scanner. The authors summarized the design and implementation of the scanner and the authors presented results with phantoms and small animals.