TY - JOUR
T1 - Practical alignment method for x-ray spectral measurement in micro-CT system based on 3D printing technology
AU - Ren, Liqiang
AU - Wu, Di
AU - Li, Yuhua
AU - Zheng, Bin
AU - Chen, Yong
AU - Yang, Kai
AU - Liu, Hong
N1 - Funding Information:
This research is supported in part by National Institutes of Health (NIH), R01 CA193378, and supported in part by a grant from the University of Oklahoma Charles and Peggy Stephenson Cancer Center funded by the Oklahoma Tobacco Settlement Endowment Trust. The authors would like to acknowledge the support of Charles and Jean Smith Chair endowment fund as well.
Publisher Copyright:
© 2016 IOP Publishing Ltd.
PY - 2016/7/5
Y1 - 2016/7/5
N2 - This study presents a practical alignment method for x-ray spectral measurement in a rotating gantry based micro-computed tomography (micro-CT) system using three-dimensional (3D) printing technology. In order to facilitate the spectrometer placement inside the gantry, supporting structures including a cover and a stand were dedicatedly designed and printed using a 3D printer. According to the relative position between the spectrometer and the stand, the upright projection of the spectrometer collimator onto the stand was determined and then marked by a tungsten pinhole. Thus, a visible alignment indicator of the x-ray central beam and the spectrometer collimator represented by the pinhole was established in the micro-CT live mode. Then, arough alignment could be achieved through repeatedly adjusting and imaging the stand until the pinhole was located at the center of the acquired projection image. With the spectrometer being positioned back onto the stand, the precise alignment was completed byslightly translating the spectrometer-stand assembly around the rough location, until finding a 'sweet spot' with the highest photon rate and proper distribution of the x-ray photons in the resultant spectrum. The spectra were acquired under precise alignment and misalignment of approximately 0.2, 0.5, and 1.0 mm away from the precise alignment position, and then were compared in qualitative and quantitative analyses. Qualitative analysis results show that, with slight misalignment, the photon rateisreduced from 1302 to 1098, 1031, and 416 photons/second (p s-1), respectively, and the characteristic peaks in the acquired spectra are gradually deteriorated. Quantitative analysis indicates that the energy resolutions for characteristic peak of Kα1 were calculatedas 1.56% for precise alignment, while were 1.84% and 2.40% for slight misalignment of 0.2 and 0.5 mm. The mean energies were reduced from 43.93 keV under precise alignment condition to 40.97, 39.63 and 37.78 keV when misaligned. Accurate spectral measurements in micro-CT systems are significantly influenced by the alignment precision. This practical alignment method using 3D printing technology couldbereadily applied to other rotating gantry based micro-CT systems with modified design of the supporting structures and careful considerations of the spectrometer and gantry dimensions.
AB - This study presents a practical alignment method for x-ray spectral measurement in a rotating gantry based micro-computed tomography (micro-CT) system using three-dimensional (3D) printing technology. In order to facilitate the spectrometer placement inside the gantry, supporting structures including a cover and a stand were dedicatedly designed and printed using a 3D printer. According to the relative position between the spectrometer and the stand, the upright projection of the spectrometer collimator onto the stand was determined and then marked by a tungsten pinhole. Thus, a visible alignment indicator of the x-ray central beam and the spectrometer collimator represented by the pinhole was established in the micro-CT live mode. Then, arough alignment could be achieved through repeatedly adjusting and imaging the stand until the pinhole was located at the center of the acquired projection image. With the spectrometer being positioned back onto the stand, the precise alignment was completed byslightly translating the spectrometer-stand assembly around the rough location, until finding a 'sweet spot' with the highest photon rate and proper distribution of the x-ray photons in the resultant spectrum. The spectra were acquired under precise alignment and misalignment of approximately 0.2, 0.5, and 1.0 mm away from the precise alignment position, and then were compared in qualitative and quantitative analyses. Qualitative analysis results show that, with slight misalignment, the photon rateisreduced from 1302 to 1098, 1031, and 416 photons/second (p s-1), respectively, and the characteristic peaks in the acquired spectra are gradually deteriorated. Quantitative analysis indicates that the energy resolutions for characteristic peak of Kα1 were calculatedas 1.56% for precise alignment, while were 1.84% and 2.40% for slight misalignment of 0.2 and 0.5 mm. The mean energies were reduced from 43.93 keV under precise alignment condition to 40.97, 39.63 and 37.78 keV when misaligned. Accurate spectral measurements in micro-CT systems are significantly influenced by the alignment precision. This practical alignment method using 3D printing technology couldbereadily applied to other rotating gantry based micro-CT systems with modified design of the supporting structures and careful considerations of the spectrometer and gantry dimensions.
KW - Micro-computed tomography (micro-CT) system
KW - Rough and precise alignment
KW - Spectral measurement
KW - Spectrometer placement
UR - http://www.scopus.com/inward/record.url?scp=85022099490&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85022099490&partnerID=8YFLogxK
U2 - 10.1088/2057-1976/2/3/037004
DO - 10.1088/2057-1976/2/3/037004
M3 - Article
C2 - 27777787
AN - SCOPUS:85022099490
SN - 2057-1976
VL - 2
JO - Biomedical Physics and Engineering Express
JF - Biomedical Physics and Engineering Express
IS - 3
M1 - 037004
ER -