Establishing a quality assurance program for photon counting detector (PCD) CT: Tips and caveats

Zaki Ahmed; Andrea Ferrero; Liqiang Ren; Thomas J. Vrieze; Kishore Rajendran; Christopher P. Favazza; Lifeng Yu; Michael R. Bruesewitz; Cynthia H. McCollough; Shuai Leng

doi:10.1002/acm2.14074

Establishing a quality assurance program for photon counting detector (PCD) CT: Tips and caveats

Zaki Ahmed, Andrea Ferrero, Liqiang Ren, Thomas J. Vrieze, Kishore Rajendran, Christopher P. Favazza, Lifeng Yu, Michael R. Bruesewitz, Cynthia H. McCollough, Shuai Leng

Research output: Contribution to journal › Article › peer-review

Abstract

Purpose: To determine the suitability of a quality assurance (QA) program based on the American College of Radiology's (ACR) CT quality control (QC) manual to fully evaluate the unique capabilities of a clinical photon-counting-detector (PCD) CT system. Methods: A daily QA program was established to evaluate CT number accuracy and artifacts for both standard and ultra-high-resolution (UHR) scan modes. A complete system performance evaluation was conducted in accordance with the ACR CT QC manual by scanning the CT Accreditation Phantom with routine clinical protocols and reconstructing low-energy-threshold (T3D) and virtual monoenergetic images (VMIs) between 40 and 120 keV. Spatial resolution was evaluated by computing the modulation transfer function (MTF) for the UHR mode, and multi-energy performance was evaluated by scanning a body phantom containing four iodine inserts with concentrations between 2 and 15 mg I/cc. Results: The daily QA program identified instances when the detector needed recalibration or replacement. CT number accuracy was impacted by image type: CT numbers at 70 keV VMI were within the acceptable range (defined for 120 kV). Other keV VMIs and the T3D reconstruction had at least one insert with CT number outside the acceptable range. The limiting resolution was nearly 40 lp/cm based on MTF measurements, which far exceeds the 12 lp/cm maximum capability of the ACR phantom. The CT numbers in the iodine inserts were accurate on all VMIs (3.8% average percentage error), while the iodine concentrations had an average root mean squared error of 0.3 mg I/cc. Conclusion: Protocols and parameters must be properly selected on PCD-CT to meet current accreditation requirements with the ACR CT phantom. Use of the 70 keV VMI allowed passing all tests prescribed in the ACR CT manual. Additional evaluations such an MTF measurement and multi-energy phantom scans are also recommended to comprehensively evaluate PCD-CT scanner performance.

Original language	English (US)
Article number	e14074
Journal	Journal of applied clinical medical physics
Volume	24
Issue number	7
DOIs	https://doi.org/10.1002/acm2.14074
State	Published - Jul 2023

Keywords

photon counting detector
quality assurance
quality control
scanner performance

ASJC Scopus subject areas

Radiation
Instrumentation
Radiology Nuclear Medicine and imaging

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10.1002/acm2.14074

Cite this

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title = "Establishing a quality assurance program for photon counting detector (PCD) CT: Tips and caveats",

abstract = "Purpose: To determine the suitability of a quality assurance (QA) program based on the American College of Radiology's (ACR) CT quality control (QC) manual to fully evaluate the unique capabilities of a clinical photon-counting-detector (PCD) CT system. Methods: A daily QA program was established to evaluate CT number accuracy and artifacts for both standard and ultra-high-resolution (UHR) scan modes. A complete system performance evaluation was conducted in accordance with the ACR CT QC manual by scanning the CT Accreditation Phantom with routine clinical protocols and reconstructing low-energy-threshold (T3D) and virtual monoenergetic images (VMIs) between 40 and 120 keV. Spatial resolution was evaluated by computing the modulation transfer function (MTF) for the UHR mode, and multi-energy performance was evaluated by scanning a body phantom containing four iodine inserts with concentrations between 2 and 15 mg I/cc. Results: The daily QA program identified instances when the detector needed recalibration or replacement. CT number accuracy was impacted by image type: CT numbers at 70 keV VMI were within the acceptable range (defined for 120 kV). Other keV VMIs and the T3D reconstruction had at least one insert with CT number outside the acceptable range. The limiting resolution was nearly 40 lp/cm based on MTF measurements, which far exceeds the 12 lp/cm maximum capability of the ACR phantom. The CT numbers in the iodine inserts were accurate on all VMIs (3.8% average percentage error), while the iodine concentrations had an average root mean squared error of 0.3 mg I/cc. Conclusion: Protocols and parameters must be properly selected on PCD-CT to meet current accreditation requirements with the ACR CT phantom. Use of the 70 keV VMI allowed passing all tests prescribed in the ACR CT manual. Additional evaluations such an MTF measurement and multi-energy phantom scans are also recommended to comprehensively evaluate PCD-CT scanner performance.",

keywords = "photon counting detector, quality assurance, quality control, scanner performance",

author = "Zaki Ahmed and Andrea Ferrero and Liqiang Ren and Vrieze, {Thomas J.} and Kishore Rajendran and Favazza, {Christopher P.} and Lifeng Yu and Bruesewitz, {Michael R.} and McCollough, {Cynthia H.} and Shuai Leng",

note = "Funding Information: Cynthia McCollough is the recipient of a research grant to the institution from Siemens Healthcare GmbH. The other authors have no relevant conflicts of interest to disclose. Publisher Copyright: {\textcopyright} 2023 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.",

year = "2023",

month = jul,

doi = "10.1002/acm2.14074",

language = "English (US)",

volume = "24",

journal = "Journal of applied clinical medical physics",

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T1 - Establishing a quality assurance program for photon counting detector (PCD) CT

T2 - Tips and caveats

AU - Ahmed, Zaki

AU - Ferrero, Andrea

AU - Ren, Liqiang

AU - Vrieze, Thomas J.

AU - Rajendran, Kishore

AU - Favazza, Christopher P.

AU - Yu, Lifeng

AU - Bruesewitz, Michael R.

AU - McCollough, Cynthia H.

AU - Leng, Shuai

N1 - Funding Information: Cynthia McCollough is the recipient of a research grant to the institution from Siemens Healthcare GmbH. The other authors have no relevant conflicts of interest to disclose. Publisher Copyright: © 2023 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.

PY - 2023/7

Y1 - 2023/7

N2 - Purpose: To determine the suitability of a quality assurance (QA) program based on the American College of Radiology's (ACR) CT quality control (QC) manual to fully evaluate the unique capabilities of a clinical photon-counting-detector (PCD) CT system. Methods: A daily QA program was established to evaluate CT number accuracy and artifacts for both standard and ultra-high-resolution (UHR) scan modes. A complete system performance evaluation was conducted in accordance with the ACR CT QC manual by scanning the CT Accreditation Phantom with routine clinical protocols and reconstructing low-energy-threshold (T3D) and virtual monoenergetic images (VMIs) between 40 and 120 keV. Spatial resolution was evaluated by computing the modulation transfer function (MTF) for the UHR mode, and multi-energy performance was evaluated by scanning a body phantom containing four iodine inserts with concentrations between 2 and 15 mg I/cc. Results: The daily QA program identified instances when the detector needed recalibration or replacement. CT number accuracy was impacted by image type: CT numbers at 70 keV VMI were within the acceptable range (defined for 120 kV). Other keV VMIs and the T3D reconstruction had at least one insert with CT number outside the acceptable range. The limiting resolution was nearly 40 lp/cm based on MTF measurements, which far exceeds the 12 lp/cm maximum capability of the ACR phantom. The CT numbers in the iodine inserts were accurate on all VMIs (3.8% average percentage error), while the iodine concentrations had an average root mean squared error of 0.3 mg I/cc. Conclusion: Protocols and parameters must be properly selected on PCD-CT to meet current accreditation requirements with the ACR CT phantom. Use of the 70 keV VMI allowed passing all tests prescribed in the ACR CT manual. Additional evaluations such an MTF measurement and multi-energy phantom scans are also recommended to comprehensively evaluate PCD-CT scanner performance.

AB - Purpose: To determine the suitability of a quality assurance (QA) program based on the American College of Radiology's (ACR) CT quality control (QC) manual to fully evaluate the unique capabilities of a clinical photon-counting-detector (PCD) CT system. Methods: A daily QA program was established to evaluate CT number accuracy and artifacts for both standard and ultra-high-resolution (UHR) scan modes. A complete system performance evaluation was conducted in accordance with the ACR CT QC manual by scanning the CT Accreditation Phantom with routine clinical protocols and reconstructing low-energy-threshold (T3D) and virtual monoenergetic images (VMIs) between 40 and 120 keV. Spatial resolution was evaluated by computing the modulation transfer function (MTF) for the UHR mode, and multi-energy performance was evaluated by scanning a body phantom containing four iodine inserts with concentrations between 2 and 15 mg I/cc. Results: The daily QA program identified instances when the detector needed recalibration or replacement. CT number accuracy was impacted by image type: CT numbers at 70 keV VMI were within the acceptable range (defined for 120 kV). Other keV VMIs and the T3D reconstruction had at least one insert with CT number outside the acceptable range. The limiting resolution was nearly 40 lp/cm based on MTF measurements, which far exceeds the 12 lp/cm maximum capability of the ACR phantom. The CT numbers in the iodine inserts were accurate on all VMIs (3.8% average percentage error), while the iodine concentrations had an average root mean squared error of 0.3 mg I/cc. Conclusion: Protocols and parameters must be properly selected on PCD-CT to meet current accreditation requirements with the ACR CT phantom. Use of the 70 keV VMI allowed passing all tests prescribed in the ACR CT manual. Additional evaluations such an MTF measurement and multi-energy phantom scans are also recommended to comprehensively evaluate PCD-CT scanner performance.

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KW - quality control

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Establishing a quality assurance program for photon counting detector (PCD) CT: Tips and caveats

Abstract

Keywords

ASJC Scopus subject areas

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