Evaluation of the truebeam machine performance check (<scp>MPC</scp>) geometric checks for daily <scp>IGRT</scp> geometric accuracy quality assurance

Barnes, Michael P.; Greer, Peter B.

doi:10.1002/acm2.12064

Cited by 31 publications

(40 citation statements)

References 14 publications

(14 reference statements)

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“…MPC provides a streamlined process to check both mechanical and dosimetric features of the LINAC by taking a set of kV and MV EPID images. Its performance has already been independently evaluated by several groups . The MPC on Halcyon comprises the same concept and process, but differs in that it must be performed daily before any clinical treatment can be delivered.…”

Section: Methodsmentioning

confidence: 99%

“…Its performance has already been independently evaluated by several groups. 15,16 The MPC on Halcyon comprises the same concept and process, but differs in that it must be performed daily before any clinical treatment can be delivered. Figure 2 Geometric accuracy test includes the test of imaging and treatment isocenter coincidence, which was evaluated with an IsoCube phantom as shown in Fig.…”

Section: B Overview Of Kv Imaging Performance Characterizationmentioning

confidence: 99%

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Characterization of a prototype rapid kilovoltage x‐ray image guidance system designed for a ring shape radiation therapy unit

et al. 2019

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Purpose This study aims to characterize the performance of a prototype rapid kilovoltage (kV) x‐ray image guidance system onboard the newly released Halcyon 2.0 linear accelerator (Varian Medical Systems, Palo Alto, CA) by use of conventional and innovatively designed testing procedures. Methods Basic imaging system performance tests and radiation dose measurements were performed for all eleven kV‐cone beam computed tomography (CBCT) imaging protocols available on a preclinical Halcyon 2.0 LINAC. Both conventional CBCT reconstruction using the Feldkamp–Davis–Kress (FDK) algorithm and a novel, advanced iterative reconstruction (iCBCT) available on this platform were evaluated. Standard image quality metrics, including slice thickness accuracy, high‐contrast resolution, low‐contrast resolution, regional uniformity and noise, and CT Hounsfield unit (HU) number accuracy and linearity were evaluated using a manufacturer‐supplied QUART phantom (GmbH, Zorneding, Germany) and an independent image quality phantom (Catphan 500, The Phantom Laboratory, New York, NY). Due to the simplified design of the QUART phantom, we developed surrogate and clinically feasible strategies for measuring slice thickness and high‐ and low‐contrast resolution. Imaging dose delivered by these eleven protocols was measured using a computed tomography dose index phantom and pencil chamber with commonly accepted methods and procedures. A subset of measurements were repeated on a conventional C‐arm LINAC (TrueBeam and Trilogy, Varian Medical System) for comparison. Clinical patient images of pelvic and abdominal regions are also presented for qualitative assessment as part of a feasibility study for clinical implementation. Results Image acquisition time was 17–42 s on the Halcyon system compared with 60 s on the C‐arm LINAC systems. The kV imager projection offset, imaging and treatment isocenter coincidence and the couch three‐dimensional match movement all achieved less than1 mm mechanical accuracy. All major image quality metrics were within either the national guideline or vendor‐recommended tolerances. The designed surrogate approach with the QUART phantom showed a range of 0.24–0.35 cycles/mm for spatial resolution, a contrast‐to‐noise ratio (CNR) of 2–20 for FDK reconstruction and a tolerance of 0.5 mm for slice thickness. Other metrics derived from the Catphan images obtained on the Halcyon and C‐arm LINACs showed comparable values for the FDK reconstruction. The iterative reconstruction tended to reduce noise, as evidenced by a higher CNR ratio. The fast scan pelvis protocols for Halcyon resulted in 50% lower dose compared to the standard scans, and the thorax fast protocol similarly delivered 10% lower dose than the standard thoracic scan. Preliminary patient images indicated that rapid kV CBCT with breath‐hold is feasible, with improved imaging quality compared to free‐breathing scans. Conclusion Independent and comprehensive characterization of the kV imaging guidance system on the Halcyon 2.0 system demonstrated acceptable image qual...

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Section: Methodsmentioning

confidence: 99%

Section: B Overview Of Kv Imaging Performance Characterizationmentioning

confidence: 99%

Characterization of a prototype rapid kilovoltage x‐ray image guidance system designed for a ring shape radiation therapy unit

et al. 2019

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“…1,2 In recent years, automated QC programs utilizing the electronic portal imaging device have been proposed, 3,4 and Linac vendors have begun to incorporate QC applications into the Linac platforms. One such application is Machine There have been a number of publications evaluating and validating the accuracy of MPC [5][6][7][8][9][10] since it was first introduced by Varian in 2015. The testing of MPC to date has been via two methods: either comparing constancy over time against another established measurement method [5][6][7][8][9] or via the introduction of deliberate errors.…”

mentioning

confidence: 99%

Long‐term experience of MPC across multiple TrueBeam linacs: MPC concordance with conventional QC and sensitivity to real‐world faults

Pearson

Eaton

Greener

2020

J Applied Clin Med Phys

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Machine Performance Check (MPC) is an automated Quality Control (QC) tool that is integrated into the TrueBeam and Halcyon linear accelerators (Linacs), utilizing the imaging systems to verify the Linac beam and geometry. This work compares the concordance of daily MPC results with conventional QC tests over a 3-year period for eight Linacs in order to assess the sensitivity of MPC in detecting faults. The MPC output measurements were compared with the monthly ionization chamber measurements for 6 and 10 MV photon beams and 6, 9, 12, 16, and 18 MeV electron beams. All 6 MV Beam and Geometry (6MVBG) MPC test failures were analyzed to determine the failure rate and the number of true and false negative results, using the conventional QC record as the reference. The concordance between conventional QC test failures and MPC test failures was investigated. The mean agreement across 1933 MPC output and monthly comparison chamber measurements for all beam energies was 0.2%, with 97.8% within 1.5%, and a maximum difference of 2.9%. Of the 5000-6000 MPC individual test parameter results for the 6MVBG test, the highest failure rate was BeamOutputChange (0.5%), then BeamCenterShift (0.3%), and was ≤ 0.1% for the remaining parameters. There were 50 true negative and 27 false negative out of tolerance MPC results, with false negatives resolved by repeating MPC or by independent measurement. The analysis of conventional QC failures demonstrated that MPC detected all failures, except occasions when MPC reported output within tolerance, a result of the MPC-chamber response variation. The variation in MPC output versus chamber measurement indicates MPC is appropriate for daily output constancy but not for the measurement of absolute output. The comparison of the 6MVBG results and conventional records provides evidence that MPC is a sensitive method of performing beam and mechanical checks in a clinical setting.

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“…Moreover, CBCT and OSMS isocenter congruence checks are not included in the current MPC. Nonetheless it is sensible to adopt the automated MPC workflow into periodic QA procedures, although, currently the manufacturer recommends against replacing daily QA with MPC.…”

Section: Introductionmentioning

confidence: 99%

Efficient quality assurance method with automated data acquisition of a single phantom setup to determine radiation and imaging isocenter congruence

Kang

Patel

Roeske

2019

J Applied Clin Med Phys

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We developed a quality assurance (QA) method to determine the isocenter congruence of Optical Surface Monitoring System (OSMS, Varian, CA, USA), kilovoltage (kV), and megavoltage (MV) imaging, and the radiation isocenter using a single setup of the OSMS phantom for frameless Stereotactic Radiosurgery (SRS) treatment. After aligning the phantom to the OSMS isocenter, a cone‐beam computed tomography (CBCT) of the phantom was acquired and registered to a computed tomography (CT) scan of the phantom to determine the CBCT isocenter. Without moving the phantom, MV and kV images were simultaneously acquired at four gantry angles to localize MV and kV isocenters. Then, Winston‐Lutz (W‐L) test images of the central BB in the phantom were acquired to analyze the radiation isocenter. The gantry and couch were automatically controlled using the TrueBeam Developer Mode during MV, kV, and W‐L image acquisition. All the images were acquired weekly for 17 weeks to track the congruence of all the imaging modalities' isocenter in six‐dimensional (6D) translations and rotations, and the radiation isocenter in three‐dimensional (3D) translations. The shifts of isocenters of all imaging modalities and the radiation isocenter from the OSMS isocenter were within 0.2 mm and 0.2° on average over 17 weeks. The maximum discrepancy between OSMS and other imaging modalities or radiation isocenters was 0.8 mm and 0.3°. However, systematic shifts of radiation isocenter anteriorly and laterally relative to the OSMS isocenter were observed. The measured discrepancies were consistent from week‐to‐week except for two weeks when the isocenter discrepancies of 0.8 mm were noted due to drifts of the OSMS isocenter. Once recalibration was performed on OSMS, the discrepancy was reduced to 0.3 mm and 0.2°.By performing the proposed QA on a weekly basis, the isocenter congruencies of multiple imaging systems and radiation isocenter were validated for a linear accelerator.

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Evaluation of the truebeam machine performance check (MPC) geometric checks for daily IGRT geometric accuracy quality assurance

Cited by 31 publications

References 14 publications

Characterization of a prototype rapid kilovoltage x‐ray image guidance system designed for a ring shape radiation therapy unit

Characterization of a prototype rapid kilovoltage x‐ray image guidance system designed for a ring shape radiation therapy unit

Long‐term experience of MPC across multiple TrueBeam linacs: MPC concordance with conventional QC and sensitivity to real‐world faults

Efficient quality assurance method with automated data acquisition of a single phantom setup to determine radiation and imaging isocenter congruence

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