Quality Control of Portal Imaging with PTW EPID QC PHANTOM®

Pesznyák, Csilla; Faludi, Gábor; Mózes, Árpád; Kiss, Balázs; Király, Réka; Polgár, I; Zaránd, P; Mayer, A.

doi:10.1007/s00066-009-1905-z

Cited by 5 publications

(3 citation statements)

References 38 publications

(14 reference statements)

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“…A preliminary evaluation of the QC phantom has been reported by Das et al (23) A similar study by Pesznyák et al (24) has reported multiple difficulties in the image processing of the associated imaging software, mainly gray scale reversal (black to white and vice versa), after exporting images from some portal imagers. When gray scale reversal took place, the signalto-noise ratio (SNR) was incorrectly recorded with increasing absorption, which may pose a problem in routine QA.…”

Section: Radiographs (Drr)mentioning

confidence: 85%

A quality assurance phantom for electronic portal imaging devices

Das

Cao

Cheng

et al. 2011

J Applied Clin Med Phys

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Electronic portal imaging device (EPID) plays an important role in radiation therapy portal imaging, geometric and dosimetric verification. Consistent image quality and stable radiation response is necessary for proper utilization that requires routine quality assurance (QA). A commercial ‘EPID QC’ phantom weighing 3.8 kg with a dimension of 25×25×4.8 cm3 is used for EPID QA. This device has five essential tools to measure the geometric accuracy, signal‐to‐noise ratio (SNR), dose linearity, and the low‐ and the high‐contrast resolutions. It is aligned with beam divergence to measure the imaging and geometric parameters in both X and Y directions, and can be used as a baseline check for routine QA. The low‐contrast tool consists of a series of holes with various diameters and depths in an aluminum slab, very similar to the Las Vegas phantom. The high‐resolution contrast tool provides the modulation transfer function (MTF) in both the x‐ and y‐dimensions to measure the focal spot of linear accelerator that is important for imaging and small field dosimetry. The device is tested in different institutions with various amorphous silicon imagers including Elekta, Siemens and Varian units. Images of the QA phantom were acquired at 95.2 cm source‐skin‐distance (SSD) in the range 1–15 MU for a 26×26 cm2 field and phantom surface is set normal to the beam direction when gantry is at 0° and 90°. The epidSoft is a software program provided with the EPID QA phantom for analysis of the data. The preliminary results using the phantom on the tested EPID showed very good low‐contrast resolution and high resolution, and an MTF (0.5) in the range of 0.3–0.4 lp/mm. All imagers also exhibit satisfactory geometric accuracy, dose linearity and SNR, and are independent of MU and spatial orientations. The epidSoft maintains an image analysis record and provides a graph of the temporal variations in imaging parameters. In conclusion, this device is simple to use and provides testing on basic and advanced imaging parameters for daily QA on any imager used in clinical practices.PACS number: 87.57 C‐, 87.57 N‐

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Section: Radiographs (Drr)mentioning

confidence: 85%

A quality assurance phantom for electronic portal imaging devices

Das

Cao

Cheng

et al. 2011

J Applied Clin Med Phys

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“…More recently, amorphous silicon (a-Si)-based EPIDs have been developed with excellent image quality [17] and requirements for dosimetric purposes [3,7,8,10,12,13,15]. So far only a few reports have addressed dosimetric applications for this type of detector from Elekta [14,18,24,25].…”

Section: Introductionmentioning

confidence: 99%

Simple Proposal for Dosimetry with an Elekta iViewGTTM Electronic Portal Imaging Device (EPID) Using Commercial Software Modules

et al. 2011

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“…The PTW EPID QC PHANTOM ® was placed on the homogeneous part of the tabletop taking into account the divergence of the beam so that the whole phantom was in the image 12. The acquired images were analysed with the epidSoft ® 2.0 computer program 13.…”

Section: Methodsmentioning

confidence: 99%

Verification of quality parameters for portal images in radiotherapy

Pesznyák¹,

Polgár²,

Weisz³

et al. 2011

Radiology and Oncology

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BackgroundThe purpose of the study was to verify different values of quality parameters of portal images in radiotherapy.Materials and methodsWe investigated image qualities of different field verification systems. Four EPIDs (Siemens OptiVue500aSi®, Siemens BeamView Plus®, Elekta iView® and Varian PortalVision™) were investigated with the PTW EPID QC PHANTOM® and compared with two portal film systems (Kodak X-OMAT® cassette with Kodak X-OMAT V® film and Kodak EC-L Lightweight® cassette with Kodak Portal Localisation ReadyPack® film).ResultsA comparison of the f50 and f25 values of the modulation transfer functions (MTFs) belonging to each of the systems revealed that the amorphous silicon EPIDs provided a slightly better high contrast resolution than the Kodak Portal Localisation ReadyPack® film with the EC-L Lightweight® cassette. The Kodak X-OMAT V® film gave a poor low contrast resolution: from the existing 27 holes only 9 were detectable.ConclusionsOn the base of physical characteristics, measured in this work, the authors suggest the use of amorphous-silicon EPIDs producing the best image quality. Parameters of the EPIDs with scanning liquid ionisation chamber (SLIC) were very stable. The disadvantage of older versions of EPIDs like SLIC and VEPID is a poor DICOM implementation, and the modulation transfer function (MTF) values (f50 and f25) are less than that of aSi detectors.

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Quality Control of Portal Imaging with PTW EPID QC PHANTOM®

Cited by 5 publications

References 38 publications

A quality assurance phantom for electronic portal imaging devices

A quality assurance phantom for electronic portal imaging devices

Simple Proposal for Dosimetry with an Elekta iViewGTTM Electronic Portal Imaging Device (EPID) Using Commercial Software Modules

Verification of quality parameters for portal images in radiotherapy

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