Daily QA of linear accelerators using only EPID and OBI

Sun, Baozhou; Goddu, S; Yaddanapudi, S; Noël, C.; Li, Hua; Cai, Bin; Kavanaugh, James; Mutic, Sasa

doi:10.1118/1.4929550

Cited by 48 publications

(59 citation statements)

References 28 publications

(26 reference statements)

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“…With submillimeter spatial resolution, and excellent dose measurement accuracy, linearity to dose and dose rate, and capability of collecting the integrated signal or dynamic signal, the EPID has been widely used for machine QA and pretreatment verification such as patient‐specific IMRT verification 7, 8, 9, 10, 11. Recently many authors have investigated using EPID for in vivo dosimetry 6, 12, 13, 14.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity study of an automated system for daily patient QA using EPID exit dose images

Zhuang

Olch

2018

J Applied Clin Med Phys

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The dosimetric consequences of errors in patient setup or beam delivery and anatomical changes are not readily known. A new product, PerFRACTION (Sun Nuclear Corporation), is designed to identify these errors by comparing the exit dose image measured on an electronic portal imaging device (EPID) from each field of each fraction to those from baseline fraction images. This work investigates the sensitivity of PerFRACTION to detect the deviation caused by these errors in a variety of realistic scenarios. Integrated EPID images were acquired in clinical mode and saved in ARIA. PerFRACTION automatically pulled the images into its database and performed the user‐defined comparison. We induced errors of 1 mm and greater in jaw, multileaf collimator (MLC), and couch position, 1° and greater in collimation rotation (patient yaw), 0.5–1.5% in machine output, rail position, and setup errors of 1–2 mm shifts and 0.5–1° roll rotation. The planning techniques included static, intensity modulated radiation therapy (IMRT) and VMAT fields. Rectangular solid water phantom or anthropomorphic head phantom were used in the beam path in the delivery of some fields. PerFRACTION detected position errors of the jaws, MLC, and couch with an accuracy of better than 0.4 mm, and 0.5° for collimator rotation error and detected the machine output error within 0.2%. The rail position error resulted in PerFRACTION detected dose deviations up to 8% and 3% in open field and VMAT field delivery, respectively. PerFRACTION detected induced errors in IMRT fields within 2.2% of the gamma passing rate using an independent conventional analysis. Using an anthropomorphic phantom, setup errors as small as 1 mm and 0.5° were detected. Our work demonstrates that PerFRACTION, using integrated EPID image, is sensitive enough to identify positional, angular, and dosimetric errors.

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Section: Introductionmentioning

confidence: 99%

Sensitivity study of an automated system for daily patient QA using EPID exit dose images

Zhuang

Olch

2018

J Applied Clin Med Phys

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“…Varian EPIDs have been used previously for beam profile QA 6, 7. However, these methods are based on flood field‐corrected EPID images.…”

Section: Introductionmentioning

confidence: 99%

A proposed method for linear accelerator photon beam steering using EPID

Barnes

Menk

Lamichhane

et al. 2018

J Applied Clin Med Phys

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Beam steering is the process of calibrating the angle and translational position with which a linear accelerator's (linac's) electron beam strikes the x‐ray target with respect to the collimator rotation axis. The shape of the dose profile is highly dependent on accurate beam steering and is essential for ensuring correct delivery of the radiotherapy treatment plan. Traditional methods of beam steering utilize a scanning water tank phantom that makes the process user‐dependent. This study is the first to provide a methodology for both beam angle steering and beam translational position steering based on EPID imaging of the beam and does not require a phantom. Both the EPID‐based beam angle steering and beam translational steering methods described have been validated against IC Profiler measurement. Wide field symmetry agreement was found between the EPID and IC Profiler to within 0.06 ± 0.14% (1 SD) and 0.32 ± 0.11% (1 SD) for flattened and flattening‐filter‐free (FFF) beams, respectively. For a 1.1% change in symmetry measured by IC Profiler the EPID method agreed to within 0.23%. For beam translational position steering, the EPID method agreed with IC Profiler method to within 0.03 ± 0.05 mm (1 SD) at isocenter. The EPID‐based methods presented are quick to perform, simple, accurate and could easily be integrated with the linac, potentially via the MPC application. The methods have the potential to remove user variability and to standardize the process of beam steering throughout the radiotherapy community.

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“…EPIDs have been useful for measuring linac photon beam energy and for daily monitoring of beam parameters for both photons and electrons . We recently published work demonstrating the use of the EPID for comprehensive, routine daily QA of linacs . These studies have proved that EPID‐based QA is possible and that the current AT methodology could be improved through the use of EPIDs for better efficiency and standardization.…”

Section: Introductionmentioning

confidence: 99%

Rapid acceptance testing of modern linac using on-board MV and kV imaging systems

et al. 2017

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Daily QA of linear accelerators using only EPID and OBI

Abstract: The exclusive use of EPID-based QA tools, including a QA phantom and simultaneous analysis software tools, has been demonstrated as a viable, efficient, and comprehensive process for daily evaluation of LINAC performance.

Cited by 48 publications

References 28 publications

Sensitivity study of an automated system for daily patient QA using EPID exit dose images

Sensitivity study of an automated system for daily patient QA using EPID exit dose images

A proposed method for linear accelerator photon beam steering using EPID

Rapid acceptance testing of modern linac using on-board MV and kV imaging systems

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