Routine pretreatment patient‐specific IMRT QA (PS‐IMRT‐QA) should be discontinued and replaced with a real‐time on‐board beam monitoring system (BMS)

Zygmanski, Piotr; Halvorsen, Per H.

doi:10.1002/mp.15048

Cited by 5 publications

(7 citation statements)

References 13 publications

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“…Therefore, cancer centres will have to also undertake FMEA review of their QA programs. There has been debate for some time [23,184,185] that not all conventional QA performed by medical physicists adds value to the centre's QM program. This does need attention, and some of the procedures long held sacrosanct may need to be reassessed (for example, spending weekends on annual water tank measurements of multiple linacs that have shown insignificant beam data variation over the years) to enable adoption of QA that better influences quality control.…”

Section: Benefits and Caveatsmentioning

confidence: 99%

End-to-End QA in Radiation Therapy Quality Management

Schreiner

2023

J. Phys.: Conf. Ser.

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End-to-End (E2E) testing is a method originating from computer science that is designed to determine whether an application communicates as required with hardware, networks, databases, and other applications. This paper is to advocate that the quality management (QM) of modern radiation therapy (RT) would benefit from more regular use of E2E based quality assurance (QA) in the local clinic. The argument is that modern RT delivery is performed through some process linked by a chain of interdependent stages and actions mediated by complex interchanges during the patient’s treatment. These actions along the chain are often modified due to decisions by clinical staff who are interpreting information acquired along the process. While physics QA can validate that each of these steps are technically achievable (e.g., through machine QA) such conventional QA does not guarantee that the overall process is being carried out as planned even when it has been described by a well-defined protocol and delivered by well-trained staff. The paper briefly reviews the changes in programmatic design as RT has become more complex, the associated changes in RT QM, and some past examples of E2E testing in RT clinics, usually performed during the implementation of some new RT technique or during external audits of the clinic’s practice. The paper then makes the case for increased E2E QA based on the lessons learned from this experience and ends with some suggestions for implementing effective and sustainable E2E testing in a clinic’s QM program.

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Section: Benefits and Caveatsmentioning

confidence: 99%

End-to-End QA in Radiation Therapy Quality Management

Schreiner

2023

J. Phys.: Conf. Ser.

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“…Despite these advancements, a comprehensive, linac-integrated, and reliable beam monitoring system has not yet been developed for medical linacs. Such beam monitoring would be beneficial for real-time quality control (QC), linac QA and might replace or at least simplify pre-treatment patient-specific IMRT quality assurance (PS-IMRT-QA) test (Zygmanski and Halvorsen 2021). With modern treatment methods such as IMRT/VMAT and adaptive radiotherapy the demand for online beam monitoring is on the rise which is further necessitated by current advancements towards adaptive treatment (Malicki 2012, Nesteruk 2014, Kron et al 2016, Park et al 2018.…”

Section: Introductionmentioning

confidence: 99%

“…With modern treatment methods such as IMRT/VMAT and adaptive radiotherapy the demand for online beam monitoring is on the rise which is further necessitated by current advancements towards adaptive treatment (Malicki 2012, Nesteruk 2014, Kron et al 2016, Park et al 2018. This challenge is also reflected in the past and ongoing debates of advantages and disadvantages of real-time linac-integrated beam monitoring in the context of QC versus the more established and common pre-treatment QA methods (Smith et al 2011, Ford et al 2012, Stasi et al 2012, Siochi et al 2013, Kry et al 2019, Zygmanski and Halvorsen 2021.…”

Section: Introductionmentioning

confidence: 99%

Remote sensing array (RSA) for linac beam monitoring

Lauber¹,

Brivio²,

Sajo³

et al. 2022

Phys. Med. Biol.

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The purpose of the present work is to evaluate the feasibility of a novel real-time beam monitoring device for medical linacs which remotely senses charge carriers produced in air by the beam without intersecting and attenuating the beamline. The primary goal is to elaborate a theoretical concept of a possible detector geometry and underlying physical model that allows for determination of clinically relevant beam data in real time, namely MLC leaf positions and dose rate. The detector consists of two opposing electrode arrays arranged in two possible orientations around the beamline. Detection of charge carriers is governed by electromagnetic principles described by Shockley-Ramo theorem. Ions produced by ionization of the air column upstream of patient move laterally in an external electric field. According to the method of images, mirror charges and mirror currents are formed in the strip electrodes. Determination of MU rate and MLC positions using the measured signal requires solution of an inverse problem. In the present work we adopted a Least-Square approach and characterized detector response and sensitivity to detection of beam properties for different electrode geometries and MLC shapes. Results were dependent on MLC field shape and the leaf position within the active volume. The accuracy of determination of leaf positions were in the sub-mm range (up to 0.25-1mm). Additionally, detector sensitivity was quantified by simulating ions/pulse delivered with a radiation transport deterministic computation in 1D in CEPXS/ONEDANT. For a 6 MV linac pulse, signal amplitude per pulse was estimated to be in the lower pA to fA range. We computationally demonstrated feasibility of the remote sensing detector capable of measuring beam parameters such as MLC leaf positions and dose range for each pulse. Future work should focus on optimizing the electrode geometry to increase sensitivity and better reconstruction algorithms to provide more accurate solutions of the inverse problem.

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“…Verification of Intensity Modulated Radiotherapy (IMRT) of cancer during patient treatment involves several levels of checks including patient anatomy, linac operation and computation of either dose in patient or other dosimetric parameters [1][2][3]. For high-throughput high-accuracy radiotherapy treatments continuous beam monitoring can become an important Quality Control (QC) tool not only for specific patient plans but also for linac Quality Assurance and linac maintenance [4]. In principle, monitoring of MLC can be achieved with detector arrays attached to the linac head [5][6][7] or mounted on a robotic arm (EPID) [8][9][10], or by using linac logfiles [11].…”

Section: Introductionmentioning

confidence: 99%

“…Such a system would be suitable for high definition monitoring of linac output in real time. Such systems are required for future advancement of radiotherapy including automation of treatment without the need for pre-treatment patient specific IMRT QA [4]. Alternative detector principles for radiotherapy QA are under intense investigation, such as remote sensor detector arrays [12], topological detectors [14] or new pixelated detectors [15], as well as advanced evaluation of existing detectors such as for EPID [8][9][10][11] or IQM TM [6] which demonstrates the clinical necessity of a practical solution to real-time radiotherapy beam monitoring.…”

Section: Introductionmentioning

confidence: 99%

Strip detector array (SDA) for beam monitoring in radiotherapy: reconstruction of MLC parameters from multiple projections of flux

Hoegele¹,

Zygmanski²

2022

Biomed. Phys. Eng. Express

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Objective: In this paper we propose and investigate a new detector with multiple strip detector arrays (SDA) for monitoring MLC shaped x-ray beams for radiotherapy treatment. Approach: Each SDA measures 1D dose profiles equivalent to dose projections. The goal of such a detector is to determine individual MLC leaf positions as well as the Monitor Units (MU) per MLC segment during radiotherapy. In the present work we investigate an optimal SDA detector configuration and reconstruction algorithm. We determine the accuracy of SDA for different treatment sites (spine, pelvis, retroperitoneum, prostate, brain SRT, SRS, lung and head and neck). We perform a simulation study accounting for different type of MLC leaf positional errors: random MLC leaf, systematic for the whole leaf bank and systematic for an individual leaf. In a similar fashion, we also account for errors in Monitor Units per segment. Main results: We demonstrate that for a broad range of IMRT treatment plans a robust reconstruction of errors is achievable with only 3 projections (3 sets of SDA oriented at at 0◦, 45◦ and 135◦). The SDA is capable of capturing both systematic errors in leaf banks and individual leaves as well as random errors sufficient for practical clinical purposes. Significance: These features of the SDA detector makes it suitable for real-time Quality Control of MLC collimated linac output.

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Routine pretreatment patient‐specific IMRT QA (PS‐IMRT‐QA) should be discontinued and replaced with a real‐time on‐board beam monitoring system (BMS)

Cited by 5 publications

References 13 publications

End-to-End QA in Radiation Therapy Quality Management

End-to-End QA in Radiation Therapy Quality Management

Remote sensing array (RSA) for linac beam monitoring

Strip detector array (SDA) for beam monitoring in radiotherapy: reconstruction of MLC parameters from multiple projections of flux

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