Evaluation of beam matching accuracy among six linacs from the same vendor

Krishnappan, C.; Radha, C. Anu; Balaji, K.; Mani, Prasanna; Subramani, Vendhan; Velmurugan, Thanigaimalai; Gunasekaran, Madhan Kumar; Ramasubramanian, Velayudham

doi:10.1007/s12194-018-0480-3

Cited by 10 publications

(8 citation statements)

References 18 publications

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“…11 , 12 The linear accelerators used were TrueBeam and Clinac IX from Varian Medical Systems (Palo Alto, CA). Krishnappan et al 13 reported that the 2 linear accelerators were within the clinically acceptable limits, as the variation in the dose difference between the 2 devices was <3%.…”

Section: Methodsmentioning

confidence: 99%

Development of Machine-Learning Prediction Programs for Delivering Adaptive Radiation Therapy With Tumor Geometry and Body Shape Changes in Head and Neck Volumetric Modulated Arc Therapy

Rachi

Ariji

Takahashi

2023

Advances in Radiation Oncology

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Section: Methodsmentioning

confidence: 99%

Development of Machine-Learning Prediction Programs for Delivering Adaptive Radiation Therapy With Tumor Geometry and Body Shape Changes in Head and Neck Volumetric Modulated Arc Therapy

Rachi

Ariji

Takahashi

2023

Advances in Radiation Oncology

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“…Dosimetric Leaf Gap (DLG) is a key parameter in matching linacs, most importantly for dynamic treatments 5,7,19 . Dosimetric Leaf Gap calibration require submillimeter precision and having many linacs to be matched in a clinic require optimizing the DLG value so it can be achieved within a certain tolerance by all linacs.…”

Section: Methodsmentioning

confidence: 99%

“…This is accomplished by having dosimetrically and mechanically equivalent linacs, that is, linacs that are beam-matched. [1][2][3][4][5][6][7] When commissioning new linacs, they are often beam-matched by the vendor upon delivery. However, it has been shown that vendor specification might not be strict enough to ensure optimal matching.…”

Section: Introductionmentioning

confidence: 99%

“…A key component in achieving high efficiency is the ability to move patients to another linac without the need to adjust the treatment plan. This is accomplished by having dosimetrically and mechanically equivalent linacs, that is, linacs that are beam‐matched 1–7 . When commissioning new linacs, they are often beam‐matched by the vendor upon delivery.…”

Section: Introductionmentioning

confidence: 99%

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Dosimetric and mechanical equivalency of Varian TrueBeam linear accelerators

Ghazal

Södergren

Westermark

et al. 2020

J Applied Clin Med Phys

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To investigate and improve the level of equivalency of Varian TrueBeam linear accelerators (linacs) in energy-, dosimetric leaf gap-(DLG) and jaw calibration. Methods: Eight linacs with four photon energies: 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV, and three electron energies (on two linacs): 6, 9, and 12 MeV were commisioned and beam-matched. Initially, symmetry of lateral profiles was calibrated for maximum field size. Energy-matching was then performed for photons by adjusting diagonal profiles at maximum field size and depth of maximum dose to coincide with the reference linac, and for electrons by matching the range at percentage depth of ionization of 90%, 80%, and 50%. Calibration of DLG was performed for 6 MV and evaluated among the linacs. The relationship between DLG and the Gap value was investigated. A method using electronic portal imaging device (EPID) was developed and implemented for jaw calibration. Results: Symmetry calibration for photons (electrons) was within 1% (0.7%), further improving the vendor's acceptance criteria. Photon and electron energy-matching was within 0.5% and 0.1 mm, respectively. Calibration of DLG was within 0.032 mm among the linacs and utilizing the relationship between DLG and the Gap value resulted in an empirical calibration method which was implemented to simplify DLG adjustment. Using EPID-based method of calibration, evaluation of the jaw-positioning among the linacs for 30 cm × 30 cm field size was within 0.4 mm and in the junction area within 0.2 mm. Dose delivery error of VMAT-plans were at least 99.2% gamma pass rate (1%, 1 mm). Conclusions: High level of equivalency, beyond clinically accepted criteria, of True-Beam linacs could be achieved which reduced dose delivery systematic errors and increased confidence in interchanging patients among linacs.

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“…Even if published PDD data is utilised, PDD measurement gives information about the dose at depth between the two units, mimicking the matching process completed on linear accelerators [12]. This study investigated the feasibility of using a single planning data set for both units [13][14][15][16]. A set of matching tolerances were proposed based on ACPSEM recommended annual quality assurance (QA) tolerances, aiming to achieve a clinical dose calculation accuracy of 2.5-3%, leading to an overall treatment uncertainty within 5% [5,9,12,17].…”

Section: Introductionmentioning

confidence: 99%

The clinical impact of using a single set of radiotherapy planning data for two kilovoltage therapy units

Peters

Nelson

Deshpande

et al. 2023

Preprint

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Kilovoltage therapy units are used for superficial radiotherapy treatment delivery. Peer reviewed studies for MV linear accelerators describe tolerances to dosimetrically match multiple LINACS enabling patient treatment on any matched machine. There is an absence of literature on using a single planning data set for multiple kilovoltage units which have limited ability for beam adjustment. This study reviewed kilovoltage dosimetry and treatment planning scenarios to evaluate the suitability of ACPSEM annual QA tolerances to determine whether two units (of the same make and model) were dosimetrically matched. The dosimetric characteristics, such as measured half value layer (HVL), percentage depth dose (PDD), applicator factor and output variation with stand-off distance for each kV unit were compared to assess the agreement. Independent planning data based on the measured HVL for each beam energy from each kV unit was prepared. Monitor unit (MU) calculations were performed using both sets of planning data for approximately 200 clinical scenarios and compared with an overall agreement between units of < 2%. Additionally, a dosimetry measurement comparison was completed at each site for a subset of nine scenarios. All machine characterisation measurements were within the ACPSEM Annual QA tolerances, and dosimetric testing was within 2.5%. This work demonstrates that using a single set of planning data for two kilovoltage units is feasible, resulting in a clinical impact within published uncertainty.

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Evaluation of beam matching accuracy among six linacs from the same vendor

Cited by 10 publications

References 18 publications

Development of Machine-Learning Prediction Programs for Delivering Adaptive Radiation Therapy With Tumor Geometry and Body Shape Changes in Head and Neck Volumetric Modulated Arc Therapy

Development of Machine-Learning Prediction Programs for Delivering Adaptive Radiation Therapy With Tumor Geometry and Body Shape Changes in Head and Neck Volumetric Modulated Arc Therapy

Dosimetric and mechanical equivalency of Varian TrueBeam linear accelerators

The clinical impact of using a single set of radiotherapy planning data for two kilovoltage therapy units

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