Beam characteristics of a retrofitted double‐focused multileaf collimator

Das, Indra J.; Desobry, G. E.; McNeeley, Shawn; Cheng, Elizabeth; Schultheiss, Timothy E.

doi:10.1118/1.598348

Cited by 72 publications

(62 citation statements)

References 45 publications

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“…Soon afterward, Jordan and Williams 54 published a paper for Elekta machines and Das et al 55 for Siemens machines. Mubata et al 21 published a paper dedicated to QA for Varian machines following these initial papers.…”

Section: Iid3 Mlcmentioning

confidence: 99%

Task Group 142 report: Quality assurance of medical acceleratorsa)

et al. 2009

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The task group ͑TG͒ for quality assurance of medical accelerators was constituted by the American Association of Physicists in Medicine's Science Council under the direction of the Radiation Therapy Committee and the Quality Assurance and Outcome Improvement Subcommittee. The task group ͑TG-142͒ had two main charges. First to update, as needed, recommendations of Table II of the AAPM TG-40 report on quality assurance and second, to add recommendations for asymmetric jaws, multileaf collimation ͑MLC͒, and dynamic/virtual wedges. The TG accomplished the update to TG-40, specifying new test and tolerances, and has added recommendations for not only the new ancillary delivery technologies but also for imaging devices that are part of the linear accelerator. The imaging devices include x-ray imaging, photon portal imaging, and cone-beam CT. The TG report was designed to account for the types of treatments delivered with the particular machine. For example, machines that are used for radiosurgery treatments or intensity-modulated radiotherapy ͑IMRT͒ require different tests and/or tolerances. There are specific recommendations for MLC quality assurance for machines performing IMRT. The report also gives recommendations as to action levels for the physicists to implement particular actions, whether they are inspection, scheduled action, or immediate and corrective action. The report is geared to be flexible for the physicist to customize the QA program depending on clinical utility. There are specific tables according to daily, monthly, and annual reviews, along with unique tables for wedge systems, MLC, and imaging checks. The report also gives specific recommendations regarding setup of a QA program by the physicist in regards to building a QA team, establishing procedures, training of personnel, documentation, and end-to-end system checks. been considerably expanded as compared with the original TG-40 report and the recommended tolerances accommodate differences in the intended use of the machine functionality ͑non-IMRT, IMRT, and stereotactic delivery͒.

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Section: Iid3 Mlcmentioning

confidence: 99%

Task Group 142 report: Quality assurance of medical acceleratorsa)

et al. 2009

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“…The dual‐focused MLC consists of 29 pairs leaves, the inner 27 pairs projecting to 1.0‐cm width at isocenter. ( 25 ) …”

Section: Methodsmentioning

confidence: 99%

Planning quality and delivery efficiency of sMLC delivered IMRT treatment of oropharyngeal cancers evaluated by RTOG H‐0022 dosimetric criteria

Zhu

Schultz

Gillin

2004

J Applied Clin Med Phys

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The time required to deliver intensity‐modulated radiation therapy (IMRT) treatments can be significantly longer than conventional treatments, especially for the segmented multileaf collimator (sMLC) delivery system with a large record and verification (R&V) overhead. In this work, we evaluate the impact of the number of intensity‐modulated beams (IMBs) and the number of intensity levels (ILs) on the quality and delivery efficiency of IMRT plans, generated by the Corvus planning system for sMLC delivery on a Siemens LINAC with the Lantis R&V system. Detailed studies were performed for three image data sets of previously treated oropharyngeal patients. Treatment plans for patient 1 were developed using 5, 7, 9, or 15 evenly spaced axial IMBs as well as one with 7 axial IMBs whose directions were user‐selected, each using ILs of 3, 5, 10, or 20. For patients 2 and 3, plans with 15 IMBs and 20 ILs were not attempted. A total of 42 plans were developed using three oropharyngeal cancer CT image data sets. Plan quality was evaluated by assessing compliance with the Radiation Therapy Oncology Group (RTOG) H‐0022 protocol criteria and the physician's clinical judgment. Plan efficiency was accessed by the number of segments of each plan. We found that for our treatment‐planning and delivery system, an IMRT plan that uses a moderate number of IMBs and ILs, such as 7 or 9 IMBs with 3 or 5 ILs, would appear to be the optimal approach when both quality of the plan and delivery efficiency are considered. Based on this study, we have routinely used 9 IMBs with 3 ILs or 7 IMBs with 5 ILs for head and neck patients. A retrospective comparison indicates that delivery efficiency is improved on the order of 30% compared to plans generated with 9 IMBs with 5 ILs.PACS number: 87.53.Tf

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“…Multileaf collimation (MLC) is standard in all modern linear accelerators used to treat patients 1 , 2 , 3 , 4 , 5 . The importance of rigorous quality assurance, especially with respect to the MLC and its impact on intensity‐modulated radiation therapy (IMRT) delivery, has been emphasized in the literature 6 , 7 , 8 .…”

Section: Introductionmentioning

confidence: 99%

Optimization of the rounded leaf offset table in modeling the multileaf collimator leaf edge in a commercial treatment planning system

Rice

2014

J Applied Clin Med Phys

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An editable rounded leaf offset (RLO) table is provided in the Pinnacle3 treatment planning software. Default tables are provided for major linear accelerator manufacturers, but it is not clear how the default table values should be adjusted by the user to optimize agreement between the calculated leaf tip value and the actual measured value. Since we wish for the calculated MLC‐defined field edge to closely match the actual delivered field edge, optimal RLO table values are crucial. This is especially true for IMRT fields containing a large number of segments, since any errors would add together. A method based on the calculated MLC‐defined field edge was developed for optimizing and modifying the default RLO table values. Modified RLO tables were developed and evaluated for both dosimetric and light field‐based MLC leaf calibrations. It was shown, using a Picket Fence type test, that the optimized RLO table better modeled the calculated leaf tip than the Pinnacle3 default table. This was demonstrated for both an Elekta Synergy 80‐leaf and a Varian 120‐leaf MLC.PACS numbers: 87.55.D‐, 87.55.de, 87.55.Qr

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Beam characteristics of a retrofitted double‐focused multileaf collimator

Cited by 72 publications

References 45 publications

Task Group 142 report: Quality assurance of medical acceleratorsa)

Task Group 142 report: Quality assurance of medical acceleratorsa)

Planning quality and delivery efficiency of sMLC delivered IMRT treatment of oropharyngeal cancers evaluated by RTOG H‐0022 dosimetric criteria

Optimization of the rounded leaf offset table in modeling the multileaf collimator leaf edge in a commercial treatment planning system

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