Implementation and verification of Virtual Wedge in a three‐dimensional radiotherapy planning system

Miften, Moyed; Zhu, X. Ron; Takahashi, Kaz; López, F.; Gillin, Michael

doi:10.1118/1.599030

Cited by 17 publications

(23 citation statements)

References 20 publications

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“…Thus, within the MU fraction model, the WF for the virtual wedge is unity. As is the case for the EDW wedge factors, investigators [102][103][104] have found that the WF is unity for most cases with the exception of the 60…”

Section: B1ii Physical Wedges a Number Of Investigatorsmentioning

confidence: 99%

Monitor unit calculations for external photon and electron beams: Report of the AAPM Therapy Physics Committee Task Group No. 71

et al. 2014

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A protocol is presented for the calculation of monitor units (MU) for photon and electron beams, delivered with and without beam modifiers, for constant source-surface distance (SSD) and source-axis distance (SAD) setups. This protocol was written by Task Group 71 of the Therapy Physics Committee of the American Association of Physicists in Medicine (AAPM) and has been formally approved by the AAPM for clinical use. The protocol defines the nomenclature for the dosimetric quantities used in these calculations, along with instructions for their determination and measurement. Calculations are made using the dose per MU under normalization conditions, D 0 , that is determined for each user's photon and electron beams. For electron beams, the depth of normalization is taken to be the depth of maximum dose along the central axis for the same field incident on a water phantom at the same SSD, where D 0 = 1 cGy/MU. For photon beams, this task group recommends that a normalization depth of 10 cm be selected, where an energy-dependent D 0 ≤ 1 cGy/MU is required. This recommendation differs from the more common approach of a normalization depth of d m , with D 0 = 1 cGy/MU, although both systems are acceptable within the current protocol. For photon beams, the formalism includes the use of blocked fields, physical or dynamic wedges, and (static) multileaf collimation. No formalism is provided for intensity modulated radiation therapy calculations, although some general considerations and a review of current calculation techniques are included. For electron beams, the formalism provides for calculations at the standard and extended SSDs using either an effective SSD or an air-gap correction factor. Example tables and problems are included to illustrate the basic concepts within the presented formalism.

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Section: B1ii Physical Wedges a Number Of Investigatorsmentioning

confidence: 99%

Monitor unit calculations for external photon and electron beams: Report of the AAPM Therapy Physics Committee Task Group No. 71

et al. 2014

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“…In Table 1, 1VW and 2VW indicate that the wedge orientation is formed by making y 1 or y 2 dynamic jaws. However, similar to the Varian EDW, Moued ( 11 ) and Miften ( 12 ) point out there may be a difference of up to 6% in the toe region on larger fields and larger wedge angles. This may be caused by overestimation by the VM model of the dose in the toe region for these field and wedge combinations.…”

Section: Resultsmentioning

confidence: 60%

“…These effects are larger for large wedge angles and large field sizes compared with other setups. ( 12 ) …”

Section: Resultsmentioning

confidence: 99%

The accuracy of dynamic wedge dose computation in the ADAC Pinnacle RTP system

Shao

Chengji

et al. 2004

J Applied Clin Med Phys

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The nonphysical wedge is a modality that uses computer‐controlled jaw motion to generate wedge‐shaped dose distributions. There are Varian enhanced dynamic wedges (EDWs) and Siemens virtual wedges (VWs). We recently commissioned dynamic wedges on both Varian and Siemens LINACs. The beam data, acquired with a Wellhöfer chamber array and a Sun Nuclear profiler, are used for modeling in the ADAC Pinnacle system. As recommended by ADAC, only a limited number of beam data is measured and used for beam modeling. Therefore, the dose distributions of dynamic wedges generated by Pinnacle must be examined. Following the commissioning of the dynamic wedges, we used Pinnacle to generate a number of dose distributions with different energies, wedge angles, field sizes, and depths. The computed data from Pinnacle are then compared with the measured data.The deviations of the output factor in all square and rectangular fields are mostly within 2.0% for both EDW and VW. For asymmetric fields, the deviations are within 3%. However, exceptions of differences more than 3% have been found in a larger field and large wedge combinations. The precision of the beam profiles generated by Pinnacle is also evaluated. As a result of this investigation, we present a scope of quality assurance tests that are necessary to ensure acceptable consistency between the delivered dose and the associated treatment plan when dynamic wedges are applied.PACS numbers: 8753 Dq, 87.53.Xd

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“…All * Electronic address: dalmeida@ffclrp.usp.br the absorbance measurements [15][16][17] were done with the visible spectrophotometric technique. The results are compared with the ones reported using Monte Carlo [1], film [4], ionization chamber [3,4] and diodes [1]. Similar measurements, made with an ionization chamber of 0.016 cm 3 , are also reported here.…”

Section: Introductionmentioning

confidence: 60%

“…There are several papers reporting the results of wedge beam profile measurements from physical, virtual and dynamic filters, using different dosimeters such as diode [1,2], ionization chamber [3][4][5], chemical dosimeter [6][7][8], film [2,4] and numerical methods that use Monte Carlo calculation codes [1,9]. In this work the Fricke Xylenol Gel (FXG) was used to measure the beam profiles of physical wedge filters used in 6 MV photons clinical beams.…”

Section: Introductionmentioning

confidence: 99%

6 MV wedge photon beam profiles with the fricke xylenol gel dosimeter

Oliveira¹,

Calcina²,

Cavalcante³

et al. 2009

Braz. J. Phys.

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Wedged beam are often used in clinical radiotherapy to compensate missing tissues and dose gradients. In this work, the Fricke Xylenol Gel (FXG) dosimeter was used for 6 MV photons radiation wedge field profiles measurements, allowing to infer the wedge filter physical attenuation coefficient. This dosimeter is a chemical system of a Fe 3+ -Xylenol complex concentration, that when measured spectrophotometrically, the absorbance is directly proportional to the absorbed dose. From theses results one can infer that the FXG can be used also as an alternative dosimetric system for measurements of wedge filters.

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Implementation and verification of Virtual Wedge in a three‐dimensional radiotherapy planning system

Cited by 17 publications

References 20 publications

Monitor unit calculations for external photon and electron beams: Report of the AAPM Therapy Physics Committee Task Group No. 71

Monitor unit calculations for external photon and electron beams: Report of the AAPM Therapy Physics Committee Task Group No. 71

The accuracy of dynamic wedge dose computation in the ADAC Pinnacle RTP system

6 MV wedge photon beam profiles with the fricke xylenol gel dosimeter

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