Dynamic wedge field techniques through computer‐controlled collimator motion and dose delivery

Leavitt, Dennis D.; Martin, Melissa; Moeller, John F.; Lee, Wing Lok

doi:10.1118/1.596533

Cited by 124 publications

(56 citation statements)

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“…The first step by commercial vendors to intensity modulate a beam was the application of the Varian dynamic wedge (DW). 33 Both DW and its successor, the enhanced dynamic wedge (EDW) takes advantage of a collimation jaw moving in conjunction with adjustment of the dose rate over the course of one treatment. The variation of jaw position and dose rate is driven by a segmented treatment table (STT), which is unique for each energy, wedge angle, and field size.…”

Section: A2c Determination Of Field Size For Tpr or Pdd Nmentioning

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: A2c Determination Of Field Size For Tpr or Pdd Nmentioning

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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“…Recent technological advances have made possible the delivery of intensity modulated radiation therapy (IMRT) [71,26,4,40,3,8,22,49,11,75]. In IMRT, each treatment beam has an individually defined intensity distribution.…”

Section: Imrt and Tomotherapymentioning

confidence: 99%

Optimizing the Delivery of Radiation Therapy to Cancer Patients

Shepard¹,

Ferris²,

Olivera³

et al. 1999

SIAM Rev.

219

163

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Abstract. In the field of radiation therapy, much of the research is aimed at developing new and innovative techniques for treating cancer patients with radiation. In recent years, new treatment machines have been developed that provide a much greater degree of computer control than was available with the machines of previous generations. One innovation has been the development of an approach called "tomotherapy." Tomotherapy can be defined as computer-controlled rotational radiotherapy delivered using an intensity-modulated fan beam of radiation. The successful implementation of the new delivery techniques requires the development of a suitable approach for optimizing each patient's treatment plan. One of the challenges is to quantify optimality in radiation therapy. We have tested a variety of objective functions and constraints in pursuit of a formulation that performs well for a wide variety of disease sites. An additional challenge stems from the sizable amount of data and the large number of variables that are involved in each optimization. This paper presents several approaches to optimizing treatment plans in radiation therapy, and the advantages and disadvantages of a number of formulations are explored.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13] There are, however, many unanswered questions about this new method of treatment delivery. The goal of this project has been the development of a test environment that provides a means for efficiently investigating some of the unresolved issues in IMRT.…”

Section: Introductionmentioning

confidence: 99%

A simple model for examining issues in radiotherapy optimization

Shepard¹,

Olivera²,

Angelos³

et al. 1999

Medical Physics

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Convolution/superposition software has been used to produce a library of photon pencil beam dose matrices. This library of pencil beams is designed to serve as a tool for both education and investigation in the field of radiotherapy optimization. The elegance of this pencil beam model stems from its cylindrical symmetry. Because of the symmetry, the dose distribution for a pencil beam from any arbitrary angle can be determined through a simple rotation of a pre-computed dose matrix. Rapid dose calculations can thus be performed while maintaining the accuracy of a convolution/superposition based dose computation. The pencil beam data sets have been made publicly available. It is hoped that the data sets will facilitate a comparison of a variety of optimization and delivery approaches. This paper will present a number of studies designed to demonstrate the usefulness of the pencil beam data sets. These studies include an examination of the extent to which a treatment plan can be improved through either an increase in the number of beam angles and/or a decrease in the collimator size. A few insights into the significance of heterogeneity corrections for treatment planning for intensity modulated radiotherapy will also be presented.

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Dynamic wedge field techniques through computer‐controlled collimator motion and dose delivery

Cited by 124 publications

References 0 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

Optimizing the Delivery of Radiation Therapy to Cancer Patients

A simple model for examining issues in radiotherapy optimization

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