Summary and recommendations of a National Cancer Institute workshop on issues limiting the clinical use of Monte Carlo dose calculation algorithms for megavoltage external beam radiation therapy

Fraass, Benedick A.; Smathers, James B.; Deye, James A.

doi:10.1118/1.1626990

Cited by 56 publications

(36 citation statements)

References 55 publications

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“…A major advantage of MC dose engine over conventional engines is the lower systematic error in dose computation 1. Verification of its dosimetric accuracy provides clinicians with a better understanding of dose in regions of heterogeneity, enabling more accurate treatment in regions which may have previously been complicated by systematic error in delivered dose.…”

Section: Discussionmentioning

confidence: 99%

“…Fraass et al had reported that a dose error of 5% could lead to a tumor control probability (TCP) change of 10–20% and an even higher change in normal tissue complication probability (NTCP) 1. Noticeable clinical effects of dose errors of 7% have been reported in TG‐65 by Papanikolaou et al2 Reducing the uncertainties in dose calculation will reduce the overall uncertainty in delivered dose to within 5% as recommended by International Commission on Radiation Units and Measurements (ICRU) report 24 3…”

Section: Introductionmentioning

confidence: 99%

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Dosimetric validation of Monaco treatment planning system on an Elekta VersaHD linear accelerator

Narayanasamy

Saenz²,

Defoor³

et al. 2017

J Applied Clin Med Phys

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The purpose of this study is to perform dosimetric validation of Monaco treatment planning system version 5.1. The Elekta VersaHD linear accelerator with high dose rate flattening filter‐free photon modes and electron energies was used in this study. The dosimetric output of the new Agility head combined with the FFF photon modes warranted this investigation into the dosimetric accuracy prior to clinical usage. A model of the VersaHD linac was created in Monaco TPS by Elekta using commissioned beam data including percent depth dose curves, beam profiles, and output factors. A variety of 3D conformal fields were created in Monaco TPS on a combined Plastic water/Styrofoam phantom and validated against measurements with a calibrated ion chamber. Some of the parameters varied including source to surface distance, field size, wedges, gantry angle, and depth for all photon and electron energies. In addition, a series of step and shoot IMRT, VMAT test plans, and patient plans on various anatomical sites were verified against measurements on a Delta4 diode array. The agreement in point dose measurements was within 2% for all photon and electron energies in the homogeneous phantom and within 3% for photon energies in the heterogeneous phantom. The mean ± SD gamma passing rates of IMRT test fields yielded 93.8 ± 4.7% based on 2% dose difference and 2 mm distance‐to‐agreement criteria. Eight previously treated IMRT patient plans were replanned in Monaco TPS and five measurements on each yielded an average gamma passing rate of 95% with 6.7% confidence limit based on 3%, 3 mm gamma criteria. This investigation on dosimetric validation ensures accuracy of modeling VersaHD linac in Monaco TPS thereby improving patient safety.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dosimetric validation of Monaco treatment planning system on an Elekta VersaHD linear accelerator

Narayanasamy

Saenz²,

Defoor³

et al. 2017

J Applied Clin Med Phys

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“…By calculating the trajectories and interactions of a very large number of photons and electrons, one can accurately model the dose distribution. Recently, several Monte Carlo codes have been devel-oped for radiotherapy treatment planning (Cygler et al 2004;Fraass et al 2003 …”

Section: Advanced Dose Calculationmentioning

confidence: 99%

Physics of Radiotherapy Planning and Delivery

et al. 2011

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“…It has been claimed that progress in development of such complex electron treatments has been limited by inaccuracies in electron beam dose calculations 14 . The principle incentive for the present study was the accurate calculation of dose distributions for narrow fields.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of mega-voltage electron pencil beam dose distributions: viability of a measurement-based approach

Barnes

Ebert

2008

Australas. Phys. Eng. Sci. Med.

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The concept of electron pencil-beam dose distributions is central to pencil-beam algorithms used in electron beam radiotherapy treatment planning. The Hogstrom algorithm, which is a common algorithm for electron treatment planning, models large electron field dose distributions by the superposition of a series of pencil beam dose distributions. This means that the accurate characterisation of an electron pencil beam is essential for the accuracy of the dose algorithm. The aim of this study was to evaluate a measurement based approach for obtaining electron pencil-beam dose distributions. The primary incentive for the study was the accurate calculation of dose distributions for narrow fields as traditional electron algorithms are generally inaccurate for such geometries. Kodak X-Omat radiographic film was used in a solid water phantom to measure the dose distribution of circular 12 MeV beams from a Varian 21EX linear accelerator. Measurements were made for beams of diameter, 1.5, 2, 4, 8, 16 and 32 mm. A blocked-field technique was used to subtract photon contamination in the beam. The "error function" derived from Fermi-Eyges Multiple Coulomb Scattering (MCS) theory for corresponding square fields was used to fit resulting dose distributions so that extrapolation down to a pencil beam distribution could be made. The Monte Carlo codes, BEAM and EGSnrc were used to simulate the experimental arrangement. The 8 mm beam dose distribution was also measured with TLD-100 microcubes. Agreement between film, TLD and Monte Carlo simulation results were found to be consistent with the spatial resolution used. The study has shown that it is possible to extrapolate narrow electron beam dose distributions down to a pencil beam dose distribution using the error function. However, due to experimental uncertainties and measurement difficulties, Monte Carlo is recommended as the method of choice for characterising electron pencil-beam dose distributions.

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Summary and recommendations of a National Cancer Institute workshop on issues limiting the clinical use of Monte Carlo dose calculation algorithms for megavoltage external beam radiation therapy

Cited by 56 publications

References 55 publications

Dosimetric validation of Monaco treatment planning system on an Elekta VersaHD linear accelerator

Dosimetric validation of Monaco treatment planning system on an Elekta VersaHD linear accelerator

Physics of Radiotherapy Planning and Delivery

Characterisation of mega-voltage electron pencil beam dose distributions: viability of a measurement-based approach

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