Potential of discrete Gaussian edge feathering method for improving abutment dosimetry in eMLC‐delivered segmented‐field electron conformal therapy

Eley, John G.; Hogstrom, Kenneth R.; Matthews, K.; Parker, Barry; Price, Michael

doi:10.1118/1.3660289

Cited by 3 publications

(4 citation statements)

References 53 publications

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“…2 Any practical method for electron intensity modulation requires an electron multileaf collimator (eMLC) on the treatment machine. [10][11][12][13][14][15] One alternative to electron intensity modulation for restoring dose homogeneity is mixing bolus ECT with intensity modulated x-ray therapy (IMXT), the latter optimized on top of the bolus ECT dose distribution. Historically, mixed beam therapy (electron and high energy x-ray) has been used to improve the electron central axis dose distribution by improving dose uniformity, increasing the therapeutic depth, and decreasing skin dose.…”

Section: Introductionmentioning

confidence: 99%

Delivery confirmation of bolus electron conformal therapy combined with intensity modulated x-ray therapy

et al. 2013

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Bolus ECT and mixed beam therapy dose delivery to the phantom were more accurate than IMXT delivery, adding confidence to the use of planning, fabrication, and delivery for bolus ECT tools either alone or as part of mixed beam therapy. The methodology reported in this work could serve as a basis for future standardization of the commissioning of bolus ECT or mixed beam therapy. When applying this technology to patients, it is recommended that an electron dose algorithm more accurate than the pencil beam algorithm, e.g., a Monte Carlo algorithm or analytical transport such as the pencil beam redefinition algorithm, be used for planning to ensure the desired accuracy.

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Section: Introductionmentioning

confidence: 99%

Delivery confirmation of bolus electron conformal therapy combined with intensity modulated x-ray therapy

et al. 2013

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“…This dose heterogeneity can be reduced by matching penumbras of abutted fields, which is possible by increasing the sharper penumbra of the higher energy field to match that of the lower energy field. This can be done by placing higher energy field collimating apertures further from the patient 33 or by modulating field edges using an eMLC 34 ; however, neither of these technologies is commercially available. Passive intensity modulators with island blocks and island apertures located near the edges of a field could provide this function, analogous to that previously reported using saw-toothed collimator edges 18 .…”

Section: Discussionmentioning

confidence: 99%

Introduction to passive electron intensity modulation

Hogstrom

Carver

Chambers

et al. 2017

J Applied Clin Med Phys

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This work introduces a new technology for electron intensity modulation, which uses small area island blocks within the collimating aperture and small area island apertures in the collimating insert. Due to multiple Coulomb scattering, electrons contribute dose under island blocks and lateral to island apertures. By selecting appropriate lateral positions and diameters of a set of island blocks and island apertures, e.g. a hexagonal grid with variable diameter circular island blocks, intensity modulated beams can be produced for appropriate air gaps between the intensity modulator (position of collimating insert) and the patient. Such a passive radiotherapy intensity modulator for electrons (PRIME) is analogous to using physical attenuators (metal compensators) for intensity modulated x-ray therapy (IMXT). For hexagonal spacing, the relationship between block (aperture) separation (r) and diameter (d) and the local intensity reduction factor (IRF) is discussed. The PRIME principle is illustrated using pencil beam calculations for select beam geometries in water with half beams modulated by 70–95% and for one head and neck field of a patient treated with bolus electron conformal therapy. Proof of principle is further illustrated by showing agreement between measurement and calculation for a prototype PRIME. Potential utilization of PRIME for bolus electron conformal therapy, segmented-field electron conformal therapy, modulated electron radiation therapy, and variable surface geometries is discussed. Further research and development of technology for the various applications is discussed. In summary, this paper introduces a practical, new technology for electron intensity modulation in the clinic, demonstrates proof of principle, discusses potential clinical applications, and suggests areas of further research and development.

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“…For an eMLC, Eley et al 27 proposed a discrete Gaussian edge feathering to overcome the above described issues with abutting segments for electron beams. For two abutting segments they subdivide the higher energy segment into five equally weighted individual segments.…”

Section: C Featheringmentioning

confidence: 99%

“…At these depths the dose profiles in leaf travel direction are extracted and the corresponding penumbras are determined. For all energy combinations of abutting segments a match of the penumbras is performed using a deconvolution 27 technique, and the resulting feathering positions are written into a look-up table. As shape and width of these pre-calculated penumbras are dependent on field-size and patient geometry (e.g., inhomogenities), the feathering positions in the look up table are used as initial positions only and can be adapted by the user for each specific case, either by modifying the look-up table or the leaf positions directly.…”

Section: C Featheringmentioning

confidence: 99%

Forward treatment planning for modulated electron radiotherapy (MERT) employing Monte Carlo methods

et al. 2014

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MERT treatments were successfully planned for phantom and clinical cases, applying a newly developed intuitive and efficient forward planning strategy that employs a MC based electron beam model for pMLC shaped electron beams. It is shown that MERT can lead to a dose reduction in OARs compared to other methods. The process of feathering MERT segments results in an improvement of the dose homogeneity in the PTV.

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Potential of discrete Gaussian edge feathering method for improving abutment dosimetry in eMLC‐delivered segmented‐field electron conformal therapy

Abstract: A five-step discrete Gaussian edge spread function applied in 2D improves the abutment dosimetry but requires an eMLC leaf resolution better than 1 cm.

Cited by 3 publications

References 53 publications

Delivery confirmation of bolus electron conformal therapy combined with intensity modulated x-ray therapy

Delivery confirmation of bolus electron conformal therapy combined with intensity modulated x-ray therapy

Introduction to passive electron intensity modulation

Forward treatment planning for modulated electron radiotherapy (MERT) employing Monte Carlo methods

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