A generic off-axis energy correction for linac photon beam dosimetry

Tailor, Ramesh; Tello, Victor M.; Schroy, Carter B.; Vossler, M; Hanson, W. F.

doi:10.1118/1.598249

Cited by 48 publications

(45 citation statements)

References 14 publications

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“…Instead the off‐axis softening is calculated based on generic data. The work presented by Tailor et al 20 . is used and this is a fit to a number of accelerators where it should be possible to improve dose calculations off‐axis by applying machine specific measurements.…”

Section: Discussionmentioning

confidence: 99%

Verification of dose calculations with a clinical treatment planning system based on a point kernel dose engine

Weber¹,

Nilsson

2002

J Applied Clin Med Phys

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Dose calculations with a collapsed cone algorithm implemented in a clinical treatment planning system have been studied. The algorithm has been evaluated in homogeneous as well as in heterogeneous media, and the results have been compared to measurements and Monte Carlo simulations. Commonly encountered clinical beam configurations as well as more complex geometries have been pursued to test the limitations of the model. The results show that the accuracy level reached allows for clinical use. Some situations, e.g., large wedge beams and dose calculations in the build up region, not specific to the collapsed cone model, show deviations (outside ±3%) compared to measurements.PACS number(s): 87.53.Bn, 87.53.–j, 87.66.–a

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Section: Discussionmentioning

confidence: 99%

Verification of dose calculations with a clinical treatment planning system based on a point kernel dose engine

Weber¹,

Nilsson

2002

J Applied Clin Med Phys

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“…The variation of mean energy is also displayed as the lateral variation of HVL in figure 6 together with the generic fit from Tailor et al (1998) Tailor et al (1998).…”

Section: Mean Energy Hvlmentioning

confidence: 99%

A Monte Carlo study of a flattening filter-free linear accelerator verified with measurements

et al. 2010

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Abstract. A Monte Carlo model of an Elekta Precise linear accelerator has been built and verified by measured data for a 6 MV and 10 MV photon beam running with and without a flattening filter in the beam line. In this study the flattening filter was replaced with a 6 mm thick copper plate, provided by the linac vendor, in order to stabilize the beam. Several studies have shown that removal of the filter improves some properties of the photon beam, which could be beneficial for radiotherapy treatments. The investigated characteristics of this new beam included output, spectra, mean energy, half value layer and the origin of scattered photons. The results showed an increased dose output per initial electron at the central axis of 1.76 and 2.66 for the 6 MV and 10 MV beams, respectively. The number of scattered photons from the accelerator head was reduced by (31.70.03) % (1 SD) for the 6 MV beam and (47.60.02) % for the 10 MV beam. The photon energy spectrum of the unflattened beam was softer compared to a conventional beam and did not vary significantly with off-axis distance, even for the largest field size (0-20 cm off-axis).

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“…6,7,14,15 This wedge factor is used in MU calculations in the case of linear accelerators to compensate for the reduction in beam transmission caused by the wedge. A normalized wedge factor (NWF) was introduced to circumvent the large differences between WF for different field sizes/depth.…”

Section: Experimental Workmentioning

confidence: 99%

Accuracy checks of physical beam modifier factors algorithm used in computerized treatment planning system for a 15MV photon beam

Maqbool

Muhammad

Shahid

et al. 2009

Reports of Practical Oncology & Radiotherapy

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reports of practical oncology and radiotherapy 1 4 ( 2 0 1 0 ) 214-220 a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : h t t p : / / w w w . r p o r . e u / a r t i c l e i n f o Keywords: Computerized treatment planning system Wedge Beam hardening and softening a b s t r a c tIn order to optimize the tumour dose by using wedge filters, systematic studies were carried out to investigate the accuracy of the beam modifier algorithm in a computerized treatment planning system (Theraplan plus, version 3.8). The effect of different parameters such as beam hardening and softening coefficients on the wedge factor was also studied. A 15 MV photon beam obtained from a linear accelerator was used throughout the experiments.Normalized wedge factors were determined experimentally as well as with the Theraplan plus system as a function of field size and depth in a water phantom for 15 • , 30 • , 45 • , and 60 • wedge filters. The attenuation coefficients, beam hardening coefficient, and beam softening coefficients were also determined experimentally using the 15 MV photon beam for each wedge angle. The measured normalized wedge factor was found to increase with increasing depth and field size for the 15 MV beam. The Theraplan plus calculated normalized wedge factor was found to be in good agreement with the experimental values. This study indicated that ignoring the dependence of the wedge factor on depth and field size will result in underexposure of the tumour.

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A generic off-axis energy correction for linac photon beam dosimetry

Cited by 48 publications

References 14 publications

Verification of dose calculations with a clinical treatment planning system based on a point kernel dose engine

Verification of dose calculations with a clinical treatment planning system based on a point kernel dose engine

A Monte Carlo study of a flattening filter-free linear accelerator verified with measurements

Accuracy checks of physical beam modifier factors algorithm used in computerized treatment planning system for a 15MV photon beam

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