Lung dose corrections for 6‐ and 15‐MV x rays

Mackie, T; El‐Khatib, Ellen; Battista, Jerry; Scrimger, John W.; Dyk, Jake Van; Cunningham, Jack R.

doi:10.1118/1.595691

Cited by 110 publications

(77 citation statements)

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“…The essential volume over which scatter of kernel contributions must be necessitated and the maximum volume used in XiO planning system is close to 30cm in the forward direction, 5cm in the backward direction, and replicate the field size dimension laterally (basically the contributions from all interaction points must be collected). Sharpe and Battista 11 have reported the same ranges, as well as Mackie et al 12,13 have described the same As well as dose contributions above such a large area needs a significant time for computation. This computation time can be reduced by accomplishment separate calculations; one with the main core for which the computation is done at a high resolution, but over a small region, the other with a scatter kernel where a computation is achieved at a lower resolution but over a large area, as suggested by Mackie et al 5,8 .…”

Section: Convolution Algorithmsupporting

confidence: 52%

Evaluation of the Algorithm’s Accuracy in the Computation of the Dose Distribution in the Brain Tumors

Ahmed¹,

Abdel-Wanis²,

Attalla³

et al. 2016

Biosci., Biotech. Res. Asia

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Section: Convolution Algorithmsupporting

confidence: 52%

Evaluation of the Algorithm’s Accuracy in the Computation of the Dose Distribution in the Brain Tumors

Ahmed¹,

Abdel-Wanis²,

Attalla³

et al. 2016

Biosci., Biotech. Res. Asia

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“…Studies involving accuracy of treatment planning software with respect to inhomogeneous phantoms have been the subject of many publications 1,4,5,7,[10][11][12][13]15,20 . These studies show significant discrepancies between measured and calculated dose near interfaces between tissues of different density.…”

Section: Introductionmentioning

confidence: 99%

Comparison of measured and calculated radiotherapy doses in the chest region of an inhomogeneous humanoid phantom

McDermott

Perkins

2004

Australas. Phys. Eng. Sci. Med.

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Errors in dose calculation by treatment planning computers are known to arise when calculation algorithms do not account for electron disequilibrium near interfaces between tissues of different density. The accuracy of a treatment planning system (Plato, Nucletron International BV) was investigated for two treatments in the chest region: tangential 6 MV photons to the chest wall and opposed AP-PA 18 MV photon fields to the mediastinum. Thermo-luminescent dosimeters were used to measure dose at 40 sites in the chest of a humanoid phantom (Rando, Alderson Associates). Measurements were compared with point doses calculated using two different versions of the Plato external beam calculation software: RTS 1.8 and the newer RTS 2.2. Measured and calculated doses differed by 3% or more at more than one quarter of all sites. The greatest discrepancies occurred for points located in lung, which were generally overestimated. The maximum discrepancies for the 6 MV tangential breast irradiation were 8.5% for RTS 1.8 and 3.5% for RTS 2.2. For the 18 MV opposed field irradiation, the maximum discrepancies were 11.4% and 8.1% respectively. RTS 2.2 was more accurate than RTS 1.8, with smaller mean and maximum discrepancies.

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“…Many investigators have shown the existence of significant dose perturbation within, and beyond, low‐density inhomogeneities for small fields of megavoltage photons 4 – 7 . The perturbations in lung result from the combined effects of a reduction in photon attenuation, loss of scattered photons, and increase in range of the secondary electrons.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric comparison of extended dose range film with ionization measurements in water and lung equivalent heterogeneous media exposed to megavoltage photons

Charland

Chetty

Yokoyama

et al. 2003

J Applied Clin Med Phys

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In this study, a dosimetric evaluation of the new Kodak extended dose range (EDR) film versus ionization measurements has been conducted in homogeneous solid water and water‐lung equivalent layered heterogeneous phantoms for a relevant range of field sizes (up to a field size of 25×25 cm2 and a depth of 15 cm) for 6 and 15 MV photon beams from a linear accelerator. The optical density of EDR film was found to be linear up to about 350 cGy and over‐responded for larger fields and depths (5% for 25×25 cm2 at depth of 15 cm compared to a 10×10 cm2, 5 cm depth reference value). Central axis depth dose measurements in solid water with the film in a perpendicular orientation were within 2% of the Wellhöfer IC‐10 measurements for the smaller field sizes. A maximum discrepancy of 8.4% and 3.9% was found for the 25×25 cm2 field at 15 cm depth for 6 and 15 MV photons, respectively (with curve normalization at a depth of 5 cm). Compared to IC‐10 measurements, film measured central axis depth dose inside the lung slab showed a slight over‐response (at most 2%). At a depth of 15 cm in the lung phantom the over‐response was found to be 7.4% and 3.7% for the 25×25 cm2 field for 6 and 15 MV photons, respectively. When results were presented as correction factors, the discrepancy between the IC‐10 and the EDR was greatest for the lowest energy and the largest field size. The effect of the finite size of the ion chamber was most evident at smaller field sizes where profile differences versus film were observed in the penumbral region. These differences were reduced at larger field sizes and in situations where lateral electron transport resulted in a lateral spread of the beam, such as inside lung material. Film profiles across a lung tumor geometry phantom agreed with the IC‐10 chamber within the experimental uncertainties. From this investigation EDR film appears to be a useful medium for relative dosimetry in higher dose ranges in both water and lung equivalent material for moderate field sizes and depths. © 2003 American College of Medical Physics.PACS number(s): 87.53.Dq, 87.66.Cd, 87.66.Jj, 87.66.Xa

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Lung dose corrections for 6‐ and 15‐MV x rays

Cited by 110 publications

References 0 publications

Evaluation of the Algorithm’s Accuracy in the Computation of the Dose Distribution in the Brain Tumors

Evaluation of the Algorithm’s Accuracy in the Computation of the Dose Distribution in the Brain Tumors

Comparison of measured and calculated radiotherapy doses in the chest region of an inhomogeneous humanoid phantom

Dosimetric comparison of extended dose range film with ionization measurements in water and lung equivalent heterogeneous media exposed to megavoltage photons

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