Field flatness and symmetry of photon beams: Review of the current recommendations

Kouloulias, Vassilis; Poortmans, Philip; Antypas, C.; Kappas, C.; Sandilos, P.

doi:10.3233/thc-2003-11408

Cited by 8 publications

(7 citation statements)

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“…The acceptance tolerance of the beam symmetry and flatness should not exceed 3%. The beam is more symmetric and flattened at higher energies, [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] which is well in agreement with our results, as our symmetry and flatness value did not exceed 3% for red and green channels, and also symmetry and flatness were better at high energies except in some cases. The results are in agreement with those of Sahani et al 33 and define the acceptance criteria of photon beam characteristics such as for symmetry, flatness and penumbra for pre-machine commissioning and for QC purposes at different energies and field sizes using International Electro Technical Commission (IEC 60976, 2008), which ensures that there is only a small negligible difference between calculated and measured data using two detectors.…”

Section: Discussionsupporting

confidence: 89%

“…The computer-controlled radiation field analyser system is used as a dose profile verification tool. Owing to this time-consuming procedure, it is not feasible for medical physicists to use this as a daily dose quality assurance testing method in radiotherapy departments 8 9 …”

Section: Introductionmentioning

confidence: 99%

“…Owing to this time-consuming procedure, it is not feasible for medical physicists to use this as a daily dose quality assurance testing method in radiotherapy departments. 8,9 Since the 1960s, radiochromic film has been an accurate dosimetric tool used to verify the photon beam properties for different field sizes and energies. Radiochromic film consists of a thin layer of colourless radiosensitive leuco-dye bonded onto a 100 μm thick Myler base.…”

Section: Introductionmentioning

confidence: 99%

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Commissioning and evaluation of a radiochromic EBT3 film dosimetry system

et al. 2018

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PurposeThis work reports our study to commission a radiochromic film dosimetry system using the timely EBT3 film. We carried out dosimetric evaluations on different characteristics of photon beams (e.g., flatness, symmetry and penumbra) in radiation dose delivery.Materials and MethodsA Varian linear accelerator producing 6 and 15 MV photon beams with 120 multi-leaf collimator was used in this study. PTW ionisation chamber was used to measure the beam characteristics such as symmetry, flatness and penumbra and these measurements were used to commission the radiochormic EBT3 film dosimetry system. The results of irradiated films were analysed using the radiochromic film QA Pro software 2016.ResultsThe measured film doses were analysed at two different colour channels (green and red) using two scanning geometries (i.e., upper or lower side of film facing the scanner light source) at two dose levels (10 and 40 Gy). The difference between the ionisation chamber and film results was found insignificant and within the acceptable range as per the World Health Organisation standard.ConclusionResults of the comparison between the ionisation chamber and film measurements show that our radiochormic EBT3 film dosimetry system is reliable and cost-effective in the output measurement of a linear accelerator. Our measurements confirm that our EBT3 film dosimetry agreed well with the ionisation chamber, and can be used as a re-validation tool for linear accelerator quality control.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Commissioning and evaluation of a radiochromic EBT3 film dosimetry system

et al. 2018

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“…5 The symmetry values do not show any significant dependence on the depth, energy of the photon beams and the field sizes. 6 Kouloulias et al 15 stated that both homogeneity and symmetry are considered as the quality determining factor of the photon beam delivered from linear accelerators. Galiano et al 16 proposed the notions for symmetry and homogeneity of beam dose, which were an extension of the description of both of these tools of dosimetry and these are given in the literature.…”

Section: Discussionmentioning

confidence: 99%

“…15 MV photon beam characteristics at 10 cmFigure 2. 15 MV beam profile at 10 cm depth for 10 × 10 cm 2 field size.…”

mentioning

confidence: 99%

Dosimetric comparison of photon beam profile characteristics for different treatment parameters

Shamsi

Atiq

et al. 2017

J Radiother Pract

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PurposeTo deliver radiation doses with higher accuracy, radiation treatment through megavoltage photon beams from linear accelerators, is accepted widely for treating malignancies. Before calibrating the linear accelerators, it is essential to make a complete analysis of all photon beam profile parameters. The main objective of this exploration was to investigate the 6 and 15 MV photon beam profile characteristics to improve the accuracy of radiation treatment plans.MethodsIn this exploration, treatment parameters like depth, field size and beam energy were varied to observe their effect on dosimetric characteristics of beam profiles in a water phantom, generated by linear accelerator Varian Clinac.ResultsThe results revealed thatDmaxandDmindecreased with increasing depth but increased with increasing field sizes. Both left and right penumbras increased with increasing depth, field size and energy. Homogeneity increased with field size but decreased with depth. Symmetry had no dependence on depth, energy and field size.ConclusionAll the characteristics of photon beam dosimetry were analysed and the characteristics like homogeneity and symmetry measured by an ion chamber in a water phantom came within clinically acceptable level of 3 and 103%, respectively, thus fulfilled the requirements of standard linear accelerator specifications. This exploration can be extended to the determination of beam profile characteristics of electron and photon beams of other energies at various depths and field sizes for designing optimum treatment plans.

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