Assessment of clinically relevant dose distributions in pelvic IOERT using Gafchromic EBT3 films

Costa, Francisco; Sarmento, S.; Sousa, Olga

doi:10.1016/j.ejmp.2015.05.013

Cited by 18 publications

(19 citation statements)

References 25 publications

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“…Likewise, below the hotspot associated to a step-like surface, there is a rapid dose decrease in depth. 4 The preliminary results presented in Tables 3 and 4 confirm that irregularities in the irradiation surface, especially step-like irregularities, have a measurable effect on clinical dose distributions. The sample size in this work is insufficient to determine the more frequently occurring scenarios from statistical analysis.…”

Section: Discussionmentioning

confidence: 52%

“…This is in good agreement with previous results obtained in phantoms, where a perfect step-like irregularity was observed to cause a lateral surface dose increase of approximately 20%. 4 The magnitude of the increase probably depends on the height of the irregularity and its location relative to the applicator, but a full characterization of possible scenarios falls outside the scope of this work. However, even a detailed phantom study cannot indicate which scenarios effectively occur in clinical practice and how often they occur.…”

Section: Measurements In Solid Phantomsmentioning

confidence: 99%

“…11 This makes sense for nearly flat surfaces such as the breast. 4 With an irregular irradiation surface, the dose distribution relative to the reference may be significantly altered. Therefore, in this work, measured doses will be expressed directly without any conversions.…”

Section: In Vivo Measurementsmentioning

confidence: 99%

“…3 Unlike the breast, the irradiation surface for rectal cancer is usually irregular and/or concave, and 45°bevelled applicators are often used. In a previous study, Costa et al 4 have shown that an irregular irradiation surface can alter the dose distribution relative to the reference situation (flat irradiation surface). This is particularly relevant when the entrance of a bevelled applicator is partly covered by the tissue, creating a step-like irregularity.…”

Section: Introductionmentioning

confidence: 99%

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In vivodosimetry using Gafchromic films during pelvic intraoperative electron radiation therapy (IOERT)

Costa¹,

Sarmento²,

Gomes³

et al. 2016

BJR

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Objective: To characterize in vivo dose distributions during pelvic intraoperative electron radiation therapy (IOERT) for rectal cancer and to assess the alterations introduced by irregular irradiation surfaces in the presence of bevelled applicators. Methods: In vivo measurements were performed with Gafchromic films during 32 IOERT procedures. 1 film per procedure was used for the first 20 procedures. The methodology was then optimized for the remaining 12 procedures by using a set of 3 films. Both the average dose and two-dimensional dose distributions for each film were determined. Phantom measurements were performed for comparison. Results: For flat and concave surfaces, the doses measured in vivo agree with expected values. For concave surfaces with step-like irregularities, measured doses tend to be higher than expected doses. Results obtained with three films per procedure show a large variability along the irradiated surface, with important differences from expected profiles. These results are consistent with the presence of surface hotspots, such as those observed in phantoms in the presence of step-like irregularities, as well as fluid build-up. Conclusion: Clinical dose distributions in the IOERT of rectal cancer are often different from the references used for prescription. Further studies are necessary to assess the impact of these differences on treatment outcomes. In vivo measurements are important, but need to be accompanied by accurate imaging of positioning and irradiated surfaces. Advances in knowledge: These results confirm that surface irregularities occur frequently in rectal cancer IOERT and have a measurable effect on the dose distribution.

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Section: Discussionmentioning

confidence: 52%

Section: Measurements In Solid Phantomsmentioning

confidence: 99%

Section: In Vivo Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In vivodosimetry using Gafchromic films during pelvic intraoperative electron radiation therapy (IOERT)

Costa¹,

Sarmento²,

Gomes³

et al. 2016

BJR

Self Cite

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“…due to organ movement such as breathing, could result in a larger than expected in vivo dose. Lastly, surface step-like irregularities may also create hot spots possibly because of lateral scatter with non-perpendicular irradiation as demonstrated by Costa et al [47]. In conclusion, the increase in dose measured in vivo could be a combination of the aforementioned effects.…”

Section: Discussionmentioning

confidence: 62%

Electron radiotherapy (IOERT) for applications outside of the breast: Dosimetry and influence of tissue inhomogeneities

et al. 2020

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Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

et al. 2020

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The use of radiochromic film (RCF) dosimetry in radiation therapy is extensive due to its high level of achievable accuracy for a wide range of dose values and its suitability under a variety of measurement conditions. However, since the publication of the 1998 AAPM Task Group 55, Report No. 63 on RCF dosimetry, the chemistry, composition, and readout systems for RCFs have evolved steadily. There are several challenges in using the new RCFs, readout systems and validation of the results depending on their applications. Accurate RCF dosimetry requires understanding of RCF selection, handling and calibration methods, calibration curves, dose conversion methods, correction methodologies as well as selection, operation and quality assurance (QA) programs of the readout systems. Acquiring this level of knowledge is not straight forward, even for some experienced users. This Task Group report addresses these issues and provides a basic understanding of available RCF models, dosimetric characteristics and properties, advantages and limitations, configurations, and overall elemental compositions of the RCFs that have changed over the past 20 yr. In addition, this report provides specific guidelines for data processing and analysis schemes and correction methodologies for clinical applications in radiation therapy.

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Assessment of clinically relevant dose distributions in pelvic IOERT using Gafchromic EBT3 films

Abstract: The shape of the irradiation surfaces alters the dose distribution. Visualization of these effects is important to assess target coverage and interpret in vivo measurements in pelvic IOERT.

Cited by 18 publications

References 25 publications

In vivodosimetry using Gafchromic films during pelvic intraoperative electron radiation therapy (IOERT)

In vivodosimetry using Gafchromic films during pelvic intraoperative electron radiation therapy (IOERT)

Electron radiotherapy (IOERT) for applications outside of the breast: Dosimetry and influence of tissue inhomogeneities

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55

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