Surface dose characterisation of the Varian Ir-192 HDR conical surface applicator set with a vertically orientated source

Buchauer, Konrad; Henke, Guido; Schiefer, Hans; Plaßwilm, Ludwig

doi:10.1007/s00066-014-0713-2

Cited by 2 publications

(2 citation statements)

References 22 publications

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“…14,138,329,331 Dosimetric measurements of HDR sources in various applicators and catheters have been reported. 139,140,143,154,326,[332][333][334][335][336] The effect of phantom material and heterogeneity (applicator/catheters) on the dose distributions can be assessed. 142,337,338 For machine QA, RCFs can be used for checking dwell position accuracy [339][340][341] and relative dwell times in a catheter or applicator based on the autoradiography method 342 previously employing XV-2 film.…”

Section: E2 Hdr Sourcesmentioning

confidence: 99%

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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Section: E2 Hdr Sourcesmentioning

confidence: 99%

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

et al. 2020

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“…The extent of source sag may differ between HDR machines due to bends in the source wire and different applicator setup geometries. It may also vary for different setups for the same machine, as previously shown in the literature [29–31]. …”

Section: Discussionmentioning

confidence: 83%

Impact of source position on high-dose-rate skin surface applicator dosimetry

et al. 2016

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Purpose Skin surface dosimetric discrepancies between measured and treatment planning system (TPS) predicted values were traced to source position sag inside the applicator and to source transit time. We quantified their dosimetric impact and propose corrections for clinical use. Material and methods We measured the dose profiles from the Varian Leipzig-style HDR skin applicator, using EBT3 film, photon diode, and optically stimulated luminescence dosimeter for three different GammaMedplus™ HDR afterloaders. The measured dose profiles at several depths were compared with BrachyVision Acuros™ calculated profiles. To assess the impact of the source sag, two different applicator orientations were considered. The dose contribution during source transit was assessed by comparing diode measurements using a HDR timer and an electrometer timer. Results Depth doses measured using the three dosimeters were in good agreement, but were consistently higher than the Acuros dose calculations. Measurements with the applicator face up were significantly (exceeding 10%) lower than those in the face down position, due to source sag inside the applicator. Based on the inverse square law, the effective source sag was evaluated to be about 0.5 mm from the planned position. The additional dose during source transit was evaluated to be about 2.8% for 30 seconds of treatment with a 40700 U (10 Ci) source. Conclusion With a very short source-to-surface distance, the small source sag inside the applicator has a significant dosimetric impact. This effect is unaccounted for in the vendor’s treatment planning template, and should be considered before the clinical use of the applicator. Further investigation of other applicators with large source lumen diameter may be warranted.

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Surface dose characterisation of the Varian Ir-192 HDR conical surface applicator set with a vertically orientated source

Cited by 2 publications

References 22 publications

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

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

Impact of source position on high-dose-rate skin surface applicator dosimetry

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