Comparison of192Ir air kerma calibration coefficients derived at ARPANSA using the interpolation method and at the National Physical Laboratory using a direct measurement

Butler, Duncan; Haworth, Annette; Sander, T; Todd, Stephen

doi:10.1007/bf03178603

Cited by 14 publications

(27 citation statements)

References 10 publications

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“…The PTW 30010 air kerma chamber calibration coefficient (

N_{K, A R P}

) for use with Ir‐192 was derived through interpolation of response in a

^{60} Co

and a kilovoltage X‐ray beam at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) laboratory, as previously described. ( 11 ) The air kerma calibration coefficient for the waterproof (PTW 30013) chamber, which has the same dimensions as the 30010 chamber, was derived through direct comparison, by measurement of the air kerma rate (AKR), using the

^{192} Ir

source and air‐kerma calibration jig described in Method 1.…”

Section: Methodsmentioning

confidence: 99%

Comparison of TLD calibration methods for dosimetry

Haworth

Butler²,

Wilfert

et al. 2013

J Applied Clin Med Phys

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For the purpose of dose measurement using a high‐dose rate 192Ir source, four methods of thermoluminescent dosimeter (TLD) calibration were investigated. Three of the four calibration methods used the 192Ir source. Dwell times were calculated to deliver 1 Gy to the TLDs irradiated either in air or water. Dwell time calculations were confirmed by direct measurement using an ionization chamber. The fourth method of calibration used 6 MV photons from a medical linear accelerator, and an energy correction factor was applied to account for the difference in sensitivity of the TLDs in 192Ir and 6 M V. The results of the four TLD calibration methods are presented in terms of the results of a brachytherapy audit where seven Australian centers irradiated three sets of TLDs in a water phantom. The results were in agreement within estimated uncertainties when the TLDs were calibrated with the 192Ir source. Calibrating TLDs in a phantom similar to that used for the audit proved to be the most practical method and provided the greatest confidence in measured dose. When calibrated using 6 MV photons, the TLD results were consistently higher than the 192Ir−calibrated TLDs, suggesting this method does not fully correct for the response of the TLDs when irradiated in the audit phantom.PACS number: 87

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“…The PTW 30010 air kerma chamber calibration coefficient (

N_{K, A R P}

) for use with Ir‐192 was derived through interpolation of response in a

^{60} Co

^{192} Ir

source and air‐kerma calibration jig described in Method 1.…”

Section: Methodsmentioning

confidence: 99%

Comparison of TLD calibration methods for dosimetry

Haworth

Butler²,

Wilfert

et al. 2013

J Applied Clin Med Phys

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show abstract

“…In most cases, this consisted of an upturned plastic waste bin that placed the phantom around 800 mm from the floor and more than 1 m from the treatment room walls. A distance of 1 m from the floor and walls is recommended by the IAEA TecDoc 1274 in the measurement of source air kerma rate, and based on scatter measurements made by Butler et al ., we believe the contribution due to scatter dose to be less than 0.01% with this geometry. The audit representative placed the TLDs in the phantom for each measurement.…”

Section: Methodsmentioning

confidence: 80%

Australasian brachytherapy audit: Results of the ‘end‐to‐end’ dosimetry pilot study

Haworth

Wilfert

Butler³

et al. 2013

J Med Imag Rad Onc

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While the limited data collected in the study demonstrated considerable heterogeneity in clinical practice, the study proved a brachytherapy dosimetry audit to be feasible. Future studies should include verification of source strength using a Standard Dosimetry Laboratory calibrated chamber, a phantom that more closely mimics the clinical situation, a more comprehensive review of safety and quality assurance (QA) procedures including source dwell time and position accuracy, and a review of patient treatment QA procedures such as applicator position verification.

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“…Calibration standards for HDR 192 Ir using similar techniques have been developed at a number of European PSDLs such as LNHB, NPL, and PTB, and at the National Research Council of Canada, 47 but not yet at NIST in the U.S. Intercomparisons of these standards have shown good agreement. [48][49][50][51][52] The preferred method for traceability in clinical source calibrations is to have the well-type chamber calibrated against the traceable standard (e.g., at an ADCL). This calibration should be carried out for each source, including the appropriate source holder made by the well chamber or source manufacturer for that source.…”

Section: A High-dose-rate (Hdr) 192 Ir Sources and Afterloadersmentioning

confidence: 99%

Guidelines by the AAPM and GEC‐ESTRO on the use of innovative brachytherapy devices and applications: Report of Task Group 167

et al. 2016

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Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used in the evaluation of innovative devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining the equivalence of the innovative treatment modality to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of innovative radiotherapy devices or applications is a critical part in which physicists should be actively involved. The physicist's role, along with physician colleagues, in this process is highlighted for innovative brachytherapy devices and applications and includes evaluation of (1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, (2) risks and benefits from a regulatory and safety perspective, and (3) resource assessment and preparedness. Further, it is suggested that any developed calibration methods be traceable to a primary standards dosimetry laboratory (PSDL) such as the National Institute of Standards and Technology in the U.S. or to other PSDLs located elsewhere such as in Europe. Clinical users should follow standards as approved by their country's regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the Accredited Dosimetry Calibration Laboratories in the U.S. is encouraged before a source is introduced into widespread routine clinical use. The American Association of Physicists in Medicine and the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) have developed guidelines for the safe and consistent application of brachytherapy using innovative devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of requirements of the U.S. Nuclear Regulatory Commission, U.S. Department of Transportation, International Electrotechnical Commission Medical Electrical Equipment Standard 60601, U.S. Food and Drug Administration, European Commission for CE Marking (Conformité Européenne), and institutional review boards and radiation safety committees.

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Comparison of192Ir air kerma calibration coefficients derived at ARPANSA using the interpolation method and at the National Physical Laboratory using a direct measurement

Cited by 14 publications

References 10 publications

Comparison of TLD calibration methods for dosimetry

Comparison of TLD calibration methods for dosimetry

Australasian brachytherapy audit: Results of the ‘end‐to‐end’ dosimetry pilot study

Guidelines by the AAPM and GEC‐ESTRO on the use of innovative brachytherapy devices and applications: Report of Task Group 167

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