Time filter

Source Type

Tilburg, Netherlands

Siebert F.-A.,Clinic of Radiotherapy | Venselaar J.L.M.,Instituut Verbeeten | Hellebust T.P.,University of Oslo | Papagiannis P.,National and Kapodistrian University of Athens | And 2 more authors.
Metrologia | Year: 2012

Independent primary standards for brachytherapy photon-emitting source calibration in terms of dose-rate to water have been developed within the framework of the Euramet T2.J06 project. The introduction of dose-rate to water calibration presents an important change in clinical brachytherapy dosimetry that is expected to result to improved dosimetric accuracy. Nevertheless, as with any change in dosimetry for radiation therapy purposes, a phase-in period of well concerted actions aimed at precluding ambiguities and accidents at the end-user level is necessary. The overall uncertainty budget of clinical brachytherapy applications, as well as current trends in brachytherapy treatment planning system dose-calculation algorithms, also need to be considered for a realistic assessment of the net benefit of improving source calibration accuracy. © 2012 BIPM & IOP Publishing Ltd.

DeWerd L.A.,University of Wisconsin - Madison | Ibbott G.S.,University of Texas M. D. Anderson Cancer Center | Mitch M.G.,U.S. National Institute of Standards and Technology | Rivard M.J.,Tufts University | And 3 more authors.
Medical Physics | Year: 2011

This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Euroṕen de Curieth́rapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments. © 2011 American Association of Physicists in Medicine.

Van De Poll-Franse L.V.,Comprehensive Cancer Center South | Van De Poll-Franse L.V.,University of Tilburg | Pijnenborg J.M.A.,TweeSteden Hospital | Boll D.,TweeSteden Hospital | And 5 more authors.
Gynecologic Oncology | Year: 2012

Objectives: Routine lymphadenectomy (LA) in early stage endometrial cancer does not improve survival. However, in the absence of lymph node metastasis, radiotherapy (RT) could be withheld and hence could result in less morbidity. Our aim was to evaluate health related quality of life (HRQL) in endometrial cancer survivors that received routine pelvic LA without RT compared to no LA, but RT in the presence of risk factors. Methods: Stage I-II endometrial cancer survivors diagnosed between 1999 and 2007 were selected from the Eindhoven Cancer Registry. Survivors completed the SF-36 and the EORTC-QLQ-EN24. ANCOVA and multiple linear regression analyses were applied. Results: 742 (77%) of the endometrial cancer survivors returned a completed questionnaire. 377 (51%) had received no LA nor RT (LA-RT-), 198 (27%) had received LA+RT-, 153 (21%) LA-RT+ and 14 patients (2%) had received both. LA+ women reported as higher lymphedema symptom scores (25 vs. 20, p = 0.04). Women who were treated with RT reported higher gastrointestinal symptom scores vs. those who did not (23 vs. 16, p = 0.04). HRQL scales were comparable between all four treatment groups. Conclusion: Despite distinct symptom patterns among women who received LA or RT, no clinically relevant differences in HRQL were observed when compared to women not receiving adjuvant therapy. Using LA to tailor adjuvant pelvic radiotherapy and prevent over-treatment in low-risk patients cannot be recommended. © 2012 Elsevier Inc.

Nath R.,Yale University | Rivard M.J.,Tufts University | DeWerd L.A.,University of Wisconsin - Madison | Dezarn W.A.,Wake forest University | And 7 more authors.
Medical Physics | Year: 2016

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. © 2016 American Association of Physicists in Medicine.

Kirisits C.,Medical University of Vienna | Rivard M.J.,Tufts University | Ballester F.,University of Valencia | De Brabandere M.,University Hospital Gasthuisberg | And 7 more authors.
Radiotherapy and Oncology | Year: 2014

Background and purpose A substantial reduction of uncertainties in clinical brachytherapy should result in improved outcome in terms of increased local control and reduced side effects. Types of uncertainties have to be identified, grouped, and quantified. Methods A detailed literature review was performed to identify uncertainty components and their relative importance to the combined overall uncertainty. Results Very few components (e.g., source strength and afterloader timer) are independent of clinical disease site and location of administered dose. While the influence of medium on dose calculation can be substantial for low energy sources or non-deeply seated implants, the influence of medium is of minor importance for high-energy sources in the pelvic region the level of uncertainties due to target, organ, applicator, and/or source movement in relation to the geometry assumed for treatment planning is highly dependent on fractionation and the level of image guided adaptive treatment. Most studies to date report the results in a manner that allows no direct reproduction and further comparison with other studies. Often, no distinction is made between variations, uncertainties, and errors or mistakes the literature review facilitated the drafting of recommendations for uniform uncertainty reporting in clinical BT, which are also provided the recommended comprehensive uncertainty investigations are key to obtain a general impression of uncertainties, and may help to identify elements of the brachytherapy treatment process that need improvement in terms of diminishing their dosimetric uncertainties. It is recommended to present data on the analyzed parameters (distance shifts, volume changes, source or applicator position, etc.), and also their influence on absorbed dose for clinically-relevant dose parameters (e.g., target parameters such as D90 or OAR doses). Publications on brachytherapy should include a statement of total dose uncertainty for the entire treatment course, taking into account the fractionation schedule and level of image guidance for adaptation. Conclusions This report on brachytherapy clinical uncertainties represents a working project developed by the Brachytherapy Physics Quality Assurances System (BRAPHYQS) subcommittee to the Physics Committee within GEC-ESTRO. Further, this report has been reviewed and approved by the American Association of Physicists in Medicine. © 2013 Elsevier Ireland Ltd. All rights reserved.

Discover hidden collaborations