Global availability of dosimetry audits in radiotherapy: The IAEA dosimetry audit networks database.
Ontology highlight
ABSTRACT:
SUBMITTER: Izewska J
PROVIDER: S-EPMC7807735 | biostudies-literature | 2018 Jan
REPOSITORIES: biostudies-literature
Publications
Global availability of dosimetry audits in radiotherapy: The IAEA dosimetry audit networks database.
Izewska Joanna J Lechner Wolfgang W Wesolowska Paulina P
Physics and imaging in radiation oncology 20180110
The International Atomic Energy Agency (IAEA) has established a database describing activities of dosimetry audit networks (DAN) in radiotherapy. Since 2010 the data on different aspects of the dosimetry audit have been collected. This information has allowed for the analysis and comparison of current practices in dosimetry auditing activities worldwide. Overall, 79 organizations in 58 countries confirmed that they offer dosimetry audit services for radiotherapy; however, access of radiotherapy ...[more]
Similar Datasets
Project description:With new radiotherapy techniques, treatment delivery is becoming more complex and accordingly, these treatment techniques require dosimetry audits to test advanced aspects of the delivery to ensure best practice and safe patient treatment. This review of novel methodologies for dosimetry audits for advanced radiotherapy techniques includes recent developments and future techniques to be applied in dosimetry audits. Phantom-based methods (i.e. phantom-detector combinations) including independent audit equipment and local measurement equipment as well as phantom-less methods (i.e. portal dosimetry, transmission detectors and log files) are presented and discussed. Methodologies for both conventional linear accelerator (linacs) and new types of delivery units, i.e. Tomotherapy, stereotactic devices and MR-linacs, are reviewed. Novel dosimetry audit techniques such as portal dosimetry or log file evaluation have the potential to allow parallel auditing (i.e. performing an audit at multiple institutions at the same time), automation of data analysis and evaluation of multiple steps of the radiotherapy treatment chain. These methods could also significantly reduce the time needed for audit and increase the information gained. However, to maximise the potential, further development and harmonisation of dosimetry audit techniques are required before these novel methodologies can be applied.
| S-EPMC7807589 | biostudies-literature
Project description:National dosimetry audits are a fundamental part of quality assurance in radiotherapy, especially for new techniques. Intraoperative radiotherapy with a compact mobile kilovoltage X-ray source is a novel approach for the treatment of breast and other cancers. All seven current clinical sites in the UK were audited by a single visiting group and set of measurement equipment.Measurements of output, isotropy and depth doses were performed using an ion chamber in solid water, thermoluminescent dosemeters and radiochromic film, respectively.The mean difference between measured and planned dose across all centres was -3.2±2.7%. Measured isotropy was within ±3% around the lateral plane of the X-ray source and +11±4% in the forward direction compared with the lateral plane. Measured depth doses were agreed within 5±2% of manufacturer-provided calibration values or a mean gamma index of 97% at a tolerance of 7%/0.5 mm.Agreement within measurement uncertainties was found for all three parameters except forward anisotropy, which is unlikely to be clinically significant. Steep dose gradients increase the sensitivity to small variations in positioning, but these tests are practical for use in interdepartmental audits and local baseline comparison.The first UK interdepartmental audit of intraoperative radiotherapy builds confidence in the delivery of this treatment.
| S-EPMC3856551 | biostudies-other
Project description:UnlabelledThe International Atomic Energy Agency (IAEA) has a long tradition of supporting development of methodologies for national networks providing quality audits in radiotherapy. A series of co-ordinated research projects (CRPs) has been conducted by the IAEA since 1995 assisting national external audit groups developing national audit programs. The CRP 'Development of Quality Audits for Radiotherapy Dosimetry for Complex Treatment Techniques' was conducted in 2009-2012 as an extension of previously developed audit programs.Material and methodsThe CRP work described in this paper focused on developing and testing two steps of dosimetry audit: verification of heterogeneity corrections, and treatment planning system (TPS) modeling of small MLC fields, which are important for the initial stages of complex radiation treatments, such as IMRT. The project involved development of a new solid slab phantom with heterogeneities containing special measurement inserts for thermoluminescent dosimeters (TLD) and radiochromic films. The phantom and the audit methodology has been developed at the IAEA and tested in multi-center studies involving the CRP participants.ResultsThe results of multi-center testing of methodology for two steps of dosimetry audit show that the design of audit procedures is adequate and the methodology is feasible for meeting the audit objectives. A total of 97% TLD results in heterogeneity situations obtained in the study were within 3% and all results within 5% agreement with the TPS predicted doses. In contrast, only 64% small beam profiles were within 3?mm agreement between the TPS calculated and film measured doses. Film dosimetry results have highlighted some limitations in TPS modeling of small beam profiles in the direction of MLC leave movements.DiscussionThrough multi-center testing, any challenges or difficulties in the proposed audit methodology were identified, and the methodology improved. Using the experience of these studies, the participants could incorporate the auditing procedures in their national programs.
| S-EPMC4926790 | biostudies-literature
Project description:Preclinical radiation research lacks standardized dosimetry procedures that provide traceability to a primary standard. Consequently, ensuring accuracy and reproducibility between studies is challenging. Using 3D printed murine phantoms we undertook a dosimetry audit of Xstrahl Small Animal Radiation Research Platforms (SARRPs) installed at 7 UK centres. The geometrically realistic phantom accommodated alanine pellets and Gafchromic EBT3 film for simultaneous measurement of the dose delivered and the dose distribution within a 2D plane, respectively. Two irradiation scenarios were developed: (1) a 10 × 10 mm2 static field targeting the pelvis, and (2) a 5 × 5 mm2 90° arc targeting the brain. For static fields, the absolute difference between the planned dose and alanine measurement across all centres was 4.1 ± 4.3% (mean ± standard deviation), with an overall range of - 2.3 to 10.5%. For arc fields, the difference was - 1.2% ± 6.1%, with a range of - 13.1 to 7.7%. EBT3 dose measurements were greater than alanine by 2.0 ± 2.5% and 3.5 ± 6.0% (mean ± standard deviation) for the static and arc fields, respectively. 2D dose distributions showed discrepancies to the planned dose at the field edges. The audit demonstrates that further work on preclinical radiotherapy quality assurance processes is merited.
| S-EPMC9042835 | biostudies-literature
Project description:Several codes of practice for photon dosimetry are currently used around the world, supported by different organizations. A comparison of IPSM 1990 with both IAEA TRS-398 and AAPM TG-51 has been performed. All three protocols are based on the calibration of ionization chambers in terms of standards of absorbed dose to water, as it is the case with other modern codes of practice. This comparison has been carried out for photon beams of nominal energies: 4 MV, 6 MV, 8 MV, 10 MV and 18 MV. An NE 2571 graphite ionization chamber was used in this study, cross-calibrated against an NE 2611A Secondary Standard, calibrated in the National Physical Laboratory (NPL). Absolute dose in reference conditions was obtained using each of these three protocols including: beam quality indices, beam quality conversion factors both theoretical and NPL experimental ones, correction factors for influence quantities and absolute dose measurements. Each protocol recommendations have been strictly followed. Uncertainties have been obtained according to the ISO Guide to the Expression of Uncertainty in Measurement. Absorbed dose obtained according to all three protocols agree within experimental uncertainty. The largest difference between absolute dose results for two protocols is obtained for the highest energy: 0.7% between IPSM 1990 and IAEA TRS-398 using theoretical beam quality conversion factors.
| S-EPMC5720500 | biostudies-literature
Project description:IntroductionMany types of audits are commonly used in hospital care to promote quality improvements. However, the evidence on the effectiveness of audits is mixed. The objectives of this proposed realist review are (1) to understand how and why audits might, or might not, work in terms of delivering the intended outcome of improved quality of hospital care and (2) to examine under what circumstances audits could potentially be effective. This protocol will provide the rationale for using a realist review approach and outline the method.Methods and analysisThis review will be conducted using an iterative four-stage approach. The first and second steps have already been executed. The first step was to develop an initial programme theory based on the literature that explains how audits are supposed to work. Second, a systematic literature search was conducted using relevant databases. Third, data will be extracted and coded for concepts relating to context, outcomes and their interrelatedness. Finally, the data will be synthesised in a five-step process: (1) organising the extracted data into evidence tables, (2) theming, (3) formulating chains of inference from the identified themes, (4) linking the chains of inference and formulating CMO configurations and (5) refining the initial programme theory. The reporting of the review will follow the 'Realist and Meta-Review Evidence Synthesis: Evolving Standards' (RAMESES) publication standards.Ethics and disseminationThis review does not require formal ethical approval. A better understanding of how and why these audits work, and how context impacts their effectiveness, will inform stakeholders in deciding how to tailor and implement audits within their local context. We will use a range of dissemination strategies to ensure that findings from this realist review are broadly disseminated to academic and non-academic audiences.Prospero registration numberCRD42016039882.
| S-EPMC5541620 | biostudies-literature
Project description:The feasibility of using portal dosimetry (PD) to verify 6 MV flattening filter-free (FFF) IMRT treatments was investigated. An Elekta Synergy linear accelerator with an Agility collimator capable of delivering FFF beams and a standard iViewGT amorphous silicon (aSi) EPID panel (RID 1640 AL5P) at a fixed SSD of 160 cm were used. Dose rates for FFF beams are up to four times higher than for conventional flattened beams, meaning images taken at maximum FFF dose rate can saturate the EPID. A dose rate of 800 MU/min was found not to saturate the EPID for open fields. This dose rate was subsequently used to characterize the EPID for FFF portal dosimetry. A range of open and phantom fields were measured with both an ion chamber and the EPID, to allow comparison between the two. The measured data were then used to create a model within The Nederlands Kanker Instituut's (NKI's) portal dosimetry software. The model was verified using simple square fields with a range of field sizes and phantom thicknesses. These were compared to calculations performed with the Monaco treatment planning system (TPS) and isocentric ion chamber measurements. It was found that the results for the FFF verification were similar to those for flattened beams with testing on square fields, indicating a difference in dose between the TPS and portal dosimetry of approximately 1%. Two FFF IMRT plans (prostate and lung SABR) were delivered to a homogeneous phantom and showed an overall dose difference at isocenter of ~0.5% and good agreement between the TPS and PD dose distributions. The feasibility of using the NKI software without any modifications for high-dose-rate FFF beams and using a standard EPID detector has been investigated and some initial limitations highlighted.
| S-EPMC5690198 | biostudies-literature
Project description:BackgroundFew data are available on the supply and consumption of nutrients at the country level. To address this data gap, we aimed to create a database that provides information on availability (ie, supply) of 156 nutrients across 195 countries and territories from 1980 to 2013.MethodsWe matched 394 food and agricultural commodities from the Food and Agriculture Organization of the United Nations Supply and Utilization Accounts (SUAs) to food items in the United States Department of Agriculture Food Composition Database and obtained data on nutrient composition of the SUAs' food items. Then, after adjusting for inedible portion of each food item, we added the contributions of individual food items to the availability of each nutrient and estimated the national availability of macronutrients and micronutrients in each year. We validated our estimates by comparing our results with those of national nutrition surveys from three countries (the USA, South Korea, and Ecuador). Using dietary consumption data from the Global Burden of Disease study and two popular machine learning algorithms (Random Forest and XGBoost [extreme gradient boosting]), we developed predictive models to estimate the consumption of each nutrient based on their national availability.FindingsGlobally 2710 kcal (95% UI 2660-2770) were available per person per day in 2013. Carbohydrates were the major contributor to energy availability (70·5%), followed by fats (17·4%), and protein (10·5%). The energy availability and the contribution of macronutrients to total energy widely varied across levels of development. Countries at the higher level of development (high Socio-demographic Index countries) had more energy available per person per day (3270 kcal, 3220-3310); greater contributions from fats (26·0%) and proteins (11·9%) to total energy availability; and lower contributions from carbohydrate (54·8%). During 1980-2013, energy availability and the contributions of protein and fats to energy availability have increased globally and across levels of development while the contribution of carbohydrates to total energy availability has decreased. The supply of the micronutrients has also increased during the same period globally and across levels of development. Our validation analysis showed that, after accounting for waste at the retail and household level, our estimates of macronutrient availability were very close to the consumption data in nationally representative surveys. Our machine-learning models closely predicted the observed intake of nutrients with the out-of-sample correlation of greater than 0·8 between predicted and observed intake for the nutrients included in the analysis.InterpretationOur global nutrient database provides a picture of the supply of various nutrients at the country level and can be useful to assess the performance of national food systems in addressing the nutritional needs of their population.FundingBill & Melinda Gates Foundation.
| S-EPMC6076406 | biostudies-literature
Project description:Background and purposeA dosimetry audit program based on alanine electron paramagnetic resonance (EPR) and radiochromic film dosimetry, may be a valuable tool for monitoring and improving the quality of lung stereotactic body radiotherapy (SBRT). The aim of this study was to report the initial, independent assessment of the dosimetric accuracy for lung SBRT practice using these dosimeters in combination with a novel phantom design.Materials and methodsThe audit service was a remote audit program performed on a commercial lung phantom preloaded with film and alanine detectors. An alanine pellet was placed in the centre of the target simulated using silicone in a 3D-printed mould. Large film detectors were placed coronally through the target and the lung/tissue interface and analysed using gamma analysis. The beam output was always checked on the same day with alanine dosimetry in water. We audited 29 plans from 14 centres up to now.ResultsFor the alanine results 28/29 plans were within 5 % with 19/29 plans being within 3 %. The passing rates were > 95 % for the film through the target for 27/29 plans and 17/29 plans for the film at the lung/tissue interface. For three plans the passing rate was < 90 % for the film on top of the lungs.ConclusionsThe preliminary results were very satisfactory for both detectors. The high passing rates for the film in the interface region indicate good performance of the treatment planning systems. The phantom design was robust and performed well on several treatment systems.
| S-EPMC10848021 | biostudies-literature
Project description:Multicentre clinical trials involving a dosimetry component are becoming more prevalent in molecular radiotherapy and are essential to generate the evidence to support individualised approaches to treatment planning and to ensure that sufficient patients are recruited to achieve the statistical significance required. Quality assurance programmes should be considered to support the standardisation required to achieve meaningful results. Trials should be designed to ensure that dosimetry results from image acquisition systems across centres are comparable by incorporating steps to standardise the methodologies used for the quantification of images and dosimetry. Furthermore, it is essential to assess the expertise and resources available at each participating site prior to trial commencement. A quality assurance plan should be drawn up and training provided if necessary. Standardisation of quantification and dosimetry methodologies used in a trial are essential to ensure that results from different centres may be collated. In addition, appropriate uncertainty analysis should be carried out to correct for differences in methodologies between centres. Recommendations are provided to support dosimetry studies based on the experience of several previous and ongoing multicentre trials.
| S-EPMC7818526 | biostudies-literature