Dosimetric assessment of the impact of low-cost materials used in stereolithography in high-dose-rate brachytherapy.

PURPOSE: 3D printing has become a popular and widely available technique of rapid prototyping. The impact of used materials on the dose distribution has been studied for high energy sources. However, brachytherapy sources emit lower energy photons, and materials used in 3D printing may differ. This study was conducted to analyze the influence of common materials (polylactic acid - PLA and acrylonitrile butadiene styrene - ABS) used in stereolithography. MATERIAL AND METHODS: A 3D-printed phantom was designed, printed, and used to calibrate Gafchromic films. In the next step, a range of 1 mm thick plates of PLA and ABS (from zero to thirty) were inserted between source and detector to measure the impact of studied materials on delivered dose. Measurements were performed using a calibrated radiochromic film and Farmer ionization chamber in water. RESULTS: No statistically significant correlation (p = 0.4854) between the thickness of inserted PLA and the dose delivered to the film was obtained. With ionization chamber, Spearman's rank order test showed a significant correlation (p = 0.00004); however, the correlation was found weak. In case of ABS measurement, a statistically significant (p = 0.0159), yet weak negative correlation was found between the thickness of used material and the dose delivered to the film. On the other hand, a weak statistically significant (p = 0.0212) but positive correlation was found when the dose was measured with Farmer ionization chamber. We find these correlations false, as all measured doses were within the measurement uncertainty range (film ±8.0%, Farmer ±8.8%) from 100% of the prescribed dose. CONCLUSIONS: According to obtained results, with the accuracy of measurement under clinical conditions, the impact of highly filled PLA and ABS printed objects on the dose distribution from an 192Ir source in water can be omitted.

Assessment of biological parameters in head and neck cancer based on in vivo distribution of 18F-FDG-FLT-FMISO-PET/CT images.

OBJECTIVE: Several genetic analyses have identified tumor diversity not only among tumors from different patients (intertumor heterogeneity) but also within individual tumors (intratumor heterogeneity). The aim of this study was to analyze the intratumor heterogeneity and other biological parameters based on in vivo distribution in triple-tracer positron emission tomography with computed tomography (PET/CT) study in patients with newly diagnosed head and neck (H&N) cancer. METHODS: Thirty-six patients with newly diagnosed H&N cancer were included in the study. Institutional Bioethical Committee approved the study protocol and informed consent was received from every participant. All patients underwent series of 3 PET/CT scans with [18F]Fluorodeoxyglucose (18F-FDG-PET), [18F]Fluorothymidine (18F-FLT-PET), and [18F]Fluoromisonidazole (18F-FMISO-PET) before treatment. Scans were performed on separate days, within a timeframe of 2 weeks. Several PET/CT parameters grading tumor biology including maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), its equivalent (total hypoxic lesion [TLH] and total proliferative lesion [TLP]), and heterogeneity (area under the curve-cumulative SUV histogram) for the primary tumor were compared. RESULTS: All patients showed increased uptake of 18F-FDG in primary tumor, ranging from 2.29 to 14.89 SUVmax. Respectively, SUVmax values for 18F-FLT ranged from 0.93 to 16.11 and for 18F-FMISO 0.36-4.07. Based on 3-year follow-up, we divided patients in terms of survival forecasts (first with good prognosis and second with worse). Higher values of TLG/TLP/TLH and SUVmax were observed in the second group in all 3 tracers (for 18F-FDG: 167.40 vs 100.32, 11.15 vs 8.95; for 18F-FLT: 116.61 vs 60.67, 7.09 vs 5.47; for 18F-FMISO: 37.34 vs 22.30, 1.70 vs 1.61 respectively). Statistically significant differences were shown in SUVmax in 18F-FDG and 18F-FLT (P<0.034, P<0.034, respectively; in TLG, P=0.05; TLP, P=0.04; and TLH, P=0.05). CONCLUSION: Our preliminary results suggest worse prognosis in patients with higher heterogeneity values of primary tumor in proliferation and hypoxia images and combination of metabolic and volumetric parameters in TLG and its equivalent and heterogeneity of primary tumor seems to be a prognostic factor.

Assessment of tumour hypoxia, proliferation and glucose metabolism in head and neck cancer before and during treatment.

OBJECTIVE: The aim of the study was to assess the feasibility of multitracer positron emission tomography (PET) imaging before and during chemoradiation and to evaluate the predictive value of image-based factors for outcome in locally advanced head and neck cancers treated with chemoradiation. METHODS: In the week prior to the treatment [18F]-2-flu-2-deoxy-D-glucose (FDG), [18F]-3'-flu-3'deoxythymidine (FLT) and [18F]-flumisonidazole (FMISO) imaging was performed. FLT scans were repeated at 14 and 28 Gy and FMISO at 36 Gy. Overall survival, disease-free survival and local control were correlated with subvolume parameters, and with tumour-to-muscle ratio for FMISO. For every tracer, total metabolic tumour volume was calculated. RESULTS: 33 patients were included. No correlation was found between pre-treatment maximum standardised uptake value for FDG, FLT, FMISO and outcomes. Tumour volume measured on initial CT scans and initial FLT volume correlated with disease-free survivall (p = 0.007 and 0.04 respectively). FDG and FLT metabolic tumour volumes correlated significantly with local control (p = 0.005 and 0.02 respectively). In multivariate Cox analysis only individual initial TMRmax correlated with overall survival. CONCLUSION: PET/CT imaging is a promising tool. However, various aspects of image analysis need further clinical validation in larger multicentre study employing uniform imaging protocol and standardisation, especially for hypoxia tracer. ADVANCES IN KNOWLEDGE: Monitoring of biological features of the tumour using multitracer PET modality seems to be a feasible option in daily clinical practice.Evaluation of hypoxic subvolumes is more patient dependent; thus, exploration of individual parameters of hypoxia is needed. tumour-to-muscle ratio seems to be the most promising so far.

Patient safety in external beam radiotherapy, results of the ACCIRAD project: Recommendations for radiotherapy institutions and national authorities on assessing risks and analysing adverse error-events and near misses.

The ACCIRAD project, commissioned by the European Commission (EC) to develop guidelines for risk analysis of accidental and unintended exposures in external beam radiotherapy (EBRT), was completed in the year 2014. In 2015, the "General guidelines on risk management in external beam radiotherapy" were published as EC report Radiation Protection (RP)-181. The present document is the third and final report of the findings from the ACCIRAD project. The main aim of this paper is to describe the key features of the risk management process and to provide general guidelines for radiotherapy departments and national authorities on risk assessment and analysis of adverse error-events and near misses. The recommendations provided here and in EC report RP-181 are aimed at promoting the harmonisation of risk management systems across Europe, improving patient safety, and enabling more reliable inter-country comparisons.

Patient safety in external beam radiotherapy, results of the ACCIRAD project: Current status of proactive risk assessment, reactive analysis of events, and reporting and learning systems in Europe.

PURPOSE: To describe the current status of implementation of European directives for risk management in radiotherapy and to assess variability in risk management in the following areas: 1) in-country regulatory framework; 2) proactive risk assessment; (3) reactive analysis of events; and (4) reporting and learning systems. MATERIAL AND METHODS: The original data were collected as part of the ACCIRAD project through two online surveys. RESULTS: Risk assessment criteria are closely associated with quality assurance programs. Only 9/32 responding countries (28%) with national regulations reported clear "requirements" for proactive risk assessment and/or reactive risk analysis, with wide variability in assessment methods. Reporting of adverse error events is mandatory in most (70%) but not all surveyed countries. CONCLUSIONS: Most European countries have taken steps to implement European directives designed to reduce the probability and magnitude of accidents in radiotherapy. Variability between countries is substantial in terms of legal frameworks, tools used to conduct proactive risk assessment and reactive analysis of events, and in the reporting and learning systems utilized. These findings underscore the need for greater harmonisation in common terminology, classification and reporting practices across Europe to improve patient safety and to enable more reliable inter-country comparisons.

Radiotherapy equipment and departments in the European countries: final results from the ESTRO-HERO survey.

BACKGROUND: Documenting the distribution of radiotherapy departments and the availability of radiotherapy equipment in the European countries is an important part of HERO - the ESTRO Health Economics in Radiation Oncology project. HERO has the overall aim to develop a knowledge base of the provision of radiotherapy in Europe and build a model for health economic evaluation of radiation treatments at the European level. The aim of the current report is to describe the distribution of radiotherapy equipment in European countries. METHODS: An 84-item questionnaire was sent out to European countries, principally through their national societies. The current report includes a detailed analysis of radiotherapy departments and equipment (questionnaire items 26-29), analyzed in relation to the annual number of treatment courses and the socio-economic status of the countries. The analysis is based on validated responses from 28 of the 40 European countries defined by the European Cancer Observatory (ECO). RESULTS: A large variation between countries was found for most parameters studied. There were 2192 linear accelerators, 96 dedicated stereotactic machines, and 77 cobalt machines reported in the 27 countries where this information was available. A total of 12 countries had at least one cobalt machine in use. There was a median of 0.5 simulator per MV unit (range 0.3-1.5) and 1.4 (range 0.4-4.4) simulators per department. Of the 874 simulators, a total of 654 (75%) were capable of 3D imaging (CT-scanner or CBCT-option). The number of MV machines (cobalt, linear accelerators, and dedicated stereotactic machines) per million inhabitants ranged from 1.4 to 9.5 (median 5.3) and the average number of MV machines per department from 0.9 to 8.2 (median 2.6). The average number of treatment courses per year per MV machine varied from 262 to 1061 (median 419). While 69% of MV units were capable of IMRT only 49% were equipped for image guidance (IGRT). There was a clear relation between socio-economic status, as measured by GNI per capita, and availability of radiotherapy equipment in the countries. In many low income countries in Southern and Central-Eastern Europe there was very limited access to radiotherapy and especially to equipment for IMRT or IGRT. CONCLUSIONS: The European average number of MV machines per million inhabitants and per department is now better in line with QUARTS recommendations from 2005, but the survey also showed a significant heterogeneity in the access to modern radiotherapy equipment in Europe. High income countries especially in Northern-Western Europe are well-served with radiotherapy resources, other countries are facing important shortages of both equipment in general and especially machines capable of delivering high precision conformal treatments (IMRT, IGRT).

Radiotherapy staffing in the European countries: final results from the ESTRO-HERO survey.

BACKGROUND: The ESTRO Health Economics in Radiation Oncology (HERO) project has the overall aim to develop a knowledge base of the provision of radiotherapy in Europe and build a model for health economic evaluation of radiation treatments at the European level. The first milestone was to assess the availability of radiotherapy resources within Europe. This paper presents the personnel data collected in the ESTRO HERO database. MATERIALS AND METHODS: An 84-item questionnaire was sent out to European countries, through their national scientific and professional radiotherapy societies. The current report includes a detailed analysis of radiotherapy staffing (questionnaire items 47-60), analysed in relation to the annual number of treatment courses and the socio-economic status of the countries. The analysis was conducted between February and July 2014, and is based on validated responses from 24 of the 40 European countries defined by the European Cancer Observatory (ECO). RESULTS: A large variation between countries was found for most parameters studied. Averages and ranges for personnel numbers per million inhabitants are 12.8 (2.5-30.9) for radiation oncologists, 7.6 (0-19.7) for medical physicists, 3.5 (0-12.6) for dosimetrists, 26.6 (1.9-78) for RTTs and 14.8 (0.4-61.0) for radiotherapy nurses. The combined average for physicists and dosimetrists is 9.8 per million inhabitants and 36.9 for RTT and nurses. Radiation oncologists on average treat 208.9 courses per year (range: 99.9-348.8), physicists and dosimetrists conjointly treat 303.3 courses (range: 85-757.7) and RTT and nurses 76.8 (range: 25.7-156.8). In countries with higher GNI per capita, all personnel categories treat fewer courses per annum than in less affluent countries. This relationship is most evident for RTTs and nurses. Different clusters of countries can be distinguished on the basis of available personnel resources and socio-economic status. CONCLUSIONS: The average personnel figures in Europe are now consistent with, or even more favourable than the QUARTS recommendations, probably reflecting a combination of better availability as such, in parallel with the current use of more complex treatments than a decade ago. A considerable variation in available personnel and delivered courses per year however persists among the highest and lowest staffing levels. This not only reflects the variation in cancer incidence and socio-economic determinants, but also the stage in technology adoption along with treatment complexity and the different professional roles and responsibilities within each country. Our data underpin the need for accurate prediction models and long-term education and training programmes.

Patient safety in external beam radiotherapy - guidelines on risk assessment and analysis of adverse error-events and near misses: introducing the ACCIRAD project.

In 2011 the European Commission launched a tender to develop guidelines for risk analysis of accidental and unintended exposures in external beam radiotherapy. This tender was awarded to a consortium of 6 institutions, including the ESTRO, in late 2011. The project, denominated "ACCIRAD", recently finished the data collection phase. Data were collected by surveys administered in 38 European countries. Results indicate non-uniform implementation of event registration and classification, as well as incomplete or zero implementation of risk assessment and events analysis. Based on the survey results and analysis thereof, project leaders are currently drafting proposed guidelines entitled "Guidelines for patient safety in external beam radiotherapy - Guidelines on risk assessment and analysis of adverse-error events and near misses". The present article describes the aims and current status of the project, including results of the surveys.

Cost-effectiveness of the modifications in the quality assurance system in radiotherapy in the example of in-vivo dosimetry.

PURPOSE: To present the methodology for the evaluation of cost-effectiveness of the quality assurance protocol modifications associated with increasing demands on accuracy and reliability in radiotherapy and to present results on cost-effectiveness of in-vivo dosimetry as the chosen example of a technical procedure. MATERIAL AND METHODS: In-vivo dosimetry was used as an example of a quality assurance procedure, whose modifications have an impact on several procedures in the QA system and thus on the cost of radiotherapy. An analysis of 6864 patients, treated between 2001 and 2005 for tumours in the head and neck, breast, pelvis, or lung, was performed. The quality of radiotherapy was expressed as the accuracy of dose delivery and the cost was estimated from labour, equipment and materials. RESULTS: Modifications implemented in the quality assurance protocol have gradually improved the quality of irradiation. Mean deviations between measured and calculated doses, recorded for several groups of treatment sites, were reduced from -1.5% to 0.5%, 3.4% to 1.4%, 3.9% to 0.1% and -2.1% to 1.8% for head and neck, breast, pelvis and lung respectively. The standard deviations of the measured values decreased also consistently. Total monthly cost in radiotherapy (related to in-vivo dosimetry) increased from euro 4376 to euro 10,696 while the unitary cost of radiotherapy procedures remained at the same level. The predominant cost component of in-vivo dosimetry was labour, limited at first to physics staff and later extended to quality assurance personnel and technicians. CONCLUSION: The application of the presented methodology revealed cost-effectiveness relationships in tested technical procedures.