An external dosimetry audit programme to credential static and rotational IMRT delivery for clinical trials quality assurance

PurposeExternal dosimetry audits give confidence in the safe and accurate delivery of radiotherapy. The RTTQA group have performed an on-site audit programme for trial recruiting centres, who have recently implemented static or rotational IMRT, and those with major changes to planning or delivery systems.MethodsMeasurements of reference beam output were performed by the host centre, and by the auditor using independent equipment. Verification of clinical plans was performed using the ArcCheck helical diode array.ResultsA total of 54 measurement sessions were performed between May 2014 and June 2016 at 28 UK institutions, reflecting the different combinations of planning and delivery systems used at each institution. Average ratio of measured output between auditor and host was 1.002 ± 0.006. Average point dose agreement for clinical plans was −0.3 ± 1.8%. Average (and 95% lower confidence intervals) of gamma pass rates at 2%/2 mm, 3%/2 mm and 3%/3 mm respectively were: 92% (80%), 96% (90%) and 98% (94%). Moderately significant differences were seen between fixed gantry angle and rotational IMRT, and between combination of planning systems and linac manufacturer, but not between anatomical treatment site or beam energy.ConclusionAn external audit programme has been implemented for universal and efficient credentialing of IMRT treatments in clinical trials. Good agreement was found between measured and expected doses, with few outliers, leading to a simple table of optimal and mandatory tolerances for approval of dosimetry audit results. Feedback was given to some centres leading to improved clinical practice.     

The European Federation of Organisations for Medical Physics Policy Statement No. 6.1: Recommended Guidelines on National Registration Schemes for Medical Physicists

This EFOMP Policy Statement is an update of Policy Statement No. 6 first published in 1994. The present version takes into account the European Union Parliament and Council Directive 2013/55/EU that amends Directive 2005/36/EU on the recognition of professional qualifications and the European Union Council Directive 2013/59/EURATOM laying down the basic safety standards for protection against the dangers arising from exposure to ionising radiation. The European Commission Radiation Protection Report No. 174, Guidelines on Medical Physics Expert and the EFOMP Policy Statement No. 12.1, Recommendations on Medical Physics Education and Training in Europe 2014, are also taken into consideration.The EFOMP National Member Organisations are encouraged to update their Medical Physics registration schemes where these exist or to develop registration schemes taking into account the present version of this EFOMP Policy Statement (Policy Statement No. 6.1“Recommended Guidelines on National Registration Schemes for Medical Physicists”).     

EFOMP policy statement 16: The role and competences of medical physicists and medical physics experts under 2013/59/EURATOM

On 5 December 2013 the European Council promulgated Directive 2013/59/EURATOM. This Directive is important for Medical Physicists and Medical Physics Experts as it puts the profession on solid foundations and describes it more comprehensively. Much commentary regarding the role and competences has been developed in the context of the European Commission project “European Guidelines on the Medical Physics Expert” published as Radiation Protection Report RP174. The guidelines elaborate on the role and responsibilities under 2013/59/EURATOM in terms of a mission statement and competence profile in the specialty areas of Medical Physics relating to medical radiological services, namely Diagnostic and Interventional Radiology, Radiation Oncology and Nuclear Medicine. The present policy statement summarises the provisions of Directive 2013/59/EURATOM regarding the role and competences, reiterates the results of the European Guidelines on the Medical Physics Expert document relating to role and competences of the profession and provides additional commentary regarding further issues arising following the publication of the RP174 guidelines.     

Towards an updated ESTRO-EFOMP core curriculum for education and training of medical physics experts in radiotherapy – A survey of current education and training practice in Europe

PurposeESTRO-EFOMP intend to update the core curriculum (CC) for education and training of medical physicists in radiotherapy in line with the European Commission (EC) guidelines on Medical Physics Experts (MPE), the CanMEDS methodology and recent developments in radiotherapy. As input, a survey of the current structure of radiotherapy MPE national training schemes (NTS) in Europe was carried out.MethodsA 35-question survey was sent to all European medical physics national societies (NS) with a focus on existence of an NTS, its format and duration, required entry-level education, and financial support for trainees.ResultsTwenty-six of 36 NS responded. Twenty had an NTS. Minimum required pre-training education varied from BSc in physics or related sciences (5/2) to MSc in medical physics, physics or related sciences (6/5/2) with 50–210 ECTS in fundamental physics and mathematics. The training period varied from 1 to 5 years (median 3 years with 50% dedicated to radiotherapy). The ratio of time spent on university lectures versus hospital training was most commonly 25%/75%. In 14 of 20 countries with an NTS, a research project was mandatory. Residents were paid in 17 of 20 countries. The recognition was mostly obtained by examination. Medical physics is recognised as a healthcare profession in 19 of 26 countries.ConclusionsThe NTS entrance level, duration and curriculum showed significant variations. This survey serves to inform the design of the updated CC to define a realistic minimum training level for safe and effective practice aiming at further harmonization in line with EC guidelines.     

Patient dose monitoring systems: A new way of managing patient dose and quality in the radiology department

PurposeDue to the upcoming European Directive (2013/59/EURATOM) and the increased focus on patient safety in international guidelines and regulations, Patient Dose Monitoring Systems, also called Dose Management Systems (DMS), are introduced in medical imaging departments. This article focusses on the requirements for a DMS, its benefits and the necessary implementation steps.MethodThe implementation of a DMS can be perceived as a lengthy, yet worthy, procedure: users have to select the appropriate system for their applications, prepare data collection, validate, perform configuration, and start using the results in quality improvement projects.ResultsA state of the art DMS improves the quality of service, ensures patient safety and optimizes the efficiency of the department. The gain is multifaceted: the initial goal is compliance monitoring against diagnostic reference levels. At a higher level, the user gets an overview of the performance of the devices or centers that are under his supervision. Error identification, generation of alerts and workflow analysis are additional benefits. It can also enable a more patient-centric approach with personalized dosimetry. Skin dose, size-specific dose estimates and organ doses can be calculated and evaluated per patient.ConclusionA DMS is a powerful tool and essential for improved quality and patient care in a radiology department. It can be configured to the needs of medical physicists, radiologists, technologists, even for the management of the hospital. Collaboration between all health professionals and stakeholders, input-output validation and communication of findings are key points in the process of a DMS implementation.     

Dose response of a radiophotoluminescent glass dosimeter for TomoTherapy,CyberKnife, and flattening-filter-free linear accelerator output measurements in dosimetry audit

PurposeWe experimentally determined the radiophotoluminescent glass dosimeter (RPLD) dose responses for TomoTherapy, CyberKnife, and flattening-filter-free (FFF) linear accelerator (linac) outputs for dosimetry audits in Japan.MethodsA custom-made solid phantom with a narrow central-axis spacing of three RPLD elements was used for output measurement to minimise the dose-gradient effect of the non-flattening filter beams. For RPLD dose estimation, we used the ISO 22127 formalism. Additional unit-specific correction factors were introduced and determined via the measured data. For TomoTherapy (7 units) and CyberKnife (4 units), the doses were measured under machine-specific reference fields. For FFF linac (5 units), in addition to the reference condition, we obtained the field-size effects for the range from 5×5 cm to 25×25 cm.ResultsThe correction factors were estimated as 1.008 and 0.999 for TomoTherapy and CyberKnife, respectively. For FFF linac, they ranged from 1.011 to 0.988 for 6 MV and from 1.011 to 0.997 for 10 MV as a function of the side length of the square field from 5 to 25 cm. The estimated uncertainties of the absorbed dose to water measured by RPLD for the units were 1.32%, 1.35%, and 1.30% for TomoTherapy, CyberKnife, and FFF linac, respectively. A summary of the dosimetry audits of these treatment units using the obtained correction factors is also presented. The average percentage differences between the measured and hospital-stated doses were <1% under all conditions.ConclusionRPLD can be successfully used as a dosimetry audit tool for modern treatment units.     

Comments on UK options for transposition of European Directive 2010/63/EU

The British Government's proposals for the transposition of European Directive 2010/63/EU are discussed under five main headings: direct transposition without major effects on the UK legislation, introduction of stricter requirements in the Directive, retention of stricter controls in the Animals [Scientific Procedures] Act 1986, questions requiring further consideration, and matters of concern. The Home Office had published a consultation on the options in 2011, which resulted in 98 responses from organisations and 13,458 responses from individuals. Our main concerns relate to the use of non-human primates, the annual publication of the UK statistics on laboratory animal use, and the provision of greater transparency on how animals are used, and why. Finally, we conclude that the new Directive and its transposition into the national laws of the Member states provide a renewed opportunity for genuine commitment to the Three Rs, leading to progressive and significant Reduction, Refinement and Replacement.     

Implementation and evaluation of a transit dosimetry system for treatment verification

PurposeTo evaluate a formalism for transit dosimetry using a phantom study and prospectively evaluate the protocol on a patient population undergoing 3D conformal radiotherapy.MethodsAmorphous silicon EPIDs were calibrated for dose and used to acquire images of delivered fields. The measured EPID dose map was back-projected using the planning CT images to calculate dose at pre-specified points within the patient using commercially available software, EPIgray (DOSIsoft, France). This software compared computed back-projected dose with treatment planning system dose. A series of tests were performed on solid water phantoms (linearity, field size effects, off-axis effects). 37 patients were enrolled in the prospective study.ResultsThe EPID dose response was stable and linear with dose. For all tested field sizes the agreement was good between EPID-derived and treatment planning system dose in the central axis, with performance stability up to a measured depth of 18 cm (agreement within −0.5% at 10 cm depth on the central axis and within −1.4% at 2 cm off-axis). 126 transit images were analysed of 37 3D-conformal patients. Patient results demonstrated the potential of EPIgray with 91% of all delivered fields achieved the initial set tolerance level of Δ_D of 0 ± 5-cGy or %Δ_D of 0 ± 5%.ConclusionsThe in vivo dose verification method was simple to implement, with very few commissioning measurements needed. The system required no extra dose to the patient, and importantly was able to detect patient position errors that impacted on dose delivery in two of cases.     

The European Federation of Organisations for Medical Physics Policy Statement No. 10.1: Recommended Guidelines on National Schemes for Continuing Professional Development of Medical Physicists

Continuing Professional Development (CPD) is vital to the medical physics profession if it is to embrace the pace of change occurring in medical practice. As CPD is the planned acquisition of knowledge, experience and skills required for professional practice throughout one's working life it promotes excellence and protects the profession and public against incompetence. Furthermore, CPD is a recommended prerequisite of registration schemes (Caruana et al. 2014 [1]; [2]) and is implied in the Council Directive 2013/59/EURATOM (EU BSS) [3] and the International Basic Safety Standards (BSS) [4]. It is to be noted that currently not all national registration schemes require CPD to maintain the registration status necessary to practise medical physics. Such schemes should consider adopting CPD as a prerequisite for renewing registration after a set period of time.This EFOMP Policy Statement, which is an amalgamation and an update of the EFOMP Policy Statements No. 8 and No. 10, presents guidelines for the establishment of national schemes for CPD and activities that should be considered for CPD.     

An in-vivo dosimetry procedure for Elekta step and shoot IMRT

PurposeThe aim of this work was to extend an in-vivo dosimetry (IVD) method, previously developed by the authors for 3D-conformal radiotherapy, to step and shoot IMRT treatments for pelvic tumors delivered by Elekta linacs.Materials and methodsThe algorithm is based on correlation functions to convert EPID transit signals into in-vivo dose values at the isocenter point, D_iso. The EPID images were obtained by the so-called “IMRT Dosimetric Weighting” mode as a superposition of many segment fields. This way each integral dosimetric image could be acquired in about 10 s after the end of beam delivery and could be processed while delivering the successive IMRT beams. A specific algorithm for D_iso reconstruction especially featured for step and shoot IMRT was implemented using a fluence inhomogeneity index, FI, introduced to describe the degree of beam modulation with respect to open beams. A γ-analysis of 2D-EPID images obtained day to day, resulted rapid enough to verify the plan delivery reproducibility.ResultsFifty clinical IMRT beams, planned for patients undergoing radiotherapy of pelvic tumors, were used to irradiate a homogeneous phantom. For each beam the agreement between the reconstructed dose, D_iso, and the TPS computed dose, D_iso,TPS, was well within 5%, while the mean ratio R = D_iso/D_iso,TPS resulted for 250 tests equal to 1.006 ± 0.036. The same beams were checked in vivo, i.e. during patient treatment delivery, obtaining 500 tests whose average R ratio resulted equal to 1.011 ± 0.042. The γ-analysis of the EPID images with 5% 3 mm criteria supplied 85% of the tests with pass rates γ_mean ≤ 0.5 and P_γ<1 ≥ 90%.     

Measuring the dose in bone for spine stereotactic body radiotherapy

PurposeCurrent quality assurance of radiotherapy involving bony regions generally utilises homogeneous phantoms and dose calculations, ignoring the challenges of heterogeneities with dosimetry problems likely occurring around bone. Anthropomorphic phantoms with synthetic bony materials enable realistic end-to-end testing in clinical scenarios. This work reports on measurements and calculated corrections required to directly report dose in bony materials in the context of comprehensive end-to-end dosimetry audit measurements (63 plans, 6 planning systems).Materials and methodsRadiochromic film and microDiamond measurements were performed in an anthropomorphic spine phantom containing bone equivalent materials. Medium dependent correction factors, k_med, were established using 6 MV and 10 MV Linear Accelerator Monte Carlo simulations to account for the detectors being calibrated in water, but measuring in regions of bony material. Both cortical and trabecular bony material were investigated for verification of dose calculations in dose-to-medium (D_m,m) and dose-to-water (D_w,w) scenarios.ResultsFor D_m,m calculations, modelled correction factors for cortical and trabecular bone in film measurements, and for trabecular bone in microDiamond measurements were 0.875(±0.1%), 0.953(±0.3%) and 0.962(±0.4%), respectively. For D_w,w calculations, the corrections were 0.920(±0.1%), 0.982(±0.3%) and 0.993(±0.4%), respectively. In the audit, application of the correction factors improves the mean agreement between treatment plans and measured microDiamond dose from −2.4%(±3.9%) to 0.4%(±3.7%).ConclusionMonte Carlo simulations provide a method for correcting the dose measured in bony materials allowing more accurate comparison with treatment planning system doses. In verification measurements, algorithm specific correction factors should be applied to account for variations in bony material for calculations based on D_m,m and D_w,w.     

End-to-end dosimetric audit: A novel procedure developed for Irish HDR brachytherapy centres

PurposeA dosimetric audit of Ir-192 high dose rate (HDR) brachytherapy remote after-loading units was carried out in 2019. All six brachytherapy departments on the island of Ireland participated in an end-to-end test and in a review of local HDR dosimetry procedures.Materials and methodsA 3D-printed customised phantom was created to position the following detectors at known distances from the HDR source: a Farmer ionization chamber, GafChromic film and thermoluminescent dosimeters (TLDs). Dedicated HDR applicator needles were used to position an Ir-192 source at 2 cm distance from these detectors. The end-to-end dosimetry audit pathway was performed at each host site and included the stages of imaging, applicator reconstruction, treatment planning and delivery. Deviations between planned and measured dose distributions were quantified using gamma analysis methods. Local procedures were also discussed between auditors and hosts.ResultsThe mean difference between Reference Air Kerma Rate (RAKR) measured during the audit and RAKR specified by the vendor source certificate was 1.3%. The results of end-to-end tests showed a mean difference between calculated and measured dose of 2.5% with TLDs and less than 0.5% with Farmer chamber measurements. GafChromic films showed a mean gamma passing rates of >95% for plastic and metal applicators with 2%/1 mm global tolerance criteria.ConclusionsThe results of this audit indicate dosimetric consistency between centres. The ‘end to end’ dosimetry audit methodology for HDR brachytherapy has been successfully implemented in a multicentre environment, which included different models of Ir-192 sources and different treatment planning systems.The ability to create a 3D-printed water-equivalent phantom customised to accurately position all three detector types simultaneously at controlled distances from the Ir-192 source under evaluation gives good reproducibility for end-to-end methodology.     

Radiation techniques used in patients with breast cancer: Results of a survey in Spain

AimTo evaluate the resources and techniques used in the irradiation of patients with breast cancer after lumpectomy or mastectomy and the status of implementation of new techniques and therapeutic schedules in our country.BackgroundThe demand for cancer care has increased among the Spanish population, as long as cancer treatment innovations have proliferated. Radiation therapy in breast cancer has evolved exponentially in recent years with the implementation of three-dimensional conformal radiotherapy, intensity modulated radiotherapy, image guided radiotherapy and hypofractionation.Material and MethodsAn original survey questionnaire was sent to institutions participating in the SEOR-Mama group (GEORM). In total, the standards of practice in 969 patients with breast cancer after surgery were evaluated.ResultsThe response rate was 70% (28/40 centers). In 98.5% of cases 3D conformal treatment was used. All the institutions employed CT-based planning treatment. Boost was performed in 56.4% of patients: electrons in 59.8%, photons in 23.7% and HDR brachytherapy in 8.8%. Fractionation was standard in 93.1% of patients. Supine position was the most frequent. Only 3 centers used prone position. The common organs of risk delimited were: homolateral lung (80.8%) and heart (80.8%). In 84% histograms were used. An 80.8% of the centers used isocentric technique. In 62.5% asymmetric fields were employed. CTV was delimited in 46.2%, PTV in 65% and both in 38.5%. A 65% of the centers checked with portal films. IMRT and hypofractionation were used in 1% and in 5.5% respectively.ConclusionIn most of centers, 3D conformal treatment and CT-based planning treatment were used. IMRT and hypofractionation are currently poorly implemented in Spain.     

Thermoluminescence dosimetry of the dose received by scrotum and testes in radiotherapy of rectal cancer,compared to the point doses calculated by 3D-planning software

PurposeRadiation received by the testes in the course of radiotherapy for rectal cancer may cause oligospermia and azospermia. We sought to determine the dose to the scrotum and testes with thermoluminescence dosimetry (TLD), and compare it to the dose calculated by 3D planning software.MethodsThe TLDs were fixed to the scrotum in six points anteriorly and posteriorly in two fractions of radiotherapy. All patients received a 50–50.4 Gy total dose in prone position with 3D-planning. The average dose of TLD measurements was compared to the average of 6 relevant point doses calculated by the planning software.ResultsThe mean scrotal dose of radiation in 33 patients as measured by TLD was 3.77 Gy (7.5% of the total prescribed dose), and the mean of point doses calculated by the planning software was 4.11 Gy (8.1% of the total dose), with no significant difference. A significant relationship was seen between the position of the inferior edge of the fields and the mean scrotal dose (P = .04). Also body mass index (BMI) was inversely related with the scrotal dose (P = .049).ConclusionWe found a dose of about 4 Gy received by the scrotum and testes from a total prescribed dose of 50 Gy in the radiotherapy of rectal carcinoma patients, with TLD measurements confirming testicular dose estimations by the planning software. This dose could be significantly harmful for spermatogenesis. Thus careful attention to the testicular dose in radiotherapy of rectal cancer for men desiring continued fertility is a necessity.     

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

PurposeTo 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 methodsIn-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.ResultsModifications 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 € 4376 to € 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.ConclusionThe application of the presented methodology revealed cost-effectiveness relationships in tested technical procedures.     

Incidence of radiation toxicity in cervical cancer and endometrial cancer patients treated with radiotherapy alone versus adjuvant radiotherapy

AimThe study was made to evaluate early and late toxicity in a diversified group of patients receiving definitive or adjuvant radiotherapy in terms of clinical diagnosis and treatment methods.BackgroundRadiotherapy is a standard way of treatment in cervical and endometrial cancer patients, both as definitive and adjuvant therapy. But every radiation treatment may be involved with toxicity.Materials and methodsA detailed analysis was performed of 263 patients with gynaecological cancer treated with definitive (90 patients with cervical cancer received radiochemotherapy or radiotherapy exclusively) and adjuvant radiotherapy (38 with cervical and 135 with endometrial cancer).ResultsAcute reactions were found in 51.3% and late reactions were found in 14.8% of patients. It was stated that early (p < 0.007) and late (p < 0.003) post radiation reaction appear more frequently in women treated with definitive than adjuvant radiotherapy. The analysis of the whole group revealed higher rate of toxicity, both early and late, in the gastrointestinal tract than in the urinary system (p < 0.004). Comparing the subgroups, it was found that intestinal reactions occurred more frequently in the definitive radiotherapy group than in the adjuvant one.The occurrence of side effects was associated with the prolongation of total irradiation time due to necessary interruptions of radiotherapy. The comparison of the subgroups showed that interruptions occurred more frequently in patients receiving definitive rather than adjuvant radiotherapy (17.7–2.9%).ConclusionsDefinitive radiotherapy compared with adjuvant treatment may by associated with higher percentage of side effects caused by dose of therapy and correlation with chemotherapy.     

Recent advances in clinical studies of selenium supplementation in radiotherapy

BackgroundRadiotherapy is one of the most important and common therapies for cancer patients. Selenium has been shown to be capable of reducing the side effects of radiotherapy because selenoproteins have anti-oxidative functions against reactive oxygen species that are induced by the radiation. They also function in DNA-repair and cytokine control.PurposeWe explored the benefits and risks of selenium supplementation in radiotherapy in our previous review to establish guidelines. In the current study, we expanded the search to cover recent advances in clinical studies of selenium supplementation in radiotherapy.MethodsWe conducted an initial screening in the PubMed using the MeSH terms and keywords “selenium”, “radiation”, “therapy”, and “radiotherapy” using the same methodology applied in our previous review. We identified 121 articles published between January 2013 and December 2019. We then identified eight articles (six studies) on selenium and radiotherapy by excluding 113 articles.ResultsIn selenium supplementation studies, selenium doses of 300−500 μg/day with duration of 10 days to 6 months were used. Selenium supplementation improved the selenium nutritional conditions of the patients and reduced the side effects of radiotherapy. Selenium supplementation did not reduce the effectiveness of radiotherapy, and no toxicities were reported.ConclusionThe results of our previous and current reviews showed that selenium supplementation offers specific benefits for several cancer types treated with radiotherapy. Here, we suggest a new guideline for selenium supplementation in radiotherapy. We recommend determining the selenium status of the patients before radiotherapy, and in cases of deficiency (<100 μg/L serum selenium level), selenium supplement can be beneficial.