Csilla Pesznyák

Quality Control of Portal Imaging with PTW EPID QC PHANTOM

Purpose:Quality assurance (QA) and quality control (QC) of different electronic portal imaging devices (EPID) and portal images with the PTW EPID QC PHANTOM®.Material and Methods:Characteristic properties of images of different file formats were measured on Siemens OptiVue500aSi®, Siemens BeamView Plus®, Elekta iView®, and Varian PortalVision™ and analyzed with the epidSoft® 2.0 program in four radiation therapy centers. The portal images were taken with Kodak X-OMAT V® and the Kodak Portal Localisation ReadyPack® films and evaluated with the same program.Results:The optimal exposition both for EPIDs and portal films of different kind was determined. For double exposition, the 2+1 MU values can be recommended in the case of Siemens OptiVue500aSi®, Elekta iView® and Kodak Portal Localisation ReadyPack® films, while for Siemens BeamView Plus®, Varian PortalVision™ and Kodak X-OMAT V® film 7+7 MU is recommended.Conclusion:The PTW EPID QC PHANTOM® can be used not only for amorphous silicon EPIDs but also for images taken with a video-based system or by using an ionization chamber matrix or for portal film. For analysis of QC tests, a standardized format (used at the acceptance test) should be applied, as the results are dependent on the file format used.Ziel:Qualitätssicherung (QA) und Qualitätskontrolle (QC) verschiedener elektronischer Feldkontrollaufnahmegeräte (EPID) und Portfilme mit einem PTW EPID QC PHANTOM®.Material und Methodik:Charakteristische Eigenschaften von Bildern unterschiedlicher Datenformate wurden bestimmt. Die Bilder wurden mit Siemens OptiVue500aSi®, Siemens BeamView Plus®, Elekta iView® und Varian PortalVision™ erzeugt und mit dem Programm epidSoft® 2.0 in vier Strahlentherapieabteilungen analysiert. Für Feldkontrollaufnahmen wurden Kodak X-OMAT V®- und Kodak Portal Localisation ReadyPack®-Filme verwendet und mit demselben Programm analysiert.Ergebnisse:Die optimalen Expositionswerte der EPID-Systeme und der Filmkombinationen wurden bestimmt. Für eine Doppelexposition empfehlen sich bei Verwendung von Siemens OptiVue500aSi®, Elekta iView® oder Kodak Portal Localisation ReadyPack®-Film 2+1 MU und bei Verwendung von Siemens BeamView Plus®, Varian PortalVision™ oder Kodak X-OMAT V®-Film 7+7 MU.Schlussfolgerung:Das PTW EPID QC PHANTOM® eignet sich nicht nur zur Kontrolle amorpher Siliciumsysteme, sondern auch für mit Hilfe eines Videosystems oder einer Ionisationskammermatrix angefertigte Bilder oder eine Film-Folien-Kombination als Detektor. Da die Resultate vom Dateiformat abhängig sind, sollte zur Analyse des QC-Tests ein konstantes Format gewählt werden.

Verification of quality parameters for portal images in radiotherapy

Verification of quality parameters for portal images in radiotherapy Background. The purpose of the study was to verify different values of quality parameters of portal images in radiotherapy. Materials and methods. We investigated image qualities of different field verification systems. Four EPIDs (Siemens OptiVue500aSi®, Siemens BeamView Plus®, Elekta iView® and Varian PortalVision™) were investigated with the PTW EPID QC PHANTOM® and compared with two portal film systems (Kodak X-OMAT® cassette with Kodak X-OMAT V® film and Kodak EC-L Lightweight® cassette with Kodak Portal Localisation ReadyPack® film). Results. A comparison of the f50 and f25 values of the modulation transfer functions (MTFs) belonging to each of the systems revealed that the amorphous silicon EPIDs provided a slightly better high contrast resolution than the Kodak Portal Localisation ReadyPack® film with the EC-L Lightweight® cassette. The Kodak X-OMAT V® film gave a poor low contrast resolution: from the existing 27 holes only 9 were detectable. Conclusions. On the base of physical characteristics, measured in this work, the authors suggest the use of amorphous-silicon EPIDs producing the best image quality. Parameters of the EPIDs with scanning liquid ionisation chamber (SLIC) were very stable. The disadvantage of older versions of EPIDs like SLIC and VEPID is a poor DICOM implementation, and the modulation transfer function (MTF) values (f50 and f25) are less than that of aSi detectors.

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 ones 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) and is implied in the Council Directive 2013/59/EURATOM (EU BSS) and the International Basic Safety Standards (BSS). 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.

Multicatheter interstitial brachytherapy versus intensity modulated external beam therapy for accelerated partial breast irradiation: A comparative treatment planning study with respect to dosimetry of organs at risk.

OBJECTIVE To dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and intensity modulated radiotherapy (IMRT) for accelerated partial breast irradiation (APBI) with special focus on dose to normal tissues and organs at risk (OAR-s). MATERIAL AND METHODS Thirty-four patients with early stage breast cancer treated with MIBT were selected for the study. For each patient an additional IMRT treatment plan was created using the same CT data and contours as used in MIBT plans. OAR-s included ipsilateral non-target and contralateral breast, lung of both sides, skin, ribs and heart for left sided lesions. The CTV was created from the outlined lumpectomy cavity with a total margin (surgical+radiation) of 20mm in six main directions. The PTV in IMRT plans was generated from CTV with an addition of isotropic 5mm margin. The prescribed dose was 30.1Gy with 7×4.3Gy fractionation for both techniques. From dose-volume histograms quality parameters including volumes receiving a given dose (e.g. V100, V90, V50) and doses to specified volumes (e.g. D0.01cm3, D0.1cm3, D1cm3) were calculated and compared. RESULTS Except for high dose, non-target breast received less dose with MIBT. V90 was 3.6% vs. 4.8% and V50 was 13.7% vs. 25.5% for MIBT and IMRT, respectively. Ipsilateral lung was spared better with MIBT. Mean lung dose was 5.1% vs. 7.1%, [Formula: see text] was 39.0% vs. 54.3% and V5 was 32.9% vs. 41.7% in favour of MIBT. For left sided lesions the heart was generally irradiated by larger doses with MIBT. Mean heart dose was 4.5% vs. 2.0% and [Formula: see text] was 18.3% vs. 19.7%, correspondingly. Volumetric maximal skin doses were similar, but regarding dose to 0.1cm3 and 1cm3 of most exposed volume MIBT provided significantly less doses (76.6% vs. 94.4% and 60.2% vs. 87.8%, respectively). Ribs received less dose with MIBT with values of 45.6% vs. 69.3% for [Formula: see text] and 1.4% vs. 4.2cm3 for V50. Dose to contralateral breast and lung was low with both techniques. No significant differences were observed in maximal doses, but dose to volumes of 0.1cm3 and 1cm3 were less with MIBT for both organs. [Formula: see text] was 3.2% vs. 6.7% for breast and 3.7% vs. 5.6% for lung with MIBT and IMRT, respectively. CONCLUSIONS The target volume can be appropriately irradiated by both techniques, but MIBT generally spares normal tissues and organs at risk better than IMRT. Except for the heart, other critical structures receive less doses with brachytherapy. To observe whether these dosimetric findings translate into clinical outcome more studies are needed with assessment of toxicity profiles.

Medical Physics in Europe following recommendations of the International Atomic Energy Agency

Abstract Background Medical physics is a health profession where principles of applied physics are mostly directed towards the application of ionizing radiation in medicine. The key role of the medical physics expert in safe and effective use of ionizing radiation in medicine was widely recognized in recent European reference documents like the European Union Council Directive 2013/59/EURATOM (2014), and European Commission Radiation Protection No. 174, European Guidelines on Medical Physics Expert (2014). Also the International Atomic Energy Agency (IAEA) has been outspoken in supporting and fostering the status of medical physics in radiation medicine through multiple initiatives as technical and cooperation projects and important documents like IAEA Human Health Series No. 25, Roles and Responsibilities, and Education and Training Requirements for Clinically Qualified Medical Physicists (2013) and the International Basic Safety Standards, General Safety Requirements Part 3 (2014). The significance of these documents and the recognition of the present insufficient fulfilment of the requirements and recommendations in many European countries have led the IAEA to organize in 2015 the Regional Meeting on Medical Physics in Europe, where major issues in medical physics in Europe were discussed. Most important outcomes of the meeting were the recommendations addressed to European member states and the survey on medical physics status in Europe conducted by the IAEA and European Federation of Organizations for Medical Physics. Conclusions Published recommendations of IAEA Regional Meeting on Medical Physics in Europe shall be followed and enforced in all European states. Appropriate qualification framework including education, clinical specialization, certification and registration of medical physicists shall be established and international recommendation regarding staffing levels in the field of medical physics shall be fulfilled in particular. European states have clear legal and moral responsibility to effectively transpose Basic Safety Standards into national legislation in order to ensure high quality and safety in patient healthcare.Background Medical physics is a health profession where principles of applied physics are mostly directed towards the application of ionizing radiation in medicine. The key role of the medical physics expert in safe and effective use of ionizing radiation in medicine was widely recognized in recent European reference documents like the European Union Council Directive 2013/59/EURATOM (2014), and European Commission Radiation Protection No. 174, European Guidelines on Medical Physics Expert (2014). Also the International Atomic Energy Agency (IAEA) has been outspoken in supporting and fostering the status of medical physics in radiation medicine through multiple initiatives as technical and cooperation projects and important documents like IAEA Human Health Series No. 25, Roles and Responsibilities, and Education and Training Requirements for Clinically Qualified Medical Physicists (2013) and the International Basic Safety Standards, General Safety Requirements Part 3 (2014). The significance of these documents and the recognition of the present insufficient fulfilment of the requirements and recommendations in many European countries have led the IAEA to organize in 2015 the Regional Meeting on Medical Physics in Europe, where major issues in medical physics in Europe were discussed. Most important outcomes of the meeting were the recommendations addressed to European member states and the survey on medical physics status in Europe conducted by the IAEA and European Federation of Organizations for Medical Physics. Conclusions Published recommendations of IAEA Regional Meeting on Medical Physics in Europe shall be followed and enforced in all European states. Appropriate qualification framework including education, clinical specialization, certification and registration of medical physicists shall be established and international recommendation regarding staffing levels in the field of medical physics shall be fulfilled in particular. European states have clear legal and moral responsibility to effectively transpose Basic Safety Standards into national legislation in order to ensure high quality and safety in patient healthcare.

EP-1957: Partial breast irradiation with brachy- and teletherapy: comparative dosimetry of treatment plans

ESTRO 35 2016 _____________________________________________________________________________________________________ energy deposition and particle fluence. The software package, written in Matlab, incorporates interaction sampling methods employed in general-purpose Monte Carlo codes. Users select the incident particle type, energy, target material and (optionally) particle cut-off energies. Modes of operation include; 3D views of particle tracks from a broad beam incident on selected media, views of interaction probabilities and outgoing particle energy and direction, or energy deposition and charged particle fluence scored as a function of depth for a user-defined number of incident particles. In addition, the ‘physics’ underlying radiation transport can be modified, by ‘switching off’ multiple Coulomb scattering, delta–ray production and radiative energy losses, in order to observe the effect this has on energy deposition and so gain a greater understanding of the physics involved.

Moving gantry method for electron beam dose profile measurement at extended source-to-surface distances

A novel method has been put forward for very large electron beam profile measurement. With this method, absorbed dose profiles can be measured at any depth in a solid phantom for total skin electron therapy. Electron beam dose profiles were collected with two different methods. Profile measurements were performed at 0.2 and 1.2 cm depths with a parallel plate and a thimble chamber, respectively. 108 cm×108 cm and 45 cm×45 cm projected size electron beams were scanned by vertically moving phantom and detector at 300 cm source‐to‐surface distance with 90° and 270° gantry angles. The profiles collected this way were used as reference. Afterwards, the phantom was fixed on the central axis and the gantry was rotated with certain angular steps. After applying correction for the different source‐to‐detector distances and incidence of angle, the profiles measured in the two different setups were compared. Correction formalism has been developed. The agreement between the cross profiles taken at the depth of maximum dose with the ‘classical’ scanning and with the new moving gantry method was better than 0.5 % in the measuring range from zero to 71.9 cm. Inverse square and attenuation corrections had to be applied. The profiles measured with the parallel plate chamber agree better than 1%, except for the penumbra region, where the maximum difference is 1.5%. With the moving gantry method, very large electron field profiles can be measured at any depth in a solid phantom with high accuracy and reproducibility and with much less time per step. No special instrumentation is needed. The method can be used for commissioning of very large electron beams for computer‐assisted treatment planning, for designing beam modifiers to improve dose uniformity, and for verification of computed dose profiles. PACS numbers: 87.53.Bn, 87.53.Jw, 87.56.jf