Current Activities
The activities of the BRAPHYSQS Work Group have been organised into the following 16 work packages:
WP1 Dose Delivery Audit
WP2 Geometric Reconstruction Audit
WP3 QA Recommendations
WP4 TG-43
WP5 Calibration Facility For 125I
WP6 Prostate Survey Practices
WP7 Phantom Studies for Physics Part
WP8 Evaluation of Clinical Part
WP9 New Recommendations
WP10 DVH Calculation Evaluation
WP11 Physics Data for Radiation Protection
WP12 QA for Implant Dosimetry in LDR and HDR
WP13 Uncertainties in Brachytherapy
WP14 In-Vivo Dosimetry
WP15 Interobserver Variability Study
WP16 Integral Doses in Brachytherapy
WP1: Dose Delivery Audit
Development of a mailed TLD audit system to validate the dose delivery in HDR and PDR brachytherapy. The system is based on the facilities for mailed dosimetry of the EQUAL-ESTRO Lab in Paris. Comparisons are performed of stated dose vs. measured dose at 5 cm from a source catheter in a large water phantom. The audit system is available for applications info@equal-estro.org By August 2006, the number of centres checked was 27. A manuscript describing the methodology has been published in Radiother & Oncol. 2007: 83-93 by Amélie Roué et al. and titled "Development of a TLD mailed system for remote dosimetry audit for Ir 192 HDR and PDR sources". The Braphyqs group finalised this project from the scientific point of view. The TLD audit system can be requested from Equal-ESTRO
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WP2: Geometric Reconstruction Audit
Development of a mailed phantom based system to validate the geometric reconstruction methods used in clinical brachytherapy (e.g. the orthogonal X-ray method and CT). The system makes use of the so-called “Baltas” phantom, in which marker points are located at well defined positions. Comparison is done of stated distances between points and known distances. By August 2006, 172 reconstruction methods were checked in 88 centres (more than one/centre is possible). The mailed phantom-based system is still available at Equal-ESTRO
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WP3: QA Recommendations
The publication of a booklet in the series of ESTRO Guidelines for QA in radiation therapy, entitled: A Practical Guide to Quality Control of Brachytherapy Equipment. The book is published in October 2004 and is available for free download (see above). The book is also available at the ESTRO desk during meetings and teaching courses. (The authors keep track of all comments and for the necessity of a new edition: contact: Jack Venselaar, Guy François).
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WP4: TG43
The TG43 data of "conventional" brachytherapy sources -mainly
137Cs and
192Ir sources- are collected by the group at the University of Valencia. New sources
or new source data can be added. Data are also included on low-energy photon emitting brachytherapy sources (125I, 103Pd) that comply with the prerequisites of AAPM TG-43. If consensus datatsets coud be obtained by the AAPM, these are incoluded on the estro web page. The contents are supervised by a BRAPHYQS expert team. A new entrance to the Braphyqs website data can be accessed. The BRAPHYQS group has written a short introductory text to the TG-43 data site with explanation on use and background information. Research data -which means: non-validated sets of TG43 data- will stay available using the 2nd website still located at the University of Valencia: www.uv.es/braphyqs. Transfer of the data from the www.uv.es/braphyqs site to this site has been done.
click on the picture to enlarge it.
José Pérez Calatayud, member of BRAPHYQS is chair of the AAPM Brachytherapy Subcommittee Working Group on High Energy Brachytherapy Dosimetry (HEBD-WG). In this position, he represents the ESTRO community, reflected in an ESTRO’s co-sponsorship of the manuscripts under preparation in the WG. (title of this manuscript: “Dosimetric prerequisites for routine clinical use of photon emitting brachytherapy sources with average energy higher than 50 keV”; by Zuofeng Li et al., Med Phys. Dec 2007; 34:37-40). Facundo Ballester, also member of BRAPHYQS occupies the position of vice chair in the HEBD-WG of the AAPM. It is hoped and expected that the work of the BRAPHYQS group will lead to a full consensus on the data of the Low-Energy Interstitial Brachytherapy Dosimetry (LIBD) subcommittee as well of the High Energy Brachytherapy Dosimetry (HEBD), with an Internet presentation of such data using links from the ESTRO site to USA counterparts and vice versa.
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WP5: Calibration Facility for 125I
Calibration facilities for 125I and 103Pd sources with easy access for European institutes are lacking. Actually, in the world only NIST provides the user with a calibration facility and recently PTB Braunschweig (H.J. Selbach) has opened a WAFAC type 125I calibration facility. The purpose of the taskgroup is to further stimulate European primary and secondary standard labs in co-operation within EUROMET to develop such standards for these low-energy sources. Following a previous contact with PTB by Alex Rijnders, Jack Venselaar and Tony Aalbers (NMi NL), a small mini-symposium in parallel to the ESTRO 25 meeting in Leipzig (Oct 2006) was organized. Invitations were sent to representatives of different EU and USA labs and ABS (on behalf of BRAPHYQS, Jack Venselaar, Alex Rijnders, Heikki Toelli, Taran Paulsen Hellebust and José Pérez-Calatayud ). The meeting was successful and it was agreed that there is a need for cooperation between labs and “customers”. Several ideas were discussed and will be brought to the attention of the board of EURAMET. The EURAMET project T2.J06 is a project of European standard laboratories with the goal to establish dose-to-water calibration in brachytherapy. BRAPHYQS is cooperating with the EURAMET T2.J03 project group, offering the expertise of BRAPHYQS to this project. As chair of BRAPHYQS F.-A. Siebert is invited to the EURAMET meetings.
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WP6: Prostate Survey of Practices
Prostate implants form the only fast rising group of patients in brachytherapy. Many institutions introduce this technique for their patients. BRAPHYQSs wants to develop systems to independently validate parts of their procedure. A first task of this BRAPHYQS subgroup was to make an inventory of practices in this area in European countries. A first analysis of this inventory was prepared by Paola Mangili and Pablo Lavagnini and further analysed in the group. This helps in defining the relevant topics for the “New Recommendations” task, below. An overview of the results of this questionnaire was prepared under guidance of the Prostate Working Group members and will soon be brought to the attention of Radiotherapy & Oncology (working title : “Permanent transperineal prostate brachytherapy: a GEC-ESTRO European questionnaire study into patterns of practice” by P.J. Hoskin and J. Venselaar, on behalf of the BRAPHYQS and PROBATE groups of GEC-ESTRO, Radiother Oncol 2007; 83:1-2).
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WP7: Phantom Studies for Physics Part
Phantom studies are presently performed for different imaging modalities used in prostate implant techniques, with the aim to validate parts of the reconstruction and dose calculation procedures. Either such phantoms, or images from such phantoms, can be used in a mailed audit system. Answers from institutions with regard to the reconstruction and/or dose calculation should be evaluated by expert physicists. Work is performed by a few subgroups with different phantom designs. The use of the Kiel phantom (Frank-Andre Siebert) was discussed in the 2006 meeting with ABS physicists and it was decided to enlarge the circle of tests to a number of USA participants (Rivard et al). The design of the Kiel phantom was published in 2005 by Frank-André Siebert et al. (Radiotherap & Oncol 2005;74:169-175). Another manuscript on CT setting influences was prepared in the last few months (working title: “
Phantom investigations on CT seed imaging for interstitial brachytherapy”, Radiotherap & Oncol. Siebert et al. 2007; 85:316-323). Seed reconstruction measurements with the Kiel Phantom were carried out in several centres in the US and in Canada in the last two years using CT and cone beam CT. The data will be analysed and compared with the alreasy published European Results.
Image of the Kiel-Phantom. With this phantom, absolute seed positions can be anaylsed using radiographs or CT data sets.
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WP8: Evaluation of Clinical Part of Implant Techniques
Clinical data of the prostate implant techniques in EU countries was obtained in the same way through the mailed audit (questionnaire) system and was evaluated by the group. It may form the basis for the creation of an expert team for feed-back to starting institutions that need help in setting up the clinical and technical procedures. Discussions still need to take place. (Peter Hoskin et al).
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WP 9: New Recommendations
The survey on implant techniques (see at 6 & 8) will lead to a re-evaluation of existing recommendations on the procedures: dose prescription, margins, quality tools, etcetera. The recommendations may include seed implantation and HDR implantation techniques. Carl Salembier reported the first ideas during the GEC-ESTRO meeting in Budapest, May 2005. A manuscript is submitted for a publication in Radiothera & Oncol (title: “Tumour and Target Volumes in Permanent Prostate Brachytherapy; a supplement to the GEC/ESTRO/EAU recommendations on prostate brachytherapy”, Carl Salembier et al). Radiother & Oncol 2007; 83:3-10). This is part of the Probate group (Carl Salembier, Peter Hoskin et al).
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WP 10: DVH Calculation Evaluation
A subgroup evaluated the tools in modern treatment planning systems to calculate and evaluate the dose-volume histogram calculations. For this purpose not only geometrically well defined structures but also more clinically realistic cases are studied. A report of the group meeting in Vienna, early February 2006, has been prepared in the form of a manuscript: “Accuracy of volume and DVH parameters determined with different brachytherapy treatment planning systems”. (Christian Kirisits, Frank-André Siebert, Dimos Baltas, Taran Paulsen Hellebust, Marisol de Brabandere, et al). The manuscript was published in 2007 (Radiother & Oncol 2007; 84:290-297).
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WP 11: Physics Data
Radiation protection data for the design of brachytherapy treatment facilities are limited to the principal radionuclides used in brachytherapy applications and present considerable variance due to differences in the method and assumptions employed for their calculation. The scope of this task is therefore to prepare a comprehensive report on radiation protection data for both conventional and contemporary brachytherapy radionuclides (60Co, 137Cs, 198Au, 192Ir, 169Yb, 131Cs, 125I, 103Pd). Since the variety of brachytherapy treatment sites and therapeutic schemes for the same source often leads to misconceptions with regards to shielding requirements, besides measures of radiation transmission in selected materials (i.e. first, second and equilibrium HVLs/TVLs), results should also be presented in a form compatible to the formalism adopted by current radiation protection protocols, to facilitate calculations for the design of new departments giving consideration to the their specific needs. Monte Carlo simulation is employed for the task using codes and methods benchmarked in recent published work, with the participation of group members. Broad beam transmission curves in water and materials of interest to structural shielding design have already been calculated for the majority of the selected radionuclides. Following completion and audit, results will be recast in the form of material thickness required to achieve certain design goals, plotted versus facility workload. The extended report of the results is vosted on the ESTRO side and a short version is published in the Medical Physics Journal ("Radiation transmission data for radionuclides and materials relevant to Brachytherapy facility shielding" Panos Papagiannis et al. Med. Phys. 2008: 35; 4898-4906).
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WP 12: Quality Assurance in Prostate Techniques
Due to the rising interest in prostate brachytherapy, the BRAPHYQS group decided to start a new project. This project covers quality assurance implant dosimetry in HDR and LDR prostate brachytherapy. The goal is to develop short and practical guidelines for experienced and un-experienced users. It is planned to cover source calibration, LDR needle commissioning checks, template grid calibration, stepper unit checks, and to test ultrasound devices. Moreover the commissioning of the planning system, treatement planning checks and LDR postimplant dosimetry will be addressed.
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WP 13: Uncertainties in Brachytherapy
This work package covers estimation on uncertainties in Brachytherapy. Due to the complexicity of this topic the project was divided into several modules:source calibration, dose calculation, accurancy of afterloader performance, imaging, contouring, and uncertainties at patien level. Because uncertainties in imaging, contouring, organ movement and swelling are dependent on the entity, this module was grouped into a prostate, gynacology, and a breast sub module. It is planned to publish a comprehensive but clear onverview on the results that are based on a review of existing literature. New studies are not planned at this time.
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WP 14: In-Vivo Dosimetry
Recommendations on in-vivo dosimetry in brachytherapy are currently missing. In this project (coordinator Kari Tanderup) the possibilities of in-vivo dosimetry in brachytherapy should be analyzed and assessed for different error types like wrong step size, mismatch of connections, reconstruction errors, afterloader malfunction, incorrect tube lenght, and application shifts. Parallel to this investigation the likelihood of such errors is evaluated. For this project an gest expert Claus-Erik Andersen from RISØ DTU in Roskilde was invited to support the work of BRAPHYQS.
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WP 15: Interobserver Variability Study
Coordinator: Marisol de Brabandere. This study strated in 2009. CT and MRI post implant data of anonymised prostate LDR patients are used for performing contouring the organs and reconstructing the sources. This will be done by different observers and the results compared against an "optimal" contour and source position set. Moreover CT-MRI image fusion will be carried out byt he observers and the interobserver variability will be monitored. In spring 2010 the collection of the data shall be completed and in a dedicated workshop to be arranged un Spring2010 the results will be analyzed. At the end of this combined BRAPHYQS-PROBATE study a general overview of interobserver variability for post planning of LDR prostate implants can be given.
example images used in interobserver variability study.
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WP 16: Integral Doses in Brachytherapy
The goal of this work package is to give an overview of the integral doses in brachytherapy with the background of secondary cancer risk, and to bring the results in relation to other treatment options like photon, proton and heavy ion radiotherapy. Because this project is not only a physical task it is defined as a joint project between BRAPHYQS and PROBATE. Until now a literature overview was collected. Shortly Monte Carlo Calculations will be performed to evaluate the physical background in more details.
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