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 former 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.
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.
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).
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 was published in October 2004 and is available as a free download. 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, Evelyn Chimfwembe).
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).
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.
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).
WP9 - 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).
WP10 - 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).
WP11 - 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 posted on the ESTRO site 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).
WP12: QA for Implant Dosimetry in LDR and HDR
Chair: Frank-André Siebert
Ultrasound is a very important imaging modality in brachytherapy (BT). In particular, for low-dose-rate (LDR) and high-dose-rate (HDR) prostate implants transrectal ultrasound (TRUS) is widespread. But also in gynecological and anal cancer brachytherapy ultrasound is used. In this working package European guidelines for quality assurance of ultrasound in brachytherapy are elaborated. Physical aspects of ultrasound are described and general quality assurance issues are explained. In the next chapters dedicated BT treatment sites as prostate, gynaecological tumors, and anal cancer are highlighted with respect of US QA. To complete the manuscript an example work sheet for QA checks in BT ultrasound will be provided to the reader. It is planned to finalize this project within 2019.
WP13 - Uncertainties in Brachytherapy
WP15 - Interobserver Variability Study
Co-ordinator: Marisol de Brabandere
This study started 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 by the 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 in Spring 2010 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.
WP16 - 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.
WP18 - LDR Source
Chair: Jose Perez-Calatayud
Prostate brachytherapy treatment using permanent implantation of low-dose rate (LDR) low-energy (LE) sources is successfully and widely applied in Europe. In addition, seeds are used in other tumor sites, as ophthalmic tumors, implanted temporarily. The calibration issues for LE-LDR photon emitting sources are specific to and different from other sources used in brachytherapy. In this WP, the BRAPHYQS working group of GEC-ESTRO is developing present recommendations to assure harmonized and high-quality seed calibration in European clinics. There are practical aspects for which a clarification/procedure is needed, including aspects not specifically accounted for in currently existing AAPM and ESTRO societal recommendations. The aim of this WP has is to provide a European wide high standard in LE-LDR source calibration at end-user level, in order to keep brachytherapy treatments with high safety and quality levels.