53rd SSRMP Annual Meeting

Paul Scherrer Institute

Paul Scherrer Institute

Auditorium WHGA/001 West Area Forschungsstrasse 111 CH-5232 Villigen

We are looking forward to welcome you to the 53rd SSRMP Annual Meeting at the Paul Scherrer Institute in Villigen. Thanks to your contribution, an attractive and engaging scientific program will be prepared. A lovely social event will take place at the FHNW Campus in Windisch with the opportunity to practice ice-skating for the adventurers. We are also delighted to offer you a guided tour of the Center of Proton Therapy at PSI.
Finally, but not least, the program will be also enriched with keynotes from three special guests:

Prof Thomas Bortfeld
Harvard Medical School and Massachusetts General Hospital, Boston, USA

Prof Rob Coppes
University Medical Center and University of Groningen, Groningen, The Netherlands

Prof Günther Dissertori
Institute for Particle Physics
and Astrophysics, ETH Zürich, Zürich, Switzerland

Abstract deadline: 30th August extended to 13th September

Registration deadline: 25th October

Social event: Thursday evening 21st of November

Tour of the Proton Therapy Center: late afternoon Friday 22nd of November

We therefore encourage you to register for the event and invite you to submit your abstract as soon as possible.

For the organizing committee

Sairos Safai, Francesca Belosi and Tony Lomax


  • Alessandra Bolsi
  • alessandro clivio
  • Alina Giger
  • Alisha Dütschler
  • Anna Fredh
  • Barbara Ott
  • Benjamin Haas
  • Carla Winterhalter
  • Christoph Jud
  • Claas Wessels
  • Corminboeuf Frédéric
  • Cécile Chatelain
  • Daniel Lempen
  • Daniel Vetterli
  • Dominik Helbich
  • Dominik Henzen
  • Florian Amstutz
  • Francesca Albertini
  • Gerhard Aigner
  • Götz Kohler
  • Günther Dissertori
  • Janita van Timmeren
  • Jean-Yves Ray
  • Juan Jose Garcia Hernandez
  • Jörg Binder
  • Jürgen Besserer
  • Karolina Klucznik
  • Karsten Salomon
  • Kuangyu Shi
  • Lena Nenoff
  • Lili Huang
  • Maria Francesca Belosi
  • Maria Trachsel
  • Martin Jermann
  • Maude Gondré
  • Michael Matter
  • Miriam Krieger
  • Muriel Debono
  • Natalia Saltybaeva
  • negin sahraei
  • Nicolas Loizeau
  • Norbert Klippel
  • Pascal Favre
  • Patrick Weber
  • Patrik Jorge
  • Peter Peier
  • Peter Pemler
  • Philippe Cattin
  • Raphaël Moeckli
  • Roger Hälg
  • Rüdiger Lauk
  • Sairos Safai
  • Sheeba Thengumpallil
  • Sibylle Bollhalder
  • Song Xue
  • Stefan Zepter
  • Stefanie Garni
  • Sylvain Jaquet
  • Zrema Chowdhuri
  • Thursday, 21 November
    • 10:15 11:30
      I: Image Guidance
      • 10:15
        Targeting arteriovenous malformations without an invasive head ring - A new software prototype 15m

        Arteriovenous malformations (AVMs) are abnormal, snarled tangles of blood vessels that cause multiple irregular connections between the arteries and veins. In order to correctly locate an AVM, typically, a digital subtraction angiography (DSA) is carried out. To use the DSA for target definition an accurate image registration between CT and DSA is required. Carrying out a non-invasive, frameless procedure, i.e. having no invasive head frame in place that serves as a fixed coordinate system, registration of the 2D-DSA images with the CT is critical. A new software prototype (called prototype below) is enabling this frameless procedure. The aim of this work was to evaluate the prototype in terms of targeting accuracy and reliability based on phantom measurements as well as with the aid of patient data. In addition, the user's ability to recognize mismatches on the present image modalities and quality was assessed.

        Materials and Methods
        Targeting accuracy was measured with a simple cubic, as well as with a more realistic anthropomorphic head phantom. Clearly defined academic targets within the two phantoms were contoured on the CT. The center of mass (COM) coordinates of these reference structures were compared with the COM coordinates of the structures generated within the prototype, based on the 2D-DSA images. A similar approach was used with patient data, where the clinically contoured target served as the reference structure.
        In order to check if the user is able to recognize registration errors on blended digitally reconstructed radiographs (DRR) and 2D-DSA projection images, a set of different registration errors (translations and rotations) was introduced to the correctly registered CT and 2D-DSA image data sets of three different patients. Each of six different users rated the whole set of registrations within the prototype.

        The target accuracy of the prototype was found to be below 0.04 cm for the simple cubic phantom and below 0.05 cm for the anthropomorphic head phantom. The mean target accuracy for the 15 patient cases was found to be below 0.3 cm.
        Almost all introduced registration errors above 1° or 0.1 cm were detected by the six users and were rated as not acceptable. Nevertheless, in order to quantify and categorize the possibility to detect mismatches (sensitivity and specificity) in the registration process more data needs to be evaluated.

        Our study shows, that the prototype is a useful tool that has the potential to fill the gap towards a frameless procedure when treating AVMs with the aid of 2D-DSA images in radiosurgery. The target accuracy of the prototype is similar to other systems, which are already well established in clinical routine.

        Speaker: Daniel Schmidhalter (Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Switzerland.)
      • 10:30
        Motion management and dose reconstruction for MRI guided cardiac radiosurgery 15m

        Purpose: To evaluate the dosimetric effect of the residual breathing motion during gating for the first patient treated with MRI guided cardiac radiosurgery.

        Methods: A patient with ventricular tachycardia was treated in one fraction with a dose of 25 Gy to the 85%-isodose line to the planning target volume (PTV). The target volume (TV) was defined according to the cardiologists interpretation of the electrophysiological mapping of the arrhythmic substrat and expanded by 2 mm axially and 3 mm craniocaudally to the PTV. The patient was treated with the MRIdian system (Viewray). A mix of instructed breath-hold and free-breathing was performed, while a structure close to the diaphragm was tracked for respiratory gating at end of-exhale using sagittal 2D cine-MR with 4 fps. A gating window of 5 mm was defined and maximal 20% of the structure were allowed outside of the window for irradiation. The residual motion during gating was evaluated in the two directions (SI and AP) and a 2mm-binned position-probability map was generated. The dose to the patient was recalculated for each possible combination of SI- and AP-shift and summed with the weighting of the probability map.

        Results: In total, 46 min of cine-MR were recorded for treatment and the target was within the gating window for 24 min. Thereof, 14 min were in breath-hold (>=10 s, 55 holds) and 10 min in free-breathing (<10 s, 257 breaths). The mean 2D offset could be reduced from 6.8 mm to 3.7 mm with gating. The reconstructed dose distribution showed a TV Dmean of 27.6 Gy (planned: 27.8 Gy) and D95 of 26.3 Gy (planned: 27 Gy). Organs at risk did not show any increase in dose, expect for the bronchial tree with a Dmean of 2.5 Gy (planned: 1.6 Gy).

        Conclusion: MRI guided cardiac radiosurgery was successfully applied. With the motion tracking and gating, the patient could be treated with a good coverage of the target volume and minimal dose to organs at risk.

        Speaker: Stefanie Ehrbar (Radiation Oncology Department, Universitätsspital Zürich, Switzerland)
    • 11:30 12:15
      Invited Speaker Rob Coppes 45m

      Rob Coppes

    • 12:15 13:30
      Lunch 1h 15m
    • 15:30 16:00
      Coffee break 30m
    • 16:00 16:45
      Invited Speaker Gunther Dissertori 45m
  • Friday, 22 November
    • 09:00 09:45
      Session IV: Dosimetry II