Thursday 01 June
07:30

Thursday 01 June

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BS10
07:30 - 08:30

BREAKFAST SEMINAR
ESTRO Session / Multiple Metastases

Coordinators: Steve BRAUNSTEIN (Faculty) (San Francisco, USA), Masaaki YAMAMOTO (Gamma Knife) (Hitachi-naka, JAPAN)
Moderator: Bodo LIPPITZ (Co-Director) (Hamburg, GERMANY)
07:30 - 08:30 Gamma Knife Radiosurgery for multiple brain metastases: a 20-year period. Masaaki YAMAMOTO (Gamma Knife) (Hitachi-naka, JAPAN)
07:30 - 08:30 Brain metastases clinic: a multidisciplinary and multimodal approach for patients with multiple lesions. Luis SCHIAPPACASSE (Consultant in Radiation Oncology) (Lausanne, SWITZERLAND)
07:30 - 08:30 Neurocognitive preservation strategies for multiple brain metastases. Jonathan KNISELY (Lake Success, USA)
07:30 - 08:30 Clinical strategies and dose planning algorithms for radiosurgery of brain metastases. Bodo LIPPITZ (Co-Director) (Hamburg, GERMANY)
07:30 - 08:30 Essentials of image-guidance for treating multiple metastases with a single isocenter. Fang-Fang YIN (Medical Physicist/Professor) (Durham, NC, USA)
Parallel 1- Prince

Thursday 01 June

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BS11
07:30 - 08:30

BREAKFAST SEMINAR
DTI for VIM Targeting

Moderators: Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL), Jean-Philippe THIRAN (Director) (Lausanne, SWITZERLAND), Constantin TULEASCA (Resident) (Lausanne, SWITZERLAND)
07:30 - 08:30 DTI for the dummies. Jean-Philippe THIRAN (Director) (Lausanne, SWITZERLAND)
07:30 - 08:30 Connectivity of VIM. Sarah MARIANI (Praticien Hospitalier) (Marseille, FRANCE)
07:30 - 08:30 VIM direct targetting. Constantin TULEASCA (Resident) (Lausanne, SWITZERLAND)
Parallel 2- Queen

Thursday 01 June

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BS12
07:30 - 08:30

BREAKFAST SEMINAR
Physics: Small Fields

Coordinator: David SCHLESINGER (Medical Physics) (Charlottesville, USA)
Moderators: Andreas MACK (Chief Physicist Radiosurgery) (Zürich, SWITZERLAND), Josef NOVOTNY (Head of department) (Prague, CZECH REPUBLIC)
07:30 - 08:30 Introduction. David SCHLESINGER (Medical Physics) (Charlottesville, USA)
07:30 - 08:30 Small field dosimetry – chase for an optimal detector. Josef NOVOTNY (Head of department) (Prague, CZECH REPUBLIC)
07:30 - 08:30 The physics challenges of small fields. Andreas MACK (Chief Physicist Radiosurgery) (Zürich, SWITZERLAND)
Parallel 3- BB King
08:45

Thursday 01 June

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PS6
08:45 - 10:00

PLENARY SESSION 6

Moderators: Douglas KONDZIOLKA (New York, USA), Jing LI (Radiation Oncologist) (Houston, USA), Jannie SCHASFOORT (Medical Physicist) (Tilburg, THE NETHERLANDS)
08:45 - 08:55 Data Blitz: Vestibular Schwannomas. Jeremy ROWE (Sheffield, UK)
08:55 - 09:05 Data Blitz: Spine Radiosurgery. Lily ANGELOV (Staff Neurosurgeon) (Cleveland, USA)
09:05 - 09:15 Data Blitz: Hypofractionation. Patrick HANSSENS (Radiation Oncologist) (Tilburg, THE NETHERLANDS)
09:15 - 09:25 Special Lecture: Small field dosimetry – Chase for an optimal detector. Josef NOVOTNY (Head of department) (Prague, CZECH REPUBLIC)
09:25 - 09:40 Special Lecture: Big Data - From evidence-based medicine to precision medicine. Jacques BECKMANN (SWITZERLAND)
09:40 - 09:50 #9957 - A novel index for assessing radiosurgery treatment plan quality.
A novel index for assessing radiosurgery treatment plan quality.

One of the hallmarks of intracranial radiosurgery is a steep dose gradient from the periphery of the target into surrounding brain. Clinical studies have consistently backed up the importance of steep dose fall off through evidence from symptomatic complications (Flickinger, Korytko, Blonigen, Minniti). The available data suggests that there are threshold doses, above which, the risk of symptomatic radionecrosis increases with volume irradiated. It therefore makes sense to concentrate on limiting doses above these thresholds, ignoring lower doses that may be clinically irrelevant. 

Several metrics have been proposed to quantify dose fall off. The Gradient Index (GI) (Paddick and Lippitz) remains the most commonly used metric, serving as a practical volumetric assessment of dose fall off. Upon the formulation of the GI the authors identified the limitation that this metric is not suitable for comparing plans of incongruent conformity. In order to overcome this limitation, Thomas et al proposed the AUC metric, as an alternative for comparative plan evaluation. The AUC metric is the integral area under the dose-volume histogram (DVH) between the 50% of the prescription dose (PD) and the prescription isodose (PI). This metric provides a useful dose-volume product (Energy in Joules) that quantifies dose fall off outside the target, which the authors have previously used as a predictor for normal tissue complications. This metric, however, still suffers from dependence to conformity and prescription dose whilst not accounting for dose deposition inside the target.

To overcome limitations of currently used metrics, we propose a novel metric, the Efficiency Index (EI), based on the same principle of integrating areas under differential DVHs:

EI=DminTVDmaxTV*dose/50%PDDmaxV*dose

where DminTV is the minimum dose in the target, Dmax is the maximum dose, PD is prescription dose, TV is target volume and V is the volume occupied by the 50%PD isodose line.

The EI can be easily calculated using differential DVHs of the TV and of volume V. The value is effectively the proportion of energy deposited inside the target within the 50% of PD isodose line. It has theoretical limits of 0 and 1, with 1 being perfect. It combines conformity, gradient and a high mean dose to the target into a single value.

The EI has been calculated for 40 clinical SRS plans (mean TV of 3.8 cc) with a GI range of 2.49 – 3.03 and a mean of 2.74. The calculated EI values ranged from 0.403-0.551 with a mean of 0.496.

Alexis DIMITRIADIS (London, UK), Ian PADDICK
Stravinski Auditorium
10:00

Thursday 01 June

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break24
10:00 - 10:30

Coffee Break

10:30

Thursday 01 June

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PS8
10:30 - 11:30

PLENARY SESSION 7

Moderators: Jean BOURHIS (Lausanne, SWITZERLAND), Marc LEVIVIER (Chef de Service) (Lausanne, SWITZERLAND), Jean REGIS (PROFESSEUR) (MARSEILLE, FRANCE)
10:30 - 10:40 Stereotactic ablative RT for early stage NSCLC. Matthias GUCKENBERGER (Chairman) (Zurich, SWITZERLAND)
10:40 - 10:50 ISRS last decade's achievements and future directions. Jonathan KNISELY (Lake Success, USA)
10:50 - 11:20 Special Lecture - CERN: Particles, the Universe - and me? Rolf LANDUA (SWITZERLAND)
Stravinski Auditorium
11:30

Thursday 01 June

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PS9
11:30 - 12:30

PLENARY CLOSING SESSION

Moderators: Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL), Laura FARISELLI (director) (milano, ITALY), Ian PADDICK (Physicist) (London, UK)
11:30 - 11:40 ISRS federating radiosurgery societies and promoting world RS quality. Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL)
11:50 - 12:10 Fabrikant Award and Lecture. Ben SLOTMAN (Professor and Chairman) (AMSTERDAM, THE NETHERLANDS)
12:10 - 12:30 Best Poster Award & Young Investigator Award.
Stravinski Auditorium