Thursday 13 June
07:30

Thursday 13 June

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A51
07:30 - 09:00

BREAKFAST SEMINAR
EVERYTHING YOU NEED TO KNOW ABOUT IMAGING

Moderators: Nelson Paes FERREIRA (BRAZIL), Jonathan KNISELY (Lake Success, USA), Georges SINCLAIR (Consultant Clinical Oncologist) (Reading, UK, UK)
07:30 - 07:50 Novel MRI Sequences for SRS. Herwin SPECKTER (Mr.) (Santo Domingo, DOMINICAN REPUBLIC)
07:50 - 08:10 Functional images for behavior disorders. Ricardo DE OLIVEIRA (BRAZIL)
08:10 - 08:30 #17884 - a51-3 Integrated Stereotactic Diffusion Tensor Tractography for Gamma Knife Stereotactic Radiosurgery.
a51-3 Integrated Stereotactic Diffusion Tensor Tractography for Gamma Knife Stereotactic Radiosurgery.

Objectives:

Integration of modern neuroimaging techniques into treatment planning has increased the therapeutic potential and safety of stereotactic radiosurgery. We report our experience over the past three years with integrating Stereotactically acquired Diffusion Tensor Tractography (DTI) into treatment planning for Gamma Knife Radiosurgery in patients with a variety of pathology in eloquent intracranial locations.

Methods:

Our study cohort comprised of 115 patients who underwent 122 Gamma Knife radiosurgical treatments at our centre.
32 Channel DTI at 1.5 T & 3T was performed at the time of standard treatment GK Protocol MR T1 & T2) imaging. DTI images were post processed with commercial software using a deterministic protocol. Generated Tracts were imported into Gamma plan to aid shot planning & perform dosimetry on vulnerable white matter tracts. Tailored & 3T sequences wer alos evaluated.

Results:

Stereotactic diffusion tensor tractography was successful in generating the appropriate ADC, FA & DEC sequences. Tractography provided additional useful clinical information for treatment planning. In patients with cerebral oligo-metastatic disease requiring multiple treatments, clinical & radiological response correlated well with preservation or improvement in adjacent tract volumes. One patient with a mesial temporal AVM developed delayed worsening of a pre-existing hemianopia & another with AVM required steroids for cerebral swelling. no other neurological deficits due to radiation were recorded at follow-up

Conclusions:

 Tractographyi is a useful technique for preventing complications in stereotactic radiosurgery by reducing radiation doses to functional organs at risk, including critical cortical areas and subcortical white matter tracts. Tractography use in SRS can further increase our knowledge of critical cerebral structure radiation tolerances. Stereotactic Tractography is a useful technique to improve the therapeutic potential and safety of stereotactic radiosurgery. 

Cormac GAVIN (London, UK), H. Ian SABIN
08:30 - 08:50 Review of MR Pulse Sequences for SRS/SBRT: What Does Each Provide. Stephen HOLMES (Imaging Consustant and Conference Organizer) (honolulu, USA)
Segovia II-III-IV

Thursday 13 June

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B51
07:30 - 09:00

BREAKFAST SEMINAR
ATYPICAL MENINGIOMAS

Moderators: Andrey GOLANOV (Head of the Department) (Moscow, RUSSIA), Carlos MATTOZO (BRAZIL), Gelareh ZADEH (Radiosurgery) (Toronto, CANADA)
07:30 - 07:45 #17896 - b51-1 A tentative strategy to management of atypical or WHO I meningiomas with high grade MIB-Ki67.
b51-1 A tentative strategy to management of atypical or WHO I meningiomas with high grade MIB-Ki67.

The efficacy of radiosurgery in the control of WHO I meningioma growth has been demonstrated both as up-front strategy and as the primary salvage therapy following surgical incomplete removal. (Santacroce et al. 2012)
Some lesions however are failing radiosurgery in a pattern closely resembling Atypical meningioma. Historically atypical meningiomas undergo conventional radiotherapy following on or multiple attempts at surgical removal. The long-term efficacy of radiotherapy in controlling the growth of meningiomas above grade I has historically been poor.
We have analyzed the meningiomas in our series of radiosurgically treated meningiomas who had failed surgery or radiosurgery or both and as a rule recognized (as also Mukhopadhyay et al. (2017) a Ki-67 labeling index equal or above 3%. In other words: some WHO I meningiomas behaved, in regard to recurrence, in a very similar way to the more aggressive atypical variants albeit missing the invasive, necrotic features of the higher grades.
We have then tried in both groups a strategy of re-operation (whenever feasible in order to reduce the target tissue volume) followed by:
•in 60 patients (2004-2018) a course of conventional radiotherapy (25 Fractions of 180cGy, Tot. 45Gy) followed after 12-15 days by a radiosurgical boost (10-14Gy). Results: 26 controlled at 3yrs F-U and 14 failed (at any time in the course of F-U)
•in 60 small size WHO I lesions (1995-2018) only radiosurgery at a higher dose than customary (21-16Gy). Results: 19 controlled at 3yrs F-U and 18 failed (at any time in the course of F-U)
Evaluation of this complex subpopulations of meningioma patients requires longer F-U times and careful analysis of the local and distant recurrence events.

Enrico MOTTI (Cotignola, ITALY)
07:45 - 08:15 Prognostic Tools. Isaac YANG (Associate Professor) (Los Angeles, USA)
08:15 - 08:30 Clinical Results. Randy JENSEN (Professor) (Salt Lake City, USA)
08:30 - 09:00 Improving the Treatment Paradigm of Atypical Meningiomas. Charles VALERY (directeur unité GK) (Paris, FRANCE)
Segovia I

Thursday 13 June

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C51
07:30 - 09:00

BREAKFAST SEMINAR
HOT TOPICS

Moderators: Yuri ANDRADE DE SOUZA (BRAZIL), David JAFFRAY (Speaker) (Toronto, CANADA), Christian VARGAS (PERU)
07:30 - 07:50 The Prescription Dose Debate. Gennady NEYMAN (Medical Physicist) (Cleveland, USA)
07:50 - 08:10 The Case for Margins. Andrea GIRARDI (Medical Physicist) (Brussels, BELGIUM)
08:10 - 08:30 The Case against Margins. David SCHLESINGER (Medical Physics) (Charlottesville, USA)
08:30 - 08:50 Dose fall-off characterization of isocentric and non-isocentric brain radiosurgery. Lijun MA (Physics) (San Francisco, USA)
El Pardo I
09:00

Thursday 13 June

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A52
09:00 - 09:40

PLENARY SESSION
SPECIAL GUEST LECTURE

Moderators: Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL), Ian PADDICK (Physicist) (London, UK)
09:00 - 09:20 Organization Funding for Research - Private and Government. Luiz Eugenio MELLO
09:20 - 09:40 Big Data or RCT: Vestibular Schwannoma as a Model. David JAFFRAY (Speaker) (Toronto, CANADA)
Segovia II-III-IV
09:40

Thursday 13 June

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A53
09:40 - 10:00

SPECIAL LECTURE
FABRIKANT LECTURE

Moderators: Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL), Ian PADDICK (Physicist) (London, UK)
09:40 - 10:00 Fabrikant lecture. John ADLER (neurosurgery) (Région de la baie de San Francisco, USA)
Segovia II-III-IV

Thursday 13 June

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B53
09:40 - 10:00

Flash Oral Session
PHYSICS

Moderators: Uriel NOVICK (Chief Medical Physicist) (CABA, ARGENTINA), Ian PADDICK (Physicist) (London, UK)
09:40 - 09:50 #17801 - B53-1 Comparison of planning techniques for single-isocenter multiple-target stereotactic radiosurgery.
Comparison of planning techniques for single-isocenter multiple-target stereotactic radiosurgery.

The purpose of this project is to compare treatment planning techniques that use a single isocenter to treat multiple brain metastases. We want to determine if volumetric modulated arc therapy (VMAT) or dynamic conformal arc (DCA) therapy is the better method to treat multiple mets patients using a single isocenter. We also want to know if using U-frame or frameless masks provide better plan quality. DCA plans were created for each of the 40 single-isocenter patients who received VMAT at Duke Hospital from 2016-2018. These patients were randomly selected based only on the number of metastases, from 2 to 14. We created the DCA plans using 5 couch positions, 2 collimator angles, and 100-degree arcs on BrainLab Elements. We modeled U-frame and frameless masks using 100-degree and 180-degree arcs, respectively. The clinical VMAT plans delivered to the 40 patients had an average conformity index of 1.47 and average gradient index of 8.57. Average whole-brain V3Gy and V5Gy were 14.07% and 5.80%, respectively. In comparison, using DCA the conformity index was 1.75 and the gradient index was 6.87. Whole-brain V3Gy and V5Gy were 11.25% and 5.59%, respectively. The frameless mask plans had conformity and gradient indexes of 1.68 and 6.39 and V3Gy and V5Gy of 11.39% and 5.09%, respectively. Overall, VMAT plans had higher conformity index with lower gradient index at the cost of healthy brain protection compared to DCA. Frameless masks also increased the conformity index and decreased the gradient index with minimal impact on low doses to the brain.

Andrew BALLESIO (Durham, USA), Zhiheng WANG
09:46 - 09:52 #17807 - B53-2 MRI only radiotherapy planning for brain metastases with Varian’s HyperArc SRS system.
B53-2 MRI only radiotherapy planning for brain metastases with Varian’s HyperArc SRS system.

Purpose or Objective: To evaluate the feasibility of MRI only non-coplanar radiotherapy planning with Varian’s HyperArc SRS treatment by comparison with CT planning.

Materials and methods: Radiotherapy plans for ten patients, previously treated with HyperArc, for cranial metastases in a single fraction were recalculated on diagnostic MRI scans. Target volumes varied in size from 1cc to 11.4cc, with a mean size of 4.4cc. The MRI scans were registered, by rigid registration, to the treatment planning CT. Brain, body, bones and PTV were outlined in the MRI scans and assigned representative bulk HU values based on the sample of patients. Brain was assigned 37HU and Bone to 787HU, all other tissue is assigned 0 HU.  Treatment plans were recalculated using the Eclipse Treatment Planning System v15.1 [Varian Medical Systems, Palo Alto, CA, USA] and the superposition/convolution Anisotropic Analytical Algorithm v15.05.07.

Comparisons were made between the original CT plan, CT_Bulk with; bone, brain and water bulk assigned, MRI_Bulk with; bone, brain and water bulk assigned and MRI_Water with the entire MRI scan assigned to 0 HU, irrespective of anatomy. Water Equivalent Depth (WED) to the geometric centre of PTV was also measured to determine the significance of bulk assigning densities.

Treatment plans were compared by D99%, Dmax, Gradient Index (V40/V80), V100%, dose to OARs and V12Gy to brain.

Results: Fitting a line to WED values for CT and MRI_Bulk gives a goodness of fit R-squared value of 0.9259, indicating strong correlation. The gradient of this line, 0.89, indicates that MRI_Bulk is displaying reduced HU to the original CT.

Average change in D99% is 0.1%, 0.9% and 2.4% and average change in DMax is 0.1%, 1.1% and 3.1% for CT_Bulk, MRI_Bulk and MRI_Water respectively. There is no significant change in Gradient Index, V100% or V12Gy to brain.

Conclusion: Bulk assigment of HU to voxels in MRI scans results in relatively shorter WEDs in comparison to CT but does not have a significantly detrimental effect on plan quality. MRI only planning with HyperArc, using bulk assignment of HU, is possible and calculated doses to PTV and OARs and plan quality metrics are similar to those on an uncorrected CT. Further work may incorporate monte-carlo style dose calculation algorithms to characterise CT-MRI planning discrepancies when modelling material properties.

Peter HOUSTON, Westley INGRAM, Suzy CURRIE (Glasgow, UK)
09:52 - 09:58 #17873 - B53-3 Radiosurgery of brain metastases using a linear accelerator (SRS-Cones vs. VMAT).
B53-3 Radiosurgery of brain metastases using a linear accelerator (SRS-Cones vs. VMAT).

Stereotactic treatment of brain metastases with high single exposures (~20 Gy) lead to high local tumour control. At the Institute for Radiation Oncology in Klagenfurt a Versa HD accelerator (Elekta) with Agility-MLC and stereotactic cones (SRS-Cones) is used for single fraction irradiation of small volumes in the brain. The Agility-MLC has the ability to create 5x5 mm2 fields at the isocentre. SRS-Cones are mounted onto the accelerator head. The collimation of the beam is closer to the patient. This leads to a smaller penumbra compared to MLC-only collimation. The objective of this research was to see if and at which target volume the Agility-MLC will reach similar results compared to SRS-Cones. Retrospectively for 20 patients 4 spherical target volumes for the cone diameter (5, 10, 15 and 20) mm were created (TV5, TV10, TV15, und TV20). For each target volume treatment plans using SRS-cones and VMAT were calculated with the TPS Monaco 5.11 using 6 MeV FFF photons. 4 arcs were used for each plan, which considered size and position of the target volumes by adapting table- and arc angle. Attention was paid to make sure that no beam was irradiating through the eyes. The beam setups were kept the same for Cone- and VMAT-plans. For the Cone-plans maximum dose was set to 25 Gy. VMAT-plans were scaled to D99% = 20 Gy. All plans were analysed by their dose distribution and comparison of their dose-volume-histograms. Special attention was paid to the 12 and 10 Gy isodose volumes, as they are an important basis for medical decision if single fraction radiation is feasible. Also RTOG and Paddick conformity index (CIRTOG und CIP) and Paddick gradient index (GIP) were calculated for each plan. Analyses of the 160 plans showed that all plans calculated with the SRS-Cones outclass the VMAT-plans. Due to the smaller penumbra of the Cones the low dose volume was clearly reduced. All plans (VMAT and Cone) were within the given criteria for Paddick conformity (0.9 to 1) and gradient index, although GIP for VMATs was higher than for Cones. While all Cone-plans met the criteria for coverage and low dose volumes, 50 % of VMAT-plans for the TV20 failed the requirement for V10Gy (< 14 cm3) and 85 % failed the V12Gy criteria (< 10 cm3). The study showed that the difference between Cones and VMAT decreases while target size increases. Still for 20 mm targets, Cones outclass VMAT.

Andrea SCHMOELZER (Klagenfurt, AUSTRIA), Andreas GMOSER, Christine ORASCH, Wolfgang RAUNIK
Segovia I
10:00 COFFEE BREAK - POSTERS & EXHIBITION
10:30

Thursday 13 June

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A55
10:30 - 11:00

PLENARY SESSION
CONGRESS OVERVIEW I

Moderators: Gilberto FONSECA (BRAZIL), Randy JENSEN (Professor) (Salt Lake City, USA), Isaac YANG (Associate Professor) (Los Angeles, USA)
10:30 - 10:40 ISRS 2019 Review: Malignant Tumors. Samuel CHAO (Radiation Oncologist) (Cleveland, USA)
10:40 - 10:50 ISRS 2019 Review: Vascular Disorders. Gus BEUTE (Neurosurgeon) (Tilburg, THE NETHERLANDS)
10:50 - 11:00 ISRS 2019 Review: Benign Tumors. Michael SCHULDER (Vice Chair, Neurosurgery) (Lake Success, NY, USA)
Segovia II-III-IV
11:00

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A56
11:00 - 11:40

PLENARY SESSION
CONGRESS OVERVIEW II

Moderators: Laura FARISELLI (director) (milano, ITALY), Alessandra GORGULHO (Director of Research Affairs) (Sao Paulo, BRAZIL), Jean SABATIER (MD, PhD) (Toulouse, FRANCE)
11:00 - 11:10 ISRS 2019 Review: FUNCTIONAL RADIOSURGERY. Jean REGIS (PROFESSEUR) (MARSEILLE, FRANCE)
11:10 - 11:20 ISRS 2019 Review: Immunotherapy + SRS. Jonathan KNISELY (Lake Success, USA)
11:20 - 11:30 ISRS 2019 Review: Extracranial SRS/SRT. Rupesh KOTECHA (Radiation Oncologist and Chief of Radiosurgery) (Miami, USA)
11:30 - 11:40 ISRS 2019 Review: Physics. Steven GOETSCH (Medical Physicist) (Solana Beach, USA)
Segovia II-III-IV
11:40

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A57
11:40 - 12:00

PLENARY SESSION
SRS/SBRT CLINICAL TRIALS OVERVIEW

Moderator: Dennis SHRIEVE (Professor and Chair) (Salt Lake City, USA)
11:40 - 11:50 International Radiosurgery Research Foundation (IRRF). Gene BARNETT (neurosurgery) (Cleveland, USA)
11:50 - 12:00 American Society of Clinical Oncology (ASCO). To Be CONFIRMED
Segovia II-III-IV
12:00

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A58
12:00 - 13:05

CLOSING SESSION & AWARDS CEREMONY

Moderators: Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL), Laura FARISELLI (director) (milano, ITALY), Ian PADDICK (Physicist) (London, UK)
12:00 - 12:10 ISRS Educational Courses. Mikhail CHERNOV (Assistant Professor) (Tokyo, JAPAN)
12:10 - 12:20 ISRS: Past, Present and Future. Ian PADDICK (Physicist) (London, UK)
12:20 - 12:25 2021 Congress Introduction. Matthew FOOTE (Co-Director) (Brisbane, AUSTRALIA)
12:25 - 12:45 Fabrikant Award.
12:45 - 12:50 Lars Leksell Fellowship Award. Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL)
12:50 - 12:55 Young Investigator Award & Young Professional Award. Laura FARISELLI (director) (milano, ITALY)
12:55 - 13:00 Best Poster Award. Marc LEVIVIER (Chef de Service) (Lausanne, SWITZERLAND)
13:00 - 13:05 Final Remarks. Antonio DE SALLES (Professor - Chief) (Sao Paulo, BRAZIL)
Segovia II-III-IV