Abstract book - ESTRO meets Asia

S23 ESTRO meets Asia 2018

Results There were 12 ANZ responses. 19 INTL responses were from Americas (47%), Europe (32%), and Asia (21%); the survey is ongoing (data analysed June 2018). International data indicated that DIR was currently used clinically for CT-CT registration (INTL 63%, ANZ 17%), followed by CT- PET (INTL 53%, ANZ 16%), CT-CBCT (INTL 32%, ANZ 5%), CT-MR (INTL 21%, ANZ 0%), and MR-MR (INTL 11%, ANZ 0%). Currently, sites tended to use DIR with dedicated software (INTL 63%, ANZ 42%) vs. treatment planning system (INTL 32%, ANZ 33%). Most sites had some form of DIR software (INTL 84%, ANZ 58%) but utilisation of DIR clinically (any use) varied (INTL 94%, ANZ 43%). In 2018, centres have implemented or are implementing DIR for clinical use for atlas-based segmentation (INTL 42%, ANZ 67%), multi-modality treatment planning (INTL 68%, ANZ 50%), and dose deformation (INTL 68%, ANZ 50%). Our data suggests that by 2019-2023, most centres will be using DIR clinically. Most respondents were aware of AAPM TG132 request and report forms (INTL 74%, ANZ 100%) however adoption as of 2018 was limited (INTL 11%, ANZ 33%) but is expected to increase (INTL 27%, ANZ 58%). Common QA mechanisms were checks of deformed image (INTL 42%, ANZ 17%) and registration instructions in protocols (INTL 21%, ANZ 21%). Common forms of training were informal peer training (INTL 68%, ANZ 92%) and vendor training (INTL 63%, ANZ 58%). Key challenges were determining whether registrations were satisfactory (INTL 52%, ANZ 33%) and actions when registrations were not (INTL 47%, ANZ 33%); internationally, physicists had dominant involvement with most major registration processes (INTL 80%, ANZ 40%). Extended survey data described staff roles and task quality on a process level, common sites for deformation (lung, head and neck), common QA datasets used (patient data, digital and physical phantoms), number of validation datasets, QA metrics (qualitative and subjective), quality/safety measures, criteria for implementation, and cost-benefit analysis by use case.

anatomy and surgical clips. For each matching protocol, plans were overlaid onto each CBCT to analyse achieved treatment dosimetry and geographical miss. Results 90 CBCT images were evaluated. For bony match, the mean geographical CTV miss ranged 0.51 - 3.17% for uniform expansions (lowest PTV10) & 2.03 - 3.28% for differential (lowest PTVa5-10). For clip match, the mean geographical CTV miss for uniform expansions ranged 0.07 - 1.2% (lowest PTV10) & 0.58 - 0.35% for differential (lowest PTVa5-10). Greater geographical miss was observed in the superior CTV & was more evident when a uniform margin was used. The mean planning rectal V60Gy ranged 20.8 - 35.5% for uniform expansions (lowest PTV5-3) & 23.3 - 28.4% for differential (lowest PTVa3-5-7). The mean planning rectal V40Gy ranged 35.8 - 52.2% for uniform expansions (lowest PTV5-3) & 39.9 - 45.1% for differential (lowest PTVa3-5- 7). For bony match, rectum tolerance was exceeded in 8.4 – 41.6% of uniform expansions (lowest PTV5-3) & 6.6 – 14.5% of differential (lowest PTVa3-5-7). For clip match, rectum tolerance was exceeded in 6.2 - 40.4% of uniform expansions (lowest PTV5-3) & 7.2 – 14.5% of differential (lowest PTVa3-5-7). The mean planning bladder V50Gy ranged 31.4 - 37.6% for uniform expansions (lowest PTV5-3) & 30.5 - 32.4% for differential (lowest PTVa3-5-7). For bony match, bladder tolerance was exceeded in 19.3 - 33.7% of uniform expansions (lowest PTV5/PTV5-3) & 18.1 - 24.1% of differential (lowest PTVa3-5-7). For clip match, tolerance was exceeded in 19.3 - 34.9% of uniform expansions (lowest PTV5-3) & 21.7% for both differential. For bony match, CTV V95<98% incidences were 1.2 – 18.1% of uniform expansions (lowest PTV10) & 9.6 – 15.7% of differential (lowest PTVa5-10). For clip match, CTV V95<98% incidences were 0 - 10.8% of uniform expansions (lowest PTV10/10-5) & 6.0 - 10.8% of differential (lowest Surgical clip match is preferable to bony match for image guidance policy. Differential margins achieved improved rectal and bladder sparing with minimal increase in geographical miss. PV-057 Rigid and Deformable Image Registration Practice Pattern: International Results J. Yuen 1 , A. Ralston 1 , A. Gray 2 , A. Walker 2 , M. Jameson 2 , N. Hardcastle 3 , L. Schmidt 1 , K. Harrison 4 , J. Poder 1 , J. Sykes 5 , J. Barber 5 1 St George Public Hospital, Cancer Care Centre, Sydney, Australia 2 Liverpool and Macarthur Cancer Therapy Centres, Medical Physics, Sydney, Australia 3 Peter MacCallum Cancer Centre, Physical Sciences-, Melbourne, Australia 4 Genesis Cancer Care, Medical Physics, Newcastle, Australia 5 Blacktown Cancer & Hematology Centre, Medical Physics, Sydney, Australia Purpose or Objective Since the release of AAPM TG132 report on rigid and deformable image registration (DIR), there has been increased awareness of the need for formal quality guidelines on image registration. This project aims to capture current international approaches to image registration. Material and Methods Survey questions were based on AAPM TG132 recommendations on a process level and identified potential variations in resources, implementation, and criteria for clinical image registration. The survey was distributed to radiotherapy sites in Australia-New-Zealand (ANZ) and internationally (INTL). PTVa5-10). Conclusion

Conclusion Practice pattern data shows who, what, when, and how tasks are performed for image registration in departments around the world. This provides a platform to facilitate consensus for institutional or state consensus on best practice for image registration in Radiation Oncology. PV-058 Retrospective analysis of prostate movement using Gold fiducial markers J. Aathilakshmi 1 , P.K. Mani 1 , S. Paulpandi 1 , K. Bayyareddygari 1 , K. Vittal 1 , N. Veeraragavan 1 ,