ESTRO 2020 Abstract Book

S783 ESTRO 2020

of total body irradiation practice in Australia and New Zealand. We received replies from 14 clinics. Some of the data, and data from a similar survey carried out in 2005 [3], are shown in Figure 1. 11 clinics participated in both surveys, 1 only in the 2005 survey and 3 only in the 2019 survey. 6 clinics are using similar linac dose rates in both surveys, 4 have lowered their linac dose rates, 1 has increased it. In 2019, 9 clinics use linac dose rates ≤ 200 MU/min, 3 use 200-300 MU/min and 1 uses 600 MU/min. In 2005, the patient dose rates were 9-25 cGy/min (the clinic using 600 MU/min did not report patient dose rate); in 2019, the patient dose rates were 5-15 cGy/min, with one outlier at 150 cGy/min, using an advanced technique (the clinic using 600 MU/min did not report patient dose rates). The most common prescriptions is 12Gy in 6 fractions over 3 days, though 3 clinics also use different prescriptions. 9 clinics use shielding, for various combinations of lungs, head, neck and/or kidneys. Most clinics use shielding to reduce the delivered dose to the prescription dose, however in two clinics the lung dose is 8 Gy while the prescription dose is 12 Gy. Lung doses vary considerably, from 8-14.4 Gy, for prescriptions of 12 Gy in 6 fractions. Conclusion The TBI practice in Australia and New Zealand remains varied, with considerable differences in lung doses and patient dose rates. [1] Quast, U.: Total body irradiation-review of treatment techniques in Europe, Radiotherapy and Oncology 1987, 9, 2, 91-106. https://doi.org/10.1016/S0167-8140(87)80197- 4 [2] Studinski, R.C.N., Fraser, D. J. , Samant, R. S. and MacPherson, M. S.: Current practice in total-body irradiation: results of a Canada-wide survey, 2017, Current Oncology, 24, 3 [3] Private communication, Jim Cramb PO-1465 Automated versus manual LINAC stereotactic radiosurgery plans in patients with 4-10 brain metastases A. Petoukhova 1 , R. Snijder 1 , R. Wiggenraad 2 , L. De Boer- de Wit 2 , I. Mudde-van der Wouden 2 , M. Florijn 1 , J. Zindler 3,4 , J. Van Santvoort 1 1 Haaglanden Medical Centre, Department of Medical Physics, Leidschendam, The Netherlands ; 2 Haaglanden Medical Centre, Department of Radiation Oncology, Leidschendam, The Netherlands ; 3 Erasmus MC Cancer Institute, Department of Radiation Oncology, Rotterdam, The Netherlands ; 4 Holland Proton Therapy Centre, Department of Radiation Oncology, Delft, The Netherlands Purpose or Objective Stereotactic radiosurgery (SRS) is a promising treatment option for patients with multiple brain metastases (BM). We studied whether automated planning or IMRT can make LINAC-based stereotactic radiosurgery plan quality with one isoc comparable or even better than a manually planned dynamic conformal arc (DCA) plan with a separate isocenter for each metastasis. Material and Methods For 12 patients with 4 up to 10 brain metastases (mean = 6), seven non-coplanar LINAC-based SRS plans with 6MV photons were created: a manually planned DCA plan with a separate isocenter for each metastasis (iPlan, BrainLAB), a dynamic IMRT plan (iPlan), a VMAT plan (Pinnacle, PHILIPS), two DCA plans with one isocenter for three (3 ∠ ) and five (5 ∠ ) couch angles (v1.6 Multiple Brain Mets SRS Elements, BrainLAB), two DCA plans with five couch angles with high and low sparing of normal tissue (NT) (v2.0 Multiple Brain Mets

Poster: Physics track: Treatment planning: applications

PO-1464 Total body irradiation practice in Australia and New Zealand: Results of a Survey L. Fog 1 , A. Wirth 2 , M. MacManus 3 , S. Downes 4 , M. Grace 5 , A. Moggre 6 , K. Mugabe 7 , G. Neveri 8 , L. Nourbehesht 9 , V. Panetieri 10 , D. Pope 11 , L. Sim 12 , C. Stanton 13 , B. Steer 14 , A. Stewart 15 , E. Ungureanu 1 , T. Kron 1 1 The Peter MacCallum Cancer Centre, Medical Physics, Melbourne, Australia ; 2 Peter MacCallum Cancer Centre, Radiation Oncology, Melbourne, Australia ; 3 The Peter MacCallum Cancer Centre, Radiation Oncology, Melbourne, Australia ; 4 Prince of Wales Hospital, Medical Physics, Randwick, Australia ; 5 St. Vincents Hospital, Medical Physics, Darlinghurst, Australia ; 6 Christchurch Hospital, Medical Physics, Christchurch, New Zealand ; 7 Waikato Hospital, Medical Physics, Hamilton, New Zealand ; 8 Sir Charles Gairdner Hospital, Medical physics, Nedlands, Australia ; 9 Crown Princess Mary Cancer Centre Westmead, Medical physics, Westmead, Australia ; 10 Alfred Health Radiation Oncology- The Alfred Hospital, Medical physics, Melbourne, Australia ; 11 Chris O’Brien Lifehouse, Medical physics, Camperdown, Australia ; 12 Radiation Oncology Princess Alexandra Raymond Terrace, Medical physics, South Brisbane, Australia ; 13 Royal North Shore Hospital, Medical physics, St. Leonards, Australia ; 14 Wellington Regional Hospital, Medical physics, Wellington, New Zealand ; 15 Auckland City Hospital, Medical physics, Auckland, New Zealand Purpose or Objective Total body irradiation (TBI) practice can vary from clinic to clinic [1,2]. Knowledge of the pattern of practice may be helpful for clinics to determine future practice. We did a survey of TBI practice in Australia and New Zealand. Material and Methods We emailed 46 TBI related questions to clinics in Australia and New Zealand, using the ACPSEM (Australasian College of Physical Scientists and Engineers in Medicine) email distribution list. Results

Table 1 – selected data from the 2005 and the 2019 survey