ESTRO 2024 - Abstract Book

S4196

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2024

[3] Poulsen P.R., Cho B. and Keall P.J., A method to estimate mean position, motion magnitude, motion correlation, and trajectory of a tumor from cone-beam CT projections for image-guided radiotherapy, Int. J. Radiat. Oncol. Biol. Phys. 72 1587–96 (2008).

[4] Ruan D, Fessler JA, Balter JM, Berbeco RI, Nishioka S, Shirato H. Inference of hysteretic respiratory tumor motion from external surrogates: a state augmentation approach. Physics in Medicine & Biology. 2008 May 6;53(11):2923.

[5] Colvill E, Petersen JB, Hansen R, Worm E, Skouboe S, Høyer M, et al. Validation of fast motion-including dose reconstruction for proton scanning therapy in the liver. Phys Med Biol (2018) 63(22):225021. doi: 10.1088/1361 6560/aaeae9

876

Mini-Oral

Same-session MRI-only simulation and treatment with SMART for spine oligometastases (NCT03878485)

Joshua P Schiff 1 , Weiren Liu 1 , Eric Morris 1 , Eric Laugeman 1 , Alex T Price 2 , Karen Miller 1 , Brandi Jansen 1 , Sai Duriseti 3 , Souman Rudra 4 , Shahed N Badiyan 5 , Pamela P Samson 1 , Hyun Kim 1 , Lauren E Henke 2 , Clifford G Robinson 1 1 Washington University School of Medicine in St. Louis, Department of Radiation Oncology, St. Louis, USA. 2 University Hospitals, Department of Radiation Oncology, Cleveland, USA. 3 University of California, Los Angeles, Department of Radiation Oncology, Los Angeles, USA. 4 Emory University, Department of Radiation Oncology, Atlanta, USA. 5 University of Texas Southwestern, Department of Radiation Oncology, Dallas, USA

Purpose/Objective:

We conducted a pilot study of same-session MRI-only simulation and treatment with stereotactic MRI-guided adaptive radiotherapy (SMART) for patients with spinal oligometastases to evaluate the feasibility of this novel treatment planning paradigm. We hypothesized that this workflow would be feasible, and that early toxicity and local control would be within the standard of care.

Material/Methods:

Ten patients with oligometastatic disease of the spine were planned for accrual to this prospective study. All patients had recent diagnostic imaging of their spine and had no prior radiotherapy within the projected treatment field. Patients with symptomatic cord compression were not included in this study. Patients were prescribed either 24 Gy in 2 fractions (fx) or 35 Gy in 5 fx. Each patient had a diagnostic-scan based pre-plan created prior to treatment. The GTV was gross tumor on imaging, and the CTV was defined according to the International Spine Radiosurgery Consortium (ISRC) consensus guidelines 1 . The PTV was a 3-7 mm expansion of the CTV. The coverage goal was a V95%>95%, and the spinal cord/cauda equina constraint was V0.03cc<17 Gy and V0.35cc<23Gy for 2 and 5 fx plans, respectively. A bulk density override method was used for electron density calculations. On the day of treatment, the patient was imaged on an MRI-guided linac in the treatment position. This image was used for adaptive contouring and treatment planning. The plan created for fx 1 was used for the subsequent fx, and adaptation was utilized if