Abstract
Purpose: To investigate the technical feasibility of SBRT dose painting using 18F-NaF positron emission tomography (PET) scans guidance in patients with spine oligometastases from prostate cancer.
Materials/methods: Six patients with 15 spine oligometastatic lesions from prostate cancer who had 18F-NaF PET/CT scan prior to treatment were retrospectively included. GTV reg was delineated according to the regular tumor boundary shown on PET and/or CT images; and GTV MATV was contoured based on a net metabolically active tumor volume (MATV) defined by 60% of the SUVmax values on 18F-NaF PET images. The PTVs (PTV reg and PTV MATV ) were defined as respective GTVs (plus involved entire vertebral body for PTV reg ) with a 3-mm isotropic expansion margin. Three 1- fraction SBRT plans using VMAT technique along with 10 MV flattened filter free (FFF) beams (Plan24Gy , Plan24 − 27Gy , and Plan24 − 30Gy ) were generated for each patient. All plans included a dose of 24 Gy prescribed to PTV reg . The Plan24 − 27Gy and Plan24 − 30Gy also included a simultaneous boost dose of 27 Gy or 30 Gy prescribed to the PTV MATV , respectively. The feasibility of 18F-NaF PET-guided SBRT dose escalation was evaluated by its ability to achieve 100% of the prescription dose to cover at least 90% of the PTV volume while adhering to organ-atrisk (OAR) dose constraints. Results: In all 33 SBRT plans generated, the planning objectives and dose constraints were met without exception. Plan24 − 27Gy and Plan24 − 30Gy had a significantly higher dose in PTV MATV than Plan24Gy (p < 0.05), respectively, while maintaining a similar OAR sparing profile. Conclusion: Using VMAT with FFF beams to incorporate a simultaneous 18F-NaF PET-guided radiation boost dose up to 30 Gy into a SBRT plan is technically feasible without violating normal tissue tolerances. The relationship between local control and normal tissue toxicity during 18F-NaF PET-guided dose escalation in SBRT should be validated in clinical trials.
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Wu, L. et al. (2015). 18F-NaF PET/CT-directed dose escalation in stereotactic body radiotherapy for spine oligometastases from prostate cancer. In: Jaffray, D. (eds) World Congress on Medical Physics and Biomedical Engineering, June 7-12, 2015, Toronto, Canada. IFMBE Proceedings, vol 51. Springer, Cham. https://doi.org/10.1007/978-3-319-19387-8_138
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DOI: https://doi.org/10.1007/978-3-319-19387-8_138
Publisher Name: Springer, Cham
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