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SU‐C‐BRA‐01: 18F‐NaF PET/CT‐Directed Dose Escalation in Stereotactic Body Radiotherapy for Spine Oligometastases From Prostate Cancer
Author(s) -
Wu L,
Zhang W,
Kwee S,
Li M,
Peng X,
Xie L,
Lin Z,
Wang H,
Kuang Y
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4923811
Subject(s) - medicine , nuclear medicine , prostate cancer , cyberknife , radiation therapy , radiosurgery , prostate , cancer , radiation treatment planning , radiology
Purpose: To investigate the technical feasibility of SBRT dose painting using 18 F‐NaF positron emission tomography (PET) scans guidance in patients with spine oligometastases from prostate cancer. Methods: As a proof of concept, six patients with 14 spine oligometastatic lesions from prostate cancer who had 18 F‐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 SUV max values on 18 F‐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 FFF beams (Plan 24Gy , Plan 24–27Gy , and Plan 24–30Gy ) were generated for each patient. All plans included a dose of 24 Gy prescribed to PTV reg . The Plan 24–27Gy and Plan 24–30Gy 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 the prescription dose objectives while adhering to organ‐at‐risk (OAR) dose constraints. The normal tissue complication probabilities (NTCP) calculated by radiological models were also compared between the plans. Results: In all 33 SBRT plans generated, the planning objectives and dose constraints were met without exception. Plan 24–27Gy and Plan 24–30Gy had a significantly higher dose in PTV MATV than Plan 24Gy (p < 0.05), respectively, while maintaining a similar OAR sparing profile and NTCP values. Conclusion: Using VMAT with FFF beams to incorporate a simultaneous 18 F‐NaF PET‐guided radiation boost dose up to 30 Gy into a SBRT plan is technically feasible. The relationship between local control and normal tissue toxicity in SBRT dose painting should be validated in clinical trials.