Timothy K Nguyen1, Arjun Sahgal1, Jay Detsky1, Hany Soliman1, Sten Myrehaug1, Chia-Lin Tseng1, Zain A Husain1, Anne Carty1, Sunit Das2, Victor Yang3, Young Lee4, Arman Sarfehnia4, Brige P Chugh4, Collins Yeboah4, Mark Ruschin5. 1. Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. 2. Division of Neurosurgery, St Michaels Hospital, University of Toronto, Toronto, Ontario, Canada. 3. Division of Neurosurgery, Sunnybrook Health Sciences Center, University of Toronto, Toronto, Ontario, Canada. 4. Department of Medical Physics, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. 5. Department of Medical Physics, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. Electronic address: Mark.Ruschin@sunnybrook.ca.
Abstract
PURPOSE: To compare normal tissue dosimetry between hippocampal-avoidance whole brain radiation therapy (HA-WBRT) and stereotactic radiosurgery (SRS) in patients with 10 to 30 brain metastases, and to describe a novel SRS strategy we term Spatially Partitioned Adaptive RadiosurgEry (SPARE). METHODS AND MATERIALS: A retrospective review identified SRS treatment plans with >10 brain metastases located >5 mm from the hippocampi. Our Gamma Knife Icon (GKI) SPARE (GKI-Spr) technique treats multiple metastases with single-fraction SRS partitioned over consecutive days while limiting the total treatment time to ≤60 minutes per day. Hippocampal and normal brain dosimetry were compared among GKI-Spr, single-fraction single-day GKI (GKI-Sfr), and 30 Gy in 10 fractions HA-WBRT. Dose metrics were converted to equivalent dose in 2 Gy fractions. RESULTS: Ten cases were analyzed. Compared with HA-WBRT, GKI-Spr significantly reduced the median equivalent dose in 2 Gy fractions hippocampal maximum point dose, mean dose, and dose to 40% of the hippocampi (D40%) by 86%, 93%, and 93%, respectively, and similarly for GKI-Sfr by 81%, 92%, and 91%, respectively. The normal brain median mean dose was reduced by 95% with GKI-Spr and 94% with GKI-Sfr. Compared with GKI-Sfr, GKI-Spr further reduced all normal brain and hippocampal dose metrics (P ≤ .014). CONCLUSIONS: GKI yields superior hippocampal and normal brain dosimetry compared with HA-WBRT, and GKI-Spr results in further dosimetric advantages.
PURPOSE: To compare normal tissue dosimetry between hippocampal-avoidance whole brain radiation therapy (HA-WBRT) and stereotactic radiosurgery (SRS) in patients with 10 to 30 brain metastases, and to describe a novel SRS strategy we term Spatially Partitioned Adaptive RadiosurgEry (SPARE). METHODS AND MATERIALS: A retrospective review identified SRS treatment plans with >10 brain metastases located >5 mm from the hippocampi. Our Gamma Knife Icon (GKI) SPARE (GKI-Spr) technique treats multiple metastases with single-fraction SRS partitioned over consecutive days while limiting the total treatment time to ≤60 minutes per day. Hippocampal and normal brain dosimetry were compared among GKI-Spr, single-fraction single-day GKI (GKI-Sfr), and 30 Gy in 10 fractions HA-WBRT. Dose metrics were converted to equivalent dose in 2 Gy fractions. RESULTS: Ten cases were analyzed. Compared with HA-WBRT, GKI-Spr significantly reduced the median equivalent dose in 2 Gy fractions hippocampal maximum point dose, mean dose, and dose to 40% of the hippocampi (D40%) by 86%, 93%, and 93%, respectively, and similarly for GKI-Sfr by 81%, 92%, and 91%, respectively. The normal brain median mean dose was reduced by 95% with GKI-Spr and 94% with GKI-Sfr. Compared with GKI-Sfr, GKI-Spr further reduced all normal brain and hippocampal dose metrics (P ≤ .014). CONCLUSIONS: GKI yields superior hippocampal and normal brain dosimetry compared with HA-WBRT, and GKI-Spr results in further dosimetric advantages.
Authors: John H Suh; Rupesh Kotecha; Samuel T Chao; Manmeet S Ahluwalia; Arjun Sahgal; Eric L Chang Journal: Nat Rev Clin Oncol Date: 2020-02-20 Impact factor: 66.675
Authors: Maria-Lisa Wilhelm; Mark K H Chan; Benedikt Abel; Florian Cremers; Frank-Andre Siebert; Stefan Wurster; David Krug; Robert Wolff; Jürgen Dunst; Guido Hildebrandt; Achim Schweikard; Dirk Rades; Floris Ernst; Oliver Blanck Journal: Strahlenther Onkol Date: 2020-06-25 Impact factor: 3.621