Perry B Johnson1, Maria I Monterroso2, Fei Yang2, Elizabeth Bossart3, Amir Keyvanloo2, Eric A Mellon2. 1. Radiation Oncology/Biomedical Engineering, University of Miami, Miami, Florida, USA. Electronic address: p.johnson41@med.miami.edu. 2. Radiation Oncology, University of Miami, Miami, Florida, USA. 3. Radiation Oncology/Biomedical Engineering, University of Miami, Miami, Florida, USA.
Abstract
OBJECTIVE: Shot-within-shot (SWS) optimization is a new planning technique that relies on various combinations of shot weighting and prescription isodose line (IDL) to reduce beam-on time. The method differs from other planning techniques that incorporate mixed collimation, multiple stereotactic coordinates, and traditionally low prescription IDLs (<60%). In this work, we evaluate the percentage of brain metastasis for which the method can be applied, the magnitude of the resultant time savings, and the possible tradeoffs in plan quality. METHODS: A retrospective analysis was performed on 75 patients treated for 241 metastatic lesions in the brain. For each lesion, the original planning metrics related to target coverage, conformity, gradient, and beam-on time were recorded. A subset of lesions were selected for replanning using the SWS technique based on size, shape, and proximity to critical structures. Two replans were done, a reference plan was prescribed at the 50% IDL, and an optimized plan was prescribed at an IDL typically >50%. Planning metrics were then compared among the original plan and the 2 replans. RESULTS: More than a third (39%) of the brain metastases were eligible for the SWS technique. For these lesions, the differences between the original plan and reference SWS plan were as follows: ΔV12Gy < 0.5 cc in 93% of cases, ΔV12Gy < 0.5 cc in 100% of cases, Δselectivity < 0.1 in 79% of cases. Negligible differences were seen between the 2 replans in terms of Δselectivity and ΔV12Gy; ΔGI < 5% in 99% of cases. After optimization, beam-on time was reduced by 25%-30% in approximately 40%-50% of eligible lesions when compared with the reference SWS plan (ΔTmax = 42%). In comparison with the original plan, beam-on time was reduced even further, ΔT > 50% in 20% of cases (ΔTmax = 70%). CONCLUSIONS: This work demonstrates clinically that optimization using the shot-within-shot technique can reduce beam-on time without degrading treatment plan quality.
OBJECTIVE: Shot-within-shot (SWS) optimization is a new planning technique that relies on various combinations of shot weighting and prescription isodose line (IDL) to reduce beam-on time. The method differs from other planning techniques that incorporate mixed collimation, multiple stereotactic coordinates, and traditionally low prescription IDLs (<60%). In this work, we evaluate the percentage of brain metastasis for which the method can be applied, the magnitude of the resultant time savings, and the possible tradeoffs in plan quality. METHODS: A retrospective analysis was performed on 75 patients treated for 241 metastatic lesions in the brain. For each lesion, the original planning metrics related to target coverage, conformity, gradient, and beam-on time were recorded. A subset of lesions were selected for replanning using the SWS technique based on size, shape, and proximity to critical structures. Two replans were done, a reference plan was prescribed at the 50% IDL, and an optimized plan was prescribed at an IDL typically >50%. Planning metrics were then compared among the original plan and the 2 replans. RESULTS: More than a third (39%) of the brain metastases were eligible for the SWS technique. For these lesions, the differences between the original plan and reference SWS plan were as follows: ΔV12Gy < 0.5 cc in 93% of cases, ΔV12Gy < 0.5 cc in 100% of cases, Δselectivity < 0.1 in 79% of cases. Negligible differences were seen between the 2 replans in terms of Δselectivity and ΔV12Gy; ΔGI < 5% in 99% of cases. After optimization, beam-on time was reduced by 25%-30% in approximately 40%-50% of eligible lesions when compared with the reference SWS plan (ΔTmax = 42%). In comparison with the original plan, beam-on time was reduced even further, ΔT > 50% in 20% of cases (ΔTmax = 70%). CONCLUSIONS: This work demonstrates clinically that optimization using the shot-within-shot technique can reduce beam-on time without degrading treatment plan quality.
Authors: J L Nakamura; L J Verhey; V Smith; P L Petti; K R Lamborn; D A Larson; W M Wara; M W McDermott; P K Sneed Journal: Int J Radiat Oncol Biol Phys Date: 2001-12-01 Impact factor: 7.038
Authors: Ashish Jani; Tzlil Rozenblat; Andrew M Yaeh; Tavish Nanda; Shumaila Saad; Yasir H Qureshi; Wenzheng Feng; Michael B Sisti; Jeffrey N Bruce; Guy M McKhann; Jeraldine Lesser; Andrew B Lassman; Steven R Isaacson; Tony J C Wang Journal: Neurosurgery Date: 2015-07 Impact factor: 4.654
Authors: Yaacov Richard Lawrence; X Allen Li; Issam el Naqa; Carol A Hahn; Lawrence B Marks; Thomas E Merchant; Adam P Dicker Journal: Int J Radiat Oncol Biol Phys Date: 2010-03-01 Impact factor: 7.038
Authors: J C Flickinger; D Kondziolka; B E Pollock; A H Maitz; L D Lunsford Journal: Int J Radiat Oncol Biol Phys Date: 1997-06-01 Impact factor: 7.038
Authors: Kara D Romano; Daniel M Trifiletti; Allison Garda; Zhiyuan Xu; David Schlesinger; William T Watkins; Brian Neal; James M Larner; Jason P Sheehan Journal: World Neurosurg Date: 2016-11-17 Impact factor: 2.104
Authors: Timothy Korytko; Tomas Radivoyevitch; Valdir Colussi; Barry W Wessels; Kunjan Pillai; Robert J Maciunas; Douglas B Einstein Journal: Int J Radiat Oncol Biol Phys Date: 2005-10-14 Impact factor: 7.038
Authors: David W Andrews; Charles B Scott; Paul W Sperduto; Adam E Flanders; Laurie E Gaspar; Michael C Schell; Maria Werner-Wasik; William Demas; Janice Ryu; Jean-Paul Bahary; Luis Souhami; Marvin Rotman; Minesh P Mehta; Walter J Curran Journal: Lancet Date: 2004-05-22 Impact factor: 79.321
Authors: Mayur Sharma; Xuefei Jia; Manmeet Ahluwalia; Gene H Barnett; Michael A Vogelbaum; Samuel T Chao; John H Suh; Erin S Murphy; Jennifer S Yu; Lilyana Angelov; Alireza M Mohammadi Journal: Cancer Med Date: 2017-08-04 Impact factor: 4.452
Authors: Terence T Sio; Sunyoung Jang; Sung-Woo Lee; Bruce Curran; Anil P Pyakuryal; Edward S Sternick Journal: J Appl Clin Med Phys Date: 2014-01-06 Impact factor: 2.102