PURPOSE: To evaluate the residual setup error and intrafraction motion following kilovoltage cone-beam CT (CBCT) image guidance, for immobilized spine stereotactic body radiotherapy (SBRT) patients, with positioning corrected for in all six degrees of freedom. METHODS AND MATERIALS: Analysis is based on 42 consecutive patients (48 thoracic and/or lumbar metastases) treated with a total of 106 fractions and 307 image registrations. Following initial setup, a CBCT was acquired for patient alignment and a pretreatment CBCT taken to verify shifts and determine the residual setup error, followed by a midtreatment and posttreatment CBCT image. For 13 single-fraction SBRT patients, two midtreatment CBCT images were obtained. Initially, a 1.5-mm and 1° tolerance was used to reposition the patient following couch shifts which was subsequently reduced to 1 mm and 1° degree after the first 10 patients. RESULTS: Small positioning errors after the initial CBCT setup were observed, with 90% occurring within 1 mm and 97% within 1°. In analyzing the impact of the time interval for verification imaging (10 ± 3 min) and subsequent image acquisitions (17 ± 4 min), the residual setup error was not significantly different (p > 0.05). A significant difference (p = 0.04) in the average three-dimensional intrafraction positional deviations favoring a more strict tolerance in translation (1 mm vs. 1.5 mm) was observed. The absolute intrafraction motion averaged over all patients and all directions along x, y, and z axis (± SD) were 0.7 ± 0.5 mm and 0.5 ± 0.4 mm for the 1.5 mm and 1 mm tolerance, respectively. Based on a 1-mm and 1° correction threshold, the target was localized to within 1.2 mm and 0.9° with 95% confidence. CONCLUSION: Near-rigid body immobilization, intrafraction CBCT imaging approximately every 15-20 min, and strict repositioning thresholds in six degrees of freedom yields minimal intrafraction motion allowing for safe spine SBRT delivery.
PURPOSE: To evaluate the residual setup error and intrafraction motion following kilovoltage cone-beam CT (CBCT) image guidance, for immobilized spine stereotactic body radiotherapy (SBRT) patients, with positioning corrected for in all six degrees of freedom. METHODS AND MATERIALS: Analysis is based on 42 consecutive patients (48 thoracic and/or lumbar metastases) treated with a total of 106 fractions and 307 image registrations. Following initial setup, a CBCT was acquired for patient alignment and a pretreatment CBCT taken to verify shifts and determine the residual setup error, followed by a midtreatment and posttreatment CBCT image. For 13 single-fraction SBRT patients, two midtreatment CBCT images were obtained. Initially, a 1.5-mm and 1° tolerance was used to reposition the patient following couch shifts which was subsequently reduced to 1 mm and 1° degree after the first 10 patients. RESULTS: Small positioning errors after the initial CBCT setup were observed, with 90% occurring within 1 mm and 97% within 1°. In analyzing the impact of the time interval for verification imaging (10 ± 3 min) and subsequent image acquisitions (17 ± 4 min), the residual setup error was not significantly different (p > 0.05). A significant difference (p = 0.04) in the average three-dimensional intrafraction positional deviations favoring a more strict tolerance in translation (1 mm vs. 1.5 mm) was observed. The absolute intrafraction motion averaged over all patients and all directions along x, y, and z axis (± SD) were 0.7 ± 0.5 mm and 0.5 ± 0.4 mm for the 1.5 mm and 1 mm tolerance, respectively. Based on a 1-mm and 1° correction threshold, the target was localized to within 1.2 mm and 0.9° with 95% confidence. CONCLUSION: Near-rigid body immobilization, intrafraction CBCT imaging approximately every 15-20 min, and strict repositioning thresholds in six degrees of freedom yields minimal intrafraction motion allowing for safe spine SBRT delivery.
Authors: Ameen Al-Omair; Laura Masucci; Laurence Masson-Cote; Mikki Campbell; Eshetu G Atenafu; Amy Parent; Daniel Letourneau; Eugene Yu; Raja Rampersaud; Eric Massicotte; Stephen Lewis; Albert Yee; Isabelle Thibault; Michael G Fehlings; Arjun Sahgal Journal: Neuro Oncol Date: 2013-10 Impact factor: 12.300
Authors: David C Weksberg; James N Yang; Alda L Tam; Jing Li; Xin A Wang; Zhongxiang Zhao; Stephen E McRae; Stephen H Settle; Laurence D Rhines; Eric L Chang; Paul D Brown; Amol J Ghia Journal: J Radiosurg SBRT Date: 2016
Authors: Rachit Kumar; Anick Nater; Ahmed Hashmi; Sten Myrehaug; Young Lee; Lijun Ma; Kristin Redmond; Simon S Lo; Eric L Chang; Albert Yee; Charles G Fisher; Michael G Fehlings; Arjun Sahgal Journal: Neurooncol Pract Date: 2015-07-27
Authors: Mahmud Mossa-Basha; Peter C Gerszten; Sten Myrehaug; Nina A Mayr; William Tc Yuh; Pejman Jabehdar Maralani; Arjun Sahgal; Simon S Lo Journal: Br J Radiol Date: 2019-07-25 Impact factor: 3.039
Authors: Arjun Sahgal; Eshetu G Atenafu; Sam Chao; Ameen Al-Omair; Nicholas Boehling; Ehsan H Balagamwala; Marcelo Cunha; Isabelle Thibault; Lilyana Angelov; Paul Brown; John Suh; Laurence D Rhines; Michael G Fehlings; Eric Chang Journal: J Clin Oncol Date: 2013-08-19 Impact factor: 44.544
Authors: Zain A Husain; Isabelle Thibault; Daniel Letourneau; Lijun Ma; Harald Keller; John Suh; Veronica Chiang; Eric L Chang; Raja K Rampersaud; James Perry; David A Larson; Arjun Sahgal Journal: CNS Oncol Date: 2013-05