scholarly journals To evaluate treatment compliance of concurrent chemo -radiotherapy for pancreatic cancer patients treated with volumetric modulated arc therapy (VMAT)

Radiography ◽  
2020 ◽  
Vol 26 ◽  
pp. S35
Author(s):  
Alice Smith ◽  
Lynsey Devlin ◽  
Aileen Duffton
2020 ◽  
Vol 61 (5) ◽  
pp. 755-765
Author(s):  
Makoto Sasaki ◽  
Mitsuhiro Nakamura ◽  
Tomohiro Ono ◽  
Ryo Ashida ◽  
Michio Yoshimura ◽  
...  

Abstract The purpose of this study was to assess the positional repeatability of internal and external markers among multiple breath-hold (BH) sessions and evaluate the positional variation of these markers within BH sessions for volumetric-modulated arc therapy (VMAT) for pancreatic cancer patients. A total of 13 consecutive pancreatic cancer patients with an internal marker were enrolled. Single full-arc coplanar VMAT was delivered under end-exhalation BH conditions while monitoring the internal marker with kilovoltage (kV) X-ray fluoroscopy. Positional repeatability of the internal and external markers was determined by the difference between the reference and zero position in all BH sessions, and positional variation was defined by the displacement from the reference position in each BH session during megavolt beam delivery. The overall positional repeatability was 0.6 ± 1.5 mm in the X-axis for the centroid of the internal marker (CoIM), −0.1 ± 2.2 mm in the Y-axis for the CoIM, and 0.8 ± 2.2 mm for the external marker. The frequency of an internal marker position appearing > 2 mm from the reference position in the Y-axis, despite the external marker position being ≤2 mm from the reference position, ranged from 0.0 to 39.9% for each patient. Meanwhile, the proportion of sessions with positional variation ≤2 mm was 93.2 and 98.7% for the CoIM and external marker, respectively. External marker motion can be used as a surrogate for pancreatic tumor motion during BH-VMAT delivery; however, margins of ~5 mm were required to ensure positional repeatability.


2020 ◽  
Author(s):  
Makoto Sasaki ◽  
Mitsuhiro Nakamura ◽  
Tomohiro Ono ◽  
Ryo Ashida ◽  
Michio Yoshimura ◽  
...  

Abstract Background: To assess the positional repeatability of internal and external markers among multiple breath-hold (BH) sessions and assess the positional variation of these markers within BH sessions for volumetric-modulated arc therapy (VMAT) for pancreatic cancer patients. Methods: A total of 13 consecutive pancreatic cancer patients with an internal marker were enrolled. Single full-arc coplanar VMAT was delivered under end-exhalation (EE) BH conditions, while monitoring the internal marker with kilovoltage (kV) X-ray fluoroscopy. Positional repeatability of internal and external markers was indicated by the difference between the reference marker position and the marker position at the beginning of each BH session, and positional variation was indicated by the maximum displacement of the marker during each BH session. Results: The overall positional repeatability was 0.6 ± 1.5 mm in the X-axis for the centroid of the internal marker (CoIM), -0.1 ± 2.2 mm in the Y-axis for the CoIM, and 0.8 ± 2.2 mm for the external marker. An internal marker position > 2 mm from the reference position in the Y-axis was observed in 19.1% of all BH sessions, despite the external marker position being ≤ 2 mm from the reference position. Meanwhile, the proportion of sessions with positional variation ≤ 2 mm was 93.2% and 98.7% for the CoIM and external marker, respectively. Conclusions: External marker motion can be used as a surrogate for pancreatic tumor motion during BH-VMAT; however, an optimal internal margin is required to ensure positional repeatability.


2021 ◽  
Author(s):  
Zuzanna Krawczyk ◽  
Robert Szmurlo ◽  
Pawel Zawadzki ◽  
Estera Kot ◽  
Jacek Starzynski ◽  
...  

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