BACKGROUND AND PURPOSE: This study aimed to investigate the magnitude of interfraction prostate bed motion during radiotherapy using both the implanted gold seed fiducials and the soft tissue registration and to define reasonable planning target volume (PTV) margins for different localization methods. MATERIAL AND METHODS: Thirteen prostatectomized prostate cancer patients, after implanting four gold seed fiducials into their prostate bed, were imaged daily using a pretreatment cone-beam computed tomography (CBCT). Linear and the rotational prostate bed motion (PBM) was measured for 466 CBCTs. RESULTS: The linear PBM mean and standard deviation values in millimeters are 0.0 ± 0.5, 0.7 ± 2.1 and 0.8 ± 1.6 in the LR, SI and AP axes, respectively. In 20% of the fractions the rotation of the prostate bed in sagittal plane exceeds ±6° and in 5% it exceeds ±10° from the position on the planning CT. In the transversal and coronal planes 1% and 2% of it exceeds ±6°. The PTV margins are 2.4, 6.5 and 6.6mm in the LR, SI and AP axes, respectively, if imaging is performed for the first three treatment fractions. CONCLUSION: The linear PBM is largest in the SI and AP axis, whereas the rotation is largest in the sagittal plane. Bone localization during the first three treatment fractions can reduce PTV margins by 52%, 18% and 10% in the LR, SI and AP axes, respectively, whereas in daily CBCT the use of the gold seed fiducials seems profitable.
BACKGROUND AND PURPOSE: This study aimed to investigate the magnitude of interfraction prostate bed motion during radiotherapy using both the implanted gold seed fiducials and the soft tissue registration and to define reasonable planning target volume (PTV) margins for different localization methods. MATERIAL AND METHODS: Thirteen prostatectomized prostate cancerpatients, after implanting four gold seed fiducials into their prostate bed, were imaged daily using a pretreatment cone-beam computed tomography (CBCT). Linear and the rotational prostate bed motion (PBM) was measured for 466 CBCTs. RESULTS: The linear PBM mean and standard deviation values in millimeters are 0.0 ± 0.5, 0.7 ± 2.1 and 0.8 ± 1.6 in the LR, SI and AP axes, respectively. In 20% of the fractions the rotation of the prostate bed in sagittal plane exceeds ±6° and in 5% it exceeds ±10° from the position on the planning CT. In the transversal and coronal planes 1% and 2% of it exceeds ±6°. The PTV margins are 2.4, 6.5 and 6.6mm in the LR, SI and AP axes, respectively, if imaging is performed for the first three treatment fractions. CONCLUSION: The linear PBM is largest in the SI and AP axis, whereas the rotation is largest in the sagittal plane. Bone localization during the first three treatment fractions can reduce PTV margins by 52%, 18% and 10% in the LR, SI and AP axes, respectively, whereas in daily CBCT the use of the gold seed fiducials seems profitable.
Authors: Florent Vilotte; Mickael Antoine; Maxime Bobin; Igor Latorzeff; Stéphane Supiot; Pierre Richaud; Laurence Thomas; Nicolas Leduc; Stephane Guérif; Jone Iriondo-Alberdi; Renaud de Crevoisier; Paul Sargos Journal: Front Oncol Date: 2017-03-09 Impact factor: 6.244
Authors: Sara Elakshar; James Man Git Tsui; Michael Jonathan Kucharczyk; Nada Tomic; Ziad Simon Fawaz; Boris Bahoric; Joseph Papayanatos; Ahmad Chaddad; Tamim Niazi Journal: Technol Cancer Res Treat Date: 2019-01-01