TY - JOUR
T1 - MR-guided Gated Stereotactic Radiation Therapy Delivery for Lung, Adrenal, and Pancreatic Tumors
T2 - A Geometric Analysis
AU - van Sörnsen de Koste, John R
AU - Palacios, Miguel A
AU - Bruynzeel, Anna M E
AU - Slotman, Ben J
AU - Senan, Suresh
AU - Lagerwaard, Frank J
PY - 2018/11/15
Y1 - 2018/11/15
N2 - PURPOSE: We implemented magnetic resonance-guided breath-hold stereotactic body radiation therapy in combination with visual feedback using the MRIdian system. Both accuracy of gated delivery and reproducibility of tumor positions were studied.METHODS AND MATERIALS: Tumor tracking is realized through repeated magnetic resonance imaging in a single sagittal plane at 4 frames per second with deformable image registration. An in-room monitor allowed visualization of the tracked gross tumor volume (GTV) contour and the planning target volume (PTV) (GTV + 3 mm), which was the gating boundary. For each delivery, a predefined threshold-region of interest percentage (ROI%) allows a percentage of GTV area to be outside the gating boundary before a beam-hold is triggered. Accuracy of gated delivery and tumor position reproducibility during breath-holds was analyzed for 15 patients (87 fractions) with lung, adrenal, and pancreas tumors. For each fraction, we analyzed (1) reproducibility of system-tracked GTV centroid position within the PTV; (2) geometric coverage of GTV area within the PTV; (3) treatment duty cycle efficiency; (4) effects of threshold ROI% settings on treatment duty cycle efficiency and GTV area coverage; and (5) beam-off latency effect on mean GTV coverage.RESULTS: For lung, adrenal, and pancreatic tumors, grouped 5th to 95th percentile distributions of GTV centroid positions in the dorsoventral direction, relative to PTV-center of mass (COM), were, respectively, -3.3 mm to 2.8 mm, -2.5 mm to 3.7 mm, and -4.4 mm to 2.9 mm. Corresponding distributions in the craniocaudal direction were -2.6 mm to 4.6 mm, -4.1 mm to 4.4 mm, and -4.4 mm to 4.5 mm, respectively. Mean GTV areas encompassed during beam-on for all fractions were 94.6%, 94.3%, and 95.3% for lung, adrenal, and pancreas tumors, respectively. Mean treatment duty cycle efficiency ranged from 67% to 87% for these tumors. Use of higher threshold-ROI% resulted in increased duty cycle efficiency, at the cost of a small decrease in GTV area coverage. The beam-off latency had a marginal impact on the GTV coverage.CONCLUSIONS: Gated stereotactic body radiation therapy delivery during breath-hold, real-time magnetic resonance guidance resulted in at least 95% geometric GTV coverage in lung, adrenal, and pancreatic tumors.
AB - PURPOSE: We implemented magnetic resonance-guided breath-hold stereotactic body radiation therapy in combination with visual feedback using the MRIdian system. Both accuracy of gated delivery and reproducibility of tumor positions were studied.METHODS AND MATERIALS: Tumor tracking is realized through repeated magnetic resonance imaging in a single sagittal plane at 4 frames per second with deformable image registration. An in-room monitor allowed visualization of the tracked gross tumor volume (GTV) contour and the planning target volume (PTV) (GTV + 3 mm), which was the gating boundary. For each delivery, a predefined threshold-region of interest percentage (ROI%) allows a percentage of GTV area to be outside the gating boundary before a beam-hold is triggered. Accuracy of gated delivery and tumor position reproducibility during breath-holds was analyzed for 15 patients (87 fractions) with lung, adrenal, and pancreas tumors. For each fraction, we analyzed (1) reproducibility of system-tracked GTV centroid position within the PTV; (2) geometric coverage of GTV area within the PTV; (3) treatment duty cycle efficiency; (4) effects of threshold ROI% settings on treatment duty cycle efficiency and GTV area coverage; and (5) beam-off latency effect on mean GTV coverage.RESULTS: For lung, adrenal, and pancreatic tumors, grouped 5th to 95th percentile distributions of GTV centroid positions in the dorsoventral direction, relative to PTV-center of mass (COM), were, respectively, -3.3 mm to 2.8 mm, -2.5 mm to 3.7 mm, and -4.4 mm to 2.9 mm. Corresponding distributions in the craniocaudal direction were -2.6 mm to 4.6 mm, -4.1 mm to 4.4 mm, and -4.4 mm to 4.5 mm, respectively. Mean GTV areas encompassed during beam-on for all fractions were 94.6%, 94.3%, and 95.3% for lung, adrenal, and pancreas tumors, respectively. Mean treatment duty cycle efficiency ranged from 67% to 87% for these tumors. Use of higher threshold-ROI% resulted in increased duty cycle efficiency, at the cost of a small decrease in GTV area coverage. The beam-off latency had a marginal impact on the GTV coverage.CONCLUSIONS: Gated stereotactic body radiation therapy delivery during breath-hold, real-time magnetic resonance guidance resulted in at least 95% geometric GTV coverage in lung, adrenal, and pancreatic tumors.
U2 - https://doi.org/10.1016/j.ijrobp.2018.05.048
DO - https://doi.org/10.1016/j.ijrobp.2018.05.048
M3 - Article
C2 - 30061007
SN - 0360-3016
VL - 102
SP - 858
EP - 866
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 4
ER -