scholarly journals Definition of internal target volumes based on planar X‐ray fluoroscopic images for lung and hepatic stereotactic body radiation therapy. Comparison to inhale/exhale CT technique

2020 ◽  
Vol 21 (8) ◽  
pp. 56-64
Author(s):  
David Sevillano ◽  
Luis Miguel Núñez ◽  
Margarita Chevalier ◽  
Feliciano García‐Vicente
Keyword(s):  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Internal Target ◽  
X Ray ◽  
Stereotactic Body Radiation ◽  
Ct Technique ◽  
Target Volumes ◽  
Definition Of

scholarly journals Investigation of 4D dose in volumetric modulated arc therapy-based stereotactic body radiation therapy: does fractional dose or number of arcs matter?

2020 ◽  
Vol 61 (2) ◽  
pp. 325-334
Author(s):  
Takashi Shintani ◽  
Mitsuhiro Nakamura ◽  
Yukinori Matsuo ◽  
Yuki Miyabe ◽  
Nobutaka Mukumoto ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Volumetric Modulated Arc Therapy ◽  
Target Volume ◽  
Lung Tumors ◽  
Internal Target ◽  
Internal Target Volume ◽  
Stereotactic Body Radiation ◽  
Arc Therapy ◽  
Fractional Dose

Abstract The aim of this study was to assess the impact of fractional dose and the number of arcs on interplay effects when volumetric modulated arc therapy (VMAT) is used to treat lung tumors with large respiratory motions. A three (fractional dose of 4, 7.5 or 12.5 Gy) by two (number of arcs, one or two) VMAT plan was created for 10 lung cancer cases. The median 3D tumor motion was 17.9 mm (range: 8.2–27.2 mm). Ten phase-specific subplans were generated by calculating the dose on each respiratory phase computed tomography (CT) scan using temporally assigned VMAT arcs. We performed temporal assignment of VMAT arcs using respiratory information obtained from infrared markers placed on the abdomens of the patients during CT simulations. Each phase-specific dose distribution was deformed onto exhale phase CT scans using contour-based deformable image registration, and a 4D plan was created by dose accumulation. The gross tumor volume dose of each 4D plan (4D GTV dose) was compared with the internal target volume dose of the original plan (3D ITV dose). The near-minimum 4D GTV dose (D99%) was higher than the near-minimum 3D internal target volume (ITV) dose, whereas the near-maximum 4D GTV dose (D1%) was lower than the near-maximum 3D ITV dose. However, the difference was negligible, and thus the 4D GTV dose corresponded well with the 3D ITV dose, regardless of the fractional dose and number of arcs. Therefore, interplay effects were negligible in VMAT-based stereotactic body radiation therapy for lung tumors with large respiratory motions.

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