Eclipse version 8

Treatment plans were generated using Eclipse version 8.6 (copyright Varian, Palo Alto). Treatment delivery was done using a 21ix Varian Linear Accelerator. VMAT was delivered in two to three arcs with maximum range of 360-degree with simultaneous variation of the gantry speed, dose rate, and leaf position. An energy of 10 MV and a max dose rate of 600 monitor units per minute were used. Treatment prescriptions are summarized in Table 2. Treatment was delivered using a simultaneous integrated boost (SIB) technique (Figure 2). Orthogonal kilovoltage images taken before the treatment confirmed patient position.

Patients were immobilized in a thermoplastic flat shell (Klarity) with infrared markers for image guidance. Contrast-enhanced computed tomography (CT) images were acquired with a Light Speed RT instrument (GE Healthcare) at a slice thickness of 1.25 mm. Treatment plans were developed with BrainSCAN version 5.3.1 (BrainLAB), iPlan RT Dose version 4.5.1 (BrainLAB), or Eclipse version 8.6 (Varian Medical Systems). Contrast-enhanced CT images were fused with contrast-enhanced magnetic resonance imaging (MRI) images on a radiotherapy planning system.
Thirty-five patients underwent radiotherapy using the Novalis system with 6-MV linear accelerator, m3 micro-multileaf collimator, the ExacTrac X-ray system, and the Robotic Tilt Motion mounted on the Exact Couch top (BrainLAB). Five patients were treated with the Vero4DRT (Hitachi, Ltd.), and one patient was treated with the Clinac iX (Varian Medical Systems).
Gross tumor volume (GTV) was defined as the volume of the tumor on contrast-enhanced T1-weighted MRI. The clinical target volume (CTV) was defined as the GTV with a thickened dural tail. The planning target volume (PTV) was defined as the CTV plus a 1–2-mm margin in all directions. CFSRT was performed using multiple dynamic conformal arc therapy (DCAT) or by intensity-modulated radiotherapy (IMRT). The PTV was covered by 90% of the prescribed dose in both the DCAT and IMRT plans.

The selected patients were in the supine position on 10°-15° angle breast-tilting board with both the arms elevated and immobilized using Vac-Lock devices. The extent of the breast parenchyma was marked using radio-opaque non-metallic wire for the target volume delineation via palpation. Simulation CT images of 2.5 mm thickness were acquired using a LightSpeed RT16 CT scanner (GE Healthcare, Waukesha, WI). Images were sent to Eclipse version 8.9 (Varian Medical Systems, Palo Alto, CA) for delineation of the target volume and organs at risk (OARs), and dose calculation.

The patients were immobilized in a head–neck–shoulder thermoplastic mask with their arms resting at their sides, while a tattoo line along the longitudinal axis of the body was drawn to facilitate setup. The GTV (Gross Tumor Volume) of the primary tumor and metastatic lesions was determined, and the CTV (Clinical Target Volume) included the whole brain, spinal cord, and terminal cisternae. The PGTV (Planning Gross Target Volume)/ PCTV (Planning Clinical Target Volume) was formed by adding a margin of 3 ~ 5 mm to the GTV/CTV. The following median were recorded: volume of PCTV 2146.2 cm³ (1965.67–2628.54 cm³), length of PCTV 76 cm (57.5–87 cm), fraction 20 (20–24), prescribed dose of PGTV 45 Gy (40–54 Gy). The detailed information was tabulated (Table 1). All planning target volumes were optimized in synchrony using a commercial TPS (Eclipse version 8.9; Varian Medical Systems, Palo Alto, CA). Colinear isocenters (iso1, iso2, and iso3) were placed in sequence. The iso1 was for cranial PCTV, iso2 was for the upper spinal cord PCTV, and iso3 was for the lower spinal cord PCTV. The field set iso1 consisted of five or seven fields with an average gantry angle, and the field sets iso2 and iso3 consisted of fields with three angles: 240°, 120°, and 180°.

Left breast cancer patients who visited our institution from November 2014 to April 2015 were included in this study. Among them, 20 patients were randomly selected and further investigated. Before simulation computed tomography (CT), whole breast tissue of each patient was wired using radio-opaque material. Simulation CT was performed using a LightSpeed RT16 CT scanner (GE Healthcare, Waukesha, WI) with 2.5 mm thickness. When simulation CT was conducted, all patients used a vac-lock immobilization device with a 10 degree tilted breast board. Eclipse version 8.9 (Varian Medical Systems, Palo Alto, CA) was used as a radiation treatment planning system.
The planning target volume (PTV) of the left breast, heart, left ventricle, both lung, and spinal cord were delineated. To evaluate the dose delivered to the skin, 2 mm thickness skin (2-mm skin) and 3 mm thickness skin (3-mm skin) were also contoured. The average volume of PTV was 453.6 cm³ (range: 180.1 to 761.4 cm³). For the consistency of target volume and OARs, all of these were contoured by a single experienced radiation oncologist. The PTV was based on the RTOG atlas [12 ]. However, the PTV was edited according to the wired area, surgical clip, and seroma, and we trimmed the anterior border by 3 mm from the skin for skin-sparing treatment planning.

For the simulations, patients underwent a CT scan with LightSpeed RT16 CT scanner (General Electric Company, Waukesha, WI). They were immobilized on a breast-tilting board with both arms in the up position with a vac-lock immobilization device. The boundaries of the remaining breast tissue were wired by nonmetallic thread through palpation and visual inspection. The CT images were acquired in 2.5-mm thickness. Eclipse version 8.9 (Varian Medical System, Palo Alto, CA) was used to process CT images, contour the regions of interest, and perform 2 kinds of dose calculations.
The clinical target volume (CTV) of the left breast (remaining breast parenchyma), levels I, II, and III of the axilla, heart, lung, and spinal cord were delineated. For the consistency and reliability of target volume and organs at risk (OARs), all of these were contoured by 1 experienced radiation oncologist and were based on the Radiation Therapy Oncology Group (RTOG) atlas.^{[7 ]} The breast CTV was edited according to the wired area and some specific CT finding such as a surgical clip and seroma, and we trimmed the anterior border by 3 mm from the skin for skin-sparing treatment planning.