Clinac 2100 cd

C57BL/6AnCrl and BALB/cAnCrl female mice were injected subcutaneously with 2.10⁵ TC1, CT26, MC38, B16F10, or B16OVA cells in 100 µL of phosphate buffered saline (PBS 1×, Gibco, France) into the left flank. Tumor growth was monitored every 3 days with a caliper and groups were formed when tumor reached a mean diameter of 50–60 mm². All CT procedures were conducted in the Pharmacy Department of the University Hospital of Besançon (France). Mice were administered a single dose of intraperitoneal cisplatin (5 mg/kg) and 5-fluorouracil (25 mg/kg). After 2 days, mice were anesthetized by injection of ketamine (100 mg/kg) and xylazine (10 mg/kg) and received single-fraction beam photon irradiation (8 Gy) using Clinac 2100 CD (Varian Medical System) with a maximal energy of 6 MV and in 2D with one beam. Mice from control group were injected with the solvent used to dilute the drug (the Pharmacy Department of the University Hospital of Besançon, France). Anti-mouse CTLA-4 antibody (9H10, Euromedex) and anti-PD-1 (RMP1-14, Euromedex) injections (200 µg/mouse two times a week for 2 weeks) started 2 days prior to CT and 3 days after RT, respectively. All experimental studies were approved by the local ethics committee in accordance with the European Union’s Directive 2010/63.

The 6 MV photon beam of the Clinac 2100C/D dual-energy linear accelerator equipped with a 120-leaf Millennium multi-leaf collimator system and an aS1000 EPID (Varian Medical Systems, Inc., USA) was used in this study. In order to measure the DLG, sweeping gap fields of varying widths were used. To measure the MLC leakage, two completely blocked MLC fields (one with MLC bank A completely closing the field, as shown in Figure 1, and the other with MLC bank B closed in a similar manner) were employed since a single blocked field with both MLC banks closed at the center would result in over-estimating the MLC leakage due to the abutting leaf-end transmission. A plan was created in Eclipse™ TPS (Varian Medical Systems, Inc., USA) consisting of seven sweeping gap fields of widths 2 mm, 4 mm, 6 mm, 10 mm, 14 mm, 16 mm, and 20 mm, respectively, apart from two closed MLC fields and an open field. A reference field size of 10 cm × 10 cm was set by the X and Y jaws for all the above ten fields, which will hereafter be referred to as DLG fields. Each sweeping gap traveled across this reference field, and had a control point for every centimeter. The leaf sequences for the same were calculated using LMC.