Page 55 - Fisica in Medicina n° 4 - 2017

commissioning data The commissioning of DC was performed in the Pisa Santa Chiara Hospital in a previous thesis work [8]. This section just mentions briefly the data required: Machine Geometry file: contains information about the linac SAD, largest field size, gantry and collimator rotation directions, couch rotations and motion directions, and jaws motion direction. Central axis beam data: contains PDDs (field size and SSD must be defined for each file). Field Size Output file: contains a table with the cGy/MU at certain depth for different field sizes. Calibration file: contains the calibration details; SDD, field size, depth and dose rate. Diagonal fan line file: off-axis values measured in water for different depths with fixed SDD. In-transit mode it is also necessary to acquire a series of EPID images using various water thickness and field sizes, ranging from 5 to 40 cm and 1X1 cm2 to 20X20 cm2, respectively. The center of the water volume must be always at the isocenter of the linac [10, 11]. The workflow of DC for pre-treatment and in-transit modes in the SCH is well described in a previous thesis work [13], here we will just give a brief explanation. Pre-treatment mode (in-air) The first step to perform DC calculations in pre-treatment mode is to export the DICOM files of the approved plan from the TPS: the beam geometry (RP), the three dimensional dose grid (RD), the