Comparison Study of portal dosimetry with PTW 2-D array system for IMRT for specific QA in Breast Cancer patients

Abstract

The IMRT (Intensity Modulation Radiation Therapy) and rapid arc give uniform desired dose distribution to the target volume with adequate sparing of the nearby critical structures. The portal dosimetry system and 2-D array system are widely used as relative dosimetry detectors, because of their consistency in results, less time consumption, and ease of use. In the current work, twenty cases of dynamic IMRT plans were selected for the patient-specific QA (Quality Assurance) study using portal dosimetry and a 2-D(Two Dimensional) array set square pattern ,spaced 10 mm apart across the entire measurement area using Detectors Number 729 (Planar dose comparison was carried out with gamma criteria of 3% -3 mm (DTA)(Distance To Agreement). For the portal, dosimetry system area gamma, passing the 3%-3mm gamma was chosen. The current study Varian Linac Unique at El Hussein Hospital Electronic Portal Imager Device (EPID) is a flat panel X-ray imager with a large area active matrix readout structure, made up of phosphor or photoconductor. The 2-D array system consists of 1020 parallel plate ion chambers arranged in a 32x32 grid, with an interdetector spacing of 7.619 mm. Each detector has a diameter of 4.5 mm, a height of 5 mm, and a chamber volume of 0.02 cc. IMRT in pre-treatments to help select Pγ%< 1 point and relevant transition criteria to assess the reproducibility of treatment fractions. Compared to a 2D Array system., although the 2D array has limited sampling capabilities. The portal dosimetry soft for portal imager device (EPID) has a good result for breast cancer plan evaluation versus 2D array results and agreement with international publish data, in addition, reduces the time for calibration due to there is no need for extended cable for measurement is compared with a 2D array