Click here to


Are you sure ?

Yes, do it No, cancel

Quantification of Standard and FFF Beam Perturbations with a New Linac Mounted Transmission Detector

N Bassiri*, J McCulloch , Z Shi , S Stathakis , D Saenz , N Kirby , N Papanikolaou , K Rasmussen , Ut Health San Antonio, San Antonio, TX


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: The purpose of this work is to quantify the effect that a new transmission detector (Delta4 Discover – Scandidos Uppsala Sweden), has with the beam profile and percent depth dose (PDD) of an Elekta Versa HD Linear Accelerator using standard and flattening filter free (FFF) beams.

Methods: The energies that are under examination are a 6 MV and an 18 MV x-ray beam. The data was collected using a PTW Water Tank and a PTW Semflex 2167 Ion Chamber. The beam profile of a 10x10 cm2 and 20x20 cm2 field size of the following beam parameters were taken, 6 MV, 6 MV flattening filter free (FFF), 10 MV, 10 MV FFF, and 18 MV, were taken with and without the Discover Disk. Alterations of the beam profile were measured with the full width at half maximum of the beam profile with and without the Discover Disk mounted on the linear accelerator. The percent depth dose was also taken and analyzed for each of the aforementioned beam energies and field sizes. Next, a two sided t-test is applied to examine if the Discover Disk had any statistically significant impact on the signal produced by the ion chamber. A significance level of 0.05 was used.

Results: Based upon the results of the statistical tests, there was no significant impact on the beam profiles or PDD due to the presence of the transmission detector on any of the photon energies. Max field size deviation was 1.42 mm for the 6 MV 10x10 cm2 beam. Max PDD deviation was 1.73 mm difference for the 10 MV FFF 20x20 cm2 beam.

Conclusion: Based upon the results of tests, it can be concluded that the presence of the Discover Disk has no statistically significant impact on the beam profile.


Not Applicable / None Entered.


Not Applicable / None Entered.

Contact Email