Purpose: To develop a solid phantom that is capable of replacing the computerized water scanning system in its entirety. This phantom is designed such that it is easy to install at the head of the gantry and within a few minutes of data collection, the user can extract profiles and percent depth dose (PDD) data quickly through the software associated with this device.
Methods: Using Monte Carlo package MCNP5 we modeled our LINAC (Varian Edge 6FFF), and confirmed that simulated PDD (10x10cm^2) and profiles at different depths agree favorably with measured data acquired in a 3D water tank (40x40x40cm^3). We then created a virtual solid device placed at 60cm source to surface distance (SSD) on modeled Linac, which is near closest distance to gantry head. The device modeled in MCNP consists of two new phantoms that interlock and are modeled using published data for solid water material and a detector grid with much smaller volume and special geometrical shape to accommodate acquisition of data for PDD and profiles. Scoring points were placed in virtual phantom representing arrays of diodes for future prototype for the measurements of PDD and profiles. New data are acquired through simulation and compared with data from the 3D water tank to demonstrate the feasibility of this new device.
Results: Simulated PDD and profiles in new designed solid water phantoms agree favorably with data from a 3D water tank (<1% error). The effective mass of the prototype phantom for profiles is 9% of 3D water tank while the phantom for PDD is only 1%, indicating much easier handling and setup.
Conclusion: Monte Carlo simulations show the feasibility of our new solid phantoms to replace 3D scanning water tank from the points of saving time in data acquisition, accurate dosimetry evaluation and convenience of equipment setup.
Not Applicable / None Entered.