(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose: Quality assurance equipment which is used for linear accelerators to ensure patients getting precisely accurate radiation treatment can be expensive investment for the radiotherapy department. Our aim is to design low cost QA equipment which can be used safely for monthly, annual and routine QAs.
Methods: 8 mm T8 threaded 400 mm rod was affixed to moisture resistant fiberboard with a pair of pillow block bearings. 5 mm to 8 mm coupler shaft was used to connect threaded rod to a NEMA 17 stepper motor. A horizontal linear rail was affixed to same base board parallel to threaded rod for accurate movement of chamber holder. Endstop mechanical limit switch sensors were placed at both ends of threaded sensor to stop in and out movement of chamber holder. The second set of same NEMA stepper motor setup was built for lateral movement of the chamber. The both stepper motors were controlled with Arduino microprocessor through stepper drivers to move chamber holder to specific position in water phantom. The data was collected by dual channel Sun Nuclear PC electrometer and the data processing is performed in MS Excel.
Results: The acquired data for TG-51 reference dosimetry and annual beam scanning was compared with available in-house beam data. Sub millimeter accuracy of stepper motor movement ensures us to have same TG-51 measurements within 0.25%. The acquired beam profiles characteristics such as field size, symmetry and flatness were also within 1%.
Conclusion: have developed low-cost point dose, PDD and beam profiles dosimetry system to use for monthly, annual and routine machine QAs. We also found that mechanical movement accuracy should be verified before in order to use it safely for routine QAs.
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