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Efficacy of Two Types of 2-D Array Detector System for Quick Beam Profile Measurements

F Duan*, B Morris , W Duggar , C Yang , University of Mississippi Medical Center, Jackson, MS


(Wednesday, 8/1/2018) 10:30 AM - 11:00 AM

Room: Exhibit Hall | Forum 7

Purpose: Both MapCHECK2 with PROFILER software and MatriXX-Evolution with myQA FastTrack software are newly designed for profile measurements. This work is to determine the agreement and sufficiency of measuring high energy photon and electron beam profiles using these two systems against water tank.

Methods: Three devices, MapCHECK2 (2D diode array), MattriXX-Evolution (2D ion chamber array), Wellhöfer compact ionization chamber CC13 in Blue Phantom², were used to measure beam flatness and symmetry for field size of 20 cm x 20 cm at 100 cm SSD on an Elekta Synergy LINAC. Measurements were performed at water equivalent depths of 2 cm and 10 cm for 6 MV and 10 MV photon beams, 2.5 cm and 10 cm for 15 MV, 2 cm for 6 MeV and 9 MeV electron beams, 3 cm for 12 MeV, 15 MeV, and 18 MeV. The beam profiles were measured on the same day to minimize day-to-day beam variation. Array calibration for MapCHECK2 was performed for all beam energies prior to beam profile measurement. Factory array calibration was used for MattriXX-Evolution. Same protocol was used for beam profile analysis. Time consumed including device setup, data collection, and cleanup was recorded.

Results: The average deviation of MapCHECK2 and MatriXX-Evolution from water tank measurement was found to be 0.32% and 0.31% for three photon energies, 0.53% and 0.47% for five electron energies. Time consumed using MapCHECK2 and MattriXX-Evolution is 5 times less than measuring in water tank.

Conclusion: Both MapCHECK2 and MattriXX-Evolution with proper software are able to provide comparable accuracy against water tank for beam profile measurement. The data is used as our baseline for the future. This approach opens up a new way of quick beam profile measurement when a machine is going through a major repair or beam tuning on a busy clinical day.


Ionization Chamber, Diodes, Quality Assurance


TH- Radiation dose measurement devices: Multi-dimensional diode/chamber arrays

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