Beam Sentry 2
Daily Output Constancy Monitor
The Beam Sentry 2, Model 105A, provides a convenient and economical means of performing daily radiation output constancy checks. It is a lightweight, portable unit with remote readout featuring the accuracy of a digital display. The unique design, featuring a separate ion chamber, eliminates radiation
damage to the electronics while allowing both the dosimeter and the ion chamber to be used independently for other purposes.
The Beam Sentry 2 is easy to use. Simply connect the electrometer to the ion chamber assembly, place the electrometer at the foot of the treatment table, collimate the beam to the 10cm field markings on the ion chamber, make the exposure and collect the reading.
The electrometer offers high accuracy, precision and repeatability and is suitable as a stand-by or back-up dosimeter. The connectors are triaxial BNC, permitted use with a standard triaxial extension cable for reading successive doses from outside of the treatment room and providing interchangeablility with other dosimetry ion chambers and electrometers.
The model 505A detector assembly contains a sealed plane-parallel ion chamber, requiring no corrections for barometric pressure and temperature changes. The detector assembly is reversible, having two entrance windows, each with a 10cm field marking. One entrance window has a build-up optimized for 6MV and electrons beams while the opposite entrance window has a build-up optimized for 18MV.
The Beam Sentry 2, Model 115A, is essentially identical to the Model 105A in concept. It consists of a Model 105A sealed ion chamber assembly and a Model 1100 full-capabilitiy, calibration-grade electrometer.