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 • Sealed ion chamber - no air density correction necessary
• Reversible detector - dual entrance windows, 6 & 18 MV
• Electrometer protected from radiation
• Remote operation using a standard triax extension cable
• Powered by a single 9V battery - no bias batteries to replace
Beam Sentry 2 provides a convenient and economical means of performing daily radiation output constancy checks. It is a light-weight 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.
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 10 cm 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 a back-up dosimeter. The connectors are triaxial BNC, permitting use with a standard triaxial extension cable for reading successive doses from outside of the treatment room and providing interchangeability with other dosimetry ion chambers and electrometers.
The detector assembly contains a sealed parallel plate ion chamber, requiring no corrections for barometric pressure and temperature changes. The detector assembly is reversible, having two entrance windows, each with a 10 cm field markings. One entrance window has a buildup optimized for 6MV and electrons, and the opposite entrance window has a buildup optimized for 18MV.
SPECIFICATIONS FOR ELECTROMETER
Display: 3 1/2 digit LCD
Range: 19.99 and 199.9
Units: Factory set: R, cGy, or nC
Accuracy: ±0.1% of reading + 1 digit
Linearity: ±0.1%, +1 digit or precision of reading, whichever is greater
Leakage: <60 fA
Temperature Stability: 20ppm/oC.
Input Connector: BNC-F triax w/cap and chain
Bias Supply: Static -150/-300V
Power: 9V battery, NEDA 1604A
Size: 6” sq. x 3.5”
Weight: 2 lbs.
SPECIFICATIONS FOR ION CHAMBER ASSEMBLY
Chamber Type: Parallel Plate
Chamber Volume: 3cc (nominal)
Sensitivity: 1nC/R (nominal)
Top Buildup: 1.5g/cm2 (6MV)
Bottom Buildup: 3.2g/cm2 (18MV)
Cable: Integral 2.3 m (7.5 ft.)
Connector: Triaxial BNC-M
Dimensions: 15 cm sq. x 3.5 cm
Weight: 2.2 lbs
Optional: Acrylic Build-Up Plate Set:
One of each size
5 cm2 x .63 cm (1/4”)
15 cm2 x 1.27 cm (1/2”)
15 cm2 x 1.90 cm (3/4”)
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