Theory Of Operation; Introduction; Section 2: Theory Of Operation; Functional Description - Fluke 35040 Operator's Manual

2.1 Introduction

The Model 35040 Therapy Dosimeter is a radiation measurement instrument intended for use in
calibration procedures for high-energy accelerators,
of the instrument is explained in the following paragraphs. For information on radiation dosimetry and ion
chamber measurement theory, the reader should refer to one of the standard radiological physics texts.

2.2 Functional Description

The Model 35040 Therapy Dosimeter is a portable instrument that measures charge and current.
Calibrated ion chamber factors convert charge and current to directly measure radiation dose and dose
rate in the user specified radiological units. The reading may be corrected for air density by the user
entering ambient temperature and barometric pressure readings. The electronic bias setting is selectable
from the front panel.
FUSE
AC Line
BATTERY
PACK
POWER
SUPPLY
POWER BATTERY
CONTROL STATUS
ELECTRONIC
BIAS SUPPLY
BIAS
ION
CHAMBER
ELECTROMETER
CONNECTOR
Figure 2-1. Hardware Block Diagram of the Model 35040 Therapy Dosimeter
POWER
SWITCH
FRONT PANEL
CONTACTS
SWITCHES
DISPLAY
SELECTION
SWITCH
CONTACTS
PROCESSOR
BIAS CONTROL
CONVERSION CONVERSION
CONTROL RESULTS
MULTIPLEXER AND
A/D CONVERTER

Theory of Operation

60
Co, and brachytherapy. Basic theory of operation
VFD
RS-232
SERIAL COMPUTER
INTERFACE
COMM.
CONNECTION
PORT
HIGH VOLTAGE ISOLATION
Theory of Operation
Introduction
Section 2
2-1
2