for moving the turntable
Compagnie Generale Radiologie (CGR), an established French radiology firm
from which AECL got some of its technology for the Therac series of machines.
Class 1 recalls: the
most serious recalls in terms of health risk
AECL: Canadian company that
designed and manufactured the Therac-25
Collimator: a device for
obtaining a particle beam of limited cross section
Dosimeter: radiation dose
electron beams: Accelerated
electrons are absorbed by phosphors, which in turn produce light
eV: the energy needed to
move one electron through a potential of one volt.
Gantry: the turntable assembly
GAO and Comptroller General:
The General Accounting Office is the investigative
arm of the Congress and is charged with examining all matters relating
to the receipt anddisbursement of public funds.
The General Accounting Office (GAO) was established
by the Budget and Accounting Act of 1921 (31 U.S.C. 702), to independently
audit Government agencies. Over the years, the Congress has expanded GAO's
audit authority, added new responsibilities and duties, and strengthened
GAO's ability to perform independently.
The Office is under the control and direction of the
Comptroller General of the United States, who is appointed by the President
with the advice and consent of the Senate for a term of 15 years.
Kludge or Kluge: a computer
system made up of poorly matched components
medical linear accelerator: a device that accelerates
electrons to create an electron beam.
Operator: the individual
responsible for the facitily room and preparing the Therac-25 machine
for a particular patient.
Potentiometer: a device
that independently monitors turntable position
rad (radiation absorbed
dose): the amount of radiation that is absorbed by tissue in a treatment.
Acceptable level for single treatment is around 200 rad.
radiation therapy: exposure
to ionizing radiation using electron, X-rays or gamma rays. It is administered
in a series of sessions occurring over several weeks,
Radiation therapy technician:
X-ray (photons): High intensity electron beam
(25 MeV) that is transformed. Often used to in treating deeper tissue
Therac-25: a medical linear accelerator that
folds the electron beam back and forth. This allows for a higher energy
beam to be produced.
25 MeV: 25 million electron volts. This is
the electron beam used in Therac 25