Cluster 1 Flashcards
A transformer with a turn ratio of 1000:1 is:
● a step-up transformer
The annual dose limit for radiation workers has been
reduced from 50mSv to 20mSv in 1990 according to
the recommendations of ICRP published as.
ICRP 60
What is the expected image that will be displayed on
a radiograph exposed to 70 kVp, 100 mA, 100ms
from a full wave 3 phase x-ray unit?
36 deg arc
Which of the following will serve to
increase theeffective energy of the x-ray beam?
increase in added filtration
increase in kilovoltage
Radiographs from a particular single-phase,
full wave-rectified x-ray unit were overexposed,
usingknown correct exposures. a spinning top
test wasperformed at 200 mA, 0.05s, and 70
kvp, and eightdots (dashes) were visualized on
the finished film.which of the following is
indicated?
the 0.05s time station is inaccurate
Comparing the mR output at 50mA @ 0.2s,
100mA@ 0.1s, and 200mA @ 0.05s while
increasing themAsusing different mA and s
combination is part of whichQC test?
Linearity
If a high voltage transformer has 100 primary
turnsand 35000 secondary turns, and is supplied
by 220volts and 75 A, what are the secondary
voltage andcurrent?
214 mA and 77 kVp
A branch of physics that describes the
motion oflarge objects such as planets,
universe, cars andplanes
classical mechanics
Focal spot size is measured with a_____.
pinhole camera (most accurate but most difficult)
Double-focus x-ray tubes have two______.
Filaments
Congruence of the x-ray beam with the light field is tested using
radiopaque objects
An automatic exposure control device can
operateon which of the following principles?
a photomultiplier tube charged by a
fluorescent screen -a parallel-plate
ionization chamber charged by x-ray
photons
The introduction of AI,Cu And Sn filters into the x-ray beam causes
Low energy x-rays to be absorbed
An electric generator is a device that
convertsmechanical energy to electrical energy
utilizing theprinciple of
Faraday’s law
It is a principle that states that no electrons
in thesame atomic system may be assigned
identicalvalues.
Pauli’s exclusion
The exposure rate to a body 2m from a
source ofradiation is 28R/hr. what distance from
the sourcewould be necessary to decrease the
exposure to7R/hr?
4m
The old concept of annual maximum
permissibledose (MPD) for the general
population isapproximately what portion of the
MPD for radiationworkers?
1/10
An example of a derived quantity is a______.
volume
What unit results when a coulumb is divided
by asecond?
ampere
A frequency of 1MHz is:
1x106 cycles/s
A single unit of electromagnetic radiation
is alsocalled a/an:
quantum
The only difference between x-rays and
gamma raysis their
Origin
The intensity of radiation on an object is
reducedwith distance because the radiation
.
is spread out over a greater area
Photons tend to interact with matter their
wavelength.
equal in size to
In the surface of an electrified object, the
chargesconcentrate __ .
on the sharpest curvatures
Calculate the power loss (in kW) in a circuit
wherethe current flowing is 100 amperes and the
total lineresistance is 2 ohms.
20 kW
Variations in power distribution to the x-ray
machineare corrected by the .
line voltage compensator
The first component to receive power in the
x-raycircuit is the .
Autotransformer
The difference in the waveform between the
primaryand secondary sides of the high voltage
transformeris the
Amplitude
In modern imaging systems, the
components forrectification are
solid state semiconductors
A three-phase, 6 pulse waveform has ripple.
14%
As an x-ray tube ages, the inside can become
coatedwith tungsten, which can cause in the
tube.
Arcing
What is the most common cause of tube
failure?
Tungsten vaporization
The rotating anode is turned by a
magnetic field
The target of the rotating anode is usually
coatedwith a alloy.
Tungsten
What is the formula for heat units for a 3 -
phase, 6 -pulse x-ray machine?
1.35 × kVp × mA × seconds
The filament in an x-ray tube is about inlength
1- 2 cm
Extra focal or off-focus radiation is produced
from
rebounding electrons
Characteristic k-shell x-rays have an effective
energyof keV.
69
The half value layer (HVL) of an x-ray
beam is ameasurement of beam
Quality
Any chromosome damage induced by
radiationcould be seen during the
Metaphase
What is the annual effective dose limit
recommended for occupational exposure?
5 rem (per year)
What is the total dose limit for the embryo and
fetus?
0.5 rem (0.05 per month)
filtration is measured by measurements.
half value layer
the measured kVp should be within + - %
of thekVp indicated in the console.
5
Measured kVp = 5%
Occupational radiation monitoring is required
if theindividual may get of the
recommended doselimit.
10%
During fluoroscopy the exposure to the
collar is times greater than exposure to the
trunk of thebody under a protective apron.
20
The preferred way to hold patients who are
unable tosupport themselves is to use a
restraining device
If the output intensity of an x-ray machine
is 6.4mR/mAs at 80 kVp, what is the patient’s ESE
for an examdone at 20 mAs at 80 kVp?
128 mR
Performing routine x-ray exams without
indication isnot acceptable for
● preemployment physicals
● all hospital admissions
● annual routine physicals
The is the primary protective barrier
for thefluoroscopic x-ray tube.
image intensifier
The bucky slot opening in the side of the table
mustbe automatically covered with mm
Pb duringfluoroscopy.
0.25
The intensity of scatter radiation 1 meter
from thepatient is approximately of the
intensity of theincident beam at the patient.
0.1%
Measuring the relationship between the
output
intensities of adjacent mA stations is a test o
●
Linearity
Controlled area is one occupied primarily by
● radiology personnel
● Patients
Relative risk is
observed cases/expected cases
A dose of rads or more to a small area
of thebody can cause skinerythema.
● 200
A person subjected to 5000 radsto the whole
bodymay survive for before death occurs.
● 3 days
The LD50/60 for humans is approximately
rads.
● 350
Ovaries are most radiosensitive during
● fetal growth
● early childhood
A type of DNA damage that may not be
reversible isa
base change or loss
when H2O receives a free electron, it
becomesunstable and dissociates into what free
radical?
● H*
Two OH free radicals can join to form
molecules
● hydrogen peroxide
. the principal radiation interactions within the
humanbody are assumed to be
● indirect effects
the lethal effect of cell irradiation are
measured by
● survival
the number of nuclear transformation
occurring in a
given quantity of material per unit time
●
activity
what is the SSD of portable fluoroscope?
● atleast 30cm
the probability or frequent of the biologic
responseto radiation dose , increases
proportionally with dose:
and there is no dose treshold
● stochastic
radiation dose that can be reduce the
number ofsperm may delay/suppress
menstruation
25 rad
. the latent period for gastrointestinal syndrome
is
● 3- 5 days
protective aprons and gloves should be
fluoroscopeto check for defect every
● once a year
if the radiologic technologist
participates influoroscopy, then the
occupational radiation monitorshould be
positioned on the collar inside the protective
apron
● false
the process by which a neutral atom or
moleculeacquires a positive or negative charge
● ionization
refers to the number of ion pairs formed per
cm oflathis any given medium
● specific ionization
the proper unit for the exposure of
radiologic techand radiologist
● REM
it is an antimatter since it undergoes
annihilation
● positron
area occupied primarily by radiology
personnel andpatients
● controlled
Refers to the process/processes involved in the transformation of an unstable nucleus into other nuclear form
● radioactive decay
a quantity that reflects not only dose but
also thevolume of tissue irradiation.
● dose area product
spontaneous abortion after irradiation
during thefirst 2 weeks of pregnancy is more
pronounced atradiation doses of:
● 25 rad
it is called the period of major organogenesis:
● 6-8 weeks of pregnancy
the maximum energy required to remove an
electronfrom its orbit.
● ionization energy
which of the following statement is true?
● the higher the temperature, the
greater theresistance of a uniform conductor
nucleons are made of bounded by gluons.
● Quarks
how many half-value layers will it take to
reduce anx-ray beam whose intensity is 78 R/
minto an intensity ofless than 10 R/min?
● 3
in which of the following portions of the x-ray
circuitis a step-down transformer located?
● filament circuit
