DOSIMETRY 2 FINAL- ALL EXAM QUESTIONS
T / F Most early radiation treatments were given using brachytherapy vs. external beam treatment.
TRUE
T / F Ordinary custom blocks cannot be used during arc therapy.
TRUE
T / F Rotational therapy is always done isocentrically (SAD technique).
TRUE
T / F Scatter, in therapy, is more forward in direction.
TRUE
T / F The absorbed dose in the medium outside the primary beam is greater for lower energy beams that for those of higher energy.
TRUE
T / F The average energy of a beam is greater at the CA than in the peripheral areas.
TRUE
T / F The energy of a photon is directly proportional to the frequency of the wave, according to Plank.
TRUE
T / F Warning lights must be in operation if the machine is set to produce radiation.
TRUE
T / F Water is the preferred material for electron calibration.
TRUE
T / F X-rays originate from outside the nucleus, which is just the opposite of radioactivity.
TRUE
T / FBrachytherapy patients should not receive a bed bath while radiation sources are in place.
TRUE
T / FRadioactive source transport devices (pigs) may not be left unattended.
TRUE
true/false: electron beams interact via elastic and inelastic collisions
TRUE
A source, such as a radium needle, thT HAS MORE active seeds at one end
Indian club
WHich material would not be used for a permanent interstitial implant
Iridium 192
E=hv
J plank
What is the innermost electron shell of an atom labeled as?.
K
What is the function of the flattening filter?
Make the beam isodose curves more uniform
Which of the following implant dosimetry systems is the most commonly used manual calculation method for intracavitary brachytherapy?
Manchester
Besides Pierre, received 1903 prize in Physics along with Bequerel
Marie Curie
coined the term "radioactivity"
Marie Curie
Who is generally considered to be the (unwilling) "Father of Quantum Mechanics?"
Max Planck
What is the two-fold goal of treatment planning?
Maximize tumor dose; minimize dose to normal tissue
What do the initials MPD stand for?
Maximum Permissible Dose
A device used to "staple" in permanent interstitial sources is a/an ______ applicator.
Mick
Reactor materials and cyclotrons are regulated by what agency?
NRC
What does NCRP stand for?
National Counsel on Radiation Protection
What do the initials NBR stand for in radiation protection?
Natural Background Radiation
Name two scientists discussed in lecture that are associated with Classical physics
Newton, Descartes
Which of the following best describes the "edge effect"?
Not treating all fields during each fraction
What does NRC stand for?
Nuclear Regulatory Commission
What do the initials OSL stand for?
Optically Stimulated Luminescence
Write out the formula for calculating the thickness of a barrier. If any squared Number is used, just simply write a "2"
P = WUT / D2 x B
Stable, last daughter product of radium (uranium)
PB 206
Sources are transported in devices called:
PIGS
What field arrangement commonly produces an "hourglass" shaped isodose curve?
POP
2 (N2)
Pauli
The dose to the bladder and rectum in an intracavitary implant should be less than the dose to what point?
Point A 75Gy
What was the name of the radioactive element discovered by Marie Curie that she named after her home country of Poland?
Polonium
These are the only subatomic particles that can carry a partial charge:
Quark
This system for interstitial implant dosimetry includes the uniform placement of interstitial sources that gives a non-uniform dose distribution.
Quimby
Define the term ionization:
Removing (or adding) orbital electrons
Discovered x-rays
Roentgen
received 1901 Nobel prize in Physics
Roentgen
A maze should create at least how many scatters?
2
Section 1B question
28
The light field should be coincident to the radiation field to within what distance?
2mm
The sagittal laser must be congruent with isocenter to within plus or minus what distance?
2mm
What is the tolerance for the stability of isocenter with respect to collimator and gantry rotation?
2mm
For a Cobalt installation, ___________ ft thick concrete is usually adequate for primary barrier shielding.
3
Å is the symbol denoting what term?
Angstrom
The combining of two or more like Adams is termed:
Fusion
Brachytherapy is characterized by high local dose and rapid fall off.
True
Radium tends to take up in the:
bones
What does the tandem treat in an intracavitary implant?
endometrial involvement
If the resistance is decreased to the cathode end thus increasing voltage, what will be the result?
increase in number of photons produced
The TSI technique that utilizes only 4 treatment angles is:
memorial
Another name for a slow neutron is:
thermal neutron
What does the term interstitial literally translate as?
through tissue
The medium of choice for phantoms is:
water
What does "Cogito ergo sum" mean, AND who said it?
"I think therefore I am"
The beam must be symmetrical and flat, concerning isodose curve structure, to within what tolerance (be very specific)?
+ - 2% Across the inner 80% of the field
The change in dose on the other side of bone for 10 MEV x-rays is how much per cm of bone?
-2%
Tungsten is chosen as the target material for x-ray tubes for at least two reasons. Give one of those reasons discussed in lecture:
-Heat resistant
name two diseases (spelled correctly) that are commonly treated with TSI
-Mycosis fungoides
What are the four basic principles/tenants of Special Relativity discussed in class
-Shorter - disappears
What information needs to be labeled on a wedge?
-Wedge angle
Describe the procedure for performing the wipe test for a cobalt teletherapy source:
-Wet collimators with Q-tip
List two of the three revolutionary features of the hot cathode tube:
-heated
List two uses of bolus in electron therapy, as described in class lecture
-increase skin dose -deacrease dose to deeper structures
1 mSv = ___________ Sv.
.001
The energy of Palladium is:
.021mev
Dose limit for Beam "on" (Co60 and linac)
.1% of the beam
Dose limit for beamstopper
.1% of the beam
The NCRP recommends that students less than 18 yrs old should receive a whole body dose not greater than how many REM per year?
.1REM (1mSv)
There is a _____ shift in an isodose curve with regard to contour irregularity when using an 18-25 MV x-ray beam.
.5
What is the SI dose equivalent limit for the embryo/fetus per month?
.5mSv
Average filtered energy of radium
.83mV
What number represents a typical Roentgen/rad conversion factor for Co60 for bone vs. muscle absorption?
.957
The shielding and safety requirements for an HDR room are comparable with those of a_______________ room
.Cobalt 60
A wedge pair technique is usually used to treat tumors how deep?
0-7cm
What is the energy range of a slow neutron?
0.025 ev to 100 ev
The leakage limits of a teletherapy (Co60) source housing with the beam "ON" is a maximum of:
0.1% of the useful beam at one meter
During the entire gestation period, the maximum permissible dose to the fetus from the occupational exposure of the expectant mother must not exceed:
0.5 REM/5mSv
1Gy= ___________ Sv.
1
The exposure rate for RADIUM at a distance of __________cm from a point source of ____________mg of radium filtered by __________mm of Pt is ____________R/HR
1 1 .5 8.25
1000mCi=
1 Ci
Sources are generally placed how far apart
1 cm
The dose in BT varies more in the first ____ cm of tissue than in the remaining
1 cm
For radiation protection purposes, it is assumed that an individual is how far away from the barrier?
1 foot
1Sv=
1 joule/ kG
4. Individual utilizes separate wedge for each field size
1,3
condenser type for energies less than 10MeV; 3. thimble or parallel plate chambers for energies above 10MeV; 4. condensor type for energies greater than 10MeV
1,3
5. Supraclavicular
1,3,4,5
About how far across (in diameter) is an atom?
1-2 Å
A two-plane implant will adequately treat a volume of tissue how many cm thick?
1-2.5cm
What is the threshold energy for pair production to occur?
1.02 MV
The HVL for Radium is
1.2cm
The annual GSD (weighted, averaged gonadal dose) is about _______ per year:
1.3 mSv
To degrade a 9 MeV electron-beam to 6 MeV, what thickness of tissue equivalent material would typically be required?
1.5 cm
The density coefficient (assumed electron density) of bone (relative to water) is:
1.65
Individuals occasionally exposed to radiation should receive ________ that of radiation workers.
1/10
Each scatter interaction reduces the beam to about:
1/1000 the original
Electron beam penetrating power generally follows the ____ rule of thumb.
1/2
Electron beam practical range generally follows the ___rule of thumb.
1/2
Electron beam therapeutic range generally follows the ___ rule of thumb.
1/3
A typical occupancy factor for a restroom would be:
1/4
When using a radon treatment applicator, the exposure rate at the end of 7.7 days will have decreased to ?
1/4 its original activity radon T1/2= 3.82 days, so 2 half lifes
1 cGy = _________ mSv.
10
At worst, research indicates that humans can expect a reduced life span of about ______ days for every rad of dose received:
10
Collimators should be at least how many HVL's thick?
10
Hot spots for wedge pair techniques are acceptable to within +- _____%.
10
The maximum allowable exposure for a single one-time planned event is______ rem.
10
Neutron protection is necessary for linacs producing beams greater than what energy?
10 Mev
Film badges are incapable of measuring doses less than:
10 mR
Dose limit for Co60 beam off maximum reading in one direction
10 mR/hr
The leakage limits of a teletherapy beam(Co60) with the beam "OFF", in any one direction, is a maximum of:
10 mR/hr at one meter
The average overall change in dose on the other side of lung for cobalt due to Inhomogeneities is:
10%
Stereo films should be taken at angles that are ____ degrees off ap:
10-15
What is the threshold energy for photo disintegration to occur?
10.86 MV
"High Radiation Area" warning signs must be posted in all areas where a person, if continuously present could receive an exposure in excess of _______ mR in any one hour.
100
Natural background (not Including Radon or man-made) accounts for about _______________ mR/yr.
100
What is the hinge angle if the wedge angle is 40'?
100
Dose limit for high radiation area
100 mR/hr
A whole body dose of 0.1 cGy (RAD) with x-rays will produce a dose equivalent of:
100 millirem/1mSv
Dose limit for controlled area (per week)
100mR/week
The "strong" nuclear force works as a force over distances up to about _____meter.
10^-14
Dose limit for uncontrolled area/week
10mR
Give the exact date (mm/dd/yyyy) of the discovery of x-rays
11/08/1895
questions
117-124 section 2 and 3 combined
How many known elements are there?
118
HDR is when the dose rate is ___________ Gy/h-1 or higher
12
QUAM 1 Question 22
12 MeV
What are some components of internal radiation?
14Carbon
for occupational workers?
150
The half-life of Palladium is:
17 days
Brachytherapy patient visitors must be at least _____ years of age.
18
Five dose readings are taken. One dose reading is 190rad, the other four are 177rad, 182rad, 188 rad, 182 rad, what is the modal dose:
182
Five dose readings are taken. One dose reading is 190rad, the other four are 177rad, 182rad, 188 rad, 182 rad, what is the median dose:
183.5
Five dose readings are taken. One dose reading is 190rad, the other four are 177rad, 182rad, 188 rad, 182 rad, what is the mean dose:
183.8
The mass of a proton is:
1836
Discovery of radioactivity - what year?
1896
First use of x-rays to treat a malignancy - what year?
1896
Year of first cure of cancer using x-rays
1899
Einstein's Theory of Special Relativity was developed in what year?
1905
1st year of the "KV Era"
1913
Decade in which the introduction of multiple fields for treatment first started
1920's
Acceptance of the unit of measurement "Roentgen" year
1937
Development of the cobalt machine for (medical) treatment (year)
1951
Development of the LINAC - what year
1952
Acceptance of the unit of measurement RAD-- what year?
1953
Linacs became more popular than cobalt machines during what decade?
1970's
Ir sources cut into seeds and placed into a nylon ribbon are usually placed how far apart?
1cm
Needles for planar implants should be how far apart?
1cm
One radium needle is generally considered to adequately treat a volume of tissue _____ cm thick.
1cm
Where is point B located and what does it represent?
1cm lateral to pelvic sidewall doses to lateral pelvic structures
Most common way of calibrating sources according to the NCRP, exposure rate at specified distances, is usually accomplished by measurements at a distance of
1m
Readings taken in a brachytherapy patients hospital room should to be taken:
1m from patient, at teh door and adjacent rooms along abutting wall
An electron beam loses roughly _______ MeV/cm of tissue.
2
QUAM 1 Question 21
2
The rate of energy loss for electron beams is approximately ___________ MeV/cm in soft tissue and water
2
Dose limit for Co60 beam "off" average
2 mR/hr
The change in dose on the other side of bone for 10 MEV x-rays is how much per cm of bone?
2%
The change in dose on the other side of lung for 10 MEV x-rays is how much per cm of lung?
2%
What is the tolerance for beam penetrative power?
2%
4. larger tumors
2,3
The actual HDR treatment, with the radioactive sources in place, takes approximately ____ minutes.
2-3 minutes
TSI is typically performed with what electron energy range (in MeV)?
2-9
WHat is the peak energy of radium
2.45mv
What is the median energy of pair production?
20 MV
QUAM 1 Question 45
20 MeV
Which electron beam has the maximum dose on the skin surface?
20 MeV
Assuming that the cataract forming dose of x-rays is 200 cGy and the quality factor for fast neutrons is 10, the cataract forming dose of neutrons is:
20 rad
Adequate hospital room wall protection for LDR brachytherapy applications is obtained with concrete thicknesses around _____
20-25cm
A highly fissionable material commonly used in nuclear reactors is:
235 Ur
An accidental dose of radiation to the whole body not exceeding ____________ REM once in a lifetime can be accumulated as part of the exposure status of the individual.
25
Forceps for use in handling BT sources must be at least how long?
25cm
Calculate the dose equivalent whole body limit for a 27 year old radiation worker.
27 REM or 270 mSv
Where is point A located and what does it represent?
2cm sup and 2cm lat to external os area where uterine vessels cross ureter
The current quarterly MPD for an occupational worker is____________rem.
3 ??? AS
In terms of meters/second, what is the velocity of light?
3 x 10 ^8
1 Ci=
3.7x10^10 DPS
The primary barrier for an orthovoltage machine should be at least:
3/8" Pb
The annual MPD (standard units) for the forearms is___________ rem.
30
The target (on Kv machines) is usually angled (tilted downward) by how many degrees?
30
If 5 mG of radium provide a certain dose in 2 hours, 20 mG would give the same dose in:
30m
Calculate the whole body dose equivalent limit (formerly known as MPD) for a 39 year old radiation worker.
39 REM 390mSv
Leaded glass ordinarily requires about ______ times the thickness of sheet lead for equivalent protection.
4
The "useful range" of a 12 MeV electron beam is approximately how many centimeters deep in tissue?
4
Transient equilibrium typically occurs after about _____half-lives, on average.
4
"Horns" created in isodose curves are most likely to be prominent in what machine?
4 MV
What field arrangement produces a "box" shaped isodose curve without manipulation by treatment accessories/modifiers?
4 field
Film badges should be worn for at least ___________ to help insure accuracy.
4 weeks
A .3mm Pt filter for radium source would represent what change in exposure rate constant?
4% increase
The latent period for leukemia is about:
4-7 years
TSI techniques are generally given with SSD's of about:
400 cm
question
44-45 exam 3 (2 and 3 combined)
What degree wedge angle would most likely be used on a partial brain treated with AP and left lateral fields?
45
Determine the number of neutrons in the following fictional element: A# = 77; Element name: XE; Z# = 31
46
A family member of a patient who has received a radioactive implant and who is over age 45 has a yearly MPD of _____ rem.
5
The annual occupational dose limit for the whole body (from the previous question) roughly translates to about how many cGy/year?
5
The current annual MPD for the general public in SI (mSv) is:
5
Dose limit for "Radiation area"
5 mR/hr
Dose limit for dose at door with beam on
5 mR/hr
The latent period for cataracts is about:
5-25 years
Section 1B Questions
5-7
In terms of mSv, what is the annual occupational dose limit for the whole body?
50
The current annual MPD (standard units) for "any other organ" is___________ rem.
50
The average energy of a 150 Kv x-ray beam is:
50 KV
Which of the following would give the same mAS as 100 mA with 1/20 of a second exposure time?
50 mA, 1/10 second
Traditionally, though Khans advocates not doing this anymore, wedge angle has been defined at what isodose line?
50%
What is the SI dose equivalent limit for the red bone marrow per year?
500 mSv
The resting mass of an electron is equal to what energy?
511 KV
The technique from the previous question utilizes how many different treatment angles?
6
The most useful energy range for electron beam therapy is:
6-20 MeV
These angles in a typical TSI are usually how far apart in degrees?
60
If a cancerous lymph node is found 2 centimeters deep in tissue, what would be the most appropriate electron beam energy according to the lecture notes?
6MeV
What is the wedge angle if the hinge angle is 40'?
70
The annual MPD (standard units) for the hands is___________ rem.
75
Section 1B question
75- beam profile
Point A usually receives what maximum dose?
75Gy or 7500 rads
math all on section 1B question
77
The "therapeutic range" of an electron beam most commonly follows what percent isodose curve line?
80%
The useful range of an electron beam is usually described as being equal to the ___% isodose line(s) and above (if applicable).
80-90
Elements with a Z number greater than _________ are "unstable" (radioactive)
83
The "penetrating power" of a 16 MeV electron beam is approximately how deep in tissue?
8cm
QUAM 1 Question 27
9 MeV
section 1B question
90
State the wedge angle formula:
90-(hinge angle/2)
1 amu is equal to how much energy?
931 mv
Five HVL's will attenuate what percent of the beam?
97%
The nucleus contains about what percent of the mass of the atom?
99.9%
Which of the following isotopes would NOT be used to treat pterygium of the eye?
AU yittrium and Sr could be used as they are pure beta emitters
stated that matter was composed of one or more of the four elements (+ Æther)
Aristotle
What does ALARA stand for?
As Little/Low As Reasonably Achievable
An orbital electron ejected from its shell by photons produced from the nucleus is called:
Auger electron
6.023 x 10 23
Avagadro
defined the molecule
Avagadro
equal volumes of gases have the same number of molecules under equal conditions of temperature and pressure.
Avagadro
In spite of my atrocious illustrations thus far, electron beam isodose curves generally form what shape?
Bell
Quantum non-locality (what Einstein called "spooky action at a distance" - where communication can occur faster than the speed of light) was experimentally formulated as a result of which of the following?
Bell's theorem
The outer circumference of a volume implant is called:
Belt
This section of a volume implant contains up to 4 parts
Belt
1st biologic reaction to radioactivity
Bequerel
discovered radioactivity
Bequerrel
associated with the year 1913
Bohr
developed the "modern" model of the atom
Bohr
A common material for neutron shielding for doors is:
Boron/boronated polyethylene
According to the Study Guide quote of Khan, which of the following is not one of the "critical organs" of the body?
Brain CNS
What is the name of the area on the previous curve - previous question - just below the letter "A"?
Brem's Tail
Dose is typically specified at (the):
CA
WHich source is the only naturally occurring neutron emitter
Califrnium 252
For which of the following radioactive sources do you think any implant dosimetry tables would be LEAST appropriate?
Cf 252 bc it is a neutron emitter
3.7 x 1010 dps defines what unit of measurement?
Ci
The only radionuclides used for HDR brachytherapy are:
Cobalt Iridium
This source has the highest specific activity?
Cobalt 60
Which interaction in tissue is most closely associated with the "pool table" analogy?
Compton
Which interaction is most commonly found in the energy range most commonly used in radiation therapy?
Compton
Primary and secondary barriers for MV units are usually made of what material?
Concrete
Without a flattening filter, what shape would the isodose curves have?
Conical, forward peaked
Another name for Brems radiation is:
Continuous and white
invented the revolutionary hot cathode tube
Coolidge
Quantum Theory was first formalized in the late 1920's in what city?
Copenhagen
Currently, the most common source for intracavitary implant
Cs 137
Advantages of cesium over radium when used for BT include
Cs storage is easier Cs has a longer 1/2 life CS costs less
HDR timer termination should be tested:
DAILY
1st x-ray fatality
Dally
developed the law of conservation of matter
Dalton
received 1901 Nobel prize in Physics (not Roentgen)
DeBroglie
Which of the following cities has the highest level of cosmic radiation?
Denver
With respect to radiation protection, what does the term "Doubling Dose" mean?
Double the amount of genetic mutations
This section of a volume implant can be "open" or "closed"
END
Name the (current) four fundamental forces in nature
Electromagnetism, gravity, strong nuclear, weak nuclear
Define mast effect - in other words, how is it possible for the mass of the atom to not be equal to the sum of the mass of its parts?
Energy from the nucleus... 12.096 = 12.000
A measure of the activity of a source as compared to radium is called
Equivalent Mass of Radium
T / F A 40 year old person will generally be more sensitive to the effects of radiation than a seventy year old person.
FALSE
T / F A film badge for a fetus/embryo should be worn outside of the lead apron.
FALSE
T / F After removal of the implant, a survey need not be performed to ensure that no sources were inadvertently left behind.
FALSE
T / F An angstrom is 10-8m.
FALSE
T / F Brems x-ray production results in a recoil electron being produced.
FALSE
T / F Bremstraahlung results in ionization of the atom in which the incident electron interacts.
FALSE
T / F Characteristic x-ray production occurs much more frequently than Brems.
FALSE
T / F Characteristic x-rays are much more useful in therapy than Brems x-rays.
FALSE
T / F Equivalent square formula is valid and useful for calculating doses for electron beams.
FALSE
T / F Film badges should not be stored at the employees work facility.
FALSE
T / F Filtration has no effect on output.
FALSE
T / F Hot spots can only occur inside the target volume.
FALSE
T / F If a warning light burns out, an output check must be performed.
FALSE
T / F Inverse square corrections are valid and useful for calculating dose rates for electron beams.
FALSE
T / F Isodose charts have to have a correction factor added to account for the hardening of the beam as a result of using wedges.
FALSE
T / F Particles can travel at the speed of light.
FALSE
T / F The primary purpose of a flattening filter is to harden the beam.
FALSE
T / F The primary purpose of a wedge is to act as a tissue compensator.
FALSE
T /F Lead lines gloves provide adequate protection when working with brachytherapy sources.
FALSE
T / F Brachytherapy personnel must wear an additional film badge (ring badge).
False
T / F Radium can be sterilized at high temperatures.
False
T / F The Manchester system takes into account variables such as large or small cervix/uterus.
False
T / FFletcher-Suite devices are never an example of an afterloading device.
False
This type of afterloading intracavitary applicator has a tandem and ovoids that are made of stainless steel.
Fletcher Suite
The instrument used for recording higher energy gamma radiation specifically for contamination and measurement of radioactivity is the:
GM counter
What type of device is most likely to be used for taking a reading and a brachytherapy patients hospital room after insertion of the implant?
GM-counter
Which of the following areas would most likely be treated with a removable intracavitary source? prostate, tongue, GYN
GYN
How do you find exposure rate constant?
Gamma factor divided by 8.25
What do the initials GSD stand for?
Genetically Significant Dose
What do the initials GTV stand for?
Gross Tumor Volume
1st to use protective lead shielding
Grubbe
1st to use x-rays to treat a disease
Grubbe
The term MPD is in the process is being replaced by the term dose equivalence. What is the abbreviation for dose equivalence?
H ???? AS
The variation across the beam as a result of the production of x-rays at different depths within the target is termed:
Heel Effect
Which of the following applicators is used most for interstitial implants fletcher suite, ernst, Manchester, henshke?
Henshke
These devices are often implanted for the treatment of ca of the uterus (endometrium).
Heymans capsules
What do the initials HDR stand for
High dose rate
Most common source for permanent interstitial
I-125
Which of the following elements comes in the form of seeds?
I-125
This isotope comes in a liquid form and treats thyroid disorders
I-131
What element is most commonly used for systemic thyroid treatment?
I-131
Name two systemic isotopes that come in the form of a liquid.
I-131 Strontium 89
Most common source for temporary interstitial
I-192
Type in the formula for Ohm's law, labeling what all the initials stand for
I=V/R
Which of the following implant dosimetry systems, according to Khan, is probably the most accurate?
ICRU
Which system of intracavitary dosimetry, according to Khan, is probably the best that can be achieved at this time?
ICRU
Draw an example of a planar implant with both ends crossed.
III
What does ICRP stand for?
International Commission on Radiation Protection
This type of external beam field can be used to treat a patient that will have an intracavitary implant.
Inverted U
proved what cathode rays really were
JJ Thompson
What is the unit of measurement for integral dose?
KG/Gy
This system for implant dosimetry is most often used for intracavitary implants and makes use of points A and B.
Manchester
discovered radium
Marie Curie
This system, based on computer generated dose distributions, was devised in 1963 and is an extension of the Quimby system:
Memorial
give two reasons why the mass stopping power is greater for low Z number materials than for high Z number of materials
More electrons per gram
the 1st biologic x-ray was taken of this persons hand (last name of the person)
Mrs. Roentgen
The primary standard setting body for the United States through publications is:
NCRP
The use of Co60 in teletherapy is licensed by a bureau of the federal government known as:
NRC
Radium, for treatment purposes, usually comes in the form of:
Needles
For this system of interstitial dosimetry, dose specification is based on an isodose surface called the "reference dose.":
Paris
Which of the following is a system of implant dosimetry for interstitial brachytherapy:
Paterson Parker Quimby Computer PAris Memorial
According to Khans, uniformity of source placement is least important for which type of implant system?
Paterson-Parker
Planar implants would most closely be associated with which dosimetry system?
Paterson-Parker
This system for interstitial implant dosimetry includes the non-uniform placement of interstitial sources that gives a uniform dose distribution.
Paterson-Parker
This type of implant dosimetry system requires a dose variation of no more than 10% within the tumor volume.
Paterson-Parker
determines max number of e-'s in a shell
Pauli
was trampled to death by horse drawn carriage
Pierre Curie
QF (quality factor) is the protection equivalent of:
RBE
What is/was the standard unit for dose equivalent?
REM
Routine calibration of brachytherapy sources is usually carried out by what type of ion chamber?
Re-entrant
discovered the proton, and that radium emitted several types of radiation
Rutherford
In an isocentric technique, the _____ remains the same.
SAD
Radium generally comes in teh form of
SALTS
What, exactly, does the Brem's tail represent?
Secondary Brems x-rays
Name the SI unit for dose equivalence:
Seivert Sv
Describe the difference between somatic and genetic effects:
Somatic: during lifetime
Which of the following is an example of an intracavitary dosimetry system?
Stockholm PAris mg/Hr ICRU Manchester
Which of the following is a pure beta emitter?
Strontium 89 90 Yitrium 90 p-32
WHat is the most common source used to treat pterygium
Strontium 90
Which of the following is a pure beta emitter?
Strontium 90
Quantum physics is defined as (finish the sentence) "the study of... (Specifically what, give a definition):
Subatomic particles and waves
What is the SI unit for dose equivalent?
Sv
What do the initials SI stand for?
Systeme Internacionale (d'Unites)
The time necessary for half of the atoms in a group to decay defines what term?
T1/2
The state agency responsible for enforcing regulations is:
TDH??? AS
Actual patient doses for TSI techniques are most commonly verified using:
TLD's
Fields for electron therapy should be set bigger than the lesion (plus normal margin) to be treated
TRUE
T / F A "step wedge" can be used to crudely determine a beams relative energy.
TRUE
T / F According to Khan, electron arc therapy is the best available treatment for large chestwall sites.
TRUE
T / F Beam energy, independent of other factors, can influence the shape of isodose curves.
TRUE
T / F Cobalt sources must be checked for leaks by the manufacturer before being shipped.
TRUE
T / F Cold spots cannot occur outside the target/treatment volume.
TRUE
T / F Each orbit (electron shell) has an associated energy level.
TRUE
T / F Electrons can exist free in nature.
TRUE
T / F Filtration and beam intensity are inversely related.
TRUE
T / F For protection purposes, there is assumed to be no minimum dose below which radiation effects can be considered absent.
TRUE
T / F Full wave rectification is more efficient than half-wave rectification.
TRUE
T / F HDR can be fractionated.
TRUE
T / F Hot labs must be ventilated to the outdoors.
TRUE
T / F If a radiation response is linear, that means that as dose increases, response increases.
TRUE
T / F In characteristic x-ray production, the energy of the projectile electron must be equal to or greater than the binding energy of the orbital electron.
TRUE
T / F Increasing filtration results in an increase in the average energy of the beam and decreases the intensity of the beam.
TRUE
T / F Most cosmic radiation is blocked by Earth's atmosphere.
TRUE
T / FA temporary implant generally provides better control of source distribution and dosimetry than a permanent source.
TRUE
The thickness of material that will reduce the intensity of a beam to one tenth its original value defines what three letter abbreviation.
TVL
Define what is meant by the "binding energy" of an electron
The energy required to eject an electron
An elastic collision is one in which:
The incoming electron gives all of its energy to the electronic it encounters
State the Bury-Bohr principal
The outermost shell can contain no more than eight electrons
What does the acronym TRAK stand for?
Total REference Air Kerma
Radium emits polyenergetic gamma rays
True
Radium is the 4th member of the uranium series
True
T / F Radioactive mean life is somewhat longer than physical half-life.
True
The exposure rate constant decreases by 2% for every .1mm increase in filtration
True
TCP stand for
Tumor Control Probabolity
If we decide to measure a particles' position precisely, it simply does not have anything that can be called momentum (energy), thus, "(observable) Reality is observer created." This is a fundamental tenet of:
Uncertainty Principle
A 3cm 3-dimensional tumor that is to be treated by an interstitial implant would probably best be treated by this type of source configuration:
Volume
For the formula in the previous question, what do the various letters in the numerator portion of the equation stand for?
W = Workload
Define the term isodose curve:
a line passing through points of equal dose
Isocenter for partial arcs should be placed:
about 3-4cm beyond isocenter
THe distance between the actual ends of a radioactive source is called:
active length
The number of disintigrations per second defines:
activity
The best method for calibrating sources, which will eventually be the most commonly used as it is being recommended by the AAPM
air KERMA strength
All of these listed factors influenced geometric penumbra
all
3. concrete is structurally strong
all of them
4. Equivalent TAR
all of them
6. SDD
all of them
Element has an "A" number of 98 and "Z" number of 28 and decays to an "A" number of 94 and "Z" number of 26. What type of radioactivity was emitted?
alpha
This radioactive particle is identical to a helium nucleus:
alpha
Though it is highly ionizing, this radioactive particle is so poorly penetrating that it cant even penetrate a sheet of paper:
alpha
Which of the following materials is not used for wedge construction?
aluminum
The maximum height of a wave describes:
amplitude
The shielding requirements of a MV room door (in a room that has a maze) is typically about the same as the requirements for:
an orthovoltage room
An arthritic like condition that causes a painful hunchback and that was treated with RTT in Great Britain earlier this century is called
ankylosing spondylitis
HDR leakage radiation should be tested
annually
The positively charged end of an x-ray tube is called the:
anode
Which of the following sites would not be suitable for rotational therapy?
any site that is round and small would work with rotational therapy
Define the term "matter":
anything that has mass and takes up space
What do the letters AMU stand for?
atomic mass unit
The loss of intensity during the process of penetrating matter is called:
attenuation
According to Khan, a plate of low Z# material that is used to reduce the energy of an electron beam is referred to as a beam______________________.
beam decelerator/degrador
This term is defined as the dose variation across the field at a specified depth:
beam profile
For partial arcs, higher doses occur:
before isocenter
Electron beams start to 'unravel' and pull apart at what location?
before the scattering foil but after the bending magnet (beam transport system)
This radioactive particle is identical to a high speed electron:
beta
An ophthalmologic applicator curved to conform to the surface of the eye is a(an):
beta plaque
For kilovoltage machines, the main tissue inhomogeneity that presents a problem in dose distributions is:
bone
Name two areas of the body that would typically need "boosts" after total skin in radiation treatment
bottoms of feet, any skin fold
What is the shape of the isodose summation for a 3 field (conventional) rectum with wedges?
box
What type of cancer was first treated using a multiple field technique?
breast
Which of the following areas would most likely be treated with temporary/removable interstitial source brain, breast, bladder
breast
What was the first type of cancer to be cured using x-rays?
buccal mucosa
One a.m.u. equals 1/12 the mass of a __________ atom.
carbon
What is the most common isotope used for intracavitary implants?
cesium
Electron arc therapy is useful for what body areas? 1. Chestwall; 2. TSI; 3. Ribs; 4. limbs
chestwall, ribs, limbs
What term (give the full term, not any initials) is defined as "The GTV plus a surrounding volume of tissue containing sub-clinical (microscopic) disease)"?
clinical target volume
Individual wedge system would most likely be used on what specific type of machine?
cobalt
What is another term for ovoids?
colpostats
With respect to personnel protection for californium (or any neutron beam), what type of material is recommended?
combo high and low z number
Which interaction(s) in tissue result in the atom being ionized? 1. Pair Production; 2. Classical; 3. Compton; 4. Photodisintegration; 5. PE
compton, and PE
Crossing Needles is not required or used in which of the following interstitial dosimetry systems
computer and Paris
The most practical material for primary barrier shielding of neutrons is:
concrete
List two areas, besides appropriate places in the treatment room, where radiation warning lights are required.
console and near the door
The nucleus of an atom:
contains a positive charge
Film dosimetry is sometimes employed in electron beam dosimetry due to its:
convenience
The purpose of oil in an x-ray tube is to:
cool and insulate
The anode is usually made of what material?
copper
The tube that was used when x-rays were first discovered was called a ___________ tube.
crookes
Radioactive materials that are man made can be made in nuclear reactors and in:
cyclotrons
List two possible acute side effects of an intracavitary implant.
cyctitis diarrhea fistula generalized irritation
The most common shape for a volume implant is:
cylindrical
For the formula in the same question as before, what do the various letters in the denominator (lower) portion of the equation stand for?
d = distance
What is the frequency for checking the effectiveness of the door interlock?
daily
HDR communication equipment should be tested:
daily every 3 months
HDR room monitors should be tested:
daily every 3 months
HDR warning lights should be tested:
daily every 3 months
The time in between bursts of radiation for pulsed radiation machines such as linacs where there is no measureable radiation is referred to as:
dead time
What is the rationale for performing 2 intracavitary implants on the same patient instead of just one?
debulking so that 2nd implant can access treatment site
In the half life formula T1/2= .693/ lambda, the symbol stands for
decay constant LAMBDA
What is given as a MAJOR advantage of remote afterloading compared to other brachytherapy techniques?
decrease exposure to personnel
Which of the following is not an advantage of parallel opposed fields:
decreased normal tissue dose
Which of the following is not one of the "major characteristics of electron beams" discussed early in the electron therapy lecture?
deep dmax depth resulting in uniform dose to deep structures such as prostate and cervix
Electrons scattered with enough energy to cause further ionization and excitations and other Adams can be referred to as:
delta rays
Electrons scattered with enough energy to cause further ionization and excitations in other atoms are called:
delta rays
What is the Pauli Exclusion Principle used for?
determine the maximum # of electrons in a shell
Electron beam energy and surface dose show a ________ relationship.
direct
The dose that will produce twice the frequency of genetic mutations as normally seen is termed:
doubling dose
Many accelerators have a:
dual scattering foil system
3. during the last trimester
during 1st trimester and during the period of major organogenesis
A technique in which a MLC moves across one axis of the beam during treatment to produce a wedge effect is termed:
dynamic wedging
What do the E, m and c stand for in Einstein's equation E=mc2?
e= energy
invented the fluoroscope
edison
Electrons interact via ________ collisions.
elastic and inelastic with nuclei and outer shell electrons
When a nucleus "sucks" in an orbital electron, usually K-shell, this process is called:
electron capture
Which particle has the strongest net charge?
electron, and proton
Cathode rays were later renamed as being:
electrons
"Absorbed dose" is defined as:
energy absorbed per unit mass
Photon penetration depends on two things: one is the density of the material it is passing through, what is the other?
energy of the x-ray
Give an example of a non-stochastic effect:
epilation
The amount of time necessary to develop a reddening of the skin defines the term _______________ dose
erythema
ntraluminal brachytherapy is emerging as an effective treatment for which of the following cancer sites:
esophagus, uterus, trachea bile duct, bronchus, rectum
HDR door interlocks should be tested
every 3 months
HDR emergency stop buttons should be tested:
every 3 months
HDR treatment interrupt should be tested:
every 3 months
How frequently is Cs source replaced?
every 7 years
question 75
exam 3, section 2 and 3 combined
What is given as a huge disadvantage of remote afterloading techniques?
expense and room shielding
The Roentgen/rad conversion factor is also known as:
f-factor
Name the four most frequently reported side effects of pelvic area brachytherapy:
fatique diarrhea urinary frequency urinary burning
The splitting of an atom is termed:
fission
"Horns" on isodose curves are created by the:
flattening filter
Of all the collimation devices, which on has the most effect on the shape of isodose curves?
flattening filter
If a brachytherapy patient's source becomes dislodged, what type of device is used to put the source(s) in a shielded container?
forceps
The energy of an electromagnetic radiation is directly proportional to its:
frequency
The number of vibrations a wave will make in one second defines:
frequency
An element has an "A" number of 99 and an "Z" number of 55 and decays to an element also having an "A" number of 99 and a "C" number of 55. What type of radioactivity was emitted?
gamma
Cs is considered a ___________ emitter
gamma
What type of cancer was the first to be treated using x-rays?
gastric
In terms of our knowledge of what effects radiation could have, this is our weakest area:
genetic effects
What two word term is described as a mistreatment due to inaccurate patient/machine geometry in simulation or in treatment set-up?
geometric miss
The minimum amount of energy required to keep and add them together" defines what term?
ground state
A single plane implant is to be designed according to the Manchester system using Paterson-Parker rules to deliver 8000 cGy to the tissue volume. The minimum acceptable dose to any point within the tumor volume would be:
has to be within 10% 8000x.90=
If a dosimeter measures independent of energy, it is said to:
have a flat energy response
The branch of radiation science that deals with the protection of individuals from unnecessary exposure to ionizing radiation.
health physics
Scattering foils are made of:
high Z number materials
Give the main disadvantage of parallel opposed fields:
high doses to all tissues
Intracavitary implants must be packed (with gauze) for 2 reasons, what are they?
hold device in place limit bladder and rectum dose
Explain why a hot spot created by a uniform source placement BT implant is not considered improper treatment planning.
hot spot to tumor is goof anoxic center needs more dose
Before being sterilized, blood must often be washed off of a source. How is this best accomplished?
hydrogen peroxide saline
Californium may be used in radiotherapy to generate higher radio biological effectiveness, especially in what type of tissues?
hypoxic
Cosmic ray exposure increases with:
increased altitude
If no kinetic energy is lost to the system in the collision, the collision is said to be:
inelastic
A body at rest tends to stay at rest. This defines the principle or law of:
inertia
An excited nucleus can transfer its excess energy in the form of a gamma ray. This process describes:
internal conversion
Tandem and ovoids are used for ___________ treatment.
intracavitary
Placing sources within body tubes best defines which of the following:
intraluminal
This is a relatively new variation of brachytherapy used in conjunction with coronary angioplasty:
intravascular
Frequency and wavelength are:
inversely propotional
Isodose charts can be measured by a variety of means, but the most reliable means includes the use of:
ion chambers
Electron beam absorbed dose data is most commonly determined by using:
ion chambers and chemical dosimeters
The point of intersection of the collimator and gantry axis of rotation defines what term?
isocenter
This method for correcting for contour irregularities is also called the "2/3rds shift" method:
isodose shift method
This method for correcting for contour irregularities is used for making full isodose curves rather than a point dose calculation:
isodose shift method
4. isotones
isomers and nuclides
Atoms with the same number of neutrons are called:
isotones
Atoms with the same Z numbers but different A numbers are called:
isotopes
This device helps keep the tandem and ovoids in place flush against the fornices:
keel
The dental film incorporated into a film badge is backed by _______ foil to absorb backscattered radiation.
lead
What is the stable and product in the uranium series?
lead/ Pb
Which of the following would have the highest average energy (closest to the primary beam energy)?
leakage
Name the two components of stray radiation:
leakage and scatter
baryon
lepton
Which of the following is an advantage of magnetically scanned electron beams?
less Brems contamination
Hot spots created in subcutaneous tissue in parallel opposed fields occur with energies:
less than 4 MV
Treating patients with an arthritic-like condition resulting in a painful hunchback have a higher risk of this late effect from RTT:
leukemia
What is the most commonly occurring (important) radiation induced malignancy?
leukemia
What machines are capable of producing a therapeutic electron beam?
linac, betatron, Van De Graaff
model.
linear/non-threshold
The state of matter in which there is a constant volume but an indefinite shape describes:
liquid
Which of the following isotopes is not a component of terrestrial radiation?
lithium
BT is most commonly used for local, regional or systemic therapy?
local
Internal shielding with electron therapy can be used for tx of the lip, buccal mucosa and eyelid to protect normal structures beyond the target volume. For this shielding, a high Z# material should be used, which is coated by a ___________ material.
low Z number
What do the initials LDR stand for?
low dose rate
What tissue does RN 222 gas damage the most?
lung
What tissue is radon gas particularly harmful to?
lung
Tube current is described in terms of:
mA
'Time intensity factor' is another term synonymous with:
mG/Hrs
The number of nucleons is determined by the:
mass number
The rate of energy loss per gram per cm squared defines:
mass stoping power
This term is defined as "the rate of energy loss per gram per centimeter squared
mass stopping power
Lip
maxillary sinus
The average "life" before a radioactive element decays is called:
mean life
Film badges and TLD's are affected by all of the following:
mechanical pressure
What is NOT a component of NBR?
medical x-rays
In T99m, what does the "m" stand for?
metastable
Another name for Compton's scattering is:
modified, incoherent, inelastic
What is the required minimum frequency for checking the emergency off devices?
monthly
The dose to a tumor several cm deeper than lung is:
more than what would be expected if all the tissue were homogenous
"Horns" are most prominent:
near the surface
What type of source would most likely be used for a temporary implant?
needles
According to Quantum theory, light is a __________ phenomena
neither wave or particle
This "particle" may have no mass and is sometimes called a "ghost particle":
neutrino
The process of converting a stable nucleus to its radioactive counterpart is termed:
neutron activation
A major advantage of electron beam therapy is:
no exit dose
Which interaction best represents total absorption of the energy of the incident photon?
not
Electron beam "Practical Range" follows which rule of thumb?
one half
scars
orbit
Films taken at right angle to each other that give a three dimensional view of the implant volume are called:
orthogonal
What type of machine was the first used for multiple field techniques?
orthovoltage
Which beam would least likely be used to treat any lesion that is underlying bone?
orthovoltage
Which of the following would have the highest backscatter?
orthovoltage
Which interaction in tissue is most closely related to Einstein's equation of mass being equal to energy?
pair production
The technique wherein isocenter is approached differently than usual for rotational techniques (partial arcs) is called:
past pointing
Intravascular brachytherapy is a rapidly emerging treatment modality with potential applications for which of the following:
peripheral vessel angioplasty
Which interaction in tissue is most closely associated with the energy range most commonly used in diagnostic x-ray?
photoelectric effect
Of all improper hot lab procedures, this is the worst:
pipetting by mouth
Another name for a brachytherapy surface applicator is a/an:
plaque
Changing field size on a daily basis along one border of a field in order to produce a wedge effect, describes what technique?
poor man's wedge
A neutral atom that loses an electron by ionization is called a:
positive ion
This radioactive particle has the same mass as an electron but carries a positive charge:
positron
Give an example of a particle that is considered "antimatter"
positron/anti-proton/etc.
After insertion of radiation sources, the radiation oncology department must:
post warning signs on patients door and in chart inculde RN instruction perform radiation exposure survey
What internal radiation source produces the highest doses to the body?
potassium
Which source of internal radiation produces the highest dose to the body?
potassium
Which of the following is not a method for correcting for contour irregularities?
power law TAR method
Secondary barriers protect against all of the following radiations except:
primary
This is a synchronous (gravity oriented) shielding device used in conjunction with rotational therapy:
priomos
Which of the following areas would most likely be treated with permanent interstitial source prostate, rectum, breast?
prostate
The number of this type of particles within an atom characterizes that element. If you change the number of these types of particles, you will change the element:
proton
The number of ________ determines the chemical properties of an element.
protons
What sub-atomic particles primarily make up cosmic rays?
protons
What does the "Z" number tell us (the number of what)?
protons in the atom
A benign condition of the conjunctiva of the eye
pterygium
How often should the wipe test be performed by the user?
quarterly ??? AS
HDR facilities should be equipped with which of the following safety requirements:
radiation monitor mobile shield same as cobalt room electrical interlock door interlocks and emergency offs
Which of the following, according to textbooks, has the longest wavelength?
radiowaves
Most common BT source throughout the first half of the century
radium
Early research with radioactive materials was performed using:
radium/uranium salts
First DAughter product of Uranium
radon
Which of the following produces the highest average dose?
radon gas
THe wall of a radium needle is constructed to block out
radon leakage
Calibration of brachytherapy sources is usually carried out with this type of ionization chamber:
re-entrant
This part of an x-ray tube changes the current from AC to DC:
rectifier
What is the primary purpose of an afterloading device?
reduce personnel exposure
In addition to reducing the amount of radioactive source material, reduction of occupational dose due to exposure to brachytherapy sources can be achieved by combining which of the following principles?
reduce time of exposure keep distance as large as possible use shielding material available
The primary advantages of HDR over LDR include:
reduced personnel exposure patient convenience less costly with similiar outcomes
What is the shape of the isodose curve for a wedge pair field arrangement using 45 degree wedges?
regular diamond
"the mass (weight) of a particle when it is not moving" defines what term?
resting mass
A Brems Tail is indicative of:
secondary x-ray contamination
When the quantity of a radioactive isotope remains constant because of its production rate, it is called:
secualr
When the decay of atoms in a radioactive element becomes equal to the number of those atoms being produced by the parent atom, (when daughter activity approaches the parent activity ) this condition is referred to as:
secular
Which of the following is NOT an example of terrestrial radiation?
selenium...
Full secular equilibrium usually takes ___________ half-lives to establish.
several
Which of the following is a method of disposal for radioactive waste?
sewer incineration burial
Regarding storage of materials in a hot lab, what factor is not as important for radiation protection?
shielding
When unloading sources from a brachytherapy patient, which protection factor is least important?
shielding
What does the term brachytherapy literally translate to
short distance therapy
Low level radiation may produce all of the following:
shortened life span
What field arrangement is the simplest and easiest?
single field
What does the abbreviation SED stand for?
skin erythema dose
Electron beam energy is characterized at:
skin surface
Organs at risk due to contamination with radioactive materials include:
skin, esp hands digestive tract eyes lungs
What are the two different theories of Relativity called?
special, general
The most commonly used TSI technique, developed at a University in northern California, is called:
stanford technique
List two possible late side effects of an intracavitary implant.
stenosis weakened pelvic bones
A type of 3-D film technique for implant localization whereby two radiographs are taken of the same view but the x-ray tube is shifted a certain distance (ex. 15 degrees or 20 cm)between the two exposures is called:
steroe shift
Effects that have no threshold dose are referred to as _____________ effects
stochastic
The nucleus of an atom is held together by what type of force?
strong interaction
Film badges for the whole body, especially when considering doses to the thyroid and lens, should be worn at the level of:
the collar
WHat does lambda (decay constant) describe
the percent decay per YEAR
In tracking the shift of an isodose curve with regard to a tissue inhomogeneity, which of the following statements are true?
the shift is toward the skin for bone and away from the skin for lung
The energy of a Brems x-ray depends on all of the following except:
the strength of the charge of the incident electron
A disadvantage of film badges is:
they do not give immediate readings of exposure
Define biological half life
time necessary for the element activity to decrease to half its original intensity through biological decay
A source inventory must contain what 4 bits of information?
time of delivery total dose delivered applicator used amount and size of source delivered
A measure of the total energy absorbed in the treated volume which is a product of dose and mass, is termed:
tissue lateral damage ???????
Hot spots created in subcutaneous tissue in parallel opposed fields are termed :
tissue lateral effect
When using a wedge, isodose curves tilt toward the:
toe
Which of the following areas would most likely be treated with temporary/removable interstitial source cervix, prostate, tongue, endometrium?
tongue
When the daughter activity is actually greater than the parent activity this is called:
transient
A term that relates in a manner similar to cobalt "Timer error" with respect to HDR treatment units is:
transit time effect
Conformal therapy (where the table moves during treatment) is used in TSI in this technique:
translational
Kilovoltage units typically have a reflection target. As the kinetic energy of the electron increases, the direction of x-ray emission becomes more forward resulting in what type of target used for MV machines?
transmission target
The filament is usually made of what material?
tungsten
The target is typically made of what material?
tungsten
Which has the highest photon energy?
ultraviolet light
As the wavelength of light is decreased, its speed is:
unchanged
Which system of wedges is more commonly used?
universal
Name the six basic types of quarks
up, down, top, bottom, strange, charm
The fraction of time that a beam is pointed at a particular barrier describes what term?
use factor
Aside from resuming sexual intercourse, what other method/device can be used to assist female brachytherapy pelvic patients with regards to making future gynecological examinations easier and with less discomfort?
vagianl dilator
What do the ovoids treat in an intracavitary implant?
vaginal cuff and fornices
The specific type of electrons responsible for chemical reactions and bonds between atoms as well as the emission of optical radiation spectra are called what type of electrons?
valence
Electrons responsible for chemical reactions and bonds between atoms are called what type of electrons?
valence electrons
The intersection point of the back projections along the most probable direction of electron motion defines what term related to electron beam therapy?
virtual source
A pregnant technologist shall have a 2nd film badge and it should be worn where on the body?
waist/abdomen
λ (lambda) is the symbol for:
wavelength
"The angle of tilt for an isodose curve at the CR at a specified depth", defines what term?
wedge angle
What is the most commonly used beam modifying device?
wedge filter
The number of rads-cGy/week at 1 meter from the source defines what term?
workload
A lateral film visualizes what dimensions?
y z
This device helps keep the tandem and ovoids together as a single unit:
yoke
What is the 10 day rule in radiology used for (describe the rule)?
you take x-rays of the women's abdomen and pelvis area between the menstral cycle and the 10th day because there is not virtual risk of the woman being pregnant