Dosimetry II Final Part 2
An orbital electron ejected from its shell by photons produced from the nucleus is called:
"Auger electron"
What is given as a huge disadvantage of remote afterloading techniques? 2
- expensive - increase room shielding
Name the four most frequently reported side effects of pelvic area brachytherapy:
- fatigue - diarrhea - urinary frequency - urinary burning
The primary advantages of HDR over LDR include: 3
- greatly reduces personnel exposure - patient convenience - less costly
The energy of Palladium is:
.021 Mev
What are the four basic principles (tenets) of Special Relativity discussed in class:
1. A moving object measures shorter as its velocity increases until, at light speed, it disappears 2. The mass of a moving object measures greater as its velocity increases until, at the speed of light, it becomes infinite 3. Moving clocks run more slowly as velocity increases until, at light speed, it stops moving altogether 4. E=mc2 (in Joules); the most famous formula in the world. It means that even the smallest piece of matter has a tremendous amount of energy, and that energy and matter are really the same thing, and that matter and energy are two sides of the same coin.
List the systems of implant dosimetry for interstitial brachytherapy:5
1. Paterson parker 2. Quimby 3. computer system 4. Paris system 5. memorial
After the insertion of radiation sources, the radiation oncology department must do what 4 things
1. Post a warning sign on or by the patient's door 2. Place a warning sign on the patient's chart 3. Include nursing instructions and place those in the patient's chart 4. Performed a radiation exposure survey
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? 3
1. Reduce the time of exposure 2. Keep the distance as large as possible 3. Used the shielding material that is available
intraluminal brachytherapy is emerging as an effective treatment for which of the following 6 cancer sites
1. esophagus 2. uterus 3. trachea 4. bile duct 5. bronchus 6. rectum
The energy of a Brems x-ray depends on 3
1. the number of protons in the nucleus 2. the kinetic energy of the incident electron 3. how close the projectile electron passes to the nucleus
Stereo films should be taken at angles that are ____ degrees off ap:
10-15 degrees
The HVL for Radium is
12.0mm Pb (lead)
The half-life of Palladium is:
17 days
Brachytherapy patient visitors must be at least _____ years of age.
18
Einstein's Theory of Special Relativity was developed in what year?
1905
Readings taken in a brachytherapy patients hospital room should to be taken:
1m from the patient, at the door, and adjacent rooms along the abutting wall
The actual HDR treatment, with the radioactive sources in place, takes approximately ____ minutes.
2-3 minutes
Adequate hospital room wall protection for LDR brachytherapy applications is obtained with concrete thicknesses around _____
20-25 cm
Forceps for use in handling BT sources must be at least how long?
25cm
If 5 mG of radium provide a certain dose in 2 hours, 20 mG would give the same dose in:
30 minutes (? but why)
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:
72000 cGy 8000x10% (8000x.90=7200)
For which of the following radioactive sources do you think any implant dosimetry tables would be LEAST appropriate? a. Ra 226 b. Cs 137 c. Co60 d. Cf 252 e. Ir 192
Cf252
The shielding and safety requirements for an HDR room are comparable with those of a_______________ room.
Co60
With respect to personnel protection for californium (or any neutron beam), what type of material is recommended?
Combination high and low Z. number
When a nucleus "sucks" in an orbital electron, usually K-shell, this process is called:
Electron capture:
HDR door interlocks should be tested
Every three months
HDR emergency stop buttons should be tested:
Every three months
HDR treatment interrupt should be tested:
Every three months
T / F (Added) Filtration has no effect on output.
F
T / F The Manchester system takes into account variables such as large or small cervix/uterus.
F
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
The time necessary for half of the atoms in a group to decay defines what term?
Half-life (T1/2)
Which system of intracavitary dosimetry, according to Khan, is probably the best that can be achieved at this time?
ICRU
An excited nucleus can transfer its excess energy in the form of a gamma ray. This process describes:
Internal conversion
Placing sources within body tubes best defines which of the following:
Intraluminal brachytherapy
The only radionuclides used for HDR brachytherapy are: 2
Iridium and cobalt
what implant dosimetry systems is the most commonly used manual calculation method for intracavitary brachytherapy?
Manchester system
This system, based on computer generated dose distributions, was devised in 1963 and is an extension of the Quimby system:
Memorial
A device used to "staple" in permanent interstitial sources is a/an ______ applicator.
Mick
Another name for a brachytherapy surface applicator is a/an:
PLAQUE or Topical brachytherapy
For this system of interstitial dosimetry, dose specification is based on an isodose surface called the "reference dose.":
Paris system
Planar implants would most closely be associated with which dosimetry system?
Paterson-Parker
Intravascular brachytherapy is a rapidly emerging treatment modality with potential applications for which of the following 2
Peripheral vessel angioplasty and, combining with the stents to reduce the rate of restenosis
Organs at risk due to contamination with radioactive materials include:
Skin, especially hands Digestive tract Eyes Lungs
list 2 isotopes would be used to treat pterygium of the eye?
Sr & Yttrium
T / F X-rays originate from outside the nucleus, which is just the opposite of radioactivity.
T
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:
The Heisenberg Uncertainty Principle
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?
Vaginal dilator
HDR facilities should be equipped with which of the following safety requirements:5
a. Radiation monitor, continuously visible light signal indicating the source is on, dedicated circuit on the facilities emergency power circuit. b. Essentially the same as those required for a cobalt therapy vault c. Mobile shield, cable cutting a vice, long forceps, mobile storage device (pig) d. Electrical interlock causing the source to return to shielded area upon opening the door e. Door interlocks and emergency off buttons
In the following decay, what type of radioactivity was emitted: 98 decay 94 XX to: YY 28 26 a. alpha b. beta c. gamma d. neutron e. none of the above
alpha
This radioactive particle is identical to a helium nucleus:
alpha
HDR handcrank functioning should be tested:
annually
HDR leakage radiation should be tested
annually
What does A=
atomic mass number (number of nucleons)
Explain why a hot spot created by a uniform source placement BT implant is not considered improper treatment planning.
because its okay to overdose the tumor (local area treatment)
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:
bells theorem
This radioactive particle is identical to a high speed electron:
beta
Radioactive materials that are man made can be made in nuclear reactors and in:
cyclotron
HDR communication equipment should be tested:
daily
HDR room monitors should be tested:
daily
HDR timer termination should be tested:
daily
HDR warning lights should be tested:
daily
T / F Fletcher-Suite devices are never an example of an afterloading device.
false
T / F Radium can be sterilized at high temperatures.
false
T / F After removal of the implant, a survey need not be performed to ensure that no sources were inadvertently left behind.
false, a survey needs to be done
If a brachytherapy patient's source becomes dislodged, what type of device is used to put the source(s) in a shielded container?
forceps
Transient equilibrium typically occurs after about _____half-lives, on average.
four half-lives
In the following decay, what type of radioactivity was emitted: 99 decay 99 XX to: XX 55 55 a. alpha b. beta c. gamma d. neutron e. proton
gamma
Before being sterilized, blood must often be washed off of a source. How is this best accomplished?
hydrogen peroxide or saline
Californium may be used in radiotherapy to generate higher radio biological effectiveness, especially in what type of tissues?
hypoxic
This is a relatively new variation of brachytherapy used in conjunction with coronary angioplasty:
intravascular brachytherapy
Atoms with the same number of neutrons are called:
isotones
What do the initials LDR stand for?
low dose rate
The average "life" before a radioactive element decays is called:
mean life
In T99m, what does the "m" stand for?
metastable
List examples of an intracavitary dosimetry system. 3
milligram hours, Manchester, and ICRU
'Time intensity factor' is another term synonymous with:
milligram-hours (mG/Hrs)
This radioactive particle has the ability to easily penetrate the nucleus of an atom without much difficulty:
neutron
According to Khans, uniformity of source placement is least important for which type of implant system? a. Paterson-Parker b. Quimby c. Paris d. ICRU/computer
paterson parker
Sources are transported in devices called:
pigs
The dose to the bladder and rectum in an intracavitary implant should be less than the dose to what point?
point A
This radioactive particle has the same mass as an electron but carries a positive charge:
positron
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
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 equilibrium
When the quantity of a radioactive isotope remains constant because of its production rate, it is called:
secular equilibrium
Full secular equilibrium usually takes ___________ half-lives to establish.
several
Which of the following is a method of disposal for radioactive waste? 3
sewer incineration burial
T / F A temporary implant generally provides better control of source distribution and dosimetry than a permanent source.
t
3.7 x 1010 dps defines what unit of measurement?
the curie
what does Z=
the number of protons
What is given as a MAJOR advantage of remote afterloading compared to other brachytherapy techniques?
to reduce personnel exposure
What does the acronym TRAK stand for?
total reference air kerma
When the daughter activity is actually greater than the parent activity this is
transient equilibrium
A term that relates in a manner similar to cobalt "Timer error" with respect to HDR treatment units is:
transit time effect
T / F Brachytherapy patients should not receive a bed bath while radiation sources are in place.
true
T / F Brachytherapy personnel must wear an additional film badge (ring badge).
true
T / F Radioactive mean life is somewhat longer than physical half-life.
true
T / F Radioactive source transport devices (pigs) may not be left unattended.
true
