1
Q
Sources of Rad. - Natural Background Radiation:
A
- cosmic rays: high energy rad. mainly originating from outside the solar system
- terrestrial rad. - long-wave electromagnetic rad. originating from earth and its atmosphere
- internal rad. - human bodies emit electromagnetic rad.
2
Q
Sources of Rad. -Types of Radiatiation:
A
- Alpha Paticles
- Beta Particles
3
Q
Sources of Rad. - What is the half-life of Iodine- 125?
A
59.4 days
4
Q
Sources of Rad. - What is the half-life of Palladium- 103?
A
17 days
5
Q
Sources of Rad. - What is the half-life of Cesium- 137?
A
30 years
6
Q
Sources of Rad. - What is the half-life of Iridium- 192?
A
73.8 days
7
Q
Sources of Rad. - What is the half-life of Strontium- 90?
A
28.8 years
8
Q
Sources of Rad. - What is the half-life of Iodine- 131?
A
8 days
9
Q
Sources of Rad. - Kilovoltage units:
A
- superficial - 50-150 kv
- orthovoltage - 150-500 kv
10
Q
Sources of Rad. - megavoltage units:
A
- linear accelerator (photons and electrons)
- cyclotron (particle therapy)
- cobalt-60 (gamma rays)
11
Q
Basic Properties of Radiation - Electromagnetic Radiation - what is frequency?
A
number of waves that pass a given point in a specified unit of time. the unit is hertz (cycles/second)
12
Q
Basic Properties of Radiation - Electromagnetic Radiation - what is wavelength?
A
distance between peaks of the wave, measured in meters
13
Q
Basic Properties of Radiation - Electromagnetic Radiation - what is the energy equation?
A
(E)=hv
v=frequency
h= Plank’s Constant (6.62 x 10^-34)
14
Q
Basic Properties of Radiation - Electromagnetic Radiation - What does a shorter wavelength mean?
A
greater energy and penetrating power
15
Q
Basic Properties of Radiation - Electromagnetic Radiation - what has no mass, no charge, and low LET?
A
Photons
16
Q
Basic Properties of Radiation - Electromagnetic Radiation - photon gamma rays are emitted from the ______.
A
nucleus
17
Q
Basic Properties of Radiation - Electromagnetic Radiation - photon x-rays are emitted from outside the _____.
A
nucleus
18
Q
Basic Properties of Radiation - Electromagnetic Radiation - what is attenuation?
A
the reduction of the force, effect, or value of something.
19
Q
Basic Properties of Radiation - Electromagnetic Radiation - Characteristics of Beta Particles:
A
- electrons emitted by the nucleus
- shielded w low Z materials
- more penetrating than alpha
Beta- Decay, Beta+ Decay, x-ray and gamma ray
20
Q
Basic Properties of Radiation - Electromagnetic Radiation - Characteristics of Alpha Particles:
A
- Helium Nucleus
- emitted from an unstable nucleus
- travels short distances
- produces intense ionizations - High Energy Linear Transfer (LET)
- Extremely hazardous if ingested or inhaled
21
Q
Basic Properties of Radiation - Electromagnetic Radiation - What is inverse square law?
A
a law stating that the intensity of an effect such as illumination or gravitational force changes in inverse proportion to the square of the distance from the source.
22
Q
Basic Properties of Radiation - Electromagnetic Radiation - What is Half Value Layer? (HVL)
A
the thickness of a given material that reduces the intensity of the intensity of the rad. beam by one half
23
Q
Basic Properties of Radiation - Electromagnetic Radiation - what is the attenuation equation used for?
A
used to calculate beam intensities for various absorber thickness
24
Q
what is monochromatic radiation?
A
all photons in the radiation beam have the same energy
25
what is polychromatic radiation?
- photons in beam have varying energies
- an absorber removes lower energy x-rays
- attenuation of polychromatic rad. results in:
change in beam quantity
change in beam quality
26
higher energy (hard) beams have:
- high half value layer
| - high penetrating power
27
low energy (soft) beams have:
- lower half value layer
- less penetrating power
- higher skin dose
28
Interactions w/ matter: What are the photon interactions with matter?
photoelectric effect, Compton scatter, and Pair Production
29
Interactions w/ matter: What are the electron interactions w matter?
Bremsstrahlung and characteristic radiation
30
Interactions w/ matter: what is attenuation?
the reduction in the number of primary photons in the beam through absorption (a total los of rad energy) and scatter (a change in direction of travel that may also involve a partial loss of rad energy) as the beam passes through the pt in it path
31
Interactions w/ matter: Describe characteristic effect:
- transfer of total energy of a photon to an inner electron of an atom
- photon interacts w an inne shell (k or l) and ejects an electron from the atom (ionization). photon disappears
- electron from outer shell fills vacancy and gives off characteristic rad
32
Interactions w/ matter: what materials is photoelectric effect more common w?
materials such as bone - low energy photons and high atomic number (Z) materials
33
Interactions w/ matter: Describe Compton scatter:
- photon interacts w an outer shell electron (loosely bound), atom absorbs all the photon energy, and electron is ejected from outer shell
-
34
Interactions w/ matter: what materials is Compton scatter more common w?
the dominant interaction w photons in diagnostic and therapeutic energy ranges
-most common interaction w energies used in rad ther
35
Interactions w/ matter: Describe Pair Production:
- high energy photon interacts w the nucleus
- incoming photon must have an energy of at least 1.02 MeV (threshold)
- photon energy creates mass of negative and positive (positron) electrons, photon disappears
- when positron stops, it undergoes annihilation and creates 2 .51 MeV photons traveling in opposite directions
36
Interactions w/ matter: describe bremsstrahlung rad:
- "braking radiation"
- interaction of a charged particle (electron)w the nucleus of an atom
- the particle loses speed and changes direction
- the kinetic energy lost by the particle is emitted as bremsstrahlung radiation
37
Interactions w/ matter: Describe Characteristic Radiation:
- photons interact w an inner shell electron, ejecting it from the atom (ionization)
- electron from outer shell jumps to fill vacancy and yields characteristic rad equal to the elements electron binding energy
- energy given off identifies the element. rd given off is characteristic of that element
38
Interactions w/ matter: What is Linear Energy Transfer?
LET - Linear Energy Transfer
- rate that energy is deposited as it ravels through matter
39
Interactions w/ matter: Low LET vs. High LET:
Low LET: x-rays and gamma rays, secondary electrons: small particles travel great distances
High LET: protons, alpha particles: bulky particles travel small distances
40
Interactions w/ matter: 2 different radiation interactions:
- direct ionizations
- indirect ionizations
cause secondary effects within the cells
41
Interactions w/ matter: Describe Direct Ionizations:
more prominent w charged particles such as protons and electrons
-particles interact w the nucleus of an atom causing damage to the DNA of the cell. DNA is the "target" for the radiation and a direct hit will kill the cell
42
Interactions w/ matter: Describe Indirect Ionizations:
usually caused by x-rays, gamma rays and neutrons
43
Interactions w/ matter: What is radiolysis?
splitting of a water molecule to form ions
44
Components and Operations: How it works: productions of radiation:
as the electrons are accelerated down the guide they gain energy. then they strike a high Z target and produce x-rays via bremsstrahlung interactions. if electron therapy is desired, the target and the flattening filter move out of the beams path and the scattering foil moves into the beam's path
45
Components and Operations: Radiation Characteristics:
Linac photon beam has a broad spectrum of energies. max energy photon is the energy of electron striking target. Avg. energy is usually 1/3 to 1/2 the max energy.
46
Components and Operations: Linear Accelerators Interactions w Matter:
for low energy linacs, Compton scattering is the most prevalent interaction, but as the energy increases, pair production becomes more prevalent. Pair production increases w energy above its threshold of 1.02 MV and is proportional to Z^2, so there is more absorption in bone than soft tissue w higher energy machines.
47
Components of a Linear Accelerator - what is the modulator?
provides electron gun and magnetron w high voltage, square, pulsed power
48
Components of a Linear Accelerator - what is the electron gun?
supplies electrons needed for x-ray production and injects them into the accelerator guide
49
Components of a Linear Accelerator - what is the magnetron/klystron?
supplies RF power for the accelerator guide, pulsed simultaneously w the electron gun. magnetrons are found in lower energy machines and produce microwave. klystrons are found in higher energy machines and amplify microwaves
50
Components of a Linear Accelerator - what is the waveguide?
transports RF power from the magnetron to the accelerator guide. waveguide is filled with hexafluoride to prevent arcing
51
Components of a Linear Accelerator - what is the circulator?
one-way door in the waveguide that allows RF into the accelerator guide but not back out to prevent damage to the magnetron
52
Components of a Linear Accelerator - what is the accelerator guide?
vacuum tube across which electrons are accelerated on the RF power
53
Components of a Linear Accelerator - what is the bend magnet?
forces the electrons around a bend so they exit the gantry head in the appropriate orientation for tx
54
Components of a Linear Accelerator - what is the transmission target?
the electrons strike the target and produce x-rays. the photons exit the target in the same direction as the entering electrons
55
Components of a Linear Accelerator - what is the flattening filter?
the lead filter that attenuates some of the beam in order to provide a more uniform dose distribution
56
Components of a Linear Accelerator - what is the ion chambers?
parallel-plate chambers that check dose rate, integrated dose, and symmetry. these chambers are sealed so their response is not influenced by outside temp. and pressure
57
Components of a Linear Accelerator - what is the scattering foil?
placed in the path of the beam for electron therapy. spreads out the beam of electrons. when in the beams path, the transmission target and flattening filter are removed
58
Components of a Linear Accelerator - 5 main components of a linac?
drive stand, gantry, pt. support assembly (PSA), electronic cabinet, and console
59
Components of a Linear Accelerator - what is the gantry responsible for?
directing the beam out toward the pt.
60
Components of a Linear Accelerator - what are the major components in the gantry?
waveguides, electron gun, accelerator structure and collimator head
61
CT Simulator: Why were CT simulators invented?
to enhance target localization; CT simulators brought the capacity to view anatomic data in three dimensions w all tissue densities easily visualized
62
CT Simulator: What do the cross-sectional images for CT simulators allow?
the planning therapist, dosimetrist, and physician to visualize the target and surrounding tissue
63
Quality Control Procedures: What does Warm up for linac consist of?
- time delay - real warm up that allows the filament to heat up correctly. when machine is turned on, it automatically goes into time delay. DO NOT BYPASS TIME DELAY
- Daily Check Out - verifies machine circuitry is functioning properly (e.g. total does, time, and dose rate). operators manual gives warm up procedures for ea machine
64
Quality Control Procedures: what is the interlocking system?
the door - machine will not turn on if door to tx rm is open
65
Quality Control Procedures: what are the emergency switches?
- emergency off buttons - located on control panel, in tx rm, on tx table, and on machine. designed to disable all control circuits and shut down machine
- circuit breakers - if emergency off button fails, the main circuit breaker is the next course f action. no normally located in tx rm, but near ctrl panel. when pulled, all power to machine is cut off
- limit switches - preset switches to prevent machine motion past the limit to prevent damage to the machine. example would be gantry rotation only traveling 360 degrees to prevent damage to the wires in the gantry
66
Quality Control Procedures: what consists of recording critical machine parameters?
during daily warmup the therapist records water pressure, temp., and fluid levels in the log book. values should be comparable to baseline settings and previous readings. if readings are off, notify physicist
67
Quality Control Procedures: what is an electrical associated machine hazard w linac?
linac operate at high voltages, so water can be hazardous
68
Quality Control Procedures: what is an mechanical associated machine hazard w linac?
the gantry and machine table can cause injury by colliding
69
Quality Control Procedures: what is an laser associated machine hazard w linac?
lasers can result in damage to the retina
70
Quality Control Procedures: what is an gaseous associated machine hazard w linac?
tx uses hazardous gases to operate. can also create toxic fumes
71
Quality Control Procedures: what is the role of sulfur hexafluoride in the linac?
colorless, odorless gas used in the tx machine to prevent arcing in the waveguide. non-toxic but can be an asphyxiant displacing oxygen
72
Quality Control Procedures: what is the role of ozone in the linac?
interaction of a high energy electron beam w air can produce ozone and oxides of nitrogen. ozone is a toxic gas that affects the respiratory system. for this reason, it is important that the tx rm be well ventilated. if pungent odor of gas is detected, shut down machine, remove pt., allow sufficient time for gas to be exhaustedly normal rm ventilation
73
Dose Verifications: constancy of calibration - how often?
must be checked weekly for linac and monthly for Cobalt- 60.
*constancy of calibration is referring to radiation output and how often the machine is calibrated
74
Dose Verifications: constancy of calibration - what are annual calibrations be performed using?
ionization chamber and electrometer that has been calibrated by a NIST, lab, and a standard phantom
75
Dose Verifications: what does NIST stand for? what do they do?
National Institute of Standards and Technology
The National Institute of Standards and Technology (NIST) was founded in 1901 and is now part of the U.S. Department of Commerce. NIST is one of the nation's oldest physical science laboratories. Congress established the agency to remove a major challenge to U.S. industrial competitiveness at the time—a second-rate measurement infrastructure that lagged behind the capabilities of the United Kingdom, Germany, and other economic rivals.
From the smart electric power grid and electronic health records to atomic clocks, advanced nanomaterials, and computer chips, innumerable products and services rely in some way on technology, measurement, and standards provided by the National Institute of Standards and Technology.
Today, NIST measurements support the smallest of technologies to the largest and most complex of human-made creations—from nanoscale devices so tiny that tens of thousands can fit on the end of a single human hair up to earthquake-resistant skyscrapers and global communication networks.
76
Dose Verifications: What are the effects of barometric pressure, temp, and humidity on ion chambers?
these chambers are not sealed and are effected by outside conditions. they are calibrated by NIST labs at 22 degrees C and 760 mm HG pressure.
*All chambers must be corrected for the present conditions using the Temperature and Pressure Correction Factor
77
Dose Verifications: All chambers must be corrected for the present conditions using the Temperature and Pressure Correction Factor. What is it?
T + 273 x 760
CF = ------------ ------
295 P
78
Quality Control Procedures: Light - checking the crosshairs consists of:
the crosshair should represent the isocenter (axis rotation for the collimator, gantry, and table). this cn be checked using graph paper by rotating the collimator to ensure there is no "walk-out" of the crosshair. malfunction is due to misalignment of the light field or crosshair (<2mm difference)
79
Quality Control Procedures: Light - The light Field:
the light field should adequately represent the radiation field. check this using film to ensure that the field does not "walk out" for different collimator angles. malfunction may be due to the target, collimator, or light source. if the walk out does not rotate, the target is causing the problem. if it does rotate, it is the collimator or light source causing the problem.
80
Quality Control Procedures: Collimator -
collimator settings should agree w the measured light field. this can be checked w graph paper. malfunction is due to the drive mechanism (<2mm difference)
81
Quality Control Procedures: Optical Distance Indicator (ODI)
ODI must be checked to ensure proper representation of distances from the source/target. This is checked w the front pointer. malfunctions include misalignment of the ODI, replacement of the light bulb, or damage to the front pointer (<2mm difference)
82
Linear Accelerator: Control Console
- monitoring and controlling of the linear accelerator occurs at the control console.
- located outside tx rm
- is a digital display, push-button panel, and/or video display terminal
- monitoring pt during tx is essential
- emergency off buttons are located on control console
-
83
spinal cord T/D
4700 cGy-necrosis
84
Lens T/D
1000 cGy-cataracts
85
Lacrimal Gland t/d
2600 cGy-dry eyes
86
Optic Chiasm t/d
5000 cGy -blindness
87
optic nerve t/d
5000 cGy-blindness
88
Paraotid Gland t/d
3200 cGy-xerostomia
89
temporomandibular joint t/d
6000 cgy- limitation of joint function
90
esophagus t/d
5500 cgy-stricture/perforation
91
thyroid t/d
4500 cgy -thyroiditis
92
larynx t/d
4500 cGy - edema
93
ear t/d
3000/5500 cGy acute/chronic serious otitis
94
heart t/d
4000 cGy pericarditis
95
lung t/d
1700 cGy pneumonitis
96
brachial plexus t/d
5500 cGy nerve damage
97
liver t/d
3000 cGy liver failure
98
kidney t/d
2300 cGy nephritis
99
stomach t/d
5500 cGy ulceration/perforation
100
small bowel t/d
4500 cGy obstruction/perforation
101
large bowel t/d
5500 cGy obstruction/perforation
102
rectum t/d
6000 cGy proctitis/necrosis/stenosis
103
femoral head & neck t/d
5200 cGy necrosis
104
bladder t/d
6500 cGy contracture
105
brain (limited) t/d
6000 cGy necrosis/infarction
106
brain (whole) t/d
4500 cGy necrosis/infarction
107
brain stem t/d
5000 cGy necrosis/infarction
108
optic nerve t/d
5000 cGy blindness
109
retina t/d
4500 cGy blindness
110
cellular radiosensitivity is dependent on?
the specific phase of the cell cycle containing the cells at the time of irradiation (this is referred to as the age response)
111
cells are more radiosensitive and resistant during what phase
radiosensitive during G2 and M phase
112
number of atom's per gram is given by
Avogadro's number 6.0228x10^23
113
ionization
when electrons collide and have sufficient energy to overcome there binding energy and eject them from orbit
114
when an X-ray beam passes through matter, the beam undergoes a gradual reduction in the number of photons or exposure rate. this is called
attenuation
115
in the human body the rate of attenuation and degree of scattering is determined by
tissue thickness, density, and effective atomic number
116
Effects of Whole Body Radiation Exposure: hematopoietic Syndrome
Dose: 200-1000cGy(whole body)
mean survival:10-60 days
symptoms: nausea, vomiting, diarrhea, anemia, leukopenia, hemorrhage, fever, infection, dehydration
C.O.D: infection and dehyration
117
Effects of Whole Body Radiation Exposure: Gastrointestinal syndrome
dose: 1000-5000 cGy (whole body)
Mean survival: 4-10 days
symptoms: same as hematopoietic plus electrolyte imbalance, lethargy, fatigue, and shock
C.O.D: severe damage to lining of he intestines
118
Effects of Whole Body Radiation Exposure: CNS Syndrome
Dose: 2000-5000 cGy (whole body)
Mean survival: 0-3 days
Symptoms: same as G.I plus ataxia, edema, vasculitis, and meningitis
C.O.D: Edema of the brain
119
public radiation dose: embryo/fetus (after declaration)
0.5 rem/entire pregnancy
stochastic:
0.5 mSv/month (0.05 rem/month)
120
Somatic Effects: Embryonic and fetal risks
lethal effects, congenital abnormalities (present at birth or late effects observed years later), usually involve the CNS and most commonly include microcephaly, mental retardation, sensory organ damage, and stunted growth. skeletal changed are most prevalent when radiation is administered between weeks 3-20 (fetus is more radiosensitive than embryo)
121
carcinogenesis
the multistage process that occurs following exposure to a carcinogen leading to malignancy
122
radiosensitizers
chemicals and drugs that help enhance the lethal effects of RT: Doxorubicin, Cisplatin (platinol), fluorouracil (5-FU, adrucil)
123
Radioprotectors
chemicals and drugs that diminish the response of cell to RT: amifostine (Ethyol)
124
Brachytherapy
"short distance" therapy. Uses materials like Cesium-137 (Cs137), iridium-192, palladium-103, or iodine-125. Radioactive sources are placed right next to or directly into the tumor, because the energy of the radioactive sources is low, a high energy is delivered to the tumor
125
intracavitary brachytherapy
place radioactive material into a body cavity (used with cervical or endometrial)
126
interluminal brachytherapy
radioactive material is placed within a body tube such as the esophagus or bronchial tree. the radioactive material is positioned in the lumen at the tumor sire and removed one the prescribed dose is delivered
127
chemotherapy
systemic tx (killing cells of the primary tumor and those that may circulate in the body using cytotoxic drugs (drugs with the ability to kill cancer cells) and hormones
128
alkylating agents
first drugs identified to have anticancer activity (related structurally to mustard gas)
129
Law of Bergonie and Tribondeau states what?
that cells that are rapidly dividing, have a long mitotic future, and are undifferentiated are the most responsive to radiatio
130
Cell division in germ cells is termed
meiosis
131
cell division in non-germ cells is called
mitosis
132
4 phases of division in non-germ cell mitosis
Mitosis, Gap 1, DNA synthesis, and Gap 2 (a phase known as Gap 0, indicated a period of rest.
133
The phase of cell division most sensitive to radiation is?
M phase
134
the phase of cell division most resistant to radiation is
S phase
135
the portion of cells in mitosis is called
mitotic index
136
changes seen within days or weeks are called
deterministic or non stochastic effects (acute), or prodromal
137
changes seen after months or years of exposure may be called
stochastic (latent)
138
4 progressive stages of skin response to RT
1. epilation 2. erythema, 3.dry desquamation, 4. wet desquamation
139
beyond what dose may skin necrosis occur?
50 Gy
140
Skin acute effects of skin RT (3 and onset dose)
Erythema- 20 Gy
Dry desquamation - 30 Gy
Wet desquamation - 40 Gy
141
Acute RT effect oral Mucosa (2 and onset dose)
Mild, patchy mucositis -30 Gy
| Confluent mucositis - 40 Gy
142
Acute RT effect esophagus and onset dose
esophagitis-25Gy
143
Acute RT side effect Salivary Gland and onset dose
Xerostomia- 20 Gy
144
Acute RT side effect rectum and onset dose
proctitis-30 Gy
145
Acute RT side effect Testis and onset dose
decreased sperm- 0.25 Gy
146
Acute RT side effect bone marrow (2 and onset dose)
lowered blood count- 2Gy
| extensive hypolasia- 50 Gy
147
Acute RT side effect stomach and onset dose
Gastritis- 20 Gy
148
Skin T/D 5/5 and injury
55 Gy ulceration/fibrosis
149
Intestine T/D 5/5 and injury
45 Gy stricture
150
Salivary gland T/D 5/5 and injury
45 permanent xerostomia 40 Gy
151
Kidneys T/D 5/5 and injury
Failure 23 Gy
152
Testis, Ovary T/D 5/5 and injury
Sterility 5-15 Gy
153
Bone T/D 5/5 and injury
Arrested growth in child 20 Gy
| Necrosis in adult 60 Gy
154
Bone marrow T/D 5/5 and injury
reduced cellularity 20 Gy
155
spinal cord T/D 5/5 and injury
necrosis 45 Gy
156
Lens T/D 5/5 and injury
Cataract 5Gy
157
Brain T/D 5/5 and injury
necrosis 50 Gy
158
prodromal symptoms
nausea, vomiting, fatigue, fever hypotension, diarrhea
159
manifest syndromes are
hematopoietic, gastrointestinal, and cerebrovascular
160
Early RT effects to the unborn embryo or fetus may include what and lethal dose?
spontaneous abortion or death in utero; lethal doses as lo as 0.05 Gy could be lethal to the embryo in the first trimester.
**as the cells mature during the 2nd and 3rd trimesters, lethal RT doses to the unborn fetus increases**
161
Somatic effects of RT
(late effects) RT induced cancers, cataract formation, chronic bone marrow depression, shortened life span, and mutations in germ cells.
162
whole body RT syndrome (3, include dose rang and time until death)
1. hematopoietic-300-800 cGy (10-15 days till death)
2. gastrointestinal- 1000-5000 cGy (3-10 days)
3. cerebrovascular - >5000 cGy (hours-3 days)
163
clinically accepted RBE (radiobiological effectiveness) for proton therapy
1.1.^37
164
what is the gantry and how is it operated?
it is responsible for directing the photon (X-ray) or electron beam at the pt tumor, this can be accomplished through single-rotational field or multiple-fixed fields.
the control for the gantry are located on the pendant or outside the room at the console
165
field size for gantry is defined by
X1, X2, Y1 and Y2
166
the major components of a linear accelerator include (5 things)
drive stand, gantry, patient support assembly (treatment couch), control console, modulator cabinet
167
major components of the gantry (3 things)
electron gun, accelerator guide, and treatment head
168
major components of the treatment head in the gantry (4 things)
bending magnet, beam-flattening filter, ion chamber, and upper-lower collimator jaws
169
what is vertical movement of the tx table?
up and down
170
what is roll on the tx table
tilting the table either way (left/right)
171
what is the pitch on the table
tilting the table towards pt head or feet
172
what is a lateral move on the tx table
moving table left or right
173
what is a longitudinal move on the tx table
moving entire table more towards pt head or feet
174
what is rotation of the table
moving the table to either side at an angle
175
what is an event (patient safety)
something that happens to or involves a patient
176
what is a harmful incident (patient safety)
an incident that results in harm to a patient
177
what is healthcare associated harm? (patient safety)
harm arising from or associated with plans or actions taken during the provisions of healthcare, rather than from an underlying disease or injury
178
a patient safety incident (patient safety)
an event or circumstance that could have resulted or did result in uncessesary harm to a patient
179
a no harm incident (patient safety)
is an incident which reached a patient, but no discernible harm resulted
180
a reportable incident (patient safety)
is a situation in which there was significant potential for harm, but no incident occurred
181
superficial Dmax (cm below skin)
0.0 cm
182
orthovoltage Dmax (cm below skin)
0.0 cm
183
cobalt-60 Dmax (cm below skin)
0.5 cm
184
4 MV Dmax (cm below skin)
1.0 cm
185
6 MV Dmax (cm below skin)
1.5 cm
186
10 MV Dmax (cm below skin)
2.5 cm
187
15 MV Dmax (cm below skin)
3.0 cm
188
20 MV Dmax (cm below skin)
3.5 cm
189
25 MV Dmax (cm below skin)
5.0 cm
190
4 major components housed in the stand
the klystron, waveguide, circulator, cooling system
191
unrestricted area sign
- can be occupied by anyone
- person in this area would receive less than 2 mrem/hour
- no one should receive more than .1 rem in one year
192
restricted (controlled area) sign
- occupied by radiation workers
| - approx 50 hours/week for workers in area of 2 rem/hour
193
radiation area
- an individual could receive a dose equivalent greater than 5 mrem/hour at 30 cm distance from the source
- should be marked "caution, radiation area"
194
high radiation area
- can receive dose equivalent greater than .1 rem/hour at 30 cm distance from the source
- should be marked "caution, high radiation area" or "danger, high radiation"
195
very high radiation area
- an individual could receive an absorbed dose greater than 500 rads/hour at 1 meter from the radiation source
- should be marked with words "grave danger, very high radiation area"
196
airborne radioactivity areas should have a sign saying
"caution, airborne radioactivity area" or "danger, airborne radioactivity area"
197
rooms in which licensed materials are stored could be marked
"caution, radioactive materials " or "danger, radioactive material"
198
containers carrying radioactive material should be marked with what
-the radiation symbols and the words "caution radioactive materials" or "danger, radioactive material"
199
most potent radiosensitizer
molecular oxygen
200
what does the "Law of Bergonie' and Tribondeau state?
states that ionizing radiation is more effective against cells that 1) are actively mitotic, 2) are undifferentiated, and 3) have a long mitotic future.
201
Cell that _____are more radiosensitive than cell that _____.
divide more frequently; divide less frequently, or not at all
202
according to Bergonie' and Tribndeau, cells that are undifferentiated are what (i.e. immature cells the primary function is to divide and replace more mature cells lost from the population)
extremely radiosensitive (these cells are also called stem cells or precursor cells)
203
5 categories of radio sensitivity in mammalian cells based on Rubin and Casarett's research
(from most sensitive to lease sensitive)
1) Vegetative intermitotic cells (VIM)-rapidly dividing, undifferentiated cells with short life spans (ex: basal cell, crypt cells, erythroblasts, and type A spermatogonia)
2) differentiating intermitotic cells(DIM)- these cells are actively mitotic but a little more differentiated than VIM cell
3) multi potential connective tissue cells-divide irregularly and are more differentiated than VIM and DIM (ex:endothelial cells of blood vessels and fibroblasts of connective tissue)
4) reverting postmtotic (RPM)- normally do not divide but are capable of doing so. typically live longer and are more differentiated than other categories, highly differentiated and radioresistant( ex: liver cells and mature lympocyte[however mature lymphocytes are extremely radiosensitive and are an acceptation to the Law of Bergonie' and Tribondeau)
5) Fixed post mitotic cells (FPM)- most radio resistant group of cells in the body. highly differentiated, do not divide, and may or may not be replaces when they die (ex: certain nerve cells, muscle cells, erythrocytes, and spermatozoa
204
hematopoietic syndrome
induced by total-body dose of 100-1000 cGy. median lethal dos3 is LD 50/60 (estimated between 350-450 cGy)
205
the prodromal stage is observed within
hours after exposure and is characterized by nausea and vomiting
206
the latent stage occurs and lasts for?
occurs after a few days and can last as long as 3 weeks
(during this stage pt. may feel fine but bone marrow stem cells are dying. Depression of all blood cell counts, hemorrhaging, and serious infection occur)
207
pancytopenia
depression of all blood cell counts
208
irradiation from 4-11 weeks utero can result in
severe CNS and skeletal abnormalities
209
irradiation from 11-16 weeks in utero can result in
mental retardation and microcephaly
210
irradiation after 20th week in utero can result in
functional defects such as sterility
211
somatic (late) effects of RT
leukemia, skin carcinoma, osteosarcoma, lung carcinoma, thyroid carcinoma, breast carcinoma
212
exposure
defined as the amount of ionization produced by photons in air per unit of mass of air.
**the use of exposure is limited to photons below 3 MeV
213
unit of exposure
roentgen
214
unit of charge (for exposure)
coulomb (C)
215
absorbed dose
defined as the amount of energy absorbed per mass of any material while radiation interacts with the material
216
traditional and SI unit for absorbed dose
traditional unit for absorbed dose is the rad
SI unit for absorbed dose is the gray (Gy)
**1Gy=100rad=
217
dose equivalent
accounts for the biological effects of different types of radiations as they interact with tissue
218
traditional and SI unit for dose equivalent
traditional- rem
SI- sievert
**1 Sv=100 rem**
219
unit activity defines
the number of radioactive disintegrations (transformations) per unit of time.
220
traditional and SI unit for activity
traditional-curie (Ci)
SI- becquerel (Bq)
** 1 Ci=3.7 x10^10 disintegrations/sec**
**1 Bq=1 disintegration/sec**
221
ionization chamber
- portable
- detector and electronics are contained in 1 unit
- device reads directly in exposure per unit of time
222
Geiger-Muller detector
- limited to 100 rem/hour or less
- useful for lost source or small radioactive contamination
- gas filled tube
- the tube has walls that are more or less thick depending on the energy of radiation being detected
- once ionization occurs in the tube gas multiplication occurs which causes a large pulse
**very sensitive and best for finding contamination or other low levels of radiation**
223
Thermoluminescent Dosimeter (TLD)
- consists of a crystal substance that when irradiated has electrons displaced in its crystal lattice.
- a typical crystal substance used for personal monitoring is lithium fluoride (LiF)
- when the crystal is heated, the electrons return to their normal position
* *the dose received is equivalent to the radiation damage in the crystal**
224
Optically Stimulated Luminescence Dosimeter (OSL)
-also contain crystals but are read by lasers
(can be read as long as 1 year after irradiation)
**for the most part these are replacing film badges)
225
ALARA
as low as reasonable achievable
226
3 basic principles of radiation protection
time, distance, shielding
- reduce the amount of "beam on" time, shorten the length of time spent in the room where radiation is produced
- use as much distance as warranted between the x-ray tube and patient, stand as great a distance as possible from an energizing x-ray beam
- always shield the patient with appropriate and/or area specific shielding, interposing a radiation-absorbent shielding material between the radiographer and the source of radiation
227
NCRP
National Council on Radiation Protection and Measurements
| -group of technical experts who make recommendations on radiation protection and units
228
NRC
The Nuclear Regulatory Commission
- determines what will be law for many radiation concerns, not just radiation protection.
- these laws are listed in the Code of Federal Regulations (CFR) and are usually based on NCRP recommendations
229
NCRP(report #116) Occupational Dose Limits: whole body (stochastic)
50 mSv/yr (5 rem/yr)
230
NCRP (report #116)Occupational Dose Limits: Cumulative Dose Limit
10 mSv times their age (1rem X age)
231
NCRP(report #116) Occupational Dose Limits: Lens of eye (deterministic)
150 mSv/yr (15 rem/yr)
232
NCRP (report #116)Occupational Dose Limits: skin, hands, and feet (deterministic)
500 mv/yr (50 rem/yr)
233
NRC (10 CFR, parts 20 & 35) Occupational Dose Limits: Total Effective Dose Equivalent (deep and organ dose)
5 rem/year
234
NRC (10 CFR, parts 20 & 35) Occupational Dose Limits: eye dose equivalent
15 rem/year
235
NRC (10 CFR, parts 20 & 35) Occupational Dose Limits: shallow dose equivalent (skin or extremity)
50 rem/year
236
NRCP (report #116)Public Dose limit (stochastic):
1 mSv/year (.1 rem/year)
237
NRC (10 CFR, parts 20 & 35) Public Dose limit for minors
10% of dose to adult worker
238
NRC (10 CFR, parts 20 & 35) general Public Dose limit
.1 rem/year
239
NRC (10 CFR, parts 20 & 35) Public Dose limit for embryo-fetus (after declaration)
.5 rem/pregnancy
240
Alpha beams are blocked by
piece of paper
241
Beta beams are blocked by
plastic, glass
242
KV photon (x-ray) blocked by
lead
243
MV photon beams (X-ray or gamma ray) are blocked by
concrete
244
Neutron are blocked by
additional shielding required due to the emission of gamma photons. neutrons are slowed and then stopped by hydrogen rich materials such as concrete, water, or borated polyethylene combined with water
245
primary barrier
materials in the radiation beam. primary barriers are designed to attenuate the direct radiation beam
246
secondary barrier
barriers provided in the floor, wall, and ceiling area. secondary barriers are designed to attenuate stray radiation.
247
dosimeter
pocket dosimeters are small ion chambers.
| -not routinely use in RT setting
248
cutie pie detector
- portable ion chamber
| - useful in determining the exposure rate outside a radioactive implant patient's room
249
Neutron detectors
-ionization chamber filled with a BF3 gas (boron trifluoride) and is surrounded by cadmium-loaded polyethylene sphere to slow neutrons so they can be detected efficiently
250
diodes
-small electric probe placed on the body or inside a body cavity to measure the actual amount of radiation being delivered to a predetermined point.
251
film badges
- small piece of film between metal filters
- the density on the original film is proportional to the exposure
- inexpensive, easy to process, relatively accurate, but should only be worn for about a month due to fogging of the film
252
shielding for alpha particles
piece of paper
253
shielding for beta particles
plastic and glass
254
shielding for KV photon (xray)
lead
255
shielding for MV photon (X-ray or gamma ray)
concrete
256
shielding for neutron
additional shielding required due to the emission of gamma photons. neutrons are slowed and then stopped by hydrogen rich materials such as concrete, water, or orated polyethylene combined with lead
257
Records of Accumulated dose are what and how long as they kept?
- state and federal regulations require monitoring of anyone who may receive 10% of the Maximal Permissible Dose
- when occupational workers change employment, exposure records should be transferred to the new employer
- institutions must keep records forever
258
handling radioactive materials should be done how?
- should be done using long-handles forceps
- wear gloves
- work behind an L block
- eating or drinking around radioactive material is prohibited
- the room should have radiation monitors and the person handling should wear a radiation monitor
259
disposal of radiative material should be accomplished how?
- material with short half-lives can be stored until there is sufficient radioactive decay,making the material virtually harm;ess
- if the radioactive source does not exceed a certain activity limit, it can be released into the sewer system where it will decay
- can also be correctly labeled and packages and sent away to an authorized recipient
260
side effects of RT for scalp
1. Alopecia-extent hair loss
- temporary 1500-3000 Cgy
- permanent 4500 cGy and up
- minimize by using mild shampoo and soft brush, avoid sun exposure
2. edema-inflammatory reaction resulting in swelling
signs: increased intracranial pressure, change in mental status, confusion, hypertension, decrease in pulses and respiration, headaches, nausea, motor and sensory changes, vomiting
management: corticosteroids
261
side effects of RT for head and neck
1. xerostomia- dryness of mucous membranes in the oral cavity
management: oral lubricants, minimize dental caries (cavities), avoid nicotine, alcohol, and irritating foods
2. taste alteration-caused by taste bud destruction, reduction in saliva, waste products of cellular destruction and disease process
management: maintian hydration of mucous membranes
3. mucositis/stomotitis-inflammatio of mucosal surfaces (candidiasis/thrush, herpes simplex, gram negative bacteria)
4. pharyngitis/esophagitis-inflammation of esophagus or pharynx resulting in dysphagia
5. ear pain
6. late head and neck side effects:
:atrophy of the skin-4-6 weeks after tx complete
:lenticular opacities
:cataracts
:fistulas and ulcerations
:osteoradionecrosis
262
RT sideeffects chest/upper back
1. esophagitis-indigestion, nausea, and vomiting
causes: epithelial cells are destroyed
2. pneumonitis: caused by the destruction of cells lining the alveoli causing inflammation and fluid accumulation
-25% or less=asymptomatic
greater than 25%=cough, dyspnea, fever, weakness
-76% or more=irreversible damage
263
RT side effects abdomen/lower back
1. nausea/vomiting
2. diarrhea
3. cystitis- inflammation of the lining of the bladder
4. sexual dysfuntion
264
creatinine blood tests
evaluated kidney function (important to assess prior to injecting contact media to visualize kidneys
265
hemoglobin blood test (Hb)
chemical compound in RBC that carried oxygen. should maintain Hb level >10 g/dl
**low LET RT will have greater effects due to OER
***Normal Values-
Men 15.5 g/dl
Women 13.7 g/dl
average 12-16 g/dl
266
WBC
fights infection. *important to assess the Absolute Neutrophil Count (ANC). a low neutrophil count makes a person more vulnerable to infection.
**WBC normal range 4,500-10,000 WBC per microliter (mcL)
267
platelets
main function is to aid in coagulation
**normal range-150,000-400,000 mcL (dangerous is count decreases below 50,000 during treatment)
268
medical emergencies:
- allergic reaction-signs are nausea, vomiting, itching, fainting, pain, edema, convulsing, cardiac arrhythmias
- cardiac arrest-signs are clutching at chest, sweating, pallor. S.O.B, irregular heartbeat
269
information included in Tx record (11 things)
1. prescription
2. monitor units
3. target dose (daily and accumulated)
4. energy and type of radiation
5. date
6. time of day (for B.I.D. tx)
7. fraction
8. elapsed days
9. field number and description
10. doses to other regions of interest
11. set-up instruction
registry
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