2nd Year: Radiation Safety Flashcards
Which report dictates that a shielding evaluation MUST be performed for each new installation or upon any changes to assumptions of an existing shielding design?
NCRP-115
What does NCRP-151 focus on?
Structural shielding design and evaluation for megavoltage X- and Gamma-Ray radiotherapy facilities
According to NCRP-115, what are some elements that a shielding design report MUST include (10 total, list as many as you can. Two of them are not included in the report, but are good practice)
- Title page describing source, facility, person performing calculations and measurements, and who prepared the report
- Review of calculations used to determine shielding
- Inspection during construction
- Description of survey methods (technique, instruments, machine operation parameters, method used to calculate skyshine dose equivalent)
- Floor plans showing locations of measurements
- Instruments used with serial numbers and calibration certificates
- Results for each location around vault including skyshine dose equivalent and time average dose equivalent rate
- Conclusions and recommendations
- A copy of the report must remain at the facility
- IF shielding modifications are required, a follow-up survey must be performed
Per NCRP-115, when would a shielding modification or follow-up shielding report/evaluation need to be performed? (two scenarios)
- when commisioning a new treatment modality (such as IMRT or TBI)
- When a assumption used in the original calculation changed, such as workload, or surrounding room changes
What does NCRP stand for?
National Council on Radiation Protection and Measurements
What does ICRP stand for?
International Commission on Radiological Protection
What is the main difference between ICRP and NCRP? What is the main similarity?
ICRP makes recommendations for dose limits given international data
NCRP determines how those recommendations will be implemented in the U.S.
Ultimately, however, they’re both recommendation boards and neither have legal enforcement like the NRC does.
Which report focuses on structural shielding design for medical x-ray imaging facilities?
NCRP 147
What is the occupancy factor for a controlled area?
1
What is the occupancy factor for a hallway?
1/5
What is the occupancy factor for a unattended patient waiting area?
1/20
What is the occupancy factor for a patient exam room?
1/2
What is the occupancy factor for an office area?
1
What is the occupancy factor for a reception area?
1
What is the shielding design goal for a controlled area?
0.1 mSv/week or 5 mSv/year
What is the shielding design goal for a uncontrolled area?
0.02 mSv/week or 1 mSv/year
Which TG report focuses on shielding for PET?
TG 108
What are the two major concerns for PET vs any other diagnostic shielding?
PET annihilation photons are 511 keV which is significantly higher energy than other diagnostic energies
The patient themselves become the source of radiation as they move throughout the hospital
What are the three patient steps of a PET study?
Step 1: Patient is injected with radionuclide and held in waiting suite for 60 minutes to allow uptake
Step 2: Patient is asked to void before imaging study
Step 3: patient is imaged
During each step of a PET study, what is the approximate activity reduction?
During the waiting time in the waiting suite, approximately 32% is lost
During the voiding, another 15% is lost
What is the equation for transmission factor calculation in uptake room shielding in PET?
218d^2 / T x Nw x Ao x tu x Rtu
218 is derived from the assumption that the dose rate from the patient is 0.092 mSv m^2/MBq hr immediately after injection. For an uncontrolled area, P = 20 mSv, so P/0.092 = 218.
T is the occupancy factor
d is distance to measurement point
Nw is number of patients per week
Ao is administered activity in MBq
tu is uptake time (hours)
Rtu is dose reduction factor over intake time
What is the equation for transmission factor calculation in imaging room shielding in PET?
256d^2 / T x Nw x Ao x Fu x Rti
256 is derived from the assumption that the dose rate from the patient is 0.092 mSv m^2/MBq hr immediately after injection. For an uncontrolled area, P = 20 mSv, so P/0.092 = 218. Then for a 15% voiding, 218/0.85 = 256.
T is the occupancy factor
d is distance to measurement point
Nw is number of patients per week
Ao is administered activity in MBq
Fu is uptake decay factor (how much of source remains purely due to source decaying in uptake room, not from the voiding. Voiding is already taken into account in the 256)
ti is the imaging time (hrs)
Rti is dose reduction factor over imaging time
What is typical shielding for a PET suite wall adjacent to controlled area?
2 mm
What is typical shielding for a PET suite wall adjacent to uncontrolled area?
12 mm
What equation is used to calcualte number of TVLs, given required transmission factor?
n = -log(B)
What is typical lead TVL for Cs-137?
2.5 cm of lead
What is typical shielding for LDR?
3 cm of lead
What equation is used to calculate required transmission factor for LDR?
B = Pd^2 / WtNT
P is design goal
d is distance to measurement point
W is dose rate at some distance
t is average time per implant procedure
N is total implants per week
T is occupancy factor
How do you calculate W for LDR shielding calculations? (Don’t give exact equations, just general idea)
Use gamma to find exposure per activity time at 1 cm
Use dimensional analysis to find exposure rate at a certain distance
Convert exposure rate to dose rate using f factor for specific isotope
Take into account inherent attenuation within the patient (typically 20% attenuation for Cs-137)
When talking about ALARA for shielding, what does “reasonable” mean?
Typically reasonable is a balance of financial budgeting to lower doses and the benefit of doing that, versus using that money for something else.
Scenario 1:
If it costs $200,000 to satisfy regulatory limits for shielding, but $220,000 to reduce dose levels in half, is the extra $20,000 a reasonable expense?
Yes, you can argue it is. For only $20,000 extra, you’re significantly dropping occupational and public dose.
Scenario 2:
If it costs $200,000 to satisfy regulatory limits, but $500,000 to reduce dose levels in half, is the extra $300,000 a reasonable expense?
I would argue no, that extra $300,000 of budget can be better used for other purposes.
Scenario 3:
What happens when economic capital is expended to lower occupational dose, but at the same time that money could have been used to improve TPS
or other equipment? Would you justify spending to lower occupational dose in this instance?
Only spending to get to regulatory limits. After that, it’d be hard to justify.
Outside of that, consider this. Lowering occupational dose decreases RISK to others
Improving TPS, or equipment for machine performance, helps patients that you KNOW have a disease.
What is the general equation used for transmission factor calculation in shielding?
B = Pd^2 / WUT
P is the design goal
d is distance to measurement
W is the workload (that is, number of patients and air kerma strength at 1 m) (Unit: Gy/wk)
U is use factor (fraction of time radiation is targeted towards a barrier)
T is occupancy factor
Which report focuses on HDR Vault shielding design criteria?
NCRP 49
What is a “controlled area”
An area occupied by workers who are directly responsible for or involved with the use and control of radiation. These workers have been trained in radiation management and are monitored
What are the radiation weighting factors for each of the following…
Photons
Electrons
Alpha
Protons
Neutrons
Which report gives these values?
Photons - 1
Electrons - 1
Alpha - 20
Protons - 2
Neutrons - 20
ICRP 103 published in 2007
For shielding design of LINACs, why does the thickness of a TVL increase for subsequent layers?
Because of beam hardening. The average energy increases with each TVL
What is a typical IMRT factor for increase in required MU?
3 - 5
What type of radiation is considered for secondary barrier calculations?
Scatter radiation and leakage radiation
What typically has higher energy, leakage radiation or primary beam radiation?
Leakage radiation due to beam hardening through the machine
What is LINAC machine requirement for leakage radiation as a percentage of primary beam radiation?
Leakage is to be kept to 0.1% of primary beam at 1 meter from LINAC head
True or false
For secondary barrier thickness calculations, you would apply the two source rule?
True
Leakage and scatter are considered two different sources with effectively different energy distributions
How would you use the two source rule for secondary barrier calculations for LINAC design?
If the scatter and leakage transmission factors are approximately equal, shielding thickness may be taken as the larger of the two barrier thicknesses + 1 HVL
If the thickness of each source differs by 1 TVL or more, the larger barrier thickness may be used
What are the layers of a vault door for LINAC?
lead –> BPE –> lead
All of it encased in 1/4 inch of steel
How heavy is a typical vault door that has a maze?
3500 pounds
True or false
In general, mazes are only used for LINAC vaults that treat with energies > 10 MV
False
They can be used for anything if design allows. In general, the more scatter paths required to reach the door, the less thick a door needs to be.
What is the typical occupancy factor for public toilets, vending areas, sotrage rooms, outdoor areas, or unattended waiting rooms?
1/20
What is the typical occupancy factor for unattended parking lots, stairways, elevators, or outdoor areas?
1/40
For 18 MV, what is the typical TVL for lead?
11 cm
For 18 MV, what is the typical TVL for concrete?
45 cm
For 18 MV, what is the typical TVL for steel?
5.7 cm
For an Ir-192 HDR suite, what is the typical barrier thickness in inches?
1.5 - 2 inches of lead
For a CT room, what is the typical barrier thickness of lead in mm?
1 mm of lead
What is the typical density of concrete?
2.35 g/cc
What is the typical density of lead?
11.34 g/cc
What is typical workload and associated assumptions used for LINACs?
W = 500 Sv/week
50 patients per day
2 Gy per patient
5 days per week
How would you measure dose rate from secondary barriers for LINAC during a shielding evaluation?
Use maximum energy, maximum field size, and phantom in beam path
What device would you use to find areas of maximum dose rate during a shielding evaluation?
You can use either a GM counter or a calibrated ion chamber. GM Counter may be better though due to fast response
What device is best to find defects in shielding?
GM counter
What device is best to measure dose rate from a barrier?
Calibrated ion chamber
Which CFR chapter gives dose limits for occupation and members of the public?
10 CFR 20
What is the official title of 10 CFR 20?
Standards for protection against radiation
What material is highlighted in 10 CFR 20?
- Dose limits
- Personnell monitoring requirements
- RSO and RSC requirements
- Quality factors
- Types of radiation areas
Where do the dose limits used in 10 CFR 20 come from?
NCRP 116 recommendations
What is the main difference between NCRP 116 and NCRP 91?
NCRP 91 was based off data of atomic bomb survivors
NCRP 116 is a revised version of NCRP 91 that indcludes additional risk-dose assessment from several national and international bodies
What is the NCRP 116 / 10 CFR 20 radiation worker effective dose exposure limits for total body?
50 mSv annual
10 mSv x age (y) cumulative effective dose limit
What is the NCRP 116 / 10 CFR 20 radiation worker effective dose exposure limits for lens?
150 mSv annual
What is the NCRP 116 / 10 CFR 20 radiation worker effective dose exposure limits for extremeties?
500 mSv annual
What is the NCRP 116 / 10 CFR 20 public effective dose exposure limits for lens?
15 mSv annual (10% of radiation worker)
What is the NCRP 116 / 10 CFR 20 public effective dose exposure limits for extremeties and skin?
50 mSv annual (10% of radiation worker)
What is the NCRP 116 / 10 CFR 20 public effective dose exposure limits for whole body?
5 mSv annual for infrequency (10% of radiation worker)
1 mSv annual for continuous
The value you should cite is 1 mSv
What is the NCRP 116 estimated risk for fatal cancer for healthcare workers with respect to effective dose?
4% per Sv
What is the NCRP 116 estimated risk for fatal cancer for members of the public with respect to effective dose?
5% per Sv
What is the NCRP 116/ 10 CFR 20 pregnant woman equivalent dose limit to embryo?
0.5 mSv per month
or
5 mSv for entire pregnancy
What do RSO and RSC stand for?
RSO - radiation safety officer
RSC - radiation safety committee
True or False
Per 10 CFR 20, every site MUST have an appointed RSO AND established RSC
True
You must have both
Per 10 CFR 20, at the minimum, who comprises the radiation safety committee in radiation oncology?
RSO
Authroized medical physicist
Authorized user
Rad onc nurse
Per 10 CFR 20, how often should the RSC meet?
Quarterly at the least
In a general statement, what is the RSC tasked with doing?
Reviewing the use of RAM and radiation at the facility and ensuring safe use of all radiation producing equipment
Per 10 CFR 20, what must a radiation safety officer keep records of? (6 things listed)
- Active licenses and amendements
- Authorized users and physicists
- Radioactive source storage and inventory
- Occupational doses to all monitored employees
- RAM patient release surveys
- RAM waste disposal records
Per 10 CFR 20, what is the criteria for ALARA Level 1 and what is the associated action
Excess of 1.25 mSv/quarter (10% of allowed limit)
Radiation safety committee will decide if this is appropriate for that individual and if any action needs to be taken
Per 10 CFR 20, what is the criteria for ALARA Level 2 and what is the associated action
Excess of 3.75 mSv/quarter (30% allowed limit)
RSO will investigate and see if doses can be reduced
Per 10 CFR 20, what is the criteria for ALARA Level 3 and what is the associated action
> 40% allowed limits, the RSO will supply the RSC with written documentation on how to reduce dose
> 70% allowed limits, RSC is required to take action to change person’s work environment until end of the year
Per 10 CFR 20, what is the quality factor for high energy protons for determining equivalent dose?
10 (notice this is different than the 2 cited by ICRP 103)
Per 10 CFR 20, what is the quality factor for neutrons of unknown energy for determining equivalent dose?
10
Per 10 CFR 20, what is the quality factor for neutrons depending on energy for determining equivalent dose?
5 - 20
Per 10 CFR 20, who must wear radiation monitors at all times?
- All personnell operating equipment producing radiation
- All persons likely to receive a dose > 10% of their annual limit
- All minors likely to receive more than 10% of their respectively annual limits
- Declared pregnant women likely to receive more than 1 mSv during pregnancy
- Any individual enetering a high or very high radiation area
- Personnell that can be exposed to single events that would exceed their dose beyond 10% of annual limit
- Any personnell that has access to areas where exposure rate could exceed 1 mSv/hr
Per 10 CFR 20, what defines a radiation area?
An area in which expected exposure exceeds 0.05 mSv in 1 hr at 30 cm away from source or any surface that radiation penetrates
Per 10 CFR 20, what defines a high radiation area?
An area in which expected exposure exceeds 1 mSv in 1 hr at 30 cm away from source or any surface that radiation penetrates
Per 10 CFR 20, what defines a very high radiation area?
An area in which expected exposure exceeds 5 Sv in 1 hr at 1 m away from source or any surface that radiation penetrates
Per 10 CFR 20, what criteria is required for a sign posting indicating radioactive material storage and containers containing RAM?
An area storing a radioactive material in excess of 10x its specified limit
Ex. for Ir-192, the limit criteria is 1 uCi. So any storage of 10 uCi of Ir-192 or more must have a sign posting
What does the sign posting for a radioactive storage say?
“Caution radioactive materials”
Per 10 CFR 20, what criteria are required for immediate notification to the NRC in the case of over exposure to individuals?
Total effective dose equivalent exceeding 250 mSv
or
Dose equivalent to lens exceeding 750 mSv
or
Skin or extremeties dose equivalent exceeding 2500 mSv
NOTE: These are all 5x the allowable annual limits
Per 10 CFR 20, what criteria is required for immediate notification of the NRC in the case of lost RAM
Losing a RAM that exceeds 1000 times the specified limit
Ex. for Ir-192, the limit criteria is 1 uCi. So any loss of 1 mCi or more of Ir-192 requires immediate notification of the NRC
Per 10 CFR 20, what criteria are required for within 24 hr notification to the NRC in the case of over exposure to individuals?
If any of the annual limits for a monitored workers are exceeded
Per 10 CFR 20, how soon after the discovery of a loss of RAM must you report to the NRC?
If > 1000x the specified limit, then you must immediately notify
If < 1000x but > 10x, you have 30 days to report
What is the title of 10 CFR 35?
Medical use of byproduct materials
Per 10 CFR 35, what is an “agreement state”
Any state with which have entered into agreements with the NRC that give them the authority to license and inspect byproduct, source, or special nuclear materials used or possessed within the borders
These states must have regulations ATLEAST as strict as the NRC
Per 10 CFR 35, what is an “authorized user”
A physician, dentist, or podiatrist meeting certain educational criteria who is authorized to permit the medical use of byproduct material
Per 10 CFR 35, what is a “writter directive”
An authorized user’s written order for the administration of byproduct material or radiation from byproduct material toa specific patient or human research subject
Per 10 CFR 35, what is an “written procedure”
Licensee must develop, implement, and maintain written procedures for medical uses that require a written directive
Per 10 CFR 35, what information must a written procedure include?
- Identification of patient’s identity prior to administration
- Verification that administration is given as per written directive
- Verification of dose calculation
- Verification that computer generated dose calcualtions are transferred to consoles of therapeutic medical units
Per 10 CFR 35, what should a written directive include? (8 are listed)
- Date of signature
- Signature of authorized user
- Identifying information on patient
- Dosage
- Route of administration
- Type of material/radionuclide
- Treatment site
- Number of sources used and their strength (for LDR)
For HDR, what must a written directive include at the minimum? (6 listed)
- Patient name
- Radionuclide used
- Treatment site
- Dose per fraction
- Number of fractions
- Total dose
Per 10 CFR 35, what constitutes a medical event for anything other than permanent implant brachytherapy? (3 possible criteria)
Any event not caused by patient intervention, and any one of the three must be true…
- Dose delivered differs from prescribed dose by more than 50 mSv effective dose equivalent, or 500 mSv to an organ or issue, or 50 mSv shallow dose equivalent to skin, AND one of the following…
1a. total dose differs by more than 20% from prescription
1b. dose from single fraction varies by more than 50% - Dose exceeding 50 mSv effective dose equivalent, or 500 mSv to an organ or tissue, or 50 mSv shallow dose equivalent to skin arising from any of the following…
2a. administration of wrong radioactive drug
2b. administration of radioactive drug by wrong route
2c. administration of a dose to the wrong individual
2d. administration of dose by the wrong mode of treatment
2e. a leaking source - Dose to skin or an organ or tissue other than the treatment site which exceeds 500 mSv to an organ or tissue AND differs by 50% or more from expected dose
Per 10 CFR 35, what constitutes a medical event for permanent implant brachytherapy? (3 possible criteria)
Any event not caused by patient intervention, and any one of the three must be true…
- Total source strength administered differs by 20% or more from total source strength documented in post-implant portion of written directive
- Total source strength administered outside of treatment site exceeds 20% of total source strength documented in the post-implant portion of written directive
- Any administration that includes any of the following..
3a. Wrong radionuclide
3b. wrong individual or human research subject
3c. Sealed sources implanted directly into a location discontiguous from treatment site as documented in post-implant portion of written directive
3d. Leaked sealed source resulting a dose that exceeds 500 mSv to an organ or tissue
How soon after the discovery of a medical event must a licensee notify NRC via phone?
No later than the next calendar day
How soon after the discovery of a medical event must a licensee submit a written report to the NRC?
Within 15 days after medical event discovery
How soon after the discovery of a medical event must a licensee notify the physician and subject?
No later than 24 hours after discovery
BUT
Note, however, the licensee does NOT need to notify the subject before notifying the physician. Meaning, if the physician is not reachable within 24 hours, the licensee must notify physician asap after the 24 hrs, then the subject afterwards
Typically, what constitutes a medical event? (unspecified version)
An even NOT CAUSED BY PATIENT INTERVENTION where…
- Wrong patient is treated or
- Wrong radionuclide is used or
- Source is leaking or
4 . Wrong delivery method is used or
- Patient’s total dose differs from prescription by more than 20% or
- Single fraction dose differs from prescription by more than 50%
What elements must a medical event report submitted to the NRC include? (6 items listed)
- Material’s license number
- Description of event
- Physician involved
- Anticipated side effects to patient
- Confirmation that referring physician and patient were notified within 24 hours
- Action plan for preventing recurrence
Per 10 CFR 35, how often must survey instruements and ion chambers be calibrated?
Survey instruments: annually
Ion chambers: every 2 years
Per 10 CFR 35, how often do eligible for leakage test sealed sources need to be checked for leakage?
At least every 6 months
Per 10 CFR 35, what criteria must a sealed source meet in order to warrant a leakage test
> 100 uCi for any beta or gamma emitters or > 10 uCi for any alpha emitters
and
Having a half-life greater than 30 days
Per 10 CFR 35, what is the limit at which a sealed source is considered leaking and must be removed from service
A wipe test measuring 0.005 uCi or more
Per 10 CFR 35, how must radioactive waste from patients be disposed?
Excretions from patients are exempt from regulation
They may be disposed as usual
Per 10 CFR 35, how many radioactive waste be disposed?
Either…
- Decay by storage (held until 10 half-lives)
- Returned to manufacturer or a designated RAM waste facility
- Some may be released down the drain if they’re water soluble and below allowable limits for that specific nuclide
What two reports highlight release of radioactive patients?
NRC 8.39 and NCRP 155
What chapter of CFR relates to release of radioactive patients?
10 CFR 35
Per NRC 8.39 and NCRP 155, what are the three possible criteria for release of a patient after administration of a radioactive material?
- Release based on administered activity
- Release based on measured dose rate at 1 meter
- Release based on patient-specific dose calculations to members of the public
What are release criteria based off of?
Ensuring that exposure to members of the public is below 5 mSv
How does activity and dose rate release criteria vary for different isotopes?
Isotopes with smaller half-lives typically have higher dose rate and activitity thresholds for release. This is because the activity will decay faster, so it’s okay if the activity or dose rate at release is higher
Per 10 CFR 35, what is the criteria for medical events for LINACs?
Trick question,
LINACs do not fall under NRC mandate. This criteria is dictated by the state.
What are some typical state defined medical events for LINACs
(keep in mind, these vary state to state, but these are some general criteria used)
- Wrong patient treated
- Wrong site treated
- Wrong treatment modality
- Weekly treatment dose differs from prescribed by more than 30%
- Total dose differs from prescribed by more than 10% for 3 or less fractions or 20% for 4 or more fractions
What is the dose rate release criteria for I-131 thyroid ablation patients?
< 7 mR/hr at 1 meter
What defines a authorized medical physicist? (three criteria)
- Must be on the license
- Board certified by the ABR
- Have a relevant degree with at least 2 years working experience and written document attesting to experiences with device in question
What defines an authorized user? (two criteria)
- Physician on site’s license
- Have been on a license prior, OR have extensive experience (500 hrs or more) with device in question
What is the definition of “byproduct material”
Material that has been made radioactive by exposure to neutrons in a nuclear reactor, or made radioactive by use of a LINAC
What is the definition of committed dose equivalent?
The dose equivalen tthat a person would receive after intake of radioactive material over the next 50 years (dose is internal)
What is the definition of committed effective dose equivalent?
Sum of committed dose equivalents for each organ weighted by the appropriate factor for those organs
(relates risk from radiation to single organs to whole body dose that would yield same dose)
What is “deep dose equivalent”
This is synonmous with whole body irradiation and is dose equivalent at 1 cm depth in person
What is dose equivalent?
Product of dose and radiation quality factor
What is effective dose equivalent?
Sum of dose equivalents from each organ weighted by the appropriate factor for those organs
(relates the risk from radiation to single organs to a whole-body dose that would yield the same risk)
What is a controlled area?
An area outside of a restricted area with access limited by licensee
What is total effective dose equivalent?
sum of the effective dose equivalent (external exposure) and the committed effective dose equivalent (internal dose)
What is a transport index?
Number placed on the labeling of radioactive packaging that is used to specify degree caution to be used while transporting material
Physicially, it is the reading at 1 meter from surface in mSv/hr multiplied by 100
What information is included in the application for radioactive materials license? (list as many as you can)
- Contact information of applicant
- Address where licensed material will be stored
- Location where records will be kept
- Which isotopes will be used, form of isotopes, and maximum amount that may be possessed at any one time
- Purposes for which the isotopes will be used
- Individuals responsible for radiaiton protection, including their training and experience
- Training for individuals working in or frequenting restricted areas
- Facilities (including shielding reports) and equipment (devices)
- Radiation protection program (including training program, emergency procedures)
- Waste management program
- Licensee fees
What is the maximum quantity that we may possess of Ir-192 at any one time?
21.5 Ci total
No single source to exceed 15 Ci
What information is typically contained on the radioactive materials license? (list as many as you can)
- License number and experation date
- Site information (name, address, phone number)
- List of authorized materials, their uses, their form, and the maximum quanitity to be possessed at any one time
- Location of material storage
- RSO
- Licensed personnell and their authorized uses of the material (physicians and physicists)
- Annual fee
- amendments
- Many other rules specified in the supplementary sheet
What does CFR stand for?
Code of federal regulations
A CFR B
What is A and what is B?
A is the department/title (Ex. NRC = 10)
B is the chapter
What is the title of 10 CFR 37?
Physical Protection of Category 1 and 2
Where does categorization of sources stem from?
Based off of IAEA safety standards
How does the source category system work?
System goes from Category 1 - 5
Category 1 sources are “Personally Extremely Dangerous”. These are sources in which exposure to them unshielded for minutes to an hour can be lethal. Examples include teletherapy sources, irradiators, radioisotope thermoelectric generators
Category 5 sources are “Not Dangerous”. These are sources in which permanent injury by exposure to these sources is impossible. These include LDR eye plaques and permanent implant sources, x-ray fluoror devices, PET, electron capture devices
Per 10 CFR 37, which category are HDR sources? Briefly describe the category.
Category 2: Personally very dangerous
If not safely managed or protected, these sources could cause permanent injury to person who was in contact for minutes to hours and can result in death to people who are in close contact to unshielded material for hours to days
Per 10 CFR 37, what are the access authorization requirements to get to sources?
Only authorized individuals are allowed to access
Requires extensive background investigation initially and every 10 years. This investigation includes criminal history, fingerprinting, credit history check, work history, character and reputation evaluation
True or False
Per 10 CFR 37, an escorted individual does not need background investigation if accessing a source.
True
As long as they are escorted by someone who has access authorization
Per 10 CFR 37, what are some physical protection requirements for sources?
- Security plan in place
- Procedures and training for accessing and storing
- Protection of information
- Coordination with local law enforcement agency
- Establishing a security zone
- Annual program review
- reporting of any threats to material
What is the title of 10 CFR 71?
Radioactive package shipping and receiving
How soon after receiving a package must a licensee do testing?
No more than 3 hours after receipt of package
What CFR chapter governs leaking source contamination testing?
49 CFR 173
What is the title number for the DOT?
49
Per 49 CFR 173 what area must a wipe test sweep?
At least 300 cm^2
Per 49 CFR 173, what is the maximum allowed activity measured in a wipe test for beta and gamma emitters?
240 dpm/cm^2
Per 49 CFR 173 and 10 CFR 71, what is the criteria for a white I shipping label?
Surface reading does not exceed 0.5 mrem/hr
and
1 meter reading should be too low to reliably measure
Per 49 CFR 173 and 10 CFR 71, what is the criteria for a yellow II shipping label?
Surface reading does is between 0.5 and 50 mrem/hr
AND
1 meter reading does not exceed 1 mrem/hr
Per 49 CFR 173 and 10 CFR 71, what is the criteria for a yellow III shipping label?
Surface reading exceeds 50 - 200 mrem/hr
OR
1 meter reading exceeds 1-10 mrem/hr
What does the transport index represent?
Reading at 1 meter in mSv/hr multiplied by 100
or an easier way of saying it
Reading at 1 meter in mrem/hr or mR/hr
This value is rounded up to nearest tenth
So a reading of 0.26 mR/hr, then the TI is 0.3
Per DOT and 49 CFR 173, what category number is assigned to radioactive material?
7
What rule is used to determine if a package is shipped in a type A or type B container?
If activity is less than 0.001 A, it is not regulated and can be shipped in a strong tight container
If activity falls within 0.001 A and A, then it is type A
If activity falls within A and 3000 A, then it’s type B
A in this case represents the specified acvitity and is dependent on the isotope and whether it’s special form or normal form. If special form, you use A1, if normal form you use A2.
What is the difference between a A1 and A2 values?
A1 is shipping special form RAM
A2 is shipping normal form RAM
Each is a different activity limit value per isotope
What content must a radioactive shipping label include? (5)
Label type
Activity
Source
TI
Class 7
What is the difference in container design between Type A and Type B shipments?
Type B is designed to survive severe accidents and is meant to store life endangering materials
Type A is designed to survive normal transportation handling and minor accidents
What are some examples of type A packages?
Nuclear medicines
Radioactive waste
Radioactive sources for LDR
What are some examples of Type B sources?
High level radioactive waste
High cocnentrations of Co-60 and Cs
Spent nuclear fuel
Radiography camera
What does the BEIR VII report cover?
Health risks and effects from exposure to low dose LET ionizing radiation
For transportation purposes, what is the definition of a “radioactive material”
Any material which has a specific activity greater than 0.002 uCi/gram
Note, this only specifies a concentration. So if you mixed a radioactive material with enough substance, such as dirt, and decrease the concentration below the definition, it no longer is considered a radioactive materil only for transportation purposes.
What are three possible packaging types that a type A package may be?
Cardboard box
Wooden crate
Metal drum
How are type B packages stored?
Either as metal drums or a huge, massive shielded transport container
What is the difference between A1 and A2?
A1 are special form radionuclides. These are usually encapsulated sources which would only pose an external radiation hazard, not a contamination hazard, if the package was ruptured
A2 are normal form radionuclides. These are not securely encapsulated and could yield significant contamination if the package was ruptured. These can pose both internal and external hazard. Typically liquids and powders
What is the absolute activity limit for both A1 and A2 packages?
1000 Curies
Which “A” value is larger? A1 or A2?
Special forms (A1)
This is because normal form radionuclides are deemed as more hazardous, so their activity for respective isotope can never exceed its counterpart special form. It can, at best, equal it.
True or false
The A1/A2 value for alpha emitters = 1
False
For alpha emitters, the normal form is much more hazardous. So the A1/A2 value is typically on the order of 1000 (that is, normal form is 1000x more hazardous)
What form of transport is used for shipping if amount of material is > 3000 times the A1 or A2 (depending on form) activity?
Highway Route Controlled
This requires state official notification and special training for carriers
True or False
The united states postal service (USPS) will only ship non-radioactive and limited quantity packages?
True
And their limits are 1/10th those of the DOT
What is the criteria of a limited quantity package?
Concentration > 0.002 uCi per gram
But activity less than 1/1000th A1 or A2 (depending on form)
These packages only require a strong tight container which can survive routine handling
True or false
The package required for transporting radioactive material is based on the activity inside the package, and the label required on the package is based on the hazard outside the package
True
What type of dosimeters are used for body badges? What about ring badges? What about control badges?
Body - OSLD, aluminum oxide
Ring - TLD
Control dosimeter - OSLD (used to subtract background radiation)
What is the purpose of a radiation safety inservice?
Role specific radiation safety training
True or False
Inservice training is required by the state of Georgia
False
Only a general annual radiation safety training is required, and it’s HDR specific.
What are some general topics reviewed during an in-service training?
ALARA principles
Time, distance, shielding
Source handling best practices/who should be handling them and when
What to do in case of an emergency situation (who has what role? What are the main considerations?)
Wearing your radiation badges and returning them
Taking note of radiation indicators throughout department
Who has what responsibility in the clinic?
Which groups of workers get inservice training?
Floor nurses
RadOnc nurses
General public
Hospital staff
Radiation Oncologists
Therapists
Physicists
What are the steps in the custody chain for us receiving and sending the HDR source? Who has transport responsibility during each step?
Step 1: Manufacturer (alpha omega) prepares inventory and ships
Step 2: FedEx transports to us, during this stage both FedEx and alpha omega assume responsibility
Step 3: We receive, and give signature acknowledging responsibility
Step 4: FedEx takes source from us and returns to manufacturer, they have responsibility
Step 5: Manufacturer receives source and sends us a letter of receipt to state they received it
We save the letter of receipt to our records, along with all other change of custody paperwork
Per NRC requirements, what is the frequency for survey and inventory check for a radioactive material storage area?
Quarterly
What is the frequency for survey meter calibration?
Annually, before initial use, and after any repair
What is the “negligible individual risk level (NIRL)” both conceptually and the numerical value?
NCRP defined “the level of average annual excess risk of fatal health effects attribuatable to radiation below which efforts to reduce radiation exposure to the individual is unwarrantable”
0.01 mSv
What is the lifetime occupational dose limit for a radiation worker?
10 mSv multiplied by your age in years
What is the difference between equivalent dose and effective dose equivalent?
Equivalent dose takes into account different biological effectiveness of different types of radiation
Effective dose equivalent takes into account different biological effectiveness of different types of radiation AND sensitivity of different tissues
Per NCRP 116, which tissue type has the highest tissue weighting factor, which has the lowesT?
Highest: Gonads (0.2)
Lowest: bone surface and skin (0.01)
Which value is given as occupational dose limits, equivalent dose or effective dose equivalent?
Effective dose equivalent
What is the purpose of the Conference of Radiation Control Program Directors (CRCPD)?
To produce suggested state regulations for control of radiation. These can be referred to by individual states as guidelines for creating their own regulations
Per ACR recommendations, when should an independent check of initial dose calculations be performed?
Ideally before the first fraction is delivered
or
Before the third fraction or before 20% of total dose is delivered
What is the typical deadline for a rad onc to check initial port films?
Prior to the 2nd fraction
And port films should be rechecked at least every 10 fractions
After a medical event occurs, how long must a record of the event be kept?
3 years
What is the shielding equation to sield again secondary radiation?
Bs = Pd2scad2sec400 / αWTF
F = beam size at patient
α = fractional scatter at 1 m from scatterer
dsca = distance from source to scatter
dsec = distance from scatter to area of interest
What is the advantage to having a maze vault design?
Decreases the burden of the vault door
A more effective maze means a easier to move vault door
In addition to lead and steel, what other materials are added to a MV vault door?
Boron and Polythylene
They are strong neutron moderators and absorbers
For what energy should a HDR room using an Ir-192 source be shielded for?
1.06 MeV
This is the maximum energy of Ir-192
What signage is required outside of a HDR brachytherapy afterloader room?
High Radiation Area
and
Radioactive Material
What is the general idea of any shielding transmission factor equation?
Your required transmission factor = goal / total dose at a measurement point over the course of the defined timeline of the goal
The total dose at a measurement point can be calculated in any which way, but almost always includes dose rate (include any decrease in dose rate due to activity decay, from Ex. PET), number of patients treated/images, how often radiation is incident on the barrier, occupancy of the surrounding area, distance to measurement point
Which report gives the occupancy factors that we refer to?
NCRP 147 and NCRP 151
147 is for imaging facilities, 151 is for MV and gamma vault shielding. But both have the same factors
What is the dose rate in any one hour shielding design goal limit set by the NRC?
0.02 mSv/hr
Note: This is only for uncontrolled areas
Fill in the blank,
A medical event has occured during an administration utilizing byproduct material if a patient’s fractional dose has exceeded ______ of the intended fractional dose, or the total dose has exceeded _______ of the intended total dose.
A medical event has occured during an administration utilizing byproduct material if a patient’s fractional dose has exceeded 50% of the intended fractional dose, or the total dose has exceeded 20% of the intended total dose.
What is the dose rate at surface (in mrem/hr) for the following…
White I
Yellow II
Yellow III
White I - no more than 0.5 mrem/hr
Yellow II - no more than 50 mrem/hr
Yellow III - more than 50 mrem/hr
What is the concept behind an occupancy factor?
The fraction of beam on time that the maximally exposed person will be present in a given area
What radiation area signs are given to…
CT sim
LINAC vault
HDR Vault
CT Sim - Radiation Area
LINAC Vault - High Radiation Area
HDR Vault - High Radiation Area
What package label do we receive for Ir-192 HDR sources?
Yellow II
What 4 pieces of information (besides the type of label), are included on a radioactive label?
Isotope
Source activity (Bq)
Transport index
Category Number
What are some things that the Georgia state inspector like to look at when they come? (7 listed)
- RSC minutes
- Survey meter calibrations
- Current source inventory
- Leak test results
- HDR dosimetry equipment records
- Latest full calibration report
- Latest spot check (daily QA)
What packaging do we receive for our Ir-192 sources?
Type A or B?
White or Yellow?
Special or Normal?
Type A
Yellow II
Special form
True or False
Even though inservice is not required by the state of Georgia, we do one anyway?
True
This is because of the recommendations of our RSO, and ACR
True or False
For a LINAC vault door, the polyethylene in the BPE is responsible for moderating the neutrons, the boron is responsible for capturing?
True
