Radiation Protection & Safety Questions

Which of the following bodies regulates the transportation of radiopharmaceuticals?

Department of Transportation

If a radiopharmaceutical is spilled on the floor, the first priority is to:

cover the area with absorbent paper and restrict access around it

what is the priority when there is a radiopharmaceutical spill (it is also a principle of ALARA)

containment

in order to contain a radiopharmaceutical spill the area must be labeled with radioactive signs, restricted access around the spill, and the contaminated items are placed in the proper labeled waste container

true

is this true regarding the inverse square law: Doubling the distance will reduce the intensity of the beam to ¼ of its original intensity

true

is this true regarding the inverse square law: Doubling the distance will increase the intensity of the beam to ¼ of its original intensity

false

is this true regarding the inverse square law: Doubling the distance will reduce the intensity of the beam by 1/9 of its original intensity

false

is this true regarding the inverse square law: Double the distance will increase the intensity of the beam by 1/9 of its original intensity

false

A brachytherapy inpatient is surveyed and found to measure 3mR/hr at bedside. What is the best way to reduce radioactive dose to visitors?

have the visitor wear a lead apron

what are the three cardinal principles of radiation protection

time, distance, shielding

what is the most efficient method of decreasing one's exposure

distance

unit of absorbed dose

Gy (traditional: Rad)

this reflects the radiation quantity that is absorbed per mass of any material, while the radiation interacts in the material.

absorbed dose

If the dose rate at 3 meters from a radioactive source is 100mrem/hr, what will the dose rate be at 6 meters?

25mR/hr

A sign reading "Caution‐Radioactive Materials"is required wherever radioisotopes are used.

true

a sign reading "caution-radioactive area" is required if the dose rate exceeds _

5mrem/hr

Employee radiation exposure records are to be maintained (kept) by the employing facility:

indefinitely (and provide a permanent record of dose received)

Devices that could be used to measure personnel exposure to radiation include:

TLD, film badges, and OSL

these radiation detection devices are used if there is a visitor to a high radiation area

pocket ionization chambers

considered the most sensitive personnel monitoring device

pocket ionization chambers

this radiation detection device is good at indicating if radiation is present, but not how much radiation is precent

Geiger Mueller

why are Geiger Mueller radiation detectors not acceptable for personnel radiation exposure measurements

because they don't indicate how much radiation is present

A barrier that attenuates the useful portion of the beam to the required degree is known as:

primary barrier

in the treatment vault, the floor, ceiling, and side walls are considered primary barriers

true

If a radioactive material has a half life less than or equal to 120 days, the material can be disposed of as ordinary trash after it goes through _ half lives in storage. Before disposal, the material must be surveyed and not read greater than background radiation, all radioactive signs must be removed, and records must be kept for 3 years.

10

100rem = 1 Sv

true

units for dose equivalent

traditional: rem; SI: sievert

The annual whole body effective dose limit for an occupational radiation worker is:

50mSv (5rem)

the cumulative exposure can be figured by

10mSv x age

The annual effective dose equivalent limit for the public (infrequent exposure) is:

5mSv (0.5rem)

The dose equivalent limit for embryo/fetus exposure of an occupational radiation worker through an entire pregnancy is:

5mSv (0.5rem)

The dose equivalent limit for embryo/fetus exposure for an occupational worker in any given month is:

0.5mSv (0.05rem)

A sign reading "Caution - High RadiationArea" must be posted if an individual can receive more than ___ in 1 hour.

1 mSv or 100 rem

A ________________ sign should be posted when a person may receive a dose of 5mrem (0.5mSv) in one hour at 30cm from a radiation source.

radiation area

_ signs are placed if levels can exceed 0.1rem, 100mrem, 1mSv/hr at 30cm from the source.

caution high radiation area

__ signs are posted if the levels may exceed 500 rads (cGy) or 5Gy/hr at 1 meter from the source

very high radiation area

required for the storage of radioactive materials?

shielding, warning signs, locking of storage room door, and area survey monitor VISIBLE upon room entrance

Film badges read exposure doses as low as ___mrem.

10

___ badges relied on the use of film in a light‐tight wrapper placed in a holder with a clip

film

the filters in a film badge are able to detect

x-rays, beta, and gamma radiation

what is used to read a film badge once the film is developed

a light densitometer

Dose equivalent is defined as the absorbed dose multiplied by a weighting factor or quality factor for the type of radiation involved in the exposure. The quality factor for x‐rays and gamma rays is:

1

Dose equivalent is defined as the absorbed dose multiplied by a weighting factor or quality factor for the type of radiation involved in the exposure. The quality factor for alpha radiation is:

20

The quality factor for THERMAL neutrons is:

5 (per Khan)

unit of dose equivalent?

sievert

unit of exposure or number of ionizations in air?

traditional: roentgen; SI: C/kg

defined as the amount of ionization produced by photons in air per unit mass of air.

exposure

1 Roentgen = ________ rads in air

.876

Radiation effects that impact future offspring are termed:

genetic effects

damage to what cells would cause genetic effects

germ cells

damage to what cells would cause a somatic effect

somatic cells

The most commonly used crystal in a thermoluminescent dosimeter (TLD) is:

lithium fluoride

When TLD's are exposed to radiation, the electrons in the crystals are _______ and move to a higher level where they get trapped, due to intentional imperfections in the crystal lattice

excited

with TLD's the _ emitted from the crystals is proportional to the radiation dose absorbed by the crystals

light

what is a limiting factor of TLD's

the reading can only be performed once

Which form of radiation is characterized as high LET, travels a short distance, and resembles a helium atom?

alpha particle

this particle resembles a helium atom that consists of two neutrons and two protons

alpha particles

alpha particles are high LET radiation

true

what is the charge of alpha particles

+2

Which radioactive decay process occurs in an unstable nucleus that has a high neutron to proton ratio, so a neutron is converted into a proton, which in turn yields an electron and an antineutrino?

beta negative decay

A beta negative differs from an electron in that an electron exists in orbital shells, whereas beta negatives are emitted as a result of

nuclear decay

With beta negative decay, there are too many in the nucleus, so it is trying to reduce that ratio to achieve stability

neutrons

With beta decay, the atom increases it's atomic number by _ but has the same atomic mass

1

Hydrogenous material such as concrete, water, or borated polyethylene combined with lead can be used to shield or block neutrons.

true

for linacs with beam energies above _MV, neutron contamination must be considered

10

polyethylene has a __________ hydrogen content and is very effective in slowing down neutrons and the boron then absorbs the thermal neutrons.

high

The total energy imparted to an irradiated area by ionizing radiation, measured in ergs/gram is termed:

integral dose

A 500KV photon beam is less penetrating than a 6MV photon beam.

true

A 500KV photon beam has a shallower Dmax depth than a 6MV photon beam.

true

A 500KV photon beam requires a thinner half value layer than a 6MV photon beam (assuming same half value layer material).

true

A 500KV photon beam will produce less skin dose than a 6MV photon beam.

false (KV photon beam has no skin sparing causing a higher skin dose)

Emergency off buttons are to be located:

on the treatment table, control panel/console, walls of treatment room, and linear accelerator unit

Barriers that attenuate leakage radiation are termed:

secondary barriers

The rooms or hallway that adjoin the hospital room of a brachytherapy inpatient cannot exceed __mSv/hr.

.02

State and federal regulations require monitoring of anyone who may receive 10% of the maximum permissible dose.

true

Per the NRC, an unrestricted or uncontrolled area is an area to which anyone has access. In this area no individual should receive more than mSv/wk.

.02

Per the NRC, an restricted or controlled area is an area that no individual should receive more than mSv/wk.

1.0

If the gantry or table spontaneously begin to move, the therapist should first press an emergency off button. If the movement is not terminated by this action plan, the therapist should use the main circuit breaker to shut down all power to the machine and then notify the physicist or engineer

true

If a patient moves during treatment, the radiation therapist should stop treatment, watch on the monitor until patient stops moving, and then resume treatment delivery.

false

A therapist makes a mistake during treatment, who should the therapist report the error to?

radiation oncologist

A standardized approach to help review the most crucial aspects of a radiation treatment delivery process just before each delivery is termed:

time out

Patients must be identified prior to treatment delivery using a minimum of ____ patient specific identifiers.

2

The highest dose of natural or background radiation exposure is from:

radon

The usual value quoted for natural background dose to the US population is

300 mrem or 3 mSv

Maintenance of a linear accelerator may only be performed by a qualified expert.

true

Before rotating the gantry, always verify the treatment couch and patient positions so a collision cannot occur.

true

Which NCRP report addresses limits for exposure to ionizing radiation:

report 116

Which NCRP report addresses equipment design, performance and use of different radiation types (electrons, x‐rays and gamma rays up to 50MeV).

report 102

Which NCRP report addresses radiation protection of medical and allied health personnel..

report 105

Which NCRP report addresses implementation of ALARA principle for medical and dental personnel.

report 107

Which NCRP report addresses maintenance of radiation protection records.

report 114

The use factor used in the calculation of barrier shielding is defined as:

The fraction of the "beam on" time that the beam is pointed toward the area to be shielded.

defined as the fraction of time that the space that is shield is occupied

occupancy factor

defined as the time integral of the absorbed dose rate determined at the depth of maximum absorbed dose 1 meter from the source.

workload

A patient receiving a permanent brachytherapy implant may be discharged if a reading measured at 1 meter is less than _mSv.

5

For multiple photon energy linear accelerators, the shielding is generally designed for the lowest beam energy.

false (designed for highest beam energies)