QA Continued

cosmic radiation

radiation from outside the solar system and charged particles from the sun surface

how does cosmic radiation intensity vary

intensity varies with latitude and altitude above sea level

cosmic ray intensity is most vs least

cosmic ray intensity is least in equatorial regions and rises towards the poles

why it cosmic intensity greater at high elevations above sea level

there is less atmosphere to absorb the cosmic rays so intensity is greater

at 30,000 feet, the dose equivalent in

5 uSv/hr

what is terrestrial radiation

natural radioactivity in the earths crust-causes gamma ray exposure

how does additional terrestrial radiation exposure occur to humands

from materials used in construction

terrestrial radiation in different places

colorado: higher radioactivity

atlastic seabord: lower

what is the biggest source of natural background radiation is

radon gas

how are humans exposed to radon gas

seeps into basements and mines

alpha particles irradiate bronchi and lungs inly

what is the most hazardous internal radiation

alpha particles

internal exposure

radiation in ingested food or airborne particles

internal exposure arises mainly from

K-40

manmade radiation sources

contribute to 310 mrem of annual exposure-largest exposure from CT scan

what model is used for predicting low dose effects

threshold linear response

for radiation protection purposes, the total risk coefficient is assumed to be

1 × 10-2 SV-1

radiation workers are limited to an annual effective dose equivalent of

50 mSv

students under age 18 who may receive exposure from education or training limit

may not receive more than 1 mSv per year

Pregnant radiation workers are considered occupationally exposed individuals per NCRP guide

T

To monitor the whole‐body exposure in brachytherapy procedures, TLD badges should be worn on chest or abdomen.

true

NCRP recommends that the cumulative effective dose limit for occupational exposure is (age‐18) x10m

false, age x 10 msv

fetus of a pregnant radiation worker is considered occupationally exposed individuals per NCRP guideline

false

The equivalent dose limit to the lens of eye for general public, based on NCRP guide

false, 1.5 mSv

NCRP report 116 recommends that the annual effective dose limit for continuous exposure to the whole body for a member of general public is 5 mS

false, 1 mSv

NCRP report 116 recommends that all organs except lens should not exceed an annual equivalent dose limi

true

The linear‐quadratic threshold model is the model applied in determining dose limits for radiation workers

false, linear no threshold

. The linear no‐threshold model is the model applied in determining dose limits for radiation workers.

true

false If a member of general public receives 0.5 cGy from an X‐ray source and 0.5 cGy from neutrons, the dose equivalent from both radiation to that person is 1mSv.

primary radiation barrier

concrete is cheap and usually used for walls and roofs

lead and steel can be used when space is at a limit

door shielding

the required shielding ended up being 6 mm of lead or less to protect from scattered x rays

lead shielding is good for (apron)

xrays produced by diagnostic machines but innapropriate for brachy sources

Skin reaction to radiation is a stochastic effect. (T/F

false

n order to reduce the radiation levels outside of a Co-60 room to an acceptable value, a typical brick wall should be used. (T/F)

false, concrete is used

Using individual monitors, the equivalent dose to the whole body or any part of the body can be assessed. (T/F)

true

Effective dose equivalent and absorbed dose are numerically the same but have different units. (T/F

false

To calculate the total occupational dose for a radiation worker, all medical radiation exposures to the worker (dental X-ray, chest xray, etc.) should be considered. (T/F)

false

The radiation exposure that is received by public (not patients, not radiation workers) in a radiation therapy department is called medical exposure. (T/F

false

he weighting factor for photons and electrons are 1. (T/F)

false

gamma rays are considered the most hazardous internal radiation. (T/F

false-its alpha

one TVL is the same as 5 HVL. (T/F)

false

Dose equivalent and effective dose equivalent have the same unit. (T/F)

true

1. A radiation worker receives 15 mSv a year from age 18 until 55. The cumulative exposure for this worker exceeds the NCRP recommendation. (T/F)

true

ALARA is a safety principle but not a regulatory requirements for radiation safety programs. (T/F)

false

3. By adhering to the regulatory dose limits, any radiation worker will receive doses at the ALARA levels. (T/F)

false

person stands in a location where the air kerma rate is 20µGy/hr for 30 minutes. The total exposure to this person is 10µGy. (T/F)

true

1Sv is equal to 1 J/kg. (T/F)

true

f you wish to limit your exposure to 1msv in a 15msv/hr field of radiation, you should limit your time in that field to 15 minutes. (T/F

false

edical exposure refers to the dose received by general public in a radiation therapy/diagnostic departments. (T/F)

false

. If you increase your distance from a source of radiation by a factor of 5, the exposure rate received to you will decrease by a factor of 10. (T

false