ASRT RRT (test 6, 5,7)
What photon interaction dominates at 50 MeV?
Photoelectric effect
Coherent scattering
Compton effect
Pair production - answerPair production
*Photoelectric effect dominates at energies less than 25 KeV, most often used in
diagnostic equipment.
*Compton effect dominates at energies between 25 KeV and 10 MeV, which
encompasses any therapeutic radiation energies.
*Pair production effect dominates at 50 MeV
If a linear accelerator nominal target to skin distance (TSD) is 100 cm and the maximum
field size dialed is a 40 cm x 40 cm field, what would the field size be at 110 cm TSD?
10 cm x 10 cm
40 cm x 40 cm
44 cm x 44 cm
110 cm x 110 cm - answer44 cm x 44 cm
Feedback Use the similar triangle philosophy or the following equation: a/b=a^'/b^'
field_1/field_2 =TSD_1/TSD_2 40/x=100/110 40*110=100x 4400 =100x
4400/100=100x/100 44 = x
Silicon diodes are useful for which of the following? Please select all that apply.
personnel monitoring
measurement of electron beams
output constancy checks
Instananeous response - answermeasurement of electron beams
output constancy checks
Instananeous response
Feedback Silicon diodes are useful due to their high sensitivity, instantaneous
response, and small size. They are also used for patient dose monitoring.
Collision interlocks of the on board imagers should be checked.
,Daily
Weekly
Monthly
Annually - answerDaily
Feedback Collision interlocks should be checked daily. The test is a pass/fail test. The
interlocks are designed to protect the safety of the patient, staff and equipment.
The interaction between x-ray photons and tissue that results in the production of a
secondary x-ray photon is the ________ interaction.
coherent
Compton
photoelectric
characteristic - answerPhotoelectric
Feedback The photoelectric interaction results in the ejection of an inner shell electron.
The loss of the inner shell electron creates an unstable atom that causes transition of an
electron from another shell into the vacant shell. The movement of the electron from
one shell to another produces a secondary x-ray photon.
The monthly equivalent dose limit for pregnant radiation workers should not exceed
________ per month.
0.1 mSv
0.5 mSv
1 mSv
5 mSv - answer0.5 mSv
Feedback The occupational dose limit for pregnant radiation workers is 0.5 mSv per
month and not to exceed 5.0 mSv for the entire pregnancy.
Which of the following describe areas of the treatment room that directly interact with
the useful beam, and are required for proper shielding?
Cerrobend blocks
Primary barriers
Secondary barriers
Constant monitoring - answerPrimary barriers
Feedback Shielding by primary barriers is required for any wall intercepting the useful or
primary beam. This includes the floor, ceiling, and side walls.
Intravenous contrast media can be toxic to the:
Heart
,Arteries
Kidneys
Bladder - answerKidneys
Feedback Blood work is required prior to contrast administration, as nephrotoxicity can
result if the renal function is poor.
Breast tumors are most commonly located in the _____________quadrant.
Upper inner
Upper outer
Lower inner
Lower outer - answerUpper inner
Feedback The upper outer quadrant is the most common location, followed by central,
upper inner, lower outer, and lower inner quadrants
The interaction that takes place between the incident x-ray photon and an inner shell
electron is called:
classical scatter.
incoherent scatter.
photoelectric absorption.
photodisintegration. - answerPhotoelectric absorption
Feedback The interaction between the incident x-ray photon and an inner shell electron
is the photoelectric absorption.
Afterloading techniques _________ exposure to operating room personnel and radiation
therapists.
increase
decrease
intensify
double - answerdecrease
Feedback The use of afterloading techniques involve no exposure to operating room
personnel or therapists.
A medical event, according to the Nuclear Regulatory Commission, is determined an
event if the total dose delivered differs from the prescribed dose by __% or more.
10
15
20
25 - answer20
, Feedback A medical event occurs when the total dose delivered differs from the
prescribed dose by 20% or more. If a medical event has occurred, the licensee in an
NRC state must notify by telephone the NRC operations center no later than the next
calendar day after the discovery of the medical event. In addition, a written report must
be submitted to the NRC regional office within 15 days after the discovery of the
medical event. The report must include the licensee's and prescribing physician's name,
a description of the event, what effect occurred, why the event occurred and actions
taken, and certification that the individual or relative was notified.
Which of the following circulating blood cells is MOST resistant to radiation?
Erythroblasts
Lymphocytes
Monocytes
Platelets - answerPlatelets
Feedback Platelets are the most radioresistant in circulating blood as they can
withstand greater than 50 cGy.
Surface brachytherapy is MOST commonly used to treat ___________ skin cancer.
melanoma
nonmelanoma
basal
squamous - answerNon melanoma
Feedback Nonmelanoma skin cancer can be treated using a custom mold of the body
part prepared by placing sources in an arranged pattern to deliver the prescribed dose
A lifetime effective dose or cumulative effective dose limits a radiation worker's
exposure limit to his/her age multiplied by _________.
1 mSv
5 mSv
10 mSv
50 mSv - answer10 mSv
Feedback The cumulative effective dose pertains to the whole body and includes
external and internal exposure.
A patient suffering from hypoglycemia should be offered:
Orange juice sweetened with sugar.
A salad.
Coffee.
What photon interaction dominates at 50 MeV?
Photoelectric effect
Coherent scattering
Compton effect
Pair production - answerPair production
*Photoelectric effect dominates at energies less than 25 KeV, most often used in
diagnostic equipment.
*Compton effect dominates at energies between 25 KeV and 10 MeV, which
encompasses any therapeutic radiation energies.
*Pair production effect dominates at 50 MeV
If a linear accelerator nominal target to skin distance (TSD) is 100 cm and the maximum
field size dialed is a 40 cm x 40 cm field, what would the field size be at 110 cm TSD?
10 cm x 10 cm
40 cm x 40 cm
44 cm x 44 cm
110 cm x 110 cm - answer44 cm x 44 cm
Feedback Use the similar triangle philosophy or the following equation: a/b=a^'/b^'
field_1/field_2 =TSD_1/TSD_2 40/x=100/110 40*110=100x 4400 =100x
4400/100=100x/100 44 = x
Silicon diodes are useful for which of the following? Please select all that apply.
personnel monitoring
measurement of electron beams
output constancy checks
Instananeous response - answermeasurement of electron beams
output constancy checks
Instananeous response
Feedback Silicon diodes are useful due to their high sensitivity, instantaneous
response, and small size. They are also used for patient dose monitoring.
Collision interlocks of the on board imagers should be checked.
,Daily
Weekly
Monthly
Annually - answerDaily
Feedback Collision interlocks should be checked daily. The test is a pass/fail test. The
interlocks are designed to protect the safety of the patient, staff and equipment.
The interaction between x-ray photons and tissue that results in the production of a
secondary x-ray photon is the ________ interaction.
coherent
Compton
photoelectric
characteristic - answerPhotoelectric
Feedback The photoelectric interaction results in the ejection of an inner shell electron.
The loss of the inner shell electron creates an unstable atom that causes transition of an
electron from another shell into the vacant shell. The movement of the electron from
one shell to another produces a secondary x-ray photon.
The monthly equivalent dose limit for pregnant radiation workers should not exceed
________ per month.
0.1 mSv
0.5 mSv
1 mSv
5 mSv - answer0.5 mSv
Feedback The occupational dose limit for pregnant radiation workers is 0.5 mSv per
month and not to exceed 5.0 mSv for the entire pregnancy.
Which of the following describe areas of the treatment room that directly interact with
the useful beam, and are required for proper shielding?
Cerrobend blocks
Primary barriers
Secondary barriers
Constant monitoring - answerPrimary barriers
Feedback Shielding by primary barriers is required for any wall intercepting the useful or
primary beam. This includes the floor, ceiling, and side walls.
Intravenous contrast media can be toxic to the:
Heart
,Arteries
Kidneys
Bladder - answerKidneys
Feedback Blood work is required prior to contrast administration, as nephrotoxicity can
result if the renal function is poor.
Breast tumors are most commonly located in the _____________quadrant.
Upper inner
Upper outer
Lower inner
Lower outer - answerUpper inner
Feedback The upper outer quadrant is the most common location, followed by central,
upper inner, lower outer, and lower inner quadrants
The interaction that takes place between the incident x-ray photon and an inner shell
electron is called:
classical scatter.
incoherent scatter.
photoelectric absorption.
photodisintegration. - answerPhotoelectric absorption
Feedback The interaction between the incident x-ray photon and an inner shell electron
is the photoelectric absorption.
Afterloading techniques _________ exposure to operating room personnel and radiation
therapists.
increase
decrease
intensify
double - answerdecrease
Feedback The use of afterloading techniques involve no exposure to operating room
personnel or therapists.
A medical event, according to the Nuclear Regulatory Commission, is determined an
event if the total dose delivered differs from the prescribed dose by __% or more.
10
15
20
25 - answer20
, Feedback A medical event occurs when the total dose delivered differs from the
prescribed dose by 20% or more. If a medical event has occurred, the licensee in an
NRC state must notify by telephone the NRC operations center no later than the next
calendar day after the discovery of the medical event. In addition, a written report must
be submitted to the NRC regional office within 15 days after the discovery of the
medical event. The report must include the licensee's and prescribing physician's name,
a description of the event, what effect occurred, why the event occurred and actions
taken, and certification that the individual or relative was notified.
Which of the following circulating blood cells is MOST resistant to radiation?
Erythroblasts
Lymphocytes
Monocytes
Platelets - answerPlatelets
Feedback Platelets are the most radioresistant in circulating blood as they can
withstand greater than 50 cGy.
Surface brachytherapy is MOST commonly used to treat ___________ skin cancer.
melanoma
nonmelanoma
basal
squamous - answerNon melanoma
Feedback Nonmelanoma skin cancer can be treated using a custom mold of the body
part prepared by placing sources in an arranged pattern to deliver the prescribed dose
A lifetime effective dose or cumulative effective dose limits a radiation worker's
exposure limit to his/her age multiplied by _________.
1 mSv
5 mSv
10 mSv
50 mSv - answer10 mSv
Feedback The cumulative effective dose pertains to the whole body and includes
external and internal exposure.
A patient suffering from hypoglycemia should be offered:
Orange juice sweetened with sugar.
A salad.
Coffee.
