1|Page
ABR Medical Physics Certification Exam||VERIFIED
QUESTIONS AND VERIFIED ANSWERS WITH
RATIONALES.pdf
What isodose line is SRS therapy prescribed to for LINAC
based treatments? - Answer-70% isodose line
What isodose line is SRS therapy using gamma knife
prescribed to? - Answer-50%
How much of the central axis dose do physical and
dynamic wedges scatter? - Answer-physical-
2.5%<br>Dynamic- 1.0%
Are electron beams a spectrum or mono energetic? -
Answer-monoenergetic
What is the therapeutic depth for electrons? - Answer-R80
What is the occupational limit for 1 year? - Answer-50 mSv
,2|Page
What is the occupational limit for a pregnant radiation
worker over the duration of their pregnancy? - Answer-5
mSv
What is the dose limit to the public in 1 year? - Answer-1
mSv
At what energy do neutrons need to be accounted for in
shielding calculations? - Answer-10 MV
What is the approximate energy of neutrons produced in
photo nuclear interactions? - Answer-2 MeV
What is the limit for leakage? - Answer-1/1000 of central
beam axis value
What energy are neutrons at the entrance of the vault? -
Answer-100 keV this is the most dangerous because
Wr=20
What is the average radiation exposure to someone in the
US? - Answer-4-5 mSv / Year <br>
,3|Page
What are the sources of background radiation exposure in
the US? (5) - Answer-Medical, Radon, ingested isotopes,
isotopes occurring naturally, and cosmic rays
As field size increases, PDD ( increases or decreases)
due to what? - Answer-PDD Increases because scatter
increases
Scatter at 1m from a phantom is what fraction of the
primary beam? - Answer-1/1000
As SSD increases, PDD (increases or decreases) due to
what? - Answer-increases due to inverse square
what is the maximum energy of lateral scatter from a
photon beam? - Answer-0.511 MeV
What is the maximum energy backscattered from a photon
beam? - Answer-0.255 MeV
What is the relationship between the photoelectric effect
and Z? - Answer-Proportional to Z^3
, 4|Page
How is the Compton effect dependent on Z? - Answer-
Independent of Z, only dependent on electron density
What is the relationship between pair production and Z? -
Answer-proportional to Zln(E)
What is the k-edge of lead? - Answer-88 keV
What is the k-edge of iodine? - Answer-33 keV
What is the increase in mortality risk due to an acute
radiation exposure? - Answer-8% per Sv
What is the increase in mortality risk due to an chronic
radiation exposure? - Answer-4% per Sv
At what dose does hematopoietic syndrome start to
occur? - Answer-2 Sv whole body
At what dose does GI syndrome start to occur? - Answer-
10 Sv whole body
ABR Medical Physics Certification Exam||VERIFIED
QUESTIONS AND VERIFIED ANSWERS WITH
RATIONALES.pdf
What isodose line is SRS therapy prescribed to for LINAC
based treatments? - Answer-70% isodose line
What isodose line is SRS therapy using gamma knife
prescribed to? - Answer-50%
How much of the central axis dose do physical and
dynamic wedges scatter? - Answer-physical-
2.5%<br>Dynamic- 1.0%
Are electron beams a spectrum or mono energetic? -
Answer-monoenergetic
What is the therapeutic depth for electrons? - Answer-R80
What is the occupational limit for 1 year? - Answer-50 mSv
,2|Page
What is the occupational limit for a pregnant radiation
worker over the duration of their pregnancy? - Answer-5
mSv
What is the dose limit to the public in 1 year? - Answer-1
mSv
At what energy do neutrons need to be accounted for in
shielding calculations? - Answer-10 MV
What is the approximate energy of neutrons produced in
photo nuclear interactions? - Answer-2 MeV
What is the limit for leakage? - Answer-1/1000 of central
beam axis value
What energy are neutrons at the entrance of the vault? -
Answer-100 keV this is the most dangerous because
Wr=20
What is the average radiation exposure to someone in the
US? - Answer-4-5 mSv / Year <br>
,3|Page
What are the sources of background radiation exposure in
the US? (5) - Answer-Medical, Radon, ingested isotopes,
isotopes occurring naturally, and cosmic rays
As field size increases, PDD ( increases or decreases)
due to what? - Answer-PDD Increases because scatter
increases
Scatter at 1m from a phantom is what fraction of the
primary beam? - Answer-1/1000
As SSD increases, PDD (increases or decreases) due to
what? - Answer-increases due to inverse square
what is the maximum energy of lateral scatter from a
photon beam? - Answer-0.511 MeV
What is the maximum energy backscattered from a photon
beam? - Answer-0.255 MeV
What is the relationship between the photoelectric effect
and Z? - Answer-Proportional to Z^3
, 4|Page
How is the Compton effect dependent on Z? - Answer-
Independent of Z, only dependent on electron density
What is the relationship between pair production and Z? -
Answer-proportional to Zln(E)
What is the k-edge of lead? - Answer-88 keV
What is the k-edge of iodine? - Answer-33 keV
What is the increase in mortality risk due to an acute
radiation exposure? - Answer-8% per Sv
What is the increase in mortality risk due to an chronic
radiation exposure? - Answer-4% per Sv
At what dose does hematopoietic syndrome start to
occur? - Answer-2 Sv whole body
At what dose does GI syndrome start to occur? - Answer-
10 Sv whole body
