Raphex Exam Fully Solved &
Updated (Latest Version Verified
for Accuracy) (Questions +
Answers) Solved 100% Correct!!
In the equation for radioactive decay, lambda represents _________ - 🧠
ANSWER ✔✔the fraction of atoms that decay per unit time
Purpose of rounded leaf ends for MLCs - 🧠 ANSWER ✔✔keep the
geometric penumbra relatively constant for different leaf positions
Neutron contamination is greatest in a _______ beam
,a. 6 MV photon
b. 10 MV photon
c. 18 MV photon
d. 6 MeV electron
e. 20 MeV electron - 🧠 ANSWER ✔✔c. 18 MV photon
remember neutrons are produced through photon interactions, begin
happening above 10 MV photons
Loss of charged particle equilibrium is greatest in lung radiotherapy for field
sizes _______ cm2 and photon energies _______ MV - 🧠 ANSWER ✔✔<
5x5; >= 15 MV
effect is greater for higher photon energies since the average energy of the
secondary electrons is greater. effect is greater for small field sizes, harder
to maintain CPE in small space
What is the relationship between HVL1 and HVL2 for a polyenergetic kV
photon beam - 🧠 ANSWER ✔✔HVL1 < HVL2 always
As a polyenergetic kV photon beam traverses a material, lower-energy
photons will be preferentially attenuated. Therefore, as the beam travels
, farther into a material, it will become hardened and its average energy will
increase. Therefore, the HVL will increase as well.
Compton scattering angles for minimum and maximum energy transference
- 🧠 ANSWER ✔✔MAX ENERGY TRANSFER --> electron scattered 0
degrees (forward) and the photon is scattered at 180 degrees (backward)
MIN ENERGY TRANSFER --> electron scattered at 90 (sideways) and
photon is scattered at 0 degrees (forward), no energy is transferred to the
electron
NOTE: all of the photon energy cannot be transferred to the electron, must
always be some energy available for the scattered photon.
what is the relationship between the mass energy transfer coefficient
(u_tr/ρ) and the mass energy absorption coefficient (u_en/ρ) - 🧠 ANSWER
✔✔u_tr/ρ ≤ u_en/ρ always
u_tr/ρ includes radiative losses, u_en/ρ does not
The quantity f_med (or f-factor) - 🧠 ANSWER ✔✔roentgen-to-rad
conversion factor
0.876 * (u_en/ρ)air/(u_en/ρ)med
as such, function of both medium density and photon energy
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2026. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
PRIVACY STATEMENT. ALL RIGHTS RESERVED
Updated (Latest Version Verified
for Accuracy) (Questions +
Answers) Solved 100% Correct!!
In the equation for radioactive decay, lambda represents _________ - 🧠
ANSWER ✔✔the fraction of atoms that decay per unit time
Purpose of rounded leaf ends for MLCs - 🧠 ANSWER ✔✔keep the
geometric penumbra relatively constant for different leaf positions
Neutron contamination is greatest in a _______ beam
,a. 6 MV photon
b. 10 MV photon
c. 18 MV photon
d. 6 MeV electron
e. 20 MeV electron - 🧠 ANSWER ✔✔c. 18 MV photon
remember neutrons are produced through photon interactions, begin
happening above 10 MV photons
Loss of charged particle equilibrium is greatest in lung radiotherapy for field
sizes _______ cm2 and photon energies _______ MV - 🧠 ANSWER ✔✔<
5x5; >= 15 MV
effect is greater for higher photon energies since the average energy of the
secondary electrons is greater. effect is greater for small field sizes, harder
to maintain CPE in small space
What is the relationship between HVL1 and HVL2 for a polyenergetic kV
photon beam - 🧠 ANSWER ✔✔HVL1 < HVL2 always
As a polyenergetic kV photon beam traverses a material, lower-energy
photons will be preferentially attenuated. Therefore, as the beam travels
, farther into a material, it will become hardened and its average energy will
increase. Therefore, the HVL will increase as well.
Compton scattering angles for minimum and maximum energy transference
- 🧠 ANSWER ✔✔MAX ENERGY TRANSFER --> electron scattered 0
degrees (forward) and the photon is scattered at 180 degrees (backward)
MIN ENERGY TRANSFER --> electron scattered at 90 (sideways) and
photon is scattered at 0 degrees (forward), no energy is transferred to the
electron
NOTE: all of the photon energy cannot be transferred to the electron, must
always be some energy available for the scattered photon.
what is the relationship between the mass energy transfer coefficient
(u_tr/ρ) and the mass energy absorption coefficient (u_en/ρ) - 🧠 ANSWER
✔✔u_tr/ρ ≤ u_en/ρ always
u_tr/ρ includes radiative losses, u_en/ρ does not
The quantity f_med (or f-factor) - 🧠 ANSWER ✔✔roentgen-to-rad
conversion factor
0.876 * (u_en/ρ)air/(u_en/ρ)med
as such, function of both medium density and photon energy
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2026. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
PRIVACY STATEMENT. ALL RIGHTS RESERVED
