MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED
GUIDE.
In TG 43, what variable is known as F?
Anisotropy: provides dose falloff info using attenuation and scatter only perpendicular to the radial dose
function
This would be the "along" portion on the along and away tables, rotation away from central axis
Steps done to complete a survey of an HDR brachytherapy procedure using an ion chamber survey
meter?
1st. Before treatment survey of afterloader to confirm source is contained
2nd. Achieve a baseline value right before treatment begins
3rd. Upon first entering the room after treatment, confirm source is in the afterloader. This value should
match the 2nd
4th. If the source is confirmed back in the afterloader, staff may enter and the patient can be released
True or False: Brachytherapy surveys are performed by using a Geiger Mueller counter.
False. Surveys require dose to be collected not just for detection, an ion chamber survey meter would be
used
What does V20 stand for?
Volume receiving at least 20 Gy
What does D95 stand for?
Minimum dose being delivered to 95% of the target
What is the common type of DVH used for treatment planning, cumulative or differential?
Cumulative DVH
What is conventional fractionation for the brain?
45-60 Gy in 180-200cGy per fx
What is conventional fractionation for head and neck?
56-70 Gy in 180-200cGy per fx
What is conventional fractionation for the breast?
50-50.4 Gy in 180-200cGy per fx
What is conventional fractionation for the lung?
, 60-66 Gy in 180-200cGy per fx
What is conventional fractionation for GI treatments?
45-54 Gy in 180-200cGy per fx
What is conventional fractionation for GU/GYN treatments?
60-80 Gy in 180-200cGy per fx
What does BED stand for? What is the typical BED for the tumor/target? What is the typical BED for
other OARs?
Biological Equivalent Dose: the tumor is typically 10 and OARs are typically 3
BED gives the fractionation scheme that provides the same biological effect between different
prescriptions
What is LET? Define LET.
Linear Energy Transfer: the amount of energy a particle transfers into a medium per unit length
What is RBE? Define RBE.
Relative Biological Effectiveness: compares the impact of dose in different particle types relative to a
standard
Standard is typically taken as 250 keV
What is the RBE for protons? RBE for photons?
Proton RBE = 1.1
Photon RBE = 1.0
Traits specific to Tomotherapy machines?
40 x 5 field size, 80 SAD, binary MLCs
Helical treatment delivery
6X-FFF energy ONLY
What are different about HDMLCs compared to traditional MLCs?
Width reduced from 5mm to 2.5mm for interior leaves and from 1cm to 5mm on exterior leaves
Allows for higher modulation in plans and increased conformality
HDMLCs reduce the maximum field size, difficult to use for large field size treatment sites
Important factors when planning/treating TBI?
Dose rate should not exceed 10Gy/min
GUIDE.
In TG 43, what variable is known as F?
Anisotropy: provides dose falloff info using attenuation and scatter only perpendicular to the radial dose
function
This would be the "along" portion on the along and away tables, rotation away from central axis
Steps done to complete a survey of an HDR brachytherapy procedure using an ion chamber survey
meter?
1st. Before treatment survey of afterloader to confirm source is contained
2nd. Achieve a baseline value right before treatment begins
3rd. Upon first entering the room after treatment, confirm source is in the afterloader. This value should
match the 2nd
4th. If the source is confirmed back in the afterloader, staff may enter and the patient can be released
True or False: Brachytherapy surveys are performed by using a Geiger Mueller counter.
False. Surveys require dose to be collected not just for detection, an ion chamber survey meter would be
used
What does V20 stand for?
Volume receiving at least 20 Gy
What does D95 stand for?
Minimum dose being delivered to 95% of the target
What is the common type of DVH used for treatment planning, cumulative or differential?
Cumulative DVH
What is conventional fractionation for the brain?
45-60 Gy in 180-200cGy per fx
What is conventional fractionation for head and neck?
56-70 Gy in 180-200cGy per fx
What is conventional fractionation for the breast?
50-50.4 Gy in 180-200cGy per fx
What is conventional fractionation for the lung?
, 60-66 Gy in 180-200cGy per fx
What is conventional fractionation for GI treatments?
45-54 Gy in 180-200cGy per fx
What is conventional fractionation for GU/GYN treatments?
60-80 Gy in 180-200cGy per fx
What does BED stand for? What is the typical BED for the tumor/target? What is the typical BED for
other OARs?
Biological Equivalent Dose: the tumor is typically 10 and OARs are typically 3
BED gives the fractionation scheme that provides the same biological effect between different
prescriptions
What is LET? Define LET.
Linear Energy Transfer: the amount of energy a particle transfers into a medium per unit length
What is RBE? Define RBE.
Relative Biological Effectiveness: compares the impact of dose in different particle types relative to a
standard
Standard is typically taken as 250 keV
What is the RBE for protons? RBE for photons?
Proton RBE = 1.1
Photon RBE = 1.0
Traits specific to Tomotherapy machines?
40 x 5 field size, 80 SAD, binary MLCs
Helical treatment delivery
6X-FFF energy ONLY
What are different about HDMLCs compared to traditional MLCs?
Width reduced from 5mm to 2.5mm for interior leaves and from 1cm to 5mm on exterior leaves
Allows for higher modulation in plans and increased conformality
HDMLCs reduce the maximum field size, difficult to use for large field size treatment sites
Important factors when planning/treating TBI?
Dose rate should not exceed 10Gy/min
