MDCB Questions Rated 100% With Complete Solutions!!!
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Course
MDCB
Institution
MDCB
For a 4-fld box techn, which of the following will deliver the lower dose to the femoral heads? - ANS 100 SSD, equal dmax dose to all fields
SSD= less hot spots
Which of the following can be classified as indirectly ionizing radiaiton? - ANS Photons
Also neutrons, x-ray and gam...
MDCB Questions Rated 100% With
Complete Solutions!!!
For a 4-fld box techn, which of the following will deliver the lower dose to the femoral heads? -
ANS 100 SSD, equal dmax dose to all fields
SSD= less hot spots
Which of the following can be classified as indirectly ionizing radiaiton? - ANS Photons
Also neutrons, x-ray and gamma rays
The presence of a shoulder on the survival curve of most mammalian cells indicates which of
the following? - ANS a reduced efficiency of cell killing at low doses
When opposing lateral fields to the pharynx are abutted at midline to the anterior field to the
suproclavicular fossae, overdose in the cord may be avoided by - ANS a small block over
the cord in the inf post corner of both lateral fields
In Photoelectric interactions - ANS the entire energy of the incident photon is absorbed by
the resulting electron
Film badges used for personnel monitoring contain filters that are used to: - ANS fitler info
about beam quality and energies
Giving too much radiation to which of the following can lead to xerostomia - ANS base of
tongue
The inguinal lymph nodes are located at a depth of - ANS 2-18 cm from the anterior skin
surface and are dependent on the pt's size
The contrast resolution for a tx planning CT scan can be described as a - ANS measure of
the ability to detect objects with small differences in hounsfield units
a small area of high density near the surface of hte pt would have the greatest impact on the
dose near the edge of the high density are with: - ANS a single 20 MeV electron field
-^energy ^ surface dose
Mass attenuation coefficient depends on the - ANS thickness of the material being
atttenuated
, The binding energy of the nucleus - ANS represents a mass defect in the nucleus
-binding energy of nucleus is proportional to the stability of a nucleus
Accuracy for radiation therapy tx require accuracy within: - ANS +/- 3%
daily output +/- 3%
the value for the Ngas calibration factor for an ioniziation chamber will depend on the: - ANS
composition of the chamber wall
Which are the following descriptors of characteristic x-rays or brems radiation is true? - ANS
Characteristic x-rays are produced following ionization
-ionization is having enough energy to eject an electron. When it's ejected then a characteristic
x-ray is produced b/c an electron falls into then empty place
According to AAPM TG report #142, when performing periodic linac quality assurance
procedures, which of the following is the acceptable tolerance for electron flatness - ANS
3%
Flatness-3%
an individual receives a dose of 0.1 cGy from a gamma source and 0.05cGy from neutrons. The
dose equivalent from both radiation sources is? - ANS 0.1x1+0.05x20=1.1cGy =11 mSv
For quality assurance of brachytherapy tx planning computers, the dose rates should agree with
published data tables to which of the following degrees? - ANS +/-2
The expected accuracy of tx planning systems that perfrom brachytherapy dose calc's should
be within - ANS +/-5%
The number of nuclei decaying per second is expresssed in terms of their? - ANS activity
Prior to tx h&n pts with IMRT, a 3 field techn was used. Choose the best option to keep the cord
dose under cord tolerance when total rx dose would normally go higher than 50Gy - ANS
reduce lateral fields post and add an electron beam fields
The adv fo an electron beam over kilovoltage x-ray beam for tx of superficial tumors is - ANS
decrease dose to bone
The five year survival rate for a pancreatic tumor tx with primary radiation is? - ANS 0-5%
If the exposure rate constant is 0.87 rcm^2hr^-1mCi^-1 and the average pt transmission factor is
0.20, the exposure rate at 12.5cm for a pt who has been injected with 20 mCi of Tc99m is - ANS
Activity x dose rate/d^2
0.87x.20x20/12.5^2= 0.0223R/hr-22.3mR/hr
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