MDCB BOARD REVIEW| 951
QUESTIONS AND ANSWERS 100%
CORRECT
In terms of a computer, what do the following acronyms stand for:
CRT
LED
LCD
ROM
RAM - ANSWER-CRT: cathode ray tube
LED: liquid emitting diode
LCD: liquid crystal display
ROM: read only memory (permanent, can't write over)
RAM: random access memory (temporary, lost when computer turns off)
What is used for MRI magnet shielding? What is used for MRI radiofrequency
shielding? - ANSWER--steel plates
-metal mesh (Faraday cage)
What strength of MRI has been shown to have no biological effects? - ANSWER-If
<10Tesla, then no biological effects
What is the cause for acoustic noise with an MRI machine? - ANSWER-The switching
of gradient fields
What is the event of a rapid boil-off of the liquid nitrogen or liquid helium surrounding the
MRI magnet, which is a failure of the emergency venting system and can cause a life-
threatening oxygen shortage in the MRI room? - ANSWER-Quench
What is the resolution of MRI? Spatial accuracy? - ANSWER--Resolution: 0.3lp/mm
-Spatial accuracy: 1mm-2mm
How can the resolution of an MRI be bettered? - ANSWER-Use stronger gradients
What are some disadvantages of MRI? - ANSWER--Image distortion due to lack of
homogeneity of magnetic fields and due to the gradients having slight spatial non-
linearities
-No electron density info
-Long scan times (motion artifacts)
-Spatial resolution not as good as CT
What 9 structures are evaluated on an MRI? - ANSWER--CSF
,-Gray matter
-White matter
-Fat
-Cortical bone
-Air
-Blood
-Oedema
-Protein
What is advantage and disadvantage of using an HDR tandem+ring vs a tandem
+ovoid? - ANSWER-Advantage: easier to place
Dis: ring has no shielding ant/post
What type of applicator is used for HDR GYN needles? What type is used for HDR skin
tx? - ANSWER--GYN needles: Syed template for extensive disease
-Skin: Friedburg flap
What is the rx for PBI txs? - ANSWER-10 fractions, 340cGy/fx, BID
For PBI txs, what is the dose on the balloon surface? - ANSWER-200%
For PBI tx, what is the target volume? What is the rx point? - ANSWER-PTV_eval,
which is the PTV minus 5mm of skin minus pectoral muscle
-Rx point: 1cm from balloon
On a T1 MRI image, how does the following anatomy look:
-CSF
-Gray matter
-White matter
-Fat
-Cortical bone
-Air
-Blood
-Oedema
-Protein - ANSWER--CSF: dark
-Gray matter: gray
-White matter: bright
-Fat: bright
-Cortical bone: dark
-Air: dark
-Blood: dark
-Oedema: grey/dark
-Protein: bright
On a T2 MRI image, how does the following anatomy look:
,-CSF
-Gray matter
-White matter
-Fat
-Cortical bone
-Air
-Blood
-Oedema
-Protein - ANSWER--CSF: bright
-Gray matter: gray
-White matter: gray
-Fat: gray
-Cortical bone: dark
-Air: dark
-Blood: dark
-Oedema: bright
-Protein: bright
For an MRI, what scan is Gadolinium used on? What does the contrast do? -
ANSWER--Used with T1 images
-Shortens the T1 time
-Bright signal
What does FLAIR stand for? What type of images is it? - ANSWER--Fluid Attenuation
Inversion Recovery
-It is a T2 image set but with CSF suppressed
What is the range of magnet strength for MRI and what units are used? - ANSWER-0.5-
3.0 Tesla
For Ir-192 what is the:
-activity
-half-life
-average energy
-source size
-exposure rate constant - ANSWER--activity: 10Ci
-half-life: 74 days
-average energy: 380 kEv, has 20 betas and 20 gammas
-source size: 4mmx0.8mm
-ERC: 4.69 R-cm^2/hr/mCi
How many inches of concrete is needed for shielding an HDR room? - ANSWER-18-24"
(2 feet)
What instrument is used to perform an area room monitor for HDR? What is the
frequency of this? - ANSWER-GM detector, daily
, What is the frequency for HDR QA interlocks? - ANSWER-daily
What is the frequency and tolerance for HDR positioning QA checks? - ANSWER--Daily
-1mm
What HDR QA checks should be done quarterly? - ANSWER--Source calibration
-Source positioning
-Timer checks
-Applicators
What is the frequency for HDR source exchange QA check? HDR calibration QA
checks? - ANSWER-Quarterly
With LDR QA, ___% of the sources need to be sampled when they are recieved by a
site. - ANSWER-10%
What equipment is used to calibrate HDR and LDR sources? - ANSWER-Re-entrant
chamber/ion chamber
What are three things that should be done in terms of radiation safety when dealing with
LDR sources? - ANSWER--Use forceps when handling
-Transfer with Pb pigs
-Use shields
Where is the rx point for an HDR lung tx? - ANSWER--1cm from the catheter
-This creates a 2cm cylinder of dose
Where is the rx point for an HDR vaginal cuff tx? - ANSWER-On the surface or 5mm
from the cylinder
A PBI HDR tx with a single lumen has ___dwells. If it is a multi-lumen it has ___. -
ANSWER-single: 1-5 dwells
multi: custom (stays off skin and is more conformal)
For PBI patients, what type of staging should the patients be? - ANSWER--Early stage
breast cancer, preferably node negative
-Protocol allows for 3 positive nodes
For PBI txs,
-The symmetry of the balloon<___mm
-Min distance to skin shall be __mm and should be ___mm
-PTV_Eval should be___
-Max skin dose
-Tissue volume V150<___cc
-Tissue volume V200<___cc - ANSWER--The symmetry of the balloon<2mm
QUESTIONS AND ANSWERS 100%
CORRECT
In terms of a computer, what do the following acronyms stand for:
CRT
LED
LCD
ROM
RAM - ANSWER-CRT: cathode ray tube
LED: liquid emitting diode
LCD: liquid crystal display
ROM: read only memory (permanent, can't write over)
RAM: random access memory (temporary, lost when computer turns off)
What is used for MRI magnet shielding? What is used for MRI radiofrequency
shielding? - ANSWER--steel plates
-metal mesh (Faraday cage)
What strength of MRI has been shown to have no biological effects? - ANSWER-If
<10Tesla, then no biological effects
What is the cause for acoustic noise with an MRI machine? - ANSWER-The switching
of gradient fields
What is the event of a rapid boil-off of the liquid nitrogen or liquid helium surrounding the
MRI magnet, which is a failure of the emergency venting system and can cause a life-
threatening oxygen shortage in the MRI room? - ANSWER-Quench
What is the resolution of MRI? Spatial accuracy? - ANSWER--Resolution: 0.3lp/mm
-Spatial accuracy: 1mm-2mm
How can the resolution of an MRI be bettered? - ANSWER-Use stronger gradients
What are some disadvantages of MRI? - ANSWER--Image distortion due to lack of
homogeneity of magnetic fields and due to the gradients having slight spatial non-
linearities
-No electron density info
-Long scan times (motion artifacts)
-Spatial resolution not as good as CT
What 9 structures are evaluated on an MRI? - ANSWER--CSF
,-Gray matter
-White matter
-Fat
-Cortical bone
-Air
-Blood
-Oedema
-Protein
What is advantage and disadvantage of using an HDR tandem+ring vs a tandem
+ovoid? - ANSWER-Advantage: easier to place
Dis: ring has no shielding ant/post
What type of applicator is used for HDR GYN needles? What type is used for HDR skin
tx? - ANSWER--GYN needles: Syed template for extensive disease
-Skin: Friedburg flap
What is the rx for PBI txs? - ANSWER-10 fractions, 340cGy/fx, BID
For PBI txs, what is the dose on the balloon surface? - ANSWER-200%
For PBI tx, what is the target volume? What is the rx point? - ANSWER-PTV_eval,
which is the PTV minus 5mm of skin minus pectoral muscle
-Rx point: 1cm from balloon
On a T1 MRI image, how does the following anatomy look:
-CSF
-Gray matter
-White matter
-Fat
-Cortical bone
-Air
-Blood
-Oedema
-Protein - ANSWER--CSF: dark
-Gray matter: gray
-White matter: bright
-Fat: bright
-Cortical bone: dark
-Air: dark
-Blood: dark
-Oedema: grey/dark
-Protein: bright
On a T2 MRI image, how does the following anatomy look:
,-CSF
-Gray matter
-White matter
-Fat
-Cortical bone
-Air
-Blood
-Oedema
-Protein - ANSWER--CSF: bright
-Gray matter: gray
-White matter: gray
-Fat: gray
-Cortical bone: dark
-Air: dark
-Blood: dark
-Oedema: bright
-Protein: bright
For an MRI, what scan is Gadolinium used on? What does the contrast do? -
ANSWER--Used with T1 images
-Shortens the T1 time
-Bright signal
What does FLAIR stand for? What type of images is it? - ANSWER--Fluid Attenuation
Inversion Recovery
-It is a T2 image set but with CSF suppressed
What is the range of magnet strength for MRI and what units are used? - ANSWER-0.5-
3.0 Tesla
For Ir-192 what is the:
-activity
-half-life
-average energy
-source size
-exposure rate constant - ANSWER--activity: 10Ci
-half-life: 74 days
-average energy: 380 kEv, has 20 betas and 20 gammas
-source size: 4mmx0.8mm
-ERC: 4.69 R-cm^2/hr/mCi
How many inches of concrete is needed for shielding an HDR room? - ANSWER-18-24"
(2 feet)
What instrument is used to perform an area room monitor for HDR? What is the
frequency of this? - ANSWER-GM detector, daily
, What is the frequency for HDR QA interlocks? - ANSWER-daily
What is the frequency and tolerance for HDR positioning QA checks? - ANSWER--Daily
-1mm
What HDR QA checks should be done quarterly? - ANSWER--Source calibration
-Source positioning
-Timer checks
-Applicators
What is the frequency for HDR source exchange QA check? HDR calibration QA
checks? - ANSWER-Quarterly
With LDR QA, ___% of the sources need to be sampled when they are recieved by a
site. - ANSWER-10%
What equipment is used to calibrate HDR and LDR sources? - ANSWER-Re-entrant
chamber/ion chamber
What are three things that should be done in terms of radiation safety when dealing with
LDR sources? - ANSWER--Use forceps when handling
-Transfer with Pb pigs
-Use shields
Where is the rx point for an HDR lung tx? - ANSWER--1cm from the catheter
-This creates a 2cm cylinder of dose
Where is the rx point for an HDR vaginal cuff tx? - ANSWER-On the surface or 5mm
from the cylinder
A PBI HDR tx with a single lumen has ___dwells. If it is a multi-lumen it has ___. -
ANSWER-single: 1-5 dwells
multi: custom (stays off skin and is more conformal)
For PBI patients, what type of staging should the patients be? - ANSWER--Early stage
breast cancer, preferably node negative
-Protocol allows for 3 positive nodes
For PBI txs,
-The symmetry of the balloon<___mm
-Min distance to skin shall be __mm and should be ___mm
-PTV_Eval should be___
-Max skin dose
-Tissue volume V150<___cc
-Tissue volume V200<___cc - ANSWER--The symmetry of the balloon<2mm
