RTTT214 Midterm Review (Dos 2)
Extended SSDs are used for 1. total body irradiation 2. large mantle fields 3. treating head and neck cancers
1&2
The purpose of using combined photon and electron beams to treat the internal mammary nodes is to: 1. increase skin sparing 2. spare deeper normal tissue 3. increase dose to deeper tissues
1&2
The wedge angle is determined by the tilt of the isodose lines at: 1. The 50% isodose line in low energy beams 2. A depth of 10 cm for high energy beams 3. The depth of the 20% isodose line in high energy beams 4. The depth of 5 cm for low energy beams
1&2
Dose volume histograms (DVHs) are useful to: 1. provide a graphic display of dose tot he target 2. optimize the radiation treatment in a reasonable time 3. give a good representation of the dose received by the normal structures 4. indicate precisely the extreme dose (hot spot) in the volume treated
1&3
An increase in which of the following factors results in an increase in the percent depth dose (PDD) of a megavoltage beam? 1. beam energy 2. source-to-skin distance 3. field size 4. dose rate
1,2,3
Organs that can be affected by motion are the: 1. lung 2. liver 3. pancreas
1,2,3
The tolerance of normal tissues is related to the: 1. Overall volume irradiated 2. Radiosensitivity of the organ under treatment 3. The time over which the radiation takes place
1,2,3
Tissue-air ratio (TAR) is dependent on: 1. beam energy 2. depth 3. field size 4. source-to-surface distance (SSD)
1,2,3
Which factors influencde the construction of a PTV from a CTV? 1. Patient set-up uncertainty 2. Organ motion 3. Proximity of critical structure 4. Extent of microscopic disease
1,2,3
Field weighting: 1. gives the relative contribution of beams to dose at target center or dmax point 2. changes the dose rates at input ports 3. improves dose uniformity across the target 4. reduces dose to normal tissues or critical structures
1,3,4
Rotational x-ray beam therapy is acceptable: 1. When the external contour of the patient is fairly cylindrical 2. When blocking is required to shield sensitive structures 3. When target volume is small 4. When target volume is centrally located
1,3,4
According to ICRU-50, the following statement(s) is correct: 1. CTV = PTV 2. Treatment volume <PTV 3. Treatment volume >PTV 4. Treament volume < Irradiated volume
3&4
Clinical proton generators consist of: 1. Linacs 2. Microtrons 3. Synchrotrons 4. Betatrons 5. Cyclotrons
3&5
Bragg peak is: A An ionization maximum near the end of the range of a heavy charged particle B A maximum in the curve of activity and time for a patient and daughter radionuclide in equilibrium C A maximum concentration of Compton interactions D The maximum activity of an isotope
A An ionization maximum near the end of the range of a heavy charged particle
The radioactive source inventory room should have a sign that reads: A Caution Radioactive Material B Caution Radiation Area C Caution High Radiation Area D Grave Danger-High Radiation Area
A Caution Radioactive Material
All of the following are true of IMRT except: A IMRT dose distributions are always more inhomogeneous than conventional 3-D plans B In prostate treatment, IMRT can reduce rectal toxicity C A 3-D data set is required for IMRT planning D Immobilization is more important because of the tighter margins
A IMRT dose distributions are always more inhomogeneous than conventional 3-D plans
Which of the following most significantly effects brachytherapy dose distributions? A Inverse square law B Absorption within tissue C Scatter within tissue D Tissue heterogeneities E Use of point or line source model
A Inverse square law
Absorbed dose at a given depth divided by the dose in air dose at a fixed reference is the definition of: A TAR B TMR C TPR D PDD
A TAR
The entire right breast will be treated in your patient diagnosed with T1 N1 M0 infiltrating ductal carcinoma. The most likely field arrangement would be: A Tangential fields with subsequent tumor bed boost B Tangential fields with internal mammary and supraclavicular fields C Parallel opposed AP/PA fields with spinal cord blocked D Single field electron field to the entire breast with bolu
A Tangential fields with subsequent tumor bed boost
When dealing with brachytherapy sources, which of the following should be kept at a minimum to reduce exposure? A Time spent in the vicinity of the sources B Distance between the operator and the source material C Shielding between the operator and the source material D All of the above
A Time spent in the vicinity of the sources
Clinical target volume (CTV) A Volume enclosing tumor and subclinical spread B Tumor volume as determined by the radiation oncologist C Volume enclosing tumor, its subclinical spread, and a margin to include patient (or organ) movements and setup error D Defined by a specified isodose surface
A Volume enclosing tumor and subclinical spread
Conformal treatment improves tumor control. A Yes B No
A Yes
When adjacent areas must be treated, it is best to: A cacluate gap necessary between the fields to prevent an overlap B set a 2-cm gap between all fields C rely on tattoos to prevent an overlap
A cacluate gap necessary between the fields to prevent an overlap
A dose-volume histogram A helps in optimizing the treatment plan B is the only method of optimizing treatment plans C is the best method for optimizing treatment plans D is a totally objective tool for optimization
A helps in optimizing the treatment plan
What effect will an increase in the nominal energy of an electron beam have on the depth of the 80% isodose line? A increase B decrease C remain the same D dose dependence
A increase
As the field size increases, the PDD: A increases B decreases C remains the same D there is no effect
A increases
The calculation of dose at a point away from the central axis requires a knowledge of the: A off-axis ratio B tissue-phantom ratio C photon fluence D photon flux E kerma
A off-axis ratio
A shifting field arrangement (feathering) often used in treatment of brain and spinal cord is used primarily to: A prevent "hot" spots B prevent "cold" spots C increase the dose of the gapped area D spare overlaying skin tissue
A prevent "hot" spots
During a 4 MV treatment, a sloping skin surface is corrected by a ___________ shift toward the skin surface of the isodose curve. A 3/4 B 2/3 C 1/2 D 1/ 4
B 2/3
A patient is to be treated with a single field of a 16 MeV electron beam. Calculate the depth of the 90% isodose line, along the central axis. A 2 cm B 4 cm C 8 cm D none of the above
B 4 cm
The range of penetration of 12 MeV electrons is: A 3 cm B 6 cm C 9 cm D 12 cm
B 6 cm
In clinical photon beam therapy planning, the PTV must be normally enclosed by: A 99% B 95% C 80% D 50%
B 95%
The Sterling formula is a method to determine: A Extended distance B Equivalent square C Skin gap D Inverse square E Dmax F Penumbra
B Equivalent square
Which of the following is not an advantage of using a multifield approach? A Minimizes side effects B Increases integral dose C Reduces a potentially high dose in any single area D Provides more homogeneous dose distribution around target
B Increases integral dose
The concept of tissue-air ratio (TAR) is most commonly employed for calculations involving: A Overlapping fields B SSD varying fields C Separated fields D Opposed fields
B SSD varying fields
According to the Bragg-Gray cavity theory, the ratio of dose to the surrounding medium to the dose to cavity air is given by: (Assume cavity size to be infinitesimally small) A The ratio of mass absorption coefficient of medium to that of air forcthe photons crossing the cavity B The ratio of mass stopping power of medium to that of air for the electrons crossing the cavity C The ratio of electron density of medium to that of air D Roentgen-to-cGy conversion factor for the medium
B The ratio of mass stopping power of medium to that of air for the electrons crossing the cavity
Wedges are used for all of the following except: A To increase dose homogeneity for breast tangent fields B To increase the anterior hot spot for a larynx treated with lateral opposed fields C To increase dose homogeneity for othogonal fields in partial-brain treatments D As a missing-tissue compensator E To increase dose homogeneity in a three-field plan (anterior and two opposing laterals)
B To increase the anterior hot spot for a larynx treated with lateral opposed fields
Which of the following is not used for brachytherapy treatments? A cesium B cobalt C iodine D iridium
B cobalt
As the depth increases, the PDD: A increases B decreases C remains the same D there is no effect
B decreases
As photon energy increases, surface dose _________ and depth of dmax ___________. A increases, increases B decreases, increases C increases, decreases D decreases, decreases
B decreases, increases
Clarkson's Method is used for: A dose calculation of a rectangular field B dose calculation of an irregular field C dose calculation of a circular field D dose calcuation of a square field
B dose calculation of an irregular field
The goal of radiation therapy planning is to deliver an evenly distributed radiation dose to the ________ while minimizing the dose to the normal surrounding tissue A isodose lines B target volume c hinge angle D penumbra
B target volume
When documenting and/or verifying off-axis SSD's, it is important to remember that the ODI is only accurate at? A extended SSD's B the central axis C mechanical isocenter D prescription depth
B the central axis
Field weighting is used: A when tumors are centrally located B when contribution from any of the fields needs to be reduced or increased with respect to other fields C in rotation therapy D in single field treatments
B when contribution from any of the fields needs to be reduced or increased with respect to other fields
The mean life of a radioactive source is given by: A 1.5 T1/2 B 2.4 T1/2 C 1.44 T1/2 D 2 T1/2
C 1.44 T1/2
Long forceps are required for direct handling of radioactive sources so that: A Exposure time to the handler's hands is decreased B Exposure time tot he handler's hands is increased C Amount of exposure to handler's hands is decreased D Amount of exposure to handler's hands is increased
C Amount of exposure to handler's hands is decreased
Which technique is most often used for the treatment of superficial tumors that extend to a depth of 7 centimeters? A Rotational therapies B Parallel opposed therapies C Angled fields using wedge-pair technique D Angled fields without wedges
C Angled fields using wedge-pair technique
Any container in which radionuclides are transported, stored, or used must have a label saying: A Caution - Breakable Container B Caution - High Radiation Area C Caution - Radioactive Material D Grave Danger - High Radiation Area
C Caution - Radioactive Material
A method for correcting an isodose chart for contour irregularities is the: A Impedance method B Field shaping method C Isodose shift method D Isocenter method
C Isodose shift method
Patients with gynecological malignancies have an increased risk of developing a thrombosis when treated with: A HDR B external beam C LDR D external beam and HDR
C LDR
Target volume delineation for lung tumors may involve cardiac or respiratory gating procedures. The rationale for this is that lung tumors: A Are often metastatic B Are difficult to image C Move with cardiac and respiratory motion D Change shape with cardiac and respiratory motion
C Move with cardiac and respiratory motion
Which of the following accounts for target motion and uncertainty in positioning? A GTV B CTV C PTV D treated volume
C PTV
Radioactive sources should be transported around the treatment facility in: A Sterile bags B Biohazard bags C Shielded containers D Sterile boxes
C Shielded containers
Planning target volume (PTV) A Volume enclosing tumor and subclinical spread B Tumor volume as determined by the radiation oncologist C Volume enclosing tumor, its subclinical spread, and a margin to include patient (or organ) movements and setup error D Defined by a specified isodose surface
C Volume enclosing tumor, its subclinical spread, and a margin to include patient (or organ) movements and setup error
When taking a patient's separation (IPD), you place the caliper at the: A thickest part B thinnest part C central axis D none of the above
C central axis
Bragg-Gray cavity theory relates ionization produced in an air cavity in a medium to the dose in the medium using the: A Roentgen to rad f-factor B Mayneord F-factor C stopping-power ratio D decay constant E mechanical equivalent of heat
C stopping-power ratio
The radiation oncologist should mark on each CT slice: A the gross tumor area B the clinical target area C the planning target area D the irradiated area
C the planning target area
An autoradiograph is taken to: A determine the energy of the source B check source placement in the patient C verify uniformity of source D determine source strength
C verify uniformity of source
A lesion is being treated using a 100 degree arc rotation. The midpoint of the tumor volume is 5 cm. The isocenter should be placed at: A 0 cm B 2.5 cm C 5 cm D 7.5 cm
D 7.5 cm
`In stereotactic radiosurgery (SRS): A All beams are coplanar B All beams are equally weighted C All beams are directed at the same point in the target volume D Geometric accuracy of isocenter localization of +/- 1 mm is acceptable
D Geometric accuracy of isocenter localization of +/- 1 mm is acceptable
Which of the following is an advantage of HDR over LDR? A HDR is noninvasive B HDR dosimetry is simpler C Treatment time is decreased from 72 hours to 24 hours D HDR can be given on an oupatient basis
D HDR can be given on an oupatient basis
Following discharge of a patient who received low dose rate brachytherapy, a room survery should be conducted to: A Ensure patient care staff members have not been exposed B Make sure the former patient's roommate has not been exposed C Make sure that the survey meter has maintained a suitable charge between the procedure and patient discharge D Make sure that there are no remaining radioactive sources in the room
D Make sure that there are no remaining radioactive sources in the room
Generally, which term would describe the largest volume of tissue in the patient planning process according to ICRU Report 50? A GTV B CTV C VTV D PTV
D PTV
The term "step-and-shoot" is sometimes used to describe which IMRT delivery technique? A Helical tomotherapy B Serial tomotherapy C IMAT D Segmental MLC - IMRT E Dynamic MLC - IMRT
D Segmental MLC - IMRT
In a head and neck treatment where left lateral, right lateral, and anterior fields are commonly used, one of the following statements is not true: A Matching of the borders is important so as to prevent underdose/overdose B The spinal cord is protected by shielding C Sometimes central lead shielding is used to protect the spinal cord and the upper area digestive tract D The field junction can be present in the area where the tumor is present
D The field junction can be present in the area where the tumor is present
When more than two planes of sources are used, it would be called a: A Stereo implant B Single-plane implant C Orthogonal D Volume implant
D Volume implant
Advantages of intracavitary brachytherapy include: A preservation of normal anatomy B sources can be easily placed at the tumor site and removed C dose is higher to the tumor than adjacent tissues D all of the above
D all of the above
The most important characteristics of the electron beam isodose curves that influence treatment planning are: A constriction of 80% to 90% isodose curves B ballooning (or lateral spred) of 50% to 20% isodose curves C therapeutic depth D all of the above
D all of the above
A brachytherapy source is encapsulated to: A produce bremsttrahlung in the encapsulation wall B reduce the intensity of the brachytherapy source C increase the useful life of the source D contain radioactivity and stop particles other than gamma in delivering tumor dose
D contain radioactivity and stop particles other than gamma in delivering tumor dose
Treatment planning and delivery systems are rapidly evolving to accomplish all of the following except: A increase tumor effects B reduce normal tissue damage C improve patient safety D decrease patient care
D decrease patient care
The shape of the isodose distribution for a tandem and ovid treatment is: A apple shaped B triangular C mushroom shpaed D pear shaped
D pear shaped
The BAT system uses __________ energy to localize the treatment target. A x-ray B microwave C radiofrequency D ultrasound
D ultrasound
Autoradiography of an encapsulated brachytherapy source is: A an automatic afterloading technique used to reduce exposure to the nursing staff B a procedure using three radiographs to automatically identify radioactive seeds C a manufacturing process used to ensure all sources have the same activity D a method of using the sources in the patient to produce radiographs E a test for gross nonuniformity of the radionuclide within a source capsule
E a test for gross nonuniformity of the radionuclide within a source capsule
The percentage depth dose (PDD) curve is an example of a two-dimensional representation of the variation of dose. T or F
False
MLCs used with various linacs are identical. Yes or No
No
The aim of treatment planning is to plan a treatment that gives the prescribed dose to the target volume of interest and no dose to surrounding normal tissues. Yes or No
No
Wedge filters and tissue compensators must be mounted close to the patient to reduce electron contamination in the beam. Yes or No
No
Appropriate disposal of radioactive sources include: A Transfer to an authorized recipient B Incineration C Burial DAll of the above
all
IGRT is useful because it can: 1. result in a more focused treatment 2. account for interfraction and intrafraction motion 3. compare in-room image set with treatment planning image set
all
Which of the following factors can be corrected to adjust the isodose lines of beams with oblique incidences? I. PDD II. TAR III. TMR
all
