Mock Exam 1 Flashcards
Which of the following does NOT represent an advantage of CT images for treatment planning?
- functional abnormalities caused by tumor extension are visualized
- density contouring can be done
- 3 dimensional information can be generated
- images can be modified to give different contrast as desired
-functional abnormalities caused by tumor extension are visualized
The pituitary gland is:
- a midline structure located in the sella turcica
- an endocrine gland
- consists of two lobes
- all of the answers are correct
- all of the answers are correct
IMRT is a treatment planning and delivery process that seeks to achieve treatment plan optimization by varying the ________ of treatment beams in addition to their position.
- field size
- area
- energy
- intensity
- intensity
The protocol currently recommended by the AAPM for calibrating megavoltage therapy units is:
- SCRAD
- The Nordic Protocol
- TG-51
- ICRU Report 21
-TG-51
This is the report No.67 of AAPM Task Group 51, published in 1999 (Protocol for clinical reference dosimetry of high energy photon and electron beams)
Thimble chambers are used to calibrate radiation beams because:
- they are sturdy
- they have good spatial resolution
- they do not significantly perturb the beams
- all of the answers are correct
-all of the answers are correct
Thermoluminescence refers to the emission of:
- heat production during electron beam delivery
- photons when an electron beam strikes the target
- light from phosphorus materials when heated
- radioactivity from a thermonuclear reaction
-light from phosphorus materials when heated
The most commonly used TLD material used in radiation dosimetry is:
- CaSo4
- CaF2
- LiF
- Li2B
-LiF
An unsealed chamber as a secondary dosimeter gives a reading of 101.0 for a 100 monitor unit exposure at a field size of 10 x 10 cm. If the ambient temperature is 25 degrees C and the atmospheric pressure is 770 mm Hg, the corrected reading per monitor unit is:
- 0.923
- 0.997
- 1.007
- 1.013
- 1.034
-1.007
(760/770) x (298/295) = 0.997
0.997 x (101/100MU)= 1.007
What of the following connects two or more networks within a city?
- Connection Area Network (CAN)
- Local Area Network (LAN)
- Metropolitan Area Network (MAN)
- Wide Area Network (WAN)
-Metropolitan Area Network (MAN)
Thin window parallel-plate chambers are useful for measuring radiation dose at or near:
- the surface
- a 5cm depth
- a 10 cm depth
- an equilibrium depth
-the surface
For stereotactic radiosurgery, accuracy and reproducibility should generally be on the order of ____ mm.
- 0.5
- 1.0
- 2.0
- 5.0
-1.0
An overall accuracy of +/- 1mm in the coverage of the intended target volume is a commonly accepted standard for the SRS and SRT procedures.
Which of the following problems may be encountered in the use of diagnostic CT data in radiation therapy treatment planning?
- vertical and horizontal scales may differ, resulting in image distortion
- small scan ring may result in side cut-off of patient contour
- the position of the patient in the scanner may not duplicate the therapy setup
- cross-sectional CT images can provide inaccurate tissue heterogeneity corrections if the data do not correlate with the CT tables in the treatment planning computer
- All are correct
-All are correct
Which of the following tissues is the least radiosensitive?
- ovaries
- ocular lens
- small intestine
- bone and cartilage
-bone and cartilage
A single field megavoltage treatment plan displays the effects of which of the following?
- penumbra
- flattening filter
- patient contour
- field normalization
- all are correct
-all are correct
Which of the following statements is true concerning a 3D pencil beam algorithm?
- It does not consider the effects of scatter to and from heterogeneities, irregular surfaces, or irregularly blocked fields
- It divides the broad beam into many small thin beams that can have their own intensity and lateral scatter spread
- It uses an equivalent pathlength calculation that converts any heterogeneity into homogenous water medium through an attenuation equivalent thickness coefficient
- The pencil beam is not a three dimensional calculation
- All are correct
-It divides the broad beam into many small thin beams that can have their own intensity and lateral scatter spread
Bolus is often used in electron beam therapy to do all of the following EXCEPT:
- reduce the amount of scatter due to inhomogeneities
- reduce the penetration of the electrons in parts of the field
- increase the surface dose
- flatten out an irregular surface
-reduce the amount of scatter due to inhomogeneities
The decay constant describes:
- the half-life of a particular radionuclide
- the number of ionizations produced in tissue per unit time
- the fraction of the number of atoms that decay per unit time
- none of the answers are true
-the fraction of the number of atoms that decay per unit time
Treatment of an anterior supraclavicular nodal field would be indicated in all of the following EXCEPT:
- T2N2 tonsil
- T4N2 oral tongue
- T2N3 nasopharynx
- T1N0 larynx
-T1N0 larynx
The tumor type that is most responsive to radiation treatment is:
- melanoma
- squamous cell carcinoma
- adenocarcinoma
- sarcoma
- seminoma
-seminoma
The professional body that promotes medical dosimetry as a specialized field is:
- the American Association of Physicists in Medicine (AAPM)
- the American Board of Radiology (ABR)
- the American Roentgen Society (ARS)
- the American Association of Medical Dosimetrists (AAMD)
- the American College of Medical Physicists (ACMP)
-the American Association of Medical Dosimetrists (AAMD)
What is the term describing certain chemicals or drugs that enhance the response of cells to radiation?
- Free radicals
- radiosensitizers
- radioprotectors
- biologic rescue factors
-radiosensitizers
According to the AAPM TG-40 report, linear accelerator output should be:
- spot checked daily before each patient
- spot checked daily before treatment
- calibrated monthly by the dosimetrist
- calibrated bi-annually using a water tank
- calibrated annually using a solid water phantom
-spot checked daily before treatment
Output checked daily by therapist; calibration is part of monthly physics QA; calibration in water is part of annual QA
What of the following defines TD5/5?
- 5% reduction of tumor cells in 5 days
- cell population reduction to 5% after 5 Gy
- 5% complication rate in 5 years
- 5% survival rate in 5 years
-5% complication rate in 5 years
Which of the following is NOT one of the four R’s of radiation biology?
- redistribution
- reoxygenation
- reconfirmation
- repopulation
-reconfirmation
The quality factor (QF) used for determining the dose equivalent for high-energy X-rays compared to high-energy gamma rays is:
- 1
- 2
- 5
- 20
-1
The presence of a shoulder on the survival curve of most mammalian cells indicates which of the following?
- a reduced efficiency of cell killing at low doses
- that cell killing is an exponential function of dose
- the random nature of radiochemical injury
- that tissue tolerance is related to the volume irradiated
- a link between cell-death and cell-division rate
-a reduced efficiency of cell killing at low doses
The distance between the ends of radioactive material in a radioisotope tube is known as:
- permanent activity
- active length
- physical length
- filtration distance
-active length
The approximate density of fat is:
- 0.30 g/cc
- 0.95 g/cc
- 1.00 g/cc
- 1.03 g/cc
- 1.65 g/cc
-0.95 g/cc
CT numbers are expressed in terms of:
- cm squared/gram
- cm -1
- Roentgen units (RU)
- Hounsfield Units (HU)
-Hounsfield Units (HU)
Which of the following precautions would most effectively reduce radiation exposure to family members visiting a patient with an Iridium implant?
- Double the distance between the patient and the family
- Place a lead shield of one HVL thickness between the patient and the family
- Reduce the visiting time by one-half
- Place a personal radiation detection monitor on each visiting family member
- All options are equally effective
-Double the distance between the patient and the family
Prior to the administration of a brachytherapy remote afterloading treatment, the following are required EXCEPT:
- preparation of a signed written directive
- independent confirmation of treatment time
- calibration of the treatment unit
- verification of the patient’s identity
-calibration of the treatment unit
Autoradiography of an encapsulated brachytherapy source is:
- an automatic afterloading technique used to reduce exposure to the nursing staff
- a procedure using three radiographs to automatically identify radioactive seeds
- a manufacturing process used to ensure all sources have the same activity
- a method of using the sources in the patient to produce radiographs
- a test for gross nonuniformity of the radionuclide within a source capsule
-a test for gross nonuniformity of the radionuclide within a source capsule
A tumor, treated at 100 cm SAD, measures 4 cm in diameter on a film with an FFD of 145 cm. What is the actual size of the tumor?
- 1.24 cm
- 2.75 cm
- 4 cm
- 12.8 cm
-2.75 cm
100 cm / 145 cm = 0.6896
0.6896 x 4 cm = 2.75 cm
Parallel-plate ionization chambers are primarily used to measure:
- ionization at deeper locations in a phantom
- surface dose
- scattered radiation dose
- interstitial dose
-surface dose
According to AAPM’s TG40 report on QA, daily linac checks should include all of the following except:
- output for each photon energy
- patient viewing system
- accuracy of laser alignment
- accuracy of distance indicator
- symmetry of each photon energy
-symmetry of each photon energy
Beam flatness and symmetry are checked by the physicist during monthly QA
Which of the following are true statements regarding linac commissioning?
- linac commissioning should be done prior to clinical use
- linac commissioning should be done by a qualified medical physicist
- linac commissioning requires measurement of all beam parameters
- all of the answers are correct
-all of the answers are correct
A good standard of practice requires that a treatment machine should undergo a complete calibration at least:
- before any treatment
- daily
- weekly
- monthly
- annually
-annually
Most federal and professional standards require an annual complete calibration
A constancy check of radiation beams should be performed at least:
- daily
- weekly
- monthly
- annually
-daily
Most federal and professional standards require at least a weekly check of output constancy. Some institutions perform it daily.
The medical dosimetrist is a member of the radiation oncology team who:
- has knowledge of characteristics and clinical relevance of treatment machines and equipment
- is cognizant of procedures used in brachytherapy
- has education and expertise necessary to generate radiation dose distributions and calculations in collaboration with medical physicist and radiation oncologist
- all of the answers are correct
-all of the answers are correct
What is the approximate density of healthy lung tissue?
- 0.30 g/cc
- 0.95 g/cc
- 1.00 g/cc
- 1.03 g/cc
- 1.65 g/cc
-0.30 g/cc
The approximate density of compact bone is:
- 0.30 g/cc
- 0.95 g/cc
- 1.00 g/cc
- 1.03 g/cc
- 1.65 g/cc
-1.65 g/cc
Why is it preferred to use a small focal spot size, if possible when filming in the simulator for planning purposes?
-there will be less penumbra and better detail
-there will be less penumbra, but also less detail
-there will be better detail, but more penumbra
there will be less stress on the x-ray tube
-there will be less penumbra and better detail
In order to calculate a magnification factor, one would:
- Divide SID by OID (or FFD/OFD)
- subtract OID from SID
- divide the object size by the image size
- divide SID by SOD (FFD/FOD)
- divide SID by SOD (FFD/FOD)
The process of leveling and windowing of CT images determines the:
- spatial resolution
- contrast
- pixel size
- matrix size
-contrast
FOV refers to:
- focal object vector: the angle of the projection
- fixed or variable-the choice of window
- fine optic voxel-the best detail available
- field of view-the diameter of the image
-field of view-the diameter of the image
Which of these tissues would have the highest CT number?
- fat
- muscle
- brain tissue
- cerebrospinal fluid
-muscle
Voxel size depends on:
- field of view
- matrix size
- slice thickness
- all are correct
-all are correct
A simulation is performed on a linear accelerator at 100 cm SAD and a field size of 12 x 15 cm. The treatment is delivered on a Co-60 treatment unit at 80 cm SAD. What is the field size at the isocenter?
- 9.6 x 12.0 cm
- 10.0 x 12.5 cm
- 12.0 x 15.0 cm
- 15.0 x 18.8 cm
- 18.8 x 23.4 cm
-12.0 x 15.0 cm
field size at iso = field size at 100 cm SAD
A simulator film is taken at 130 cm SFD for making blocks to be used on a 100 cm SAD linear accelerator and an STD (source-tray-distance) of 65 cm. The treatment is rescheduled on an 80 cm SAD linear accelerator with an STD of 52cm. The SFD on the cutting apparatus must be set to:
- 100.0 cm
- 104.0 cm
- 110.0 cm
- 125.0 cm
- 162.5 cm
-104.0 cm
52 cm STD/ 65 cm STD = 0.8
0.8 x 130 cm SFD = 104 cm SFD
80 cm SAD/ 100 cm SAD = 0.8
0.8 x 130 cm SFD = 104 cm SFD
An object on a radiograph measures 12 cm. The SOD distance is 90 cm and the SFD is 110 cm. The actual size of the object is:
- 9.8 cm
- 10.8 cm
- 12.0 cm
- 12.8 cm
- 13.2 cm
-9.8 cm
90 / 110 = 0.81818 x 12 = 9.8
Vaginal brachytherapy (VBT) can be used to treat the vaginal cuff following surgery for endometrial cancer.
- True
- False
-True
Which of the following is an example of an orthogonal pair?
- 0 and 180 degrees
- 20 and 70 degrees
- 40 and 115 degrees
- 85 and 355 degrees
- 90 and 270 degrees
-85 and 355 degrees
What is the approximate density of muscle?
- 0.65 g/cc
- 0.95 g/cc
- 1.00 g/cc
- 1.03 g/cc
- 1.65 g/cc
-1.03 g/cc
The reference or “zero” CT number on the Hounsfield scale is for:
- air
- soft tissue
- water
- solid bone
-water
In situ cancers are cancers that have not penetrated the lining or basement membrane of the surface where they began.
- True
- False
-True
Which of the following CT parameters is NOT ideal for radiation therapy treatment planning?
- large gantry aperture
- small scan field of view
- alignment lasers
- flat couch top with provision for attaching immobilization devices
-small scan field of view
Digitally reconstructed radiographs (DRRs) are generated from:
- The simulator’s fluoroscopy images
- Ultrasound images
- x-ray images
- CT images
-CT images
CT slices are acquired in:
- the coronal plane
- the transverse plane
- The sagittal plane
- all planes
-the transverse plane
Radiation damage to the fetus resulting in severe birth defects would most often occur when radiation was delivered at which time post-fertilization?
- 0 - 2 weeks
- 3 - 12 weeks
- 13 - 24 weeks
- 23 - 32 weeks
- 33 - 40 weeks
-3 - 12 weeks
Exposure is defined for ionization produced in:
- water
- tissue
- air
- fat
-air