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Dosi Mock Exam Q's > Mock Exam 2 > Flashcards

Mock Exam 2 Flashcards

1
Q

A patient receiving treatment to the head and neck region has experienced a skin reaction and mucositis at a total dose much lower than anticipated. The radiation oncologist requests an evaluation of the treatment. Which of the following steps should be taken?

  • recalculate the treatment plan
  • ensure that the depth dose, build-up region, wedge parameters, and other pertinent information for the treatment unit are correct
  • review the treatment setup with the therapist
  • recalculate the monitor unit settings
  • all are correct
A
  • all are correct
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2
Q

For megavoltage dosimetry, TLD can provide accuracy of:

  • plus/minus 20%
  • plus/minus 10%
  • plus/minus 3%
  • plus/minus 1%
A
  • plus/minus 3%
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3
Q

With megavoltage film dosimetry, isodose curves can be measured to within:

  • plus/minus 10%
  • plus/minus 7%
  • plus/minus 3%
  • plus/minus 1%
A
  • plus/minus 3%
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4
Q

In megavoltage therapy, typical use(s) of diodes is for:

  • patient dosimetry
  • beam scanning
  • quality assurance
  • all of the answers are correct
A
  • all of the answers are correct
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5
Q

Which of the following is best suited for calibration of a megavoltage beam:

  • diode detector
  • thermoluminescence dosimetry
  • film
  • ionization chamber
A
  • ionization chamber
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6
Q

The f-factor:

  • is the roentgen to cGy conversion factor
  • is greatest for high Z materials and low energy photons
  • is 0.873 in air
  • all of the answers are correct
  • none of the answers are correct
A
  • all of the answers are correct
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7
Q

Clinical application of MLC include which of the following?

  • shaping of electron fields as a replacement for cerrobend blocks
  • dynamic field shaping as a function of patient respiration
  • field shaping without penumbra
  • modulating beam intensity
A
  • modulating beam intensity
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8
Q

The 104% isodose lines at the four corners of the target shown are due to the:

  • inhomogeneity of the femur
  • scatter from the femur
  • horns of the beams
  • weights of the lateral beams
  • use of a wrong algorithm
A

-horns of the beams

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9
Q

Exposure is:

  • the amount of energy in Joules/kg transferred from a photon beam to a material
  • only defined for photons and charged particles below 3 MeV
  • the charge liberated by photons in a given mass of air
  • the absorbed dose multiplied by the quality factor
  • None of the answers
A

-the charge liberated by photons in a given mass of air

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10
Q

The quantity that an ionization chamber actually measures is:

  • roentgen
  • gray
  • charge
  • kerma
  • voltage
A

-charge

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11
Q

Geiger counters:

  • are sensitive enough to detect individual photons or particles
  • are less sensitive than ionization chambers
  • are used to calibrate linac output
  • operate on the principle of scintillation
A

-are sensitive enough to detect individual photons or particles

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12
Q

Which of the following is an advantage of using an MRI for treatment planning?

  • there is no patient anatomy distortion on the images
  • it is reliable for locating tumors within tissue
  • it always displays an accurate external patient contour
  • the brightness of the image is directly related to tissue density
A

-it is reliable for locating tumors within tissue

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13
Q

Based on clinical experiences with TBI before bone marrow transplantation and hemibody irradiation, the most important dose-limiting tissue is the:

  • lens of the eye
  • spinal cord
  • lung
  • skin
  • liver
A

-lung

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14
Q

Dose volume histograms are useful to:

  • identify the location of the global dose maximum in the volume treated
  • optimize the radiation treatment in a reasonable time
  • display location of uniform dose, low dose or high dose within a structure
  • provide a graphic display of dose to the target
  • all are correct
A

-provide a graphic display of dose to the target

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15
Q

OER for photon or electron therapy is:

  • 1
  • 2.5 to 3
  • 10
  • none of the answers are correct
A
  • 2.5 to 3
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16
Q

Disregarding the effects of tissue inhomogeneity can result in errors in delivered dose that are:

  • inversely dependent on photon energy
  • directly dependent on the dimensions of the inhomogeneity
  • dependent on the depth of the inhomogeneity
  • all are correct
A

-all are correct

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17
Q

In the image below, the label “a” is referencing what structure?

  • left atrium
  • right atrium
  • left ventricle
  • right ventricle
A
  • left ventricle
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18
Q

For an Ir-192 implant, it is found that the sources were 0.5 mg-Ra equivalent instead of 0.5 mCi. The exposure rate constant for Ir-192 is 4.69 R-cm/mCi-hr. What impact does this change have on the dose rate in the patient?

  • increase
  • decrease
  • remain the same
A
  • increase
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19
Q

Treatment planning for pediatric cancer patients assumes increased importance because:

  • many pediatric patients are treated with curative intent
  • children often receive chemotherapy which can interact with the complications of the radiation treatment
  • growth disturbances due to radiation treatment are expected so exposed tissues must be kept to a minimum volume
  • growth disturbances occur as a long term complication at relatively low doses (far below those required for control of many tumors)
  • all are correct
A

-all are correct

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20
Q

A patient is treated to the left chest wall with electron arc therapy. In order to sharpen the distribution at the medial and lateral field borders, the medical dosimetrist should:

  • place the isocenter at the skin surface
  • shape the field with a cerrobend electron insert in the cone
  • choose the highest electron beam energy available
  • use a field size larger than the target defined by the physician
  • shape the field on the skin surface with lead strips
A

-shape the field on the skin surface with lead strips

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21
Q

When an enface electron beam is used for chest wall irradiation, which of the following described the dose at the interface between the chest wall and lung?

  • decreased due to reduced scatter from the lung
  • decreased due to irregular surface contour effects
  • increased due to an increase in the electron fluence
  • increased due to a larger angle of electron scatter
  • unchanged from that in a homogeneous phantom
A

-decreased due to reduced scatter from the lung

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22
Q

A beam degrader/spoiler is used in a photon beam for TBI in order to:

  • decrease beam energy
  • effectively hold lung transmission blocks close to the patient
  • increase the surface dose to the patient
  • decrease background radiation
  • all are correct
A

-increase the surface dose to the patient

23
Q

A diode dosimeter is:

  • an ionization chamber coated with silicon
  • a vacuum tube
  • a solid state detector
  • Baldwin Farmer chamber
A

-a solid state detector

24
Q

Five beam arrangments are shown. Which one would yield the desired plan?

  • arrangement 1
  • arrangement 2
  • arrangement 3
  • arrangement 4
  • arrangement 5
A

-arrangement 3

25
Q

The closest dose limiting critical structure to the pituitary gland is:

  • optic chiasm
  • occipital lobe
  • orbit
  • lens
A

-optic chiasm

26
Q

Which of the following modalities is most often used to treat small cell carcinoma?

  • surgery + radiation
  • radiation + chemotherapy
  • chemotherapy + surgery
  • surgery alone
  • radiation alone
A

-radiation + chemotherapy

27
Q

In High Dose Rate (HDR) brachytherapy, the dose rate at the treatment location is typically:

  • 40 cGy/hr
  • 100 cGy/hr
  • 200 cGy/hr
  • 1000 cGy/hr
  • 100,000 cGy/hr
A
  • 1000 cGy/hr
28
Q

NRC regulations require that LDR brachytherapy calculations are checked for accuracy before:

  • any sources are applied to the patient
  • 10% of the prescribed dose is delivered
  • 50% of the prescribed dose is delivered
  • the sources are removed
A
  • the sources are removed
29
Q

A patient diagnosed with a T1N1M0 breast cancer would be classified as what stage?

  • Stage IIIA
  • Stage IIB
  • Stage IIA
  • Stage I
A
  • Stage IIA
30
Q

For 3D treatment planning of the pancreas, which of the following are dose-limiting structures that should be carefully observed?

  • heart & stomach
  • heart & large intestine
  • stomach & small intestine
  • small intestine & large intestine
A

-stomach & small intestine

31
Q

According to the Law of Bergonie and Tribondeau, ionizing radiation is more effective against cells that are:

  • actively mitotic, differentiated, and have a long mitotic future
  • actively mitotic, differentiated, and have a short mitotic future
  • not actively mitotic, undifferentiated, and have a long mitotic future
  • actively mitotic, undifferentiated, and have a long mitotic future
A

-actively mitotic, undifferentiated, and have a long mitotic future

32
Q

Gross structural changes in chromosomes resulting from radiation damage are referred to as:

  • chromosome stickiness or clumping
  • aberrations, lesions, or anomalies
  • deletions and inversions
  • interphase death or replication failure
A

-aberrations, lesions, or anomalies

33
Q

The radiosensitive phase of cell cycle is:

  • M
  • G1
  • M/G2
  • G2
  • S/G2
A

-M/G2

34
Q

Hypoxic tumors, compared to well oxygenated normal tissues, for photon or electron irradiation:

  • are more radioresistant
  • are more radiosensitive
  • exhibit no change in radiosensitivity
A

-are more radioresistant

35
Q

The shoulder portion of the cell survival curve:

  • indicates no damage to cells due to small radiation doses
  • is the same for all types of radiation
  • is absent for high LET radiation (i.e. alpha particles)
  • references the dose required to reduce the cell population by 63%
  • is defined as the number of critical targets the cell has to cause lethal damage
A
  • is absent for high LET radiation (i.e. alpha particles)
36
Q

According to the AAPM standards (TG40), when performing periodic linear accelerator quality assurance procedures, which of the following is the acceptable tolerance for light/radiation field coincidence?

  • plus/minus 0.5mm
  • plus/minus 1.0mm
  • plus/minus 2.0mm
  • plus/minus 3.0mm
  • plus/minus 4.0mm
A
  • plus/minus 2.0mm
37
Q

The air-kerma strength of a point source of radium having an activity of 1 mg at a distance of 1 cm is:

  • 8.25 cGy cm-squared/hr
  • 8.25 R. cm-squared/hr
  • 7.23 cGy cm-squared/hr
  • 6.5 cGy cm-squared/hr
  • 6.5 R. cm-squared/hr
A
  • 7.23 cGy cm-squared/hr
38
Q

Match the half-lives and the corresponding radioisotopes:

Isotopes = Ra-226, Pd-103, I-125, Au-198, Ir-192

1622 years
2.7 days
60 days
74 days
17 days
A 
1622 years = Ra-226
2.7 days = Au-198
60 days = I-125
74 days = Ir-192
17 days = Pd-103
39
Q

A remote after-loading device is useful in brachytherapy treatments because of the:

  • long half-life of the radioisotope used
  • advantages in reducing the radiation exposure to personnel involved in treatment
  • high energy of the gamma rays from the after-loading unit
  • improved cure rate
  • reduction in patient discomfort
A
  • advantages in reducing the radiation exposure to personnel involved in treatment
40
Q

The half-life of I-125 is 60 days. In 6 months the activity of a source will be ______ of original.

  • 70%
  • 50%
  • 1/8
  • 5%
  • 1/64
A
  • 1/8
41
Q

A Pd-103 seed with an activity of 1.4 mCi and exposure rate constant of 1.48 Rcm2/mCi.hr will have the following exposure rate at 1 meter?

  • 20.7 R/hr
  • 0.207 R/hr
  • 0.207 mR/hr
  • 2.07 mR/hr
  • 20.7 mR/hr
A
  • 0.207 mR/hr

0. 148 / 1.4 mCi

42
Q

When treating the cervix using brachytherapy, which of the following is true regarding point A?

  • 3 cm superior to the external cervical os in the plane of the tandem
  • 5 cm lateral to the cervical canal, measured perpendicular to the tandem
  • the point in which recieves 50% of the prescription dose
  • the point of intersection of the uterine artery and the ureter in the paracervical triangle
A
  • the point of intersection of the uterine artery and the ureter in the paracervical triangle
43
Q

MRI/CT fusion is optimal in 3D treatment planning for brain tumors.

  • True
  • False
A

-True

44
Q

All of the following QA tests are required to be performed on the day of an HDR implant EXCEPT:

  • verify source activity used in planning
  • complete source calibration
  • verify correct date and time on the computer
  • ensure door interlocks are functioning
A

-complete source calibration

45
Q

The three planes in a patient are across the body, along the body in a lateral view, and along the body in an anterior view. (Think of the three views on a planning computer) Respectively, they are referred to as:

  • axial, coronal, and sagittal
  • coronal, axial, and sagittal
  • axial, sagittal, and coronal
  • sagittal, axial, and coronal
A

-axial, sagittal, and coronal

46
Q

According to recent AAPM recommendations, a brachytherapy source must be specified in terms of:

  • mg-Ra-equivalent
  • effective activity
  • Air Kerma Strength (AKS)
  • Reference Air Kerma Rate (RAKR)
A

-Air Kerma Strength (AKS)

47
Q

Radiation protectors:

  • increase the radioresistance of cells to radiation
  • protect (increase the radioresistance of) only the normal tissues
  • move the NTCP (normal tissue complication probability) vs. dose curve to the left
  • are very simple elements such as Ag or Na
A

-increase the radioresistance of cells to radiation

48
Q

The approximate length of the rectum is ____cm.

  • 7
  • 11
  • 15
  • 22
A
  • 15
49
Q

The Quimby system specifies dose as:

  • the maximum dose in the plane of treatment
  • the minimum dose 2cm from the implant
  • the average dose at the surface of the implant
  • the uniform prescribed dose throughout the volume
A
  • the maximum dose in the plane of treatment
50
Q

How long does a temporary Ir-192 implant need to be left in place to deliver 3000cGy? The initial dose rate is 0.5 Gy/hr.

  • 25 hours
  • 1 day
  • 4 days
  • 2.5 days
A
  • 2.5 days
51
Q

What is the dose for a permanent implant using Pd-103? The initial dose rate is 4Gy/day.

  • 125 Gy
  • 98 Gy
  • 68 Gy
  • 200 Gy
A
  • 98 Gy

4 x 1.44 x 17

52
Q

With modern afterloading equipment:

  • the point A dose must be obtained from standard Manchester tables
  • the treatment time can be reduced by increasing source activity
  • time, distance, and shielding safety measures no longer apply
  • the dose distribution can be customized
A
  • the dose distribution can be customized
53
Q

Why is MRI NOT considered “radiographic imaging?”

  • it uses digital technology
  • it does not produce films
  • electromagnetic radiation is not produced in the imaging process
  • it does not use radiation capable of ionization
A
  • it does not use radiation capable of ionization

Dosi Mock Exam Q's (2 decks)

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