Radiation physics and radiobiology

• All of the following radiation exposure responses exhibit a nonlinear threshold dose-response relationship except:

  1. skin erythema

  2. hematologic depression

  3. radiation lethality

  4. leukemia

  leukemia (this a linear-dose response)
• Which has no threshold, linear dose response or nonlinear dose response curve?

  linear dose response
• Which has a threshold, linear does response or nonlinear dose response curve?

  nonlinear dose response curve
• Nonlinear dose response curve, has somatic effects of what?

  skin erythema, epilation, hematologic depression, and radiation lethality (death).
• Late or long term effects of radiation exposure are generally represented by which of the following dose-response?

  linear non threshold

  
  

  (most late effects do not have a threshold)
• Which of the following expresses the gonadal dose that, if received by every member of the population, would be expected to produce the same total genetic effect on that population as the actual doses received by each of the individuals?

  genetically significant dose
• Muscle tissue absorbs more radiation than fat tissue because muscle tissue has which of the following?

  1. vastly higher average atomic number

  2. vastly lower average atomic number

  3. higher tissue density (mass/volume)

  4. lower tissue density (mass/volume)

  higher tissue density (mass/volume)
• Which type of dose response relationship represents radiation induced leukemia and genetic effects ?

  1. linear, threshold

  2. nonlinear, threshold

  3. linear, non threshold

  4. nonlinear, nonthreshold

  linear, non threshold
• Biologic material is least sensitive to irradiation under which of the following conditions?

  1. anoxic

  2. hypoxic

  3. oxygenated

  4. hyperbaric

  Anoxic

  
  

  (this refers to tissue without oxygen. This answer is correct because tissue is most sensitive when it is oxygenated and least when it lacking oxygen.)
• The dose-response curve that appears to be valid for genetic and some somatic effects is the

  1. linear

  2. nonlinear

  3. nonthreshold

  1 and 3 only
• Select the factors that lead to the production of a high-energy bremsstrahlung (brems) x-ray when a filament (projectile) electron interacts with an anode tungsten atom (select the four that apply)

  A. The filament electron passes far away from the nucleus of a tungsten atom.

  B. The filament electron travels close to the nucleus of a tungsten atom.

  C. The nuclear electrostatic field creates a strong force of attraction on the passing filament electron.

  D. The nuclear electrostatic field creates a weak force of attraction on the passing filament electron.

  E. The filament electron arrives at the anode with high kinetic energy.

  F. The filament electron arrives at the anode with low kinetic energy.

  G. The atomic number of the tungsten atom is high.

  H. The atomic number of the tungsten atom is low.

  -the filament electron travels close to the nucleus of a tungsten atom

  -the nuclear electrostatic field creates a strong force of attraction on the passing filament electron

  -the filament electron arrives at the anode with high kinetic energy

  -the atomic of the tungsten atom is high
• Which of the following radiographic factors will affect x-ray intensity at the IR?

  1. Kilovoltage-peak (kVp)

  2. Source-image-distance (SID)

  3. Beam filtration

  1,2, and 3
• What does kVp affect/control?

  the quantity(intensity) and energy (quality).
• As SID decreases, x-ray quantity to the IR _____.

  increases
• Beam filtration increases, will ____ the x-ray quantity due to increased absorption of x-ray photons in the beam filter.

  decrease
• The positive electrode of the x-ray tube is the __.

  anode
• The negative electrode of the x-ray tube is the ___.

  cathode
• The dose required to cause erythema in 50% of those exposed is roughly

  5 Gy
• Examples of potential late effects of ionizing radiation on humans can include

  1. leukemia

  2. genetic defects

  3. malignant disease

  1, 2 and 3
• The law of Bergonié and Tribondeau states that cells are more radiosensitive if they are

  1. highly proliferative

  2. highly differentiated

  3. immature

  1 and 3 only
• Superficial reddening of the skin caused by radiation exposure is called:

  erythema

  
  

  ( a single 2Gyt can cause this to the exposure area within 24 to 48 hours)
• Disease caused by measles virus, which is characterized by a red skin rash is called:

  rubeola
• A condition which causes an abnormal increase in the number of circulating red blood cells in the body?

  erthrocytosis
• an abnormal decrease in the number of white blood cells is called:

  leukopenia
• During x-ray production at the target anode, which of the following interactions yields a photon of discrete energy?

  1. compton production

  2. bremsstrahlung production

  3. characteristic production

  4. pair production

  characteristic production
• If an individual receives an exposure of 150 mR/h at a distance of 2 feet from a radiation source, what will be their dose after 30 minutes at a distance of 5 feet from the source?

  12 mR

  
  

  Use inverse square law

  I1/I2= D2^2/D1^2

  150mR/h/x=25/4

  600=25x

  x=24mR in 60 seconds.

  therefore, 12mR in 30minutes
• Damage to the DNA double helix ladder structure, which results in spurs that form unintended bonds that join the macromolecule into irregular loops, is called:

  cross-linking
• What are the three types of DNA macromolecule damages classified as?

  1. single side scissions or point lesions (simplest type)

  2. Main chain or double side rail scission occurs when both sides are broken, resulting a free floating fragment

  3. Cross-links
• What is radiolysis?

  it is the breakdown of water molecules by ionizing radiation
• As a dose of 250 mGy to the fetus during the 4th or 5th week of pregnancy is more likely to cause which of the following:

  1. spontaneous abortion

  2. skeletal abnomalies

  3. neurologic anomalies

  4. organogenesis

  skeletal anomalies
• When does major organogenesis occur in pregnancy?

  the first trimester
• Between which weeks of pregnancy can fetal anomalies occur?

  2 to 8 weeks

  
  

  -During the earlier parts skeletal anomalies occur

  - during the later part neurologic anomalies occur

  -other things that can occur during the first part of the pregnancy is mental retardation/intellectual disability and childhood malignant cancers such as cancers or leukemia
• During which weeks of pregnancy can spontaneous abortion occur?

  the first two weeks
• How many half-value layers will it take to reduce an x-ray beam whose intensity is 78 Gy to an intensity of less than 10 Gy?

  3See an expert-written answer!We have an expert-written solution to this problem!
• What is the HVL?

  -used to express the quality of an x-ray beam

  -particular beam is that thickness of an absorber that will decrease the intensity of the beam to 1/2 its original value.
• Which of the following are considered most radiosensitive?

  1. lymphocytes

  2. ova

  3. neurons

  4. myocytes

  lymphocytes
• What are lymphocytes?

  mature white blood cells
• What is an ova?

  female germ cells
• What are myocytes?

  muscle cells
• What are neurons?

  nerve cells and are radio resistant