Essential Concepts of Radiologic Science and Radiation Biology

Comprehensive practice flashcards covering radiologic physics, x-ray production, tube components, interactions with matter, and radiation biology principles based on the lecture notes.

What is mass?

The quantity of matter contained in any physical object, as described by its energy equivalence.

What is the SI unit for energy?

Joule ($J$).

What is the acceleration of gravity on Earth according to the text?

$9.8\,m/s^2$.

What is the acceleration of gravity on the Moon?

$1.6\,m/s^2$.

What is ionization?

The removal of an orbital electron from an atom with which it interacts.

Which three forms of electromagnetic radiation possess sufficient energy to ionize matter?

X-rays, gamma rays, and ultraviolet light.

What is the average annual radiation dose from natural environmental sources?

$3.0\,mSv/yr$.

What source accounts for the largest component of natural environmental radiation?

Radon.

What is the average annual radiation dose from man-made radiation sources?

$3.2\,mSv/yr$.

On what date were x-rays discovered by Sir Wilhelm Conrad Roentgen?

November 8, 1895.

What fluorescent material coated the plate during Sir Wilhelm Conrad Roentgen's discovery of x-rays?

Barium platinocyanide.

Who was the first recorded x-ray fatality in 1904?

Clarence Dally.

Who introduced collimation and filtration to radiology in the early 20th century?

William Rollins.

Who developed the hot cathode x-ray tube in 1913?

William D. Coolidge.

What equation represents Newton's second law of motion?

$F = ma$.

How is heat transferred through the mechanical motion of hot molecules in a liquid or gas?

Convection.

What is the primary mechanism by which an x-ray tube cools?

Thermal radiation (radiation).

What standard prefix represents the multiple $10^{12}$?

tera- (symbol $T$).

What standard prefix represents the multiple $10^{-6}$?

micro- (symbol $\mu$).

What is the SI unit of radioactivity?

Becquerel ($Bq$).

What customary unit of absorbed dose is multiplied by $0.01$ to obtain gray ($Gy_t$)?

rad.

What is the third commandment of radiation protection according to Box 1-2?

Never stand in the primary beam.

What atomic model was proposed by J.J. Thomson in the late 1890s?

Plum-Pudding model.

What is the mass of an electron in kilograms?

$9.109 \times 10^{-31}\,kg$.

What is the mass of a proton in kilograms?

$1.673 \times 10^{-27}\,kg$.

Who discovered the neutron in 1932?

James Chadwick.

What formula determines the maximum electron capacity of an orbital shell?

$2n^2$, where $n$ is the principal quantum number.

What rule dictates that no outer shell of an atom can contain more than 8 electrons?

Octet Rule.

Which electron shell possesses the highest electron binding energy ($E_b$)?

K shell.

How are isotopes defined in nuclear nomenclature?

Atoms having the same atomic number ($Z$) but different atomic mass numbers ($A$).

How are isobars defined in nuclear nomenclature?

Atoms having the same atomic mass number ($A$) but different atomic numbers ($Z$).

How many half-lives are equivalent to 1 tenth-life?

$3.3$ half-lives.

What percentage of radioactivity remains after 4 half-lives?

$6.25\%$.

What is the composition of an alpha particle?

A helium nucleus consisting of 2 protons and 2 neutrons ($A = 4$).

What process occurs when a positron unites with a free electron, converting their mass into energy?

Annihilation.

What energy is carried by each of the two photons released during positron-electron annihilation?

$0.51\,MeV$ (or $511\,keV$).

What is the primary difference between x-rays and gamma rays?

Their origin (x-rays originate from electron shells, whereas gamma rays originate from the nucleus).

What is the speed of light in a vacuum?

$3 \times 10^8\,m/s$ (or $186,000\,mi/s$).

What unit is used to measure wave frequency?

Hertz ($Hz$).

What is the defining equation for electromagnetic wave velocity ($c$)?

$c = f\lambda$.

What wavelength range corresponds to the visible light spectrum?

$400\,nm$ (violet) to $700\,nm$ (red).

What term describes materials that partially transmit and scatter light?

Translucent.

What term refers to anatomical structures that absorb x-rays?

Radiopaque.

What equation expresses the Inverse Square Law?

$\frac{I_1}{I_2} = \left(\frac{d_2}{d_1}\right)^2$.

What is the value of Planck's constant in electron-volt seconds?

$4.15 \times 10^{-15}\,eV\cdot s$.

How many electric charges equal 1 Coulomb ($C$)?

$6.3 \times 10^{18}$ electric charges.

What electrostatic law states that electrostatic force is directly proportional to the product of charges and inversely proportional to the square of the distance?

Coulomb's Law.

What state of matter exhibits no resistance to electron flow?

Superconductor.

What unit measures electric current?

Ampere ($A$), defined as $1\,C/s$.

What equation represents Ohm's Law?

$V = IR$.

How is total resistance calculated in a series circuit?

$R_T = R_1 + R_2 + R_3 \dots$.

What type of electric current features electrons oscillating back and forth along a conductor?

Alternating Current (AC).

What formula calculates Electric Power ($P$) in Watts?

$P = IV$ (or $P = I^2R$).

What magnetic state of matter includes materials like iron, cobalt, and nickel that can be strongly magnetized?

Ferromagnetic.

What is the SI unit of magnetic field strength?

Tesla ($T$), where $1\,T = 10,000\,\text{Gauss}$.

What law states that the magnitude of an induced current depends on magnetic field strength, velocity, angle, and turn count?

Faraday's Law.

What electromechanical device converts electrical energy into mechanical energy?

Motor.

What equation expresses the Transformer Law for voltage and turn count?

$\frac{V_s}{V_p} = \frac{N_s}{N_p}$.

What are the three principal components of an x-ray imaging system?

X-ray tube, operating console, and high-voltage generator.

What device in the operating console compensates for incoming voltage fluctuations to maintain exactly $220\,V$?

Line compensator.

At what current range does the x-ray tube filament circuit operate?

$3\,A$ to $6\,A$.

What equation defines the effect of the Transformer Law on current?

$\frac{I_s}{I_p} = \frac{N_p}{N_s}$.

What is the minimum exposure time provided by a synchronous timer at $60\,Hz$?

$\frac{1}{60}\,s$ (or $17\,ms$).

What turns ratio is typical for high-voltage step-up transformers in x-ray systems?

$500:1$ to $1000:1$.

What percentage of voltage ripple is associated with single-phase high-voltage power?

$100\%$.

What percentage of voltage ripple is produced by high-frequency generators?

$1\%$.

What is the maximum allowed leakage radiation from a protective x-ray tube housing at a distance of $1\,m$?

Less than $1\,mGy_a/hr$ (or $100\,mR/hr$).

What element is added to the tungsten filament ($1\%$ to $$2\%$) to increase thermionic emission efficiency and prolong tube life?

Thorium.

What is the melting temperature of tungsten?

$3400\,^\circ C$ (or $3410\,^\circ C$).

What term describes the cloud of electrons formed around the heated filament that prevents further electron emission at low $kVp$?

Space Charge Effect.

What percentage of projectile electron kinetic energy is converted into x-ray production at the anode target?

Approximately $1\%$ (with $99\%$ converted to heat).

What design concept maintains a small effective focal spot while spreading heat over a larger actual focal spot?

Line-focus Principle.

According to the Anode Heel Effect, on which side of the x-ray tube is radiation intensity highest?

Cathode side.

What formula calculates Heat Units ($HU$) for a single-phase x-ray unit?

$HU = kVp \times mA \times s$.

What type of radiation is produced when a projectile electron is slowed down by the nuclear field of a target atom?

Bremsstrahlung radiation.

Which characteristic x-rays of tungsten possess sufficient energy to be useful in diagnostic radiologic imaging?

K-characteristic x-rays.

How does doubling the $kVp$ affect x-ray beam quantity?

It increases x-ray quantity by a factor of 4 (proportional to $kVp^2$).

What formula represents the Square Law for maintaining image receptor exposure when changing distance?

$\frac{mAs_1}{mAs_2} = \frac{SID_1^2}{SID_2^2}$.

What is defined as the thickness of absorber material required to reduce x-ray intensity to one-half its original value?

Half-Value Layer (HVL).

How does adding filtration affect x-ray beam quantity and quality?

It decreases quantity and increases quality (beam hardening).

What type of compensating filter is designed specifically for chest radiography?

Bilateral wedge filter (or trough filter).

What interaction occurs when low-energy x-rays (below $10\,keV$) cause target atom excitation without ionization?

Coherent scattering (Classical / Thompson scattering).

What x-ray interaction with matter is depicted in this image?

Compton Scattering.

What x-ray interaction with matter is illustrated in this diagram?

Photoelectric Effect.

How is the probability of the photoelectric effect related to the atomic number ($Z$) of the absorber material?

It is directly proportional to the third power of the atomic number ($Z^3$).

What high-energy interaction between an incident photon and the nuclear field is shown below?

Pair Production.

What minimum incident photon energy is necessary for photodisintegration to occur?

Greater than $10\,MeV$.

What is differential absorption in radiologic imaging?

The difference between x-rays absorbed photoelectrically in patient tissue and those transmitted to the image receptor.

Who described the double-helix molecular structure of DNA in 1953?

Watson and Crick.

What percentage of the body's molecular composition consists of water ($H_2O$)?

$80\%$.

Which purine base in DNA forms a complementary bond exclusively with Thymine?

Adenine.

In RNA molecules, which pyrimidine base replaces Thymine?

Uracil.

During which phase of mitosis are chromosomes aligned along the equatorial plate, making it ideal for cytogenetic analysis?

Metaphase.

During which cell cycle phase are human cells most radioresistant?

Late S Phase.

What macromolecular radiation damage effect is shown in section B of this diagram?

Cross-linking.

What law states that the radiosensitivity of biological tissues depends on their metabolic activity and degree of proliferation?

Law of Bergonie and Tribondeau.

What is the Linear Energy Transfer (LET) value of diagnostic x-rays?

$3\,keV/\mu m$.

What is the mean survival time for Gastrointestinal (GI) Syndrome following acute high-dose radiation exposure?

$4$ to $10$ days.

What radiation dose to the gonads will result in permanent sterility in both males and females?

$5\,Gy_t$ (or $500\,rad$).

What is the threshold dose for radiation-induced skin erythema affecting $50\%$ of exposed individuals ($SED_{50}$)?

$5\,Gy_t$ (or $500\,rad$).