Lecture 1

• Scientific notation is used for describing very large and very small numbers in mathematical operations without introducing large quantities of zeros.
• Visible light is more harmful than microwave due to its high energy levels.
• Visible light is more harmful than microwave.
• Scientific notation can also be used to describe very large numbers, such as 12340000.0 = ?.
• Reciprocal values describe quantities that are inversely related: as x increases then y decreases.
• An inverse relationship plays an important role in radiology between distance d and radiation intensity I so that: Radiation Intensity is inversely proportion to Reciprocal values are frequently used for describing measurements.
• On the 8th of November 1895 a German physicist named “Wilhelm Röntgen” was experimenting high voltages using a Crookes tube.
• A Crookes tube is an evacuated tube with electrodes inserted.
• Electrons (cathode rays) travel in straight lines from the cathode, and the anode is the electrode at which electrons leave the cell.
• Within a year of their discovery, X-rays were being used for medical imaging.
• Radiation is the emission of energy in the form of waves or particles through space or through a material medium.
• Wilhelm Röntgen named the radiation X-rays, symbolizing their unknown origin.
• The wavelength of a wave is the distance between two crests, and is measured in length units, such as nanometers, centimeters, or meters.
• Radiation may be classified as electromagnetic or particulate, including visible light, infrared, ultraviolet, X rays and gamma rays, and electrons, positrons, protons and neutrons respectively.
• Ionizing radiation, which is more of a health threat to humans because it involves changing the basic makeup of atoms in cells, and more specifically the DNA molecules inside of cells, does, of course, take a very strong dose of radiation to damage a cell’s structure.
• The amplitude of a wave is the intensity of the wave.
• The discovery of X-Ray was made by Wilhelm Röntgen who observed that invisible radiation was being produced that penetrated the soft tissue of his hand revealing skeletal structure.
• Frequency is the number of crests that pass a given point within one second, and one wave—or cycle—per second is called a Hertz.
• The speed of a wave is equal to the product of the frequency and the wavelength.
• In 1901, Wilhelm Röntgen received the first Nobel Prize for physics.