Physics x-ray

• X-rays are produced by high energy electrons colliding with atoms, causing them to emit X-rays.
• Scientific notation is used for describing very large and very small numbers in mathematical operations without introducing large quantities of zeros.
• The format for scientific notation is 𝑎 × 10 𝑛 where a has the values of 1 to 9 and n can be a positive or negative integer.
• Typical examples of scientific notation include: 123.4 =1.234 × 10 2 and 0.0001234 =1.234 × 10 −4.
• Reciprocal values describe quantities that are inversely related: as x increases then y decreases, i.e 𝑦 = 1 𝑥.
• Reciprocal values are frequently used for describing measurements.
• The early system of measurement used centimeter – gram – second (c.g.s) as the standard but this has been replaced by the meter – kilogram – second – ampere (MKSA) system or the Systeme International d’Unites (SI units) which is now the standard measurement system in physics.
• On the 8th of November 1895 a German physicist named “Wilhelm Röntgen” was experimenting high voltages using a Crookes tube.
• Crookes tube is an evacuated tube with electrodes inserted.
• Electrodes are materials that conduct electricity and enable electrical current to be passed from one point to another.
• There are two kinds of electrodes: Cathode, and Anode.
• More Distance = Less Radiation Exposure
• Doubling distance from source, decreases dose by factor of four
• This is why dentists place a lead blanket on patients receiving x- rays of their teeth
• Insertion of the proper shield between patient and a radiation source greatly reduces or eliminates the dose the patient receives
• Ways to minimize radiation exposure include always collimating to the area of interest, providing a protective apron to the attendant while holding patients, and always operating the equipment from behind the protective barrier or using a lead equivalent apron.
• Shielding Radiation Safety – Operation safety
• Inverse Square Law
• To reduce the Radiation dose to the individual: Reduce the time spent near the X-ray source, increase the distance from the X-ray source, and interpose a shielding material between X-ray source and operator
• The intensity is inversely proportional to the distance from the source
• Inverse Square Law accounts for the fact that the intensity of radiation becomes weaker as it spreads out from the source since the same about of radiation becomes spread over a larger area
• The radiation spreads out as it travels away from the gamma or x-ray source
• Posting and Warning sign Sources and distribution of average radiation exposure to the world’s population
• Barriers of lead, concrete, or very dense material provide protection from penetrating radiation
• The technologist is responsible for protecting the patient, protecting himself, using safe exposure factors, and avoiding repeating exposures.
• The cathode is the electrode at which electrons enter the cell.
• The anode is the electrode at which electrons leave the cell.
• Wilhelm Röntgen discovered that invisible radiation was being produced that penetrated the soft tissue of his hand revealing skeletal structure.
• Wilhelm Röntgen called the radiation X-rays: X denoting their unknown origin.
• Within a year of their discovery X-rays were being used for medical imaging.
• In 1901 Wilhelm Röntgen received the first Nobel Prize for physics.
• Cobalt-60 decays by beta-minus emission, with decay products being Nickel-60 plus an electron and an electron antineutrino.
• An unstable nucleus tries to achieve a balanced state by giving off a neutron or proton, this process is known as radioactive decay.
• The unstable nuclei lie above and below the line of stability, with those above the line containing too many neutrons and referred to as “neutron rich”, and those below the line containing too many protons and referred to as “proton rich”.
• The strength (energy emission) of a radioactive source is called its activity, which is defined as the rate at which the isotope decays.
• Gamma ray is used in radiotherapy, such as gamma knife surgery.
• Neutrons are important for stabilising the nucleus, with the number of neutrons increasing as the atomic number increases.
• Radioactivity is the process by which atoms that are unstable decay and eventually become stable through the emission of particles or electromagnetic radiation or both.
• A stable atom has a net charge of 0, with an equal number of protons and neutrons.
• Most of the stable nuclei have neutrons more than protons, with only 1 H and 3 He having neutrons less than protons but are stable.