Lecture 7.pdf

Medical Chemistry Almaaqal University Collage of Dentistry Radiochemistry Dr/ Wael Sobhy Darwish Lec-7 1ST stage&2024  What is Radiation?...

Medical Chemistry Almaaqal University Collage of Dentistry Radiochemistry Dr/ Wael Sobhy Darwish Lec-7 1ST stage&2024  What is Radiation? Radiation is invisible energy waves or particles. It can come from unstable atoms that undergo radioactive decay, or it can be produced by machines. What is Radioactivity? The radioactivity is the property of some atoms to spontaneously give off energy by isotope Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons. Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles (ionizing radiation).  Non-Ionizing and Ionizing Radiation Non-ionizing radiation has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons from atoms. Examples: radio waves, visible light and microwaves. Ionizing radiation has so much energy it can knock electrons out of atoms, a process known as ionization. Ionizing radiation can affect the atoms in living things, so it poses a health risk by damaging tissue and DNA in genes. Ionizing radiation comes from x-ray machines, cosmic particles from outer space and radioactive elements. Radioactive elements emit ionizing radiation as their atoms undergo radioactive decay.  Types of Ionizing Radiation 1- α (alpha) radiation- The emission of an alpha particle (which contains 2protons and 2 neutrons) from an atomic nucleus. When this occurs, the atom’s atomic mass will decrease by 4 units and atomic No will decrease by 2 particles. Alpha particles (α) are positively charged and made up of two protons and two neutrons from the atom’s nucleus. Alpha particles may be written as: Alpha particles come from the decay of the heaviest radioactive elements, such as uranium, radium and polonium. Transfer energy in very short distances (10cm in air).  The health effect from exposure to alpha particles Alpha particles lack the energy to penetrate even the outer layer of skin, so exposure to the outside of the body is not a major concern. Inside the body, however, they can be very harmful. If alpha-emitters are inhaled, swallowed, or get into the body through a cut, the alpha particles can damage sensitive living tissue. The way these large, heavy particles cause damage makes them more dangerous than other types of radiation. The ionizations they cause are very close together - they can release all their energy in a few cells. This results in more severe damage to cells and DNA.  2- Beta particles (β) Beta particles (β) are small, fast-moving particles with a negative electrical charge that are emitted from an atom’s nucleus during radioactive decay. These particles are emitted by certain unstable atoms such as hydrogen-3 (tritium), carbon-14 and strontium-90.  Beta particles are more penetrating than alpha particles, but are less damaging to living tissue and DNA because the ionizations they produce are more widely spaced. They travel farther in air than alpha particles, but can be stopped by a layer of clothing or by a thin layer of a substance such as aluminum. Some beta particles are capable of penetrating the skin and causing damage such as skin burns. However, as with alpha-emitters, beta-emitters are most hazardous when they are inhaled or swallowed. 3- Gamma Rays Gamma rays (γ) are weightless packets of energy called photons. Unlike alpha and beta particles, which have both energy and mass, gamma rays are pure energy. Gamma rays are similar to visible light, but have much higher energy. Gamma rays are often emitted along with alpha or beta particles during radioactive decay.  Gamma rays are a radiation hazard for the entire body. They can easily penetrate barriers that can stop alpha and beta particles, such as skin and clothing. Gamma rays have so much penetrating power that several inches of a dense material like lead, or even a few feet of concrete may be required to stop them. Gamma rays can pass completely through the human body; as they pass through, they can cause ionizations that damage tissue and DNA.  4- X-Rays X-rays are similar to gamma rays in that they are photons of pure energy. X-rays and gamma rays have the same basic properties but come from different parts of the atom. X-rays are emitted from processes outside the nucleus, but gamma rays originate inside the nucleus. They also are generally lower in energy and, therefore less penetrating than gamma rays. X-rays can be produced naturally or by machines using electricity.  Medical uses of Radiochemistry 1. Medical Imaging and Diagnosis: Radioisotopes are used in various medical imaging techniques, such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). These techniques allow for the detection and diagnosis of diseases, including cancer, cardiovascular conditions, and neurological disorders. 2. Radiation Therapy: Radioisotopes and radiation sources are used in radiation therapy for the treatment of cancer. Radioactive substances can be targeted to destroy cancer cells, helping to shrink tumors and improve patient outcomes. 3. Nuclear Medicine: Radioisotopes are used in nuclear medicine procedures for diagnostic and therapeutic purposes. Radioactive tracers are introduced into the body to visualize and evaluate the functioning of organs and tissues.  Potential Negative Effects and Risks Exposure to ionizing radiation emitted by radioactive substances can damage cells and tissues, leading to acute or long-term health effects, including cancer and genetic mutations. Contamination and Environmental Impact: including air, soil, and water. This contamination can persist for extended periods and may pose risks to both human health and ecosystems. Occupational Hazards: Workers involved in radiochemistry research or nuclear facilities may face occupational hazards related to radiation exposure. These risks can be mitigated through strict safety protocols, proper shielding, and adherence to radiation safety guidelines.  Radiotherapy Radiotherapy means the use of radiation, usually x-rays, to treat cancer. You might have radiotherapy from inside the body, called internal radiotherapy. Or external radiotherapy, which is from outside the body. Uses of radiotherapy: To treat cancer Reduce the chance of cancer coming back To help relieve symptoms You might have it by itself or with other treatments, such as chemotherapy or surgery.  How radiotherapy works? Radiotherapy is a type of ionising radiation (high energy) that destroys cancer cells in the treated area by damaging the DNA. Radiation also affects normal cells. This can cause side effects in the treatment area. Usually the side effects improve a few weeks after treatment. But some might continue long term.