Nuclear Medicine Prelim PDF

NUCLEAR MEDICINE PRELIM TYPES OF RADIATIONS detected by using sophisticated imaging devices, whereas simpler detection devices are used to ALPHA RADIATION...

NUCLEAR MEDICINE PRELIM TYPES OF RADIATIONS detected by using sophisticated imaging devices, whereas simpler detection devices are used to ALPHA RADIATION quantify activity for the following applications:  Alpha particles or double ionized helium nuclei are SCINTILLATION-BASED METHODS OF DETECTING the fast-moving helium atoms. RADIATION.  They have high energy ranging in MeV.  They have low penetration depth; typically a few  A scintillator-based detector, also known as a cms of air or skin due to their large mass. scintillation counter, is a device that measures  Alpha particles cannot penetrate intact skin. ionizing radiation by detecting light pulses.  It's made up of a scintillator and a photodetector, which converts the light into an electrical signal. BETA RADIATION  Measuring doses of radiopharmaceuticals,  They are fast-moving electrons. performing radiotracer bioassays, and monitoring  Their energy ranges from hundreds of KeV to and controlling radiation risk in the clinical several MeV. environment.  They have better penetration depth due to their The ionization detector: comparatively lighter mass. Typically, several feet of air, several millimeters of lighter materials. 1. Geiger-Muller detector,  Beta particles can partially penetrate skin, causing 2. Extremity and area monitor "beta burns" 3. Dose calibrator 4. Well counter 5. Thyroid uptake probe GAMMA RADIATION 6. Anger Scintillation camera  They are the stream of photons. 7. Positron emission tomographic scanner  Typical energy ranges from Several KeV to Several 8. Solid-state personnel dosimeter, and MeV. 9. Intraoperative probe are examples of detectors  They have comparatively very low mass. used in clinical nuclear medicine practice.  Thus, possess good penetration depth. Typically, a TYPES OF DETECTORS OF IONIZING RADIATION few inches of lead  Gamma rays are a form of electromagnetic As a result, there are four (4) basic types of Gaseous radiation. ionization detectors, which are categorized according to the  They are the similar to X-rays, distinguished only voltage applied to the detector: by the fact that they are emitted from an excited nucleus.  Ionization chambers  Used as tracers in medicine.  Proportional counters  Radio Therapy- In oncology, to kill cancerous  Geiger-Miller tubes cells.  Scintillation RADIATION DETECTION RADIATION DETECTOR INSTRUMENTS  Radiation detection and monitoring systems are GASEOUS IONIZATION DETECTORS essential for the detection and monitoring of  Are radiation detection instruments used in ionizing radiation (alpha particles, beta particles, radiation protection applications to measure gamma rays, and X-rays) and neutrons. ionizing radiation and particle physics to detect the  These systems are typically based on either direct presence of ionizing particles. or indirect (scintillation-based) methods of  These detectors are designed to measure the detecting radiation. ionization produced when an incident particle  Single-photon-emitting or positron-emitting traverses some medium and are based on radionuclides employed in nuclear medicine are radiation's ionizing effect.  NUCLEAR MEDICINE PRELIM  For ionizing radiation to occur, the kinetic energy visible or near-visible light photons) by the of particles of ionizing radiation is must be absorbed photons or particles. sufficient.  They are widely used as detectors in medical  The ionization chamber is the simplest type of gas- diagnostics, high energy physics and geophysical filled radiation detector, and is widely used for the exploration detection and measurement of certain types of  To Measure Radioactivity ionizing radiation, including X-rays, gamma rays,  Since the early days of radiation testing by and beta particles. Roentgen and Becquerel, scientists have sought  Ionization chamber, radiation detector used for ways to measure and observe other radiation given determining the intensity of a beam of radiation or off by the materials they worked with for counting individual charged particles.  One of the earliest means of capturing any sort of  Gas used in ionization chamber are Nitrogen (N7) data from , radioactivity was a photographic plate. and Argon (Ar18)  A photographic plate would be placed in the path/vicinity of a radioactive beam or material. THE PROPORTIONAL COUNTER  When the plate was developed, it would have spots  Is a type of gaseous ionization detector device used or be fogged from the exposure to the radiation. to measure particles of ionizing radiation.  Henri Becquerel used a method similar to this to  It has the ability to measure the energy of incident demonstrate the existence of radiation in 1896. radiation, by producing a detector output pulse that is proportional to the radiation energy absorbed by the detector due to an ionizing event.  Another common early detector was the  It is widely used where energy levels of incident electroscope. These Roused a pair of gold leaves radiation must be known, such as in the that would become charged by the ionization discrimination between alpha and beta particles, or caused by radiation and repel each other. accurate measurement of X-ray radiation dose.  Radiation protection is similar to radiation  Argon gas material measurement applications in the sense that it is usually in a setting where radiation is expected to GEIGER COUNTER (GEIGER- MULLER COUNTER) be found.  Is an electronic instrument used for detecting and  The goal is to monitor the radioactivity itself, to be measuring ionizing radiation. It is widely used Rein aware of fluctuations, boundaries, etc. With applications such as radiation dosimetry, radiation protection, the goal is monitoring people. radiological protection, experimental physics, and the nuclear industry.  One of the world's best-known radiation detection RADIATION MEASUREMENT instruments.  Relatively low cost. Here are several common ways in which radiation levels can  Filled with an inert gas such as helium, neon, or be measured and different units of measure apply argon at low pressure, to which a high voltage is depending on the instrument and what is being measured. applied. A few of the more common measurements for radiation include:  The specific energy levels of the radiation (in kV or SCINTILLATION DETECTORS mV)  The counts per unit time (minutes or seconds)  Scintillation detectors are used for the  The biological risk of exposure to radiation is determination of the high-energy part of the X-ray measured in rem or sievert (Sv) spectrum.  100 rem is = 1 Sv  In scintillation detectors the material of the detector is excited to luminescence (emission of THE IMPORTANCE OF RADIATION MEASUREMENT  NUCLEAR MEDICINE PRELIM  Radiation measurements are important because  Radiation detectors use gases to measure the they help ensure safety and protect people from ionization produced by radiation. radiation exposure.  When a particle with enough energy passes  They also provide crucial information for medical through the gas, it ionizes the gas atoms or professionals and authorities molecules.  This produces electrons and ions that create a current flow that can be measured. WHY ARE RADIATION MEASUREMENTS IMPORTANT  Safety Radiation measurements help determine if GASES USED IN DETECTORS safety actions are needed  Health Radiation measurements help protect  Argon and Helium, although Used to detect alpha, people from radiation exposure and can help beta, and gamma radiation identify health risks.  Boron-trifluoride (BFs) is utilized when the  Medical imaging Radiation measurements help detector is to be used to measure neutrons. ensure that radiation is used safely and effectively o Colorless, toxic, corrosive gas with a in medical imaging. pungent odor. It's used as a catalyst in  Quality control Radiation measurements help organic reactions and in the ensure that radiation measurement systems are semiconductor industry. working properly.  Methane: Used as a quenching gas to stop a Geiger-Müller discharge.  Greenhouse gas that contributes to climate WHAT DO RADIATION MEASUREMENTS MEASURE? change.  Dose rate: The amount of radiation coming from  It's the second most abundant greenhouse gas a source over a period of time after carbon dioxide  Dose: The amount of radiation absorbed by matter, such as the body  Activity: The amount of radioactivity in a  Gases are important in nuclear detectors because substance, such as water, soil, or air they react with radiation to produce an electronic  The measurements are taken by trained personnel. charge that can be measured.  This charge is produced when charged particles ionize the gas in the detector. IMPORTANCE OF RADIATION DETECTOR  Gas detectors protect employees by warning them of gas leaks, allowing them to take necessary  awareness of the levels of radiation precautions or evacuate the area promptly.  use of radiation detectors  Prevent Accidents: Gas leaks can lead to  presence of radioactive materials catastrophic accidents, explosions, and fires.  maximizing the benefits of operating that detector.  When the gas in the detector comes in contact with INERT GAS radiation, it reacts, with the gas becoming ionized and the resulting electronic charge being measured  An inert gas is a gas that does not readily undergo by a meter. chemical reactions with other chemical substances  Gas detectors can be used to detect combustible, and therefore does not readily form chemical flammable and toxic gases, and oxygen depletion. compounds.  The benefit of a gas detection system is that it will  The noble gases often do not react with many provide you with 24/7 monitoring, and you can substances and were historically referred to as the watch all areas. inert gases.  Inert gases are used generally to avoid unwanted chemical reactions degrading a sample. These DIFFERENT GASSES USED IN RADIATION DETECTOR undesirable chemical reactions are often oxidation  NUCLEAR MEDICINE PRELIM and hydrolysis reactions with the oxygen and USE OF INERT GASES IN NUCLEAR MEDICINE moisture in air.  Inert gases (eg,133Xe) in nuclear medicine should XENON GAS (XE) be used in such a manner that no individual, other than the patient, is likely to receive a submersion  Xenon is a medical gas capable of establishing dose greater than 2500 mrem over the course of neuroprotection, inducing anesthesia as well as one year. serving in modern laser technology and nuclear  Inert gases shall be used in such a manner that the medicine as a contrast agent. instantaneous levels of airborne radioactivity shall  In spite of its high cost, its lack of side effects, safe not exceed 5 times the inhalation derived air cardiovascular and organo protective profile and concentration. effective neuroprotective role after hypoxic-  The room where the inert radioactive gas is used ischemic injury (HI) favor its applications in clinics. must be under negative pressure.  Symbol of Xe/atomic number of 54 THE MACHINE MUST FEATURE: HELIUM (HE)  A rebreathing system.  Helium is used to cool thermographic cameras and  A charcoal filtered exhaust trap which will trap or equipment used by search and rescue teams and hold most of the radioactive gases such that medical personnel to detect and monitor certain airborne radioactivity levels are not likely to exceed physiological processes. Various industries use one DAC fraction at 1 meter from the machine's helium to detect gas leaks in their products. Helium exhaust. is a safe tracer gas because it is inert.  A radiation monitor or other alarm system which  Helium is a gas used for medical conditions where indicates that the trap has failed or reached its there is a need for increased oxygen intake, such as maximum loading. upper airway obstruction in asthma and COPD.  Helium is a second most abundant chemical element in the universe with symbol He and atomic number 2.  A chemical element that is the second most abundant element in the universe, after hydrogen. It is a colorless, odorless, and non-toxic gas that is the first noble gas in the periodic table. NEON (NE)  Neon is the second noble gas in the periodic table.  It has an atomic number of 10.  It is a rare gas.  It is non-toxic and chemically inert.  It is less expensive than helium as a refrigerant.  It is used in neon lamps and vacuum discharge tubes. ARGON (AR)  A colorless, odorless, and inert noble gas. It's the third most abundant gas in Earth's atmosphere, Argon is used in many industries, including welding, heat treating, and metal production.  Atomic number: 18