Lecture 2 - Radiation Protection PDF

Lecture 2 Radiation Protection Radiologic Science for Technologists Page 10 to 13, 503 to 505 LEARNING OUTCOME #7- Identify radiation safety practices and apply them in the laboratory and clinical settings. MINISTERIAL COMPETENCIES LINKED TO THIS TOPIC 01X0; E2- Analyser les paramètres...

Lecture 2 Radiation Protection Radiologic Science for Technologists Page 10 to 13, 503 to 505 LEARNING OUTCOME #7- Identify radiation safety practices and apply them in the laboratory and clinical settings. MINISTERIAL COMPETENCIES LINKED TO THIS TOPIC 01X0; E2- Analyser les paramètres ayant une influence sur le niveau d’exposition des personnes. 01X0; E3- Prévenir les risques associés à l’exposition aux radiations ionisantes, au champ magnétique et aux ondes de radiofréquence. 01X0; E5- Reconnaître les principaux organismes régissant la protection. OBJECTIVES: 2.1- Identify the importance of technical parameters and how they relate to radiation protection. (LO7 - 01X0; E2) 2.2- Describe the ALARA/ALADA principles. (LO7 - 01X0; E3) 2.3- Recognize the various ways technologists protect the public and themselves from radiation exposure (LO7 - 01X0; E3) 2.4- Describe the principle of personnel dosimetry, and how to properly utilize a personal dosimeter. (LO7 - 01X0; E3) 2.5- Define the organizations that regulate protection. (LO7 - 01X0; E5)  What is radiation? Radiation is any energy that comes from a source and travels through space, such as light or heat. X-rays are a form of radiant energy, like light or radio waves, but unlike light, X-rays are ionizing radiation that can penetrate the body, which enables X-rays to produce images of internal body structures.  What is radiation? Radiation Oncology (RO) & Nuclear Medicine (NM) are examples where they use radioactive sources that naturally produce radiation - - Anowande opens  & Radiation Protection Why protection against radiation whenever possible is necessary? Harmful biological effects that worsen with the radiation exposure dose Radiation protection can be defined as effective measures employed by radiation workers to safeguard patients, personnel and the general public from unnecessary exposure of ionizing radiation It is the MIT’s responsibility to keep the radiation ALARA to exposure as low as possible · changed ALADA Occupational Exposure is the exposure received by the worker 3 Cardinal Principles of Radiation Protection important  TIME to learn keep to a minimum  DISTANCE move as far away as possible  SHIELDING use protective barriers and clothing  Radiation Protection  TIME Operator-controlled radiation source: o RADIOGRAPHY - - imaging modality that uses x-rays to obtain static images of body structures. o RADIOSCOPY - imaging modality that uses x-rays to allow real-time visualization of body structures. During fluoroscopy, x-ray beams are continually emitted and captured on a screen, producing a real-time, dynamic image. This allows for dynamic assessment of anatomy and function.  Radiation Protection the further the less you exposed are from the you'll source be 16ft. away  DISTANCE good and you'll be Inverse Square Law (ISL): the intensity of radiation passing through any unit area is inversely proportional to the square of the distance from the source The radiation exposure from a point will get smaller the farther away it is If the source is 2x as far away, it's 1/4 as much exposure The MIT or any other HCW may stand a minimum of 6 feet away from the source of radiation to avoid absorbing any scatter radiation  Radiation Protection ↑ SHIELDING PHYSICAL BARRIERS placed between the radiation source and the exposed person windows leaded walls Radiation Protection ↑ SHIELDING Wear apparel made of lead (Pb)  SHIELDING in RO 2 to 3 feet concrete walls are used as shielding in RO due to the use of higher energies of radiation cement does the same as lead walls International Commission on Radiological Protection (ICRP) radiation they use calculate and validate why we ICRP is an independent, international organization ICRP’s Fundamental with more than 200 volunteer members who Principles of represent the world’s leading scientists and policy Radiological Protection makers in the field of radiological protection Founded in 1928 in Ottawa Justification for using radiation is formerly referred to as the Benefits vs. Risks Principle o the BENEFITS gained from radiation exposure must EXCEED the potential RISKS  International Commission on Radiological Protection (ICRP) https://www.icrp.org/ Benefits vs. Risks Principle the benefits of medical radiation exposure (diagnostic or therapeutic) must EXCEED the potential risks! MD acts with prudence when prescribing radiation procedures and treatments ALADA: As low as diagnostically achievable Formerly referred to as the ALARA Principle – all exposure to radiation should be kept As Low As Reasonably Achievable  Radiobiology Science that evaluates the effects of radiation on biological tissues and living organisms RADIATION PHYSICS BIOLOGY X-ray radiation is IONIZING! energy deposit at the atomic level atoms  molecules  cells  tissues  organs  systems  organism Ionizing radiation has enough energy so that during an interaction with an atom, it can remove tightly bound electrons from the atom orbit, causing the X-ray radiation is IONIZING! atom to become charged or ionized Radiosensitive vs. Radioresistant Human Tissues what are Radiosensitive tissues in the adult: they what do they gonads do ? blood forming organs (i.e bone marrow) blood Radioresistant tissues in the adult: bone fat CNS a central nervous system sensitive with & only babies  Radiosensitive vs. Radioresistant Human Tissues Fetuses are more radiosensitive than adults o Unlike that of an adult, the Central Nervous System of a developing fetus is extremely radiosensitive  Benefits Diagnosis (DI & NM) Treatment (RO)  A bad sun burn , we know to the Skin Risks in the Sun with protection aren't certain we definitely get damage & we might get skin cancer but we Deterministic effects (certainty) Stochastic effects (probability) know the meaning and examples Risks  OPTIMIZATION To produce an exam of diagnostic quality using the least radiation dose possible o The ALARA Principle (formerly used): As Low As Reasonably Achievable o The ALADA Principle As Low As Diagnostically Acceptable (recommended)  OPTIMIZATION X-Ray RO NM Using ↑ kVp and↓ mAs Shielding critical organs Decreasing the half life of techniques the radiation source Treating the patient using highly radiation sensitive multiple planes during highly radiation sensitive image receptors (IR) treatment image receptors (IR) Who should be protected??? Radiation Protection Devices Protective structural shielding: o lead o concrete Protective lead clothing: o gonadal & thyroid shields o aprons & gloves o glasses  Radiation Protection Devices Beam limiting devices: o Collimators o Lead strips Beam modifying devices (Filtration): o Filters used to modify the x-ray beam o Filters decrease the radiation dose to the skin of the patient  Other Factors that Contribute to Dose Reduction  Proper selection of technical factors: – ↑ kVp and ↓ mAs combination – ↑ distance – ↓ exposure time  High performing devices: – highly sensitive IR – effective processing techniques  Other Factors that Contribute to Dose Reduction Use of immobilization devices prevents repeats Sandbags octostop Tape Straps RADIATION EXPOSURE LIMITS  RADIATION EXPOSURE LIMITS Dose Limits (DL) o RADIATION WORKERS o GENERAL PUBLIC Diagnostic Reference Levels (DRL) o DOSE LIMITS ON PATIENTS RECEIVING MEDICAL EXPOSURES  Annual Dose Limits (DL) Applicable Members Radiation Body organ or of the Workers Public tissue (mSv) (mSv) Whole Body 20 1 Lens of the eye 20 15 Skin 500 50 Hands 500 50 All other organs 500 50 BASED ON THE ICRP RECOMMENDATIONS  Personnel Dosimetry Optically Stimulated Luminescent (OSL) Dosimeter: o Uses ALUMINUM OXIDE COVERED WITH CARBON (Al2O3 :C) as the radiation detector & o When Al2O3:C is irradiated some electrons are excited and remain in an excited state o During the reading of the detector, a laser light stimulates these electrons, causing them to return to their ground state with the emission of visible light. o The intensity of the visible light emission is proportional to the radiation dose received by the Al2O3  Personnel Dosimetry Thermoluminescent dosimeter (TLD): Following exposure to radiation, the TLD lithium fluoride crystal is thermally stimulated and as a result emission of light occurs in proportion to the radiation absorbed  Personnel Dosimetry Important Facts About the OSL Dosimeter o When should an OSL dosimeter be worn? at all times when in a radiation environment; includes Hospital and DI Lab (4A.11) o Where should it be worn?  between the shoulders & waist  on anterior aspect of body, over clothing  under a protective apron o Where should it be stored? on the dosimeter rack in the DI Lab (4A.11)  Personnel Dosimetry OSL Advantages With a minimum reportable dose, the OSL is more sensitive than TLD With a minimum reportable dose, the OSL is more accurate than TLD Other features of OSL include: o reanalysis for confirmation of dose o qualitative information about exposure conditions o wide dynamic range o excellent long-term stability National Dosimetry Services (NDS) o Sent every 3 months for exposure reports  Radiation Protection Organizations Provincial: o OTIMROEPMQ (Standards of Practice) o Avis de radioprotection o MSSS (Ministère de la Santé et des Services sociaux) o CECR (Centres of Excellence for Commercialization and Research program) Federal: o CAMRT Canadian Association of Medical Radiation Technologists o CCRPB Consumer and Clinical Radiation Protection Bureau o CNSC Canadian Nuclear Safety Commission o SC35 Safety Code 35 Guidelines and Recommendations International o ICRP International Commission on Radiological Protection  The Ten Commandments of Radiation Protection 1. Understand and apply the cardinal principles of radiation control: time, distance, and shielding 2. Do not allow familiarity to result in false security 3. Never stand in the primary beam 4. Always wear protective apparel when not behind a protective barrier 5. In fluoroscopy, always wear an occup. radiation monitor & position it outside the protective apron at the collar 6. Never hold a patient during a radiographic examination, rather, use mechanical restraining devices when possible. Otherwise, have family or friends hold the patient 7. The person who is holding the patient must always wear a protective apron &, if possible, protective gloves & goggles 8. Use gonadal shields on all people of childbearing age or younger when exams in the region between the diaphragms and above the knees are to be done and such use will not interfere with exam 9. Pelvis & lower abdomen exams of pregnant patients should be avoided, if possible, especially during 1st trimester 10. Always collimate to the smallest field size appropriate for the examination  Student Pregnancy Policy It is the responsibility of the student to inform the PC if pregnancy is suspected or confirmed. The student will probably be permitted to continue in the Program during the first 2 years; during the 3rd year, the student may be required to interrupt their clinical training. The student will be issued a second DOSIMETER for closer fetal monitoring.  TERM DESCRIPTION Absorption/Attenuation Reduction in the intensity of the radiation beam as it traverses an object by absorption and/or scattering of the photon Beam Quality Penetrating power of the beam. Central Ray (C.R.) Middle of the useful radiation beam. All rays within the useful beam, except the central ray. The useful beam diverges from a point source (focal spot or Divergent Beam radioactive source). Dose Amount of radiation measured in air (exposure dose), at the skin (skin dose) or in tissues (absorbed dose) Dose-Rate Dose per unit of time (sec./min./hour/week/year). Exposure Intensity or amount of radiation in air. Gamma Rays Monochromatic radiant energy produced from the nucleus of decaying atoms called radioisotopes. ICRP International Commission on Radiological Protection. Intensity Amount of radiation. Kilovoltage peak: maximum voltage applied to the X-ray tube during exposure. Voltage is the electrical force that allows kVp electrical charges to move between electrodes. mA Milli-amperage: amount of electrons flowing between the cathode and the anode of the X-ray tube/sec. mAs Total electrical charges flowing between the cathode and the anode during an X-ray exposure: mA X sec. Biological hazard relating to the nature of one's work. The biological hazard to radiation workers is the increased risk of Occupational Hazard radiation-induced cancer which may cause death. This risk is extremely low when compared to the risk of death related to other professions. Photon Individual X-/gamma ray.  TERM DESCRIPTION Primary Beam Useful beam before it interacts with matter. Properties of They have a very low mass, a charge of –1; they can ionize matter and be deflected by an electrical or magnetic field. Electrons They originate from the nucleus of a radioactive element; they are part of the electromagnetic spectrum, have no mass and Properties of no charge, but can ionize matter; they are monochromatic and highly penetrating; they travel in a straight line and diverge Gamma Rays from the source at a constant speed. They originate from the orbital shell of a high atomic number (Z) element; they are part of the electromagnetic spectrum, Properties of X- have no mass and no charge, but can ionize matter; they are polychromatic and highly penetrating; they travel in a straight Rays line and diverge from the source at a constant speed. They can be produced by an X-ray tube or a linear accelerator. Cardinal Principles:  Time -  Distance -  Shielding; Radiation ICRP’s Fundamental Principles: Justification, Optimization, Limitation; Protection Benefits vs. Risks: the examination or treatment is justified if the benefit gained exceeds the risk of biological damage due to ionizing radiation; ALARA: As Low As Reasonably Achievable; ALADA: As Low As DIAGNOSTICALLY Achievable. Radiation Source Target of the X-ray tube/linear accelerator. Radioactive source for gamma. Radioactivity Spontaneous emission of energy in the form of particles (alpha/beta) and gamma rays from radioisotopes. Scattered Change in the direction of the primary radiation following partial absorption of the photon's energy. Radiation Technical Factors Exposure factors set on the control panel: kVp, mA, sec. & focal spot size. Time Duration of the radiation exposure. Transmission Passage of an x-ray beam through an anatomical part with no interaction with atomic structures.