[01.36] Radiation Harm & Benefit (TG07-CG15) (V2) - Stephanie Mae Obias.pdf

Radiation Benefit & Harm Module 01: Principles & Perspectives II Jonathan Rogel N. Uichico, MD-MBA, FPCR, FUSP, FCTMRISP | August 24, 2023 II. KINDS OF RADIATION TABLE OF CONTENTS I. RADIATION....................................................................................... 1 A. NON-IONIZING...

Radiation Benefit & Harm Module 01: Principles & Perspectives II Jonathan Rogel N. Uichico, MD-MBA, FPCR, FUSP, FCTMRISP | August 24, 2023 II. KINDS OF RADIATION TABLE OF CONTENTS I. RADIATION....................................................................................... 1 A. NON-IONIZING RADIATION II. KINDS OF RADIATION...................................................................... 1 ● Involves those for everyday use ● Includes visible light, heat, radar, microwaves, and radio waves ● Deposits energy in the materials through which it passes, but it does not have sufficient energy to break molecular bonds or remove electrons from atoms ● It exists everyday but the radiation dose is not enough to cause a molecular change in the cellular composition A. NON-IONIZING RADIATION.......................................................... 1 B. IONIZING RADIATION................................................................... 1 III. QUANTIFYING RADIATION.............................................................. 3 A. TERMS FOR QUANTIFYING RADIATION........................................3 IV. SOURCES OF RADIATION.................................................................4 A. NATURALLY OCCURRING.............................................................. 4 B. RADIATION IN MEDICINE............................................................. 4 V. USES OF RADIATION IN MEDICINE................................................... 4 A. DIAGNOSTIC USES........................................................................4 B. THERAPEUTIC USES......................................................................5 VI. RADIATION EFFECTS....................................................................... 5 A. DETERMINISTIC EFFECTS..............................................................5 B. STOCHASTIC EFFECTS................................................................... 6 VII. UNDERSTANDING RADIATION RISKS............................................. 6 A. RISKS OF RADIATION.................................................................... 6 B. RADIATION INDUCED CANCER RISK............................................. 6 C. LINEAR, NO-THRESHOLD THEORY................................................ 7 VIII. GENERAL PRINCIPLES FOR MINIMIZING RADIATION RISK IN MEDICAL USE...................................................................................... 7 A. WHO ARE AT RISK?.......................................................................7 B. ALARA PRINCIPLE......................................................................... 7 C. RADIATION PROTECTION..............................................................7 QUESTIONS......................................................................................... 7 ANSWER KEY.......................................................................................8 RATIONALE..........................................................................................8 LEARNING OBJECTIVES 1. Know the different types of radiation 2. Be familiar with the terms and units associated with dose and exposure 3. Understand how much radiation medical imaging contributes to total yearly exposure for an individual 4. Know the harmful effects of ionizing radiation 5. Discuss the benefits of radiation in medicine I. RADIATION ● Energy given off by matter in the form of rays or high-speed particles ○ Seen in sunlight, x-rays, altitude ○ Comes in different waveforms and speeds ● Recall: Forces within the atom work toward a strong, stable balance by getting rid of excess atomic energy (radioactivity) ● Unstable nuclei may emit a quantity of energy ○ These quantities are how they measure the radiation given off by the material ● Spontaneous emission = radiation YL6:01.36 Figure 1. Non-ionizing radiation spectrum ● Visible light comes in a wide range ○ From sunlight, ROYGBIV, to UV rays, which are high frequency waveforms that can cause skin cancer when one does not use sunblock or proper skincare ● The longer, slower waveforms are the ones we are usually in contact with ○ E.g., MRI, electricity, AM/FM radios, TV, wireless and cellular signals, satellites, heat lamps (seen in tanning salons) Nice to Know! ● Tanning salons need to control the UV rays/ infrared properly because it can cause cancer in the long-term ● Disease depends on the amount of radiation, length of exposure, and how often the exposure is B. IONIZING RADIATION ● More energetic than non-ionizing radiation ● As it passes through material, it deposits enough energy to break molecular bonds and displace (or remove) electrons from atoms creating ions ● More harmful sources of radiation because of the chemical and cellular response of the body against it, which may or may not be repaired by the immune system ○ With enough radiation dose and exposure, the body will not be able to repair the damage ○ At medically appropriate thresholds, the body will still have the ability to repair any damage TG07: Araneta, Cuanang, Dela Cruz, Gue, Jacob, King, Mercado, Obias, Orlina, Santiago, Yap CG15: Bennett, Bunag, Cabrera, Chan, Kim, Lim, Parfan, Pesalbon, Rosario, Siongco, Usa, Zuñiga 1 ● Beyond the ultraviolet range, the types of radiation have so much energy that they can knock electrons out of atoms (ionization) ● Includes x-rays and gamma rays (01.32, 2026) Figure 4. Beta particle Gamma & X-Ray Radiation Figure 2. Ionizing radiation spectrum PHYSICAL FORMS OF IONIZING RADIATION ● Particle ○ Tiny fast-moving particles that have both energy and mass (weight) ○ Alpha particles, beta particles, neutrons ● Electromagnetic Particles ○ Pure energy with no weight ○ Sunlight (cosmic radiation), x-rays, gamma rays ● The Ozone layer is the defense mechanism against the cosmic rays, UV light, and radioactive particles that hit the earth coming from the sun and other stars ○ Earth's natural sunblock ○ Has been thinned and degraded by pollution ▸ Has improved since the 90s because of envronmental laws Alpha Particles ● Charged particles, which are emitted from naturally occurring materials (e.g., uranium, thorium, and radium) and man-made elements (e.g., plutonium and americium) ● Primarily used in items such as smoke detectors ● Have a very limited ability to penetrate other materials ● Can be blocked by a sheet of paper, skin, or even a few inches of air ● Potentially dangerous if they are inhaled or swallowed ● Consist of high-energy waves that can travel great distances at the speed of light ● Have a great ability to penetrate other materials ○ Important in creating images in X-ray and CT scans ● Gamma rays (such as cobalt-60) are often used in medical applications to treat cancer and sterilize medical instruments ● X-rays are used to provide static images of body parts and are also used in industry to find defects in welds ● Do not have the ability to make anything radioactive; can be blocked by concrete or a few inches of dense material (e.g, lead) Nice to Know! ● X-ray suite wall should be thick and lead-lined ○ Thickness of walls when constructing a suite need to be FDA- and DOH-approved ● Not to expose the physician and technician to radiation ○ Leaving doors open during scans is grounds for an incident report ○ Although gamma and x-ray radiation do not have the ability to make anything radioactive, it is still unnecessary radiation exposure Figure 5. Gamma rays and x-rays Neutrons Figure 3. Alpha particle Beta Particles ● ● ● ● Similar to electrons Emitted from materials naturally occurring Used in medical applications, such as treating eye disease Lighter than alpha particles and have a greater ability to penetrate other materials ● Can travel a few feet in the air, and can penetrate skin but can be stopped by a thin sheet of metal or plastic or a block of wood YL6:01.36 Radiation Harm & Benefit ● High-speed nuclear particles that have an exceptional ability to penetrate other materials ● Only one that can make objects radioactive ● Neutron activation - produces many of the radioactive sources that are used in medical, academic, and industrial applications ○ E.g., Radiation oncology – targeted beams are focused on a particular area of the patient such as a tumor of the liver, aimed at the tumor of the liver, ▸ Although these cause damage to tissues, it can be used as a benefit for cancer treatment ○ Cells and tissues get damaged by radiation ● Can travel great distances in air and require very thick hydrogen-containing materials (such as concrete or water) to block them ○ E.g., Chernobyl disaster had a problem in water cooling system ▸ A temperature threshold was exceeded and the water was unable to contain the radioactive material, creating a nuclear reaction 2 ● Neutron radiation primarily occurs inside a nuclear reactor, where many feet of water provide effective shielding ○ Issues with water cooling and the type of material used to line the reactor are often the causes of nuclear disaster ○ Becquerel (Bq) ▸ After Henri Becquerel EXPOSURE ● Amount of radiation traveling through the air ● Many radiation monitors measure exposure ○ Dosimeter attached to scrubs which the FDA checks to see the amount of exposure at a given time ● Units for exposure are the roentgen (R) and coulomb/kilogram (C/kg) ● Radiologists attach a dosimeter and FDA checks their level ○ Will be given leave if it exceeds Figure 6. Neutron particle Take Note! ● Alpha and beta particles are not included in the exam. Gamma and X-rays are included Refer to Table 1 in Appendix A for summary of ionizing radiation particles Figure 8. Dosimeter ABSORBED DOSE ● Amount of radiation absorbed by an object or person ○ Amount of energy that radioactive sources deposit in materials through which they pass ○ Some radiation deposits as they pass through you, this deposit is the absorbed dose ● Units for absorbed dose are the radiation absorbed dose (rad) and gray (Gy) ○ In practice: values used are miligrays—values in gray are considered high and usually indicate problems DOSE EQUIVALENT Figure 7. Types of radiation and penetration Active Recall Box 1. T/F. We are usually in contact with shorter, slower waveforms on a day-to-day basis. 2. Identification. What type of particle has the ability to make objects radioactive? Answers: 1F, 2 Nuclear Particle III. QUANTIFYING RADIATION A. TERMS FOR QUANTIFYING RADIATION RADIOACTIVITY ● Amount of ionizing radiation released by a material ○ When we talk about radiation we talk about ionizing radiation ● A quantity of radioactive material → radioactivity (or simply its activity); amount of atoms in the material decay in a given time period ● Units of measure for radioactivity: ○ Curie (Ci) ▸ After Marie Curie YL6:01.36 Radiation Harm & Benefit ● Also known as effective dose ● Combines the amount of radiation absorbed and the medical effects of that type of radiation ● Units for dose equivalent are the roentgen equivalent man (rem) and sievert (Sv) ● Biological dose equivalents are commonly measured in 1/1000th of a rem (known as a millirem or mrem) ● Because different tissues and organs have varying sensitivity to radiation exposure, the actual radiation risk to different parts of the body from an x-ray procedure varies ○ The term effective dose is used when referring to the radiation risk averaged over the entire body ● Some systems are more sensitive to radiation compared to others ○ E.g., GI is more sensitive to radiation compared to bones Refer to Table 2 in Appendix B for the comparison of terms used to define radiation and dose TAKE NOTE! ● Roentgen (R), Gray (Gy), Sievert (Sv), and Becquerel are clinically relevant since it is used by radiologists in hospitals. ● A tip to remember Gray is to remember Meredith Grey, wherein during the first few seasons she soaked up all the pain around her. 3 IV. SOURCES OF RADIATION A. NATURALLY OCCURRING ● Elements found in the earth’s crust emit radioactivity (uranium, radium, polonium, thorium and potassium) ○ Can also include cosmic radiation ● Levels of exposure will depend on the make-up of the local soil and rocks ● Radon is the most damaging source of natural radiation ○ Produced by the decay of radium ▸ Radium: an element present in nearly all rocks and soils ● Other sources of radiation: Altitude ○ Pilots would have higher doses of radiation but it is not as risky ● Pilots and Flight attendants are exposed to more radiation compared to other people B. RADIATION IN MEDICINE ● Diagnostic ○ X-rays ○ CT scan ● Therapeutic ○ Radiation therapy ○ Brachytherapy ● Average annual radiation dose that a person experience is 2.8 mSv Figure 9. Source of radiation exposure Active Recall Box 3. T/F. Radiologists use a dosimeter in order to monitor how much exposure they were exposed to 4. It is the amount of radiation absorbed by an object or person A. Dose Equivalent B. Exposure C. Absorbed dose D. Adsorbed dose Answers: 3T, 4C Table 1. Average annual radiation dose sources Source of Radiation Natural sources V. USES OF RADIATION IN MEDICINE Average Annual Dose, mSv Radon 1.2 Gamma rays 0.5 Cosmic 0.4 Internal 0.3 Total of natural sources 2.4 Artificial sources Medical 0.4 Nuclear testing 0.005 Chernobyl 0.002 Nuclear power 0.0002 Total of artificial sources 0.04 All sources 2.8 Note! ● The “Uses of Radiation in Medicine” section was not discussed during the face-to-face class but was included in the PowerPoint slides. A. DIAGNOSTIC USES ● X-Radiation ○ Radiographs ○ Fluoroscopy ○ CT Scan ● Nuclear Medicine ○ Radioactive material injected into the patient ○ Gamma radiation detected - computer analysis - image production ○ Used to locate tumors; determine organ function Refer to Table 4 in Appendix D for the radiation doses of medical imaging procedures and Table 5 in Appendix E for the effective radiation dose in adults (Note: 80% is from natural sources) Nice to Know! Figure 10. Results of the CT scan of the head YL6:01.36 Radiation Harm & Benefit 4 Prodromal Syndrome B. THERAPEUTIC USES ● Radiotherapy ○ Specifically uses radiation to kill cancer cells when trying to cure the cancer ○ Gamma rays; Electron beams; X-radiation ● To be effective, such doses typically require 20-60 Gy (or 20-60 Sv for x-ray equivalent) ○ Brachytherapy ○ Radiation from internally deposited radioactivity VI. RADIATION EFFECTS A. DETERMINISTIC EFFECTS ● Predictable, occurring with dose-dependent severity ● Generally do not occur below a certain threshold value ● Associated with intermediate to high radiation exposure – orders of magnitude above most doses used in diagnostic radiology ○ Not really felt in everyday activity life ● Cataracts ● Skin Changes - erythema, desquamation, epilation ● Sterility ● Note: certain people have higher radiation tolerance than others ● Associated with exposures as low as 100 rads (1 Gy), nearly universal above 2 Gy ● Radiation to the epigastric region most likely to elicit this syndrome ● Has a latent period of 2-6 hours ● Signs and symptoms (Si/Sx) ○ Fatigue ○ Withdrawn and uncooperative ○ Possible headache ○ Could be confused with depression ○ GI symptoms vary with dose (mild nausea to retching/vomiting; diarrhea is an ominous sign of higher dose exposure) ● Recovery after 2-3 days (may be shorter for very mild cases or decreased radiation exposure) ● Epidemiology ○ More common in women than men ○ Age <10 years or >60 years at higher risk Bone Marrow Syndrome ● Associated with exposures of at least 3 Gy (300 rad) ● Mechanism: loss of pluripotent stem cells from hematopoietic tissues ● Si/Sx: pancytopenia, leading to infection and hemorrhage ● Has a latency period 2-4 weeks ● Rx (treatment): Blood products, bone marrow transplant, and antibiotics ● Survival: 50% spontaneous recovery at exposure of 3.5 Gy ○ 180 days required to regain maximum function. ● Few survive doses greater than 6-7 Gy (at doses above 8 Gy, >90% long-term immunosuppression is observed) ○ Death is 1-2 months post-exposure from infection ○ Anemia is not a cause of death Bone Marrow Syndrome: MEMORY ● 3, 3.5, 6-7 GI Syndrome Figure 11. Threshold doses for deterministic effects Figure 11 ● There is a higher dose after the threshold and a steeper line ● Shows how high the dose has to be to give you cataract (measured in milligray) Nice to Know! ● Interventional Radiology: for diagnosing and treating diseases ○ E.g., Transarterial Chemoembolization (TACE) ▸ Cancer treatment that blocks a tumor’s blood supply ● Minimizing radiation effects ○ In fluoroscopic procedures, the lead cap is used to prevent radiation exposure effects such as dry eyes and nausea WHOLE BODY IRRADIATION ● Distinct clinical courses observed after acute, high-dose exposure to radiation ○ Last three are associated with a high degree of lethality YL6:01.36 Radiation Harm & Benefit ● Associated with exposures of at least 7 to 10 Gy (700 to 1000 rad) ● Mechanism: loss of stem cells from intestinal crypts, leading to eventual loss of GI mucosa ● Si/Sx: diarrhea and vomiting leading to profound dehydration ● Has a latency period 3-5 days ● Rx: Fluid resuscitation ○ Ultimately futile ○ Due to radiation’s effects on tissue. ○ The fluid resuscitation will be futile because there is inherent change in the anatomy of the gut ● Survival: none ○ Death in 1-2 weeks post-exposure ○ You die from the changes in the body, not by the short-term effects of radiation ▸ GI system become non-functional Cerebrovascular Syndrome ● Associated with catastrophically high acute exposures (close to 100 Gy) ● Mechanism: severe damage to CNS, cardiovascular, and respiratory systems 5 ● Si/Sx ○ Ataxia ○ Disorientation ○ Hypotension ○ Shock ○ Respiratory distress ● Latency period of minutes to hours ● Rx: Supportive therapy (futile) ● Survival: none ○ Fulminant within one day ○ Lethal within one day ▸ Related to pregnancy (stillbirths, congenital abnormalities, decreased birth weight, infant and childhood mortality) ○ Carcinogenesis ▸ Cancers associated with high-dose exposure (greater than 50,000 MREM, or 500 mSv—500 times the NRC limit to the public) include leukemia, breast, bladder, colon, liver, lung, esophagus, ovarian, multiple myeloma and stomach cancers ⎻ Length, amount, and frequency of exposure is important Take Note! ● The following may be asked in the exams: ○ At 6-7 Gy, what could be the effects on the GI system? ○ What is the threshold dose for cerebrovascular syndrome? ▸ 100 Gy DETERMINIST EFFECTS IN PREGNANCY ● Period of organogenesis (3rd – 8th week): vulnerable window for any type of radiation exposure ● Exposure between the 8th and 15th week can lead to malformations of the forebrain, resulting in mental retardation ● Threshold dose: 100-200 mSv ○ High doses to the embryo or fetus can result in death or gross malformations at 0.1 mSv to 1 mSv ● Fetal radiation exposure can increase the risk of cancer in later childhood ● Pregnant women should avoid all ionizing radiation, if possible, since x-rays to one site on the body provide some scatter dose to the fetus ○ Medical necessity may require x-ray imaging of pregnant women in some circumstances ● Fetal exposure to a dose under 50 mGy (<5 rads) is currently regarded as reasonably safe ○ At a dose of 50 mGy, there is approximately 0.2-0.8% excess risk of inducing cancer during childhood and <1% risk of fetal death Take Note! ● It is important for radiologists to ask if the patient is pregnant and/or when their last menstrual period was because of the determinist effects of radiation on pregnancy ○ If a pregnant woman needs an urgent chest x-ray, it is still possible to order a chest x-ray ▸ The patient can be draped with a lead gown to minimize any risks to the child ● Radiologists must also consider the thyroid ○ Make sure to take a good history and really probe the patient Figure 12. Deterministic and scholastic effect VII. UNDERSTANDING RADIATION RISKS ● Radiation can damage living tissue by changing cellular structure and damaging an organism's DNA ● Depends on: ○ Type and quantity of radiation absorbed ○ Energy (strength of radiation), frequency ● Damage done at the cellular level ○ Minor or even moderate exposure may be difficult to detect → often, successfully repaired by the body ▸ E.g., proper medical procedures, everyday UV ● Some cells are more sensitive than others ○ Good and bad ▸ Bad: Can kill cells outright, as well as damage their DNA ⎻ Kills cells outright: GI tract anomalies that can damage the mucosa and stomach cells ○ Good: opportunities for medical intervention, if cellular death can be precisely targeted (E.g., radiation therapy for cancer) A. RISKS OF RADIATION ● Survivors from the atomic bombs at Hiroshima and Nagasaki in Japan at the end of WW2 ● Radiation from industry workers ● People receiving high doses of medical radiation ● Environmentally exposed groups ○ E.g., those working in the airline industry, radiation technologists B. RADIATION INDUCED CANCER RISK B. STOCHASTIC EFFECTS ● Probability that an effect will occur is related to exposed dose ● Severity of effect is unrelated to exposed dose – i.e., these are “all or nothing” events ○ If you are exposed to a radiation dose, either you get stochastic effect or none ● Two major examples of stochastic radiation risk: ○ Hereditary/Genetic Effects YL6:01.36 Radiation Harm & Benefit ● Data on Japanese atomic bomb survivors: ○ Clear evidence of radiation-induced cancer risk at doses above 100 mSv ○ Of little relevance to medical imaging except in cases of multiple high-dose examinations in a short time period ● More controversial at doses between 10 and 100 mSv, the dose range relevant to medical imaging and in particular CT 6 ● Below 10 mSv, which is a dose range relevant to radiography and some nuclear medicine and CT studies, no direct epidemiological data support increased cancer risk ○ This does not mean that this risk is not present C. LINEAR, NO-THRESHOLD THEORY ● Risk increases as the dose increases ○ E.g., cutting the dose in half, cuts the risk in half ● No threshold below which radiation doses are safe ○ No complete way to avoid radiation exposure since it is found in natural sources ○ Any type of radiation is harmful, but some are more harmful than others ○ There is no good radiation but there is lesser evil radiation VIII. GENERAL PRINCIPLES FOR MINIMIZING RADIATION RISK IN MEDICAL USE A. WHO ARE AT RISK? ● Children and young adults ● Pregnant women ● Individuals with medical conditions sensitive to radiation, such as diabetes mellitus and hyperthyroidism ● Individuals receiving multiple doses over time B. ALARA PRINCIPLE ● As Low As Reasonably Achievable ● Introduced by the International Council of Radiation Protection (1966) ○ Radiation exposure must have a specific benefit ○ All exposures should be kept as low as reasonably achievable ○ Dose of individuals shall not exceed limits for appropriate circumstances C. RADIATION PROTECTION ● Keep the time of exposure to radiation as short as possible ● Maintain a large distance as possible between the source of radiation and the exposed person ● Insert shielding material between the radiation source and the exposed person Figure 14. Radiation Protection (L: Thyroid shield; R: Gonadal shield) Nice to Know! ● CT scans and X-rays have a filter to minimize the dose ○ Currents of the machine can be minimized ● Lead gowns are used only during interventional radiology procedures or CT-guided procedures ● You should use protection even in thyroidectomy ● “While experts disagree on the extent of the risks of cancer from diagnostic imaging, there is agreement that care should be taken to weigh the medical necessity of a given level of radiation exposure against the risks, and that steps should be taken to eliminate avoidable exposure to radiation.” – The Joint Commission Sentinel Event Alert ○ Risk-benefit ○ Radiological procedures are medically prescriptive and should only be used for specific purposes when patient benefit outweighs potential risk. Active Recall Box 5. T/F. Certain people have higher radiation tolerance than others. 6. The linear, no-threshold theory states that: A. Risk increases as the dose decreases B. Risk decreases as the dose increases C. Risk increases as the dose increases 7. T/F: Below 10 mSv, there is increased cancer risk with radiation. 8. What does the ALARA Principle stand for? Answers: 5T, 6C, 7F, 8As Low As Reasonably Achievable QUICK REVIEW QUESTIONS Figure 13. Radiation Protection (Lead Gown) YL6:01.36 Radiation Harm & Benefit 1. Beta particles are heavier than alpha particles and have a greater ability to penetrate materials. Gamma and X-ray radiation can be blocked by thin plates of wood and aluminum. A. The first statement is true. B. The second statement is true. C. Both statements are true. D. Both statements are false. 2. What is not part of the ALARA principle? A. Radiation exposure must have a specific benefit B. Dose of individuals shall not exceed limits for appropriate circumstances C. The type of radiation should be considered D. All exposures should be kept as low as reasonably achievable 7 3. T/F: Hypotension, shock, and respiratory distress are symptoms of bone marrow syndrome. 4. Which syndrome is associated with exposures of at least 7 to 10 Gy (700 to 1000 rad)? A. Prodromal Syndrome B. Bone Marrow Syndrome C. GI Syndrome D. Cerebrovascular Syndrome 5. Which among the following statements is FALSE? A. The term effective dose is used when referring to the radiation risk averaged over the entire body B. Dose equivalent combines the amount of radiation absorbed and the medical effects of that type of radiation C. Absorbed dose is the amount of radiation absorbed by an object or person D. Radioactivity, in radiology, refers to the ease at which the atoms cause other atoms to fuse. 6. Which of the following is incorrectly matched?. A. Absorbed Dose = Gray B. Radioactivity = Becquerel C. Dose Equivalent = Sievert D. Exposure = Roentgen E. NOTA 7. Bone marrow suppression is associated with exposures of at least 3.5 Gy. Survival: 50% spontaneous recovery at exposure of 3.0 Gy. A. The first statement is true. B. The second statement is true. C. Both statements are true. D. Both statements are false. 8. John wants to sanitize his lab equipment. He said he needed radiation coming from high-energy waves that can travel great distances at the speed of light and have a great ability to penetrate other materials. Which of the following forms of ionizing radiation would be appropriate to use? A. Gamma particles B. Beta Particles C. Alpha Particles D. Neutrons ANSWER KEY 1D, 2C, 3F, 4C, 5D, 6E, 7D, 8A 5. 6. 7. 8. at least 3 Gy (300 rad). And, Cerebrovascular Syndrome with catastrophically high acute exposures (close to 100 Gy). D. Radioactivity, in radiology, refers to the ease at which the atoms cause other atoms to fuse. In radiology, radioactivity refers to the amount of ionizing radiation released by a material. E. NOTA. All of the following choices are correctly matched with the units used for each specific parameter. D. Both statements are false. Bone marrow suppression is associated with exposures of at least 3.0 Gy. Survival: 50% spontaneous recovery at exposure of 3.5 Gy. A. Gamma Particles. Gamma particles are commonly used to sterilize medical equipment. The description “radiation coming from high-energy waves that can travel great distances at the speed of light and have a great ability to penetrate other materials” also pertains to gamma particles. REFERENCES REQUIRED 📄 ASMPH2027. 01.36: Radiation Harm & BenefIt by Uichico, J.R.N., MD-MBA, FPCR, FUSP, FCTMRISP. ● 📄 Uichico, J.R.N., MD-MBA, FPCR, FUSP, FCTMRISP. (2023, August) Radiation Harm & BenefIt [Lecture slides]. ● SUPPLEMENTARY 📄 ASMPH2025. 01.38: Radiation Harm & BenefIt by Evangelista-Espino, L.G., MD, FPCR, FUSP, FDBISP, FCTMRISP. ● 📄 ASMPH2026. 01.32: Radiation Harm & BenefIt by Co, J.T., MD, MBA, FPCR, FUSP, FCTMRISP. ● Concerns and Feedback form: http://bit.ly/YL6CFF2027 How’s My Transing? form: https://bit.ly/2027YL6HMT Mid-Semester Evaluation form: https://bit.ly/2027YL6MidSem End-of-Semester Evaluation form: https://bit.ly/2027YL6EndofSem YL6 TransMap: https://bit.ly/2027YL6TransMap FREEDOM SPACE RATIONALE 1. D. Both statements are false. Beta particles are lighter than alpha particles. Gamma and x-ray radiation can travel through plates of wood and aluminum but are blocked by thick metal plates and concrete. 2. C. The type of radiation should be considered. Only this statement is not included in the ALARA principle introduced by the International Council of Radiation Protection (1966). 3. False. Hypotension, shock, and respiratory distress, as well as ataxia and disorientation, are signs and symptoms of Cerebrovascular Syndrome. 4. C. GI Syndrome. GI Syndrome is associated with exposures of at least 7 to 10 Gy (700 to 1000 rad). Prodromal Syndrome with exposures as low as 100 rads (1 Gy), nearly universal above 2 Gy. While Bone Marrow Syndrome has exposures of YL6:01.36 Radiation Harm & Benefit Figure 15. Source of Orlinizing Radiation (cute) 8 Figure 16. Raminizing Radiation (deadly) YL6:01.36 Radiation Harm & Benefit 9 APPENDIX APPENDIX A: Table 1. Summary of Ionizing Radiation Particles (01.38, 2025) Form of Ionizing Radiation Soure Penetration Ability Distance Travelled Effect Use Alpha Natural and man-made Limited N/A Dangerous if swallowed Small amounts Beta Natural Significant Few feet in air N/A Medical applications Gamma Natural and man-made Significant Great distances N/A Treat cancer and sterilize medical instruments Neutron Man-made Most significant Great distances Make objects radioactive Medical, academic, and industrial application APPENDIX B: Table 2. Comparison of Terms Used to Define Radiation and Dose Conventional Units System International (SI) Units Unit Name Definition Distance Travelled Effect Activity Curie (Ci) 3.7 x 1010 disintegration/s Becquerel (Bq) 1 disintegration/s Absorbed dose Rad (rad) 100 ergs/g of absorbing material Gray (Gy) 100 rad Dose equivalent Rem (rem) Rad x Q factor or RWF Sievert (Sv) 100 rem APPENDIX C: Table 3. Radiation sources around the globe (01.38, 2025) Radiation Source World US Japan Inhalation of air 1.26 2.28 0.40 Mainly from radon, depends on indoor accumulation Ingestion of food and water 0.29 0.28 0.40 (K-40, C-14, etc.) Terrestrial radiation from ground 0.48 0.21 0.40 Depends on soil and building material Cosmic radiation from space 0.39 0.33 0.30 Depends on altitude Subtotal (Natural) 2.40 3.10 1.50 Sizeable population group receive 10-20 mSv Medical 0.60 3.00 2.30 Worldwide figure excludes radiotherapy, US figure is mostly CT scans and nuclear medicine - 0.13 - Cigarettes, air travel, building materials, etc. Atmospheric nuclear testing 0.005 - 0.01 Peak of 0.11 mSv in 1963 and declining since; higher near sites Occupational nuclear testing 0.005 0.005 0.01 Worldwide average to workers only is 0.7 mSv, mostly due to radon in mines, US is mostly due to medical and aviation workers Chernobyl accident 0.002 1 0.01 Peak of 0.04 mSv in 1986 and declining since; higher near site Nuclear fuel cycle 0.0002 0.001 Up to 0.02 mSv near sites; excludes occupational exposure Consumer items YL6:01.36 Radiation Harm & Benefit Remark 10 Other - 0.003 - Industrial, security, medical, educational, and research Subtotal (Artificial) 0.61 3.14 2.33 - Total 3.01 6.24 3.83 Millisieverts (mSv) per year APPENDIX D: Table 4. Radiation Doses of Medical Imaging Procedures X-Rays Dose Range, mSv Average Dose, mSv Chest X-ray Equivalent Dose Chest* 0.02-0.67 0.34 1 C-spine 0.063-0.27 0.17 0.5 T-spine 0.4-1.4 0.9 2.6 L-spine 0.4-2.4 1.6 4.7 Pelvis 0.8-2.4 0.78 2.3 0.5-1 0.75 2.2 0.3-0.6 0.4 1.1 0.01-0.06 0.035 0.1 7-9 8 23.5 2.5-5.7 4.1 12 Mammography 0.07-0.89 0.48 1.4 Upper GI tract 3.6 3.6 10.6 0.02-0.334 0.18 0.53 Dose Range, mSv Average Dose, mSv Chest X-ray Equivalent Dose Head* 1.5-2.3 1.9 5.6 Chest 4.1-8 6 17.6 Thoracic 8.3-11.7 10 29.4 Lumbar 3.5-5.2 4.4 13 Abdominal* 7.6-16 11.8 35 Pelvis 10-13 11.5 33.8 Dose Range, mSv Average Dose, mSv Chest X-ray Equivalent Dose Cerebral 7.5 7.5 22 Cardiac 71.9 71.9 211.5 Vascular 19.4 19.4 57 Abdomen, kidneys, ureters, bladder Hip Limbs Barium enema Intravenous pyelogram Dental CT Scans Angiographs *Emphasized by Doc Espino during the lecture YL6:01.36 Radiation Harm & Benefit 11 APPENDIX E: Table 5. Effective Radiation Dose in Adults Abdominal Region Procedure Adult’s approximate effective radiation dose Comparable to natural background radiation for Computed Tomography (CT) – Abdomen and Pelvis* 10 mSv 3 years Computed Tomography (CT) – Abdomen and Pelvis, repeated with and without contrast material 20 mSv 7 years Computed Tomography (CT) – Colonography 6 mSv 2 years Intravenous Pyelogram (IVP) 3 mSv 1 years Radiography (X-ray) – Lower GI Tract 8 mSv 3 years Radiography (X-ray) – Upper GI Tract 6 mSv 2 years Bone Procedure Radiography (X-ray) – Spine* Radiography (X-ray) – Extremity Adult’s approximate effective radiation dose Comparable to natural background radiation for 1.5 mSv 6 months 0.001 mSv 3 hours Central Nervous System Procedure Adult’s approximate effective radiation dose Comparable to natural background radiation for Computed Tomography (CT) – Head 2 mSv 8 months Computed Tomography (CT) – Head, repeated with and without contrast material 4 mSv 16 months Computed Tomography (CT) – Spine 6 mSv 2 years Computed Tomography (CT) – Chest 7 mSv 2 years Computed Tomography (CT) – Lung Cancer Screening 1 1.5 mSv 6 months Radiography – Chest 0.1 mSv 10 days Dental Procedure Intraoral X-ray Adult’s approximate effective radiation dose Comparable to natural background radiation for 0.005 mSv 1 day Heart Procedure Adult’s approximate effective radiation dose Comparable to natural background radiation for Coronary Computed Tomography Angiography (CTA) 1 12 mSv 4 years Cardiac CT for Calcium Scoring 3 mSv 1 year YL6:01.36 Radiation Harm & Benefit 12 Men’s Imaging Procedure Bone Densitometry (DEXA) Adult’s approximate effective radiation dose Comparable to natural background radiation for 0.001 mSv 3 hours Nuclear Medicine Procedure Positron Emission Tomography – Computed Tomography (PET/CT) Adult’s approximate effective radiation dose Comparable to natural background radiation for 25 mSv 8 years Women’s Imaging Procedure Bone Densitometry (DEXA) Mammography* Adult’s approximate effective radiation dose Comparable to natural background radiation for 0.001 mSv 3 hours 0.4 mSv 7 weeks *Emphasized by Doc Espino during the lecture YL6:01.36 Radiation Harm & Benefit 13