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Effects of Radiatio
Early and Late Effects of Radiation
| Question | Answer |
|---|---|
| In the 1920's and 30's, how were RT's checked for radiation exposure? | Through blood testing once a week. |
| What is considered Early Effects of Radiation? | Response to radiation occurring within hours or days. |
| What is the worst possible effect of radiation and today's diagnostic worries? | Death is the most severe, but in diagnostic radiation today the most worrisome is skin effects. |
| Can diagnostic x-rays cause acute effects or death? | No, diagnostic beams are not intense enough or large enough to cause death.There is no "whole body" exposure in today's diagnostic x-rays. |
| How have studies been done on the effects of radiation? | From accidents such as Chernobyl 1986, 3-mile Island 1979 and Atomic bombs during WWII. Also convicts have been used in studies. |
| What is acute radiation syndrome? | The sequence of events that follow high-level radiation exposure leading to death within days or weeks. |
| What are the three syndromes of acute radiation syndrome? | Hematologic death, gastrointestinal (GI) death and Central nervous system death (CNS). |
| In addition to the 3 lethal syndromes, Four periods are associated with acute radiation lethality? | The Prodromal Period > 100 rad(Sickness immediately,can last hours or days),Latent Period 100-10000 rad(seem to be better,think you are recovering),then manifest illness(depending on dose), then recovery or death. |
| What period has acute clinical symptoms that occur within hours of exposure and contiunue for up to a day or two? N/V/D | The Prodromal Period. The severity of the symptoms are dose related. Prodromal dose approx. >100 Rad. |
| Which period does the patient seem free of visible effects and mistakenly thought to be early recovery from a moderate radiation dose. | The Latent Period. It is misleading giving no indication of the extensive radiation response yet to come. Latent dose 100-10,000 rad |
| Hematologic-dose,days prodromal,latent, manifest illness, mean survival time? | 200-1000 rad dose, Prodromal period lasts several days,mild symptoms. Latent-as long as 4 weeks, seem fine, Manifest illness-V/D, malaise,lethargy & fever 2-4 weeks.iF If dose not lethal revovery in 2-4 wks up to 6 months. Mean survival time 10-60 days. |
| GI- dose,days prodromal,latent, manifest illness, mean survival time? | 1000-5000rad. Prodromal period-V/D within hours for up to a day, next latent period 3-5 days(no symptoms),manifest illness-N/V/D,anorexia,bloody stools, electrolyte imbalance, death within 4-10 days.intestines |
| What is the principal cause in the GI syndrome death | Severe damage to the cells lining the intestines. |
| What is the principal cause of hematologic syndrome? | A reduction in white cells, red cells and platelets. |
| CNS-dose,days prodromal,latent, manifest illness, mean survival time? | >5000rad.Min.of exp.severeN/V,nervous &confused,skin burning sensation,may lose vision,conciousness in hrs.Latent-symptoms subside,disappear up to 12 hrs. Manifest illness-sypmtoms of prodromal period appear worse and outcome is always death.MST-0-3 days |
| What is LD 50/60? | The Lethal Dose of radiation to the whole body that causes 50% of irradiated subjects to die within 60 days. |
| Radiation induced death in humans follows a ______, ______ dose-response relationship. | non-linear, threshold. |
| The ultimate cause of death in CNS syndrome is? | Elevated fluid content of the brain. |
| As the whole body radiation dose increases, the average time between exposure and death decreases. What is this called? | MST- Mean survival time. |
| How much of GI lining is replaced daily compared to skin cell replacement daily? | 50% of GI lining is replaced daily(high proliferation rate) whereas 2% of skin cells are replaced daily. |
| True or False - When only part of the body is being irradiated, rather than the whole body a higher dose is required to produce a response. | True |
| Every organ or tissue of the body can be affected by partial-body irradiation. What is the effect and the results? | The effect is cell death which results in shrinkage or atrophy of the organ or tissue. |
| What is the outermost layers of the skin? | Epidermis has 5 layers. |
| Name the 5 layers in order from outermost to inner. | 1.Stratum corneum (horny layer)2. stratum lucidum (clear layer)3.stratum granulosum(granular layer)4.stratum spinosum(prickle layer)5.stratum germinativum(germinal layer) |
| What are the two layers of the innermost skin? | Dermis or "true skin" has 2 layers:1.papillary layer(finger prints)2.reticular layer (blood & nerves pass through) |
| What is layer under the skin? | Hypodermis (loose connective tissue) |
| What is the largest organ in the body? | Skin |
| What are the functions of skin? | Used for protection, excretion of water & waste products. Regulates body temp. |
| What was the first biological response to the skin after radiation exposure? | Erythema. a single dose of 300-1000 rad, may result within the 1st or 2nd day after exp. |
| What is the latent period of skin exposure? | After the first wave of erythema, it subsides only to be followed by a 2nd wave that reaches intensity in about 2 weeks. |
| What is SED/50, and the dose? | Skin Erythema dose required to affect 50% of those irradiated is 500 rad. |
| What is another response of skin radiation besides erythema? | Epilation or hair loss. |
| What are "grenz rays"? | Soft rays 10-20kVp were used as treatment for ringworm. |
| What is the rad level that effects the gonads? | As low as 10 rad. |
| What are thought to be a cause of late effects? | Multi-hit aberrations (multi chromosomes hit (worse than a DNA hit) |
| What is radiodermatitis? | IN early radiologists doing fluoro w/o gloves got discolored, callused, weathered hands and forearms. |
| What are epidemiologic studies? | Studies of large # of people exposed to a toxic subtance, when the 3 of persons affected is small. These studies are difficult because of unknown dose & frequency. |
| What are late effects? | The results of low doses given over a long period of time. Like how RT's get it. |
| What are some late effects on skin? | Skin cancer or other non-malignant changes. |
| What is the dose-response relationship for radiation induced cataracts? | Non-linear, threshold. Cataracts occur on the posterior pole of the lens.Latent periods ang. 15 years.Non-linear, threshold response. |
| At worst, humans exposed to radiation can expect a reduced life span of what? | 10 days for every rad. |
| What are response on chromosomes? | Irradiation of blood-forming organs can cause early and late effects by hematologic depression: Early decreased white count;Late effects-leukemia(can take up to 20 years) |
| What is the threshold dose for cataracts? | EStimated 200rad or 1000 rad fractionated dose. |
| Radiation induced malignancies (leukemia)follow what kind of dose response? | Linear, non-threshold dose response. Chances of Leukemia increase as dose increases. |
| A-bomb survivors had up to 100 times more incidence of leukemia, What was the latent period and the at risk period? | Latent period was 4-7 years and at risk period was up to 20 years. |
| What were the studies on thyroid cancer? | Ann Arbor- children that had thymus gland irradiated 20-3 rad (from scatter)got thyroid cancer 20 yrs. later, Rochester -kids thyroid radiated w/ no collimation (300 rad)& kids exposed to fallout during an A-bomb test. |
| What are the late effects of skin cancer? | Starts with radiodermatitis, follows threshold dose response with a 5-10 year latent period. Number of cases is dose-dependent. |
| During fluoroscopy what are the risks of breast cancer? What about mammography? | In fluoro there is a 10 times incident of breast CA of pts. facing toward fluoro, but most pts are on their back so no increase there. Mammo= benefits vs risks. |
| Minors (up to 50%) died of lung cancer once thought to be from the dust, later found to be what? | Radon gas (poor ventilation)Linear-non-threshold. |
| What was given to patients for testing that was later found to be causing liver cancer? | Old contrast called "thorostast" made from 1925-1945. |
| What is BEIR and NCRP? | Committee on Biologic Effects of Ionizing Radiation and National Council on Radiation Protection and Measurements. They studied mortality rate in detail and found that radiology is a safe field. |
| How does Radiation effect Pregnancy, before, during and after? | Before preg.- interrupted fertility, during preg.-possible congenital effects, After preg.-suspected genetic effects. |
| How much dose affects fertility? | Low dose chronic irradiation does not effect fertility. |
| When is the most radiosensitive time in-utero? | 1st 3 months are the most radiosensitive. |
| Why should patient and tech always wear protective gear during exposure? | During the 1st two weeks after fertilization (when pt. may not know they are pregnant) |
| What are the effects of dose related exposure during the first two weeks? | Prenatal deatrh, neonatal death, congenital abnormalities, malignancy induction, general impaired growth, genetic effects, mental ret |
| Affects during weeks 2-10 in-utero? | Bone or neurologic abnormalities may occur resulting in neonatal death. This is rare (1% increase in neonatal death)Leukemia is most common effect. |
| What do a-bomber survivors' offspring have a higher incidence of? | Mental retardation. |
| Nothing has been proven with doses in medical radiology so we always assume what? | Linear, non-threshold doses and ALARA principles. |
| Maximum Population sample required to show that the given radiation dose significantly elevated the incidence of leukemia. | 6,000,000=5rad, 1,600,00=10rad, 750,000=15rad, 500,000=20rad, 100,000=50rad. |
Created by:
sewwhat4
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