Health and Biological Effects of Radiation

Radiation Risks: Non-stochastic Commonly referred to as deterministric or somatic effects Threshold-related symptoms that worsen with dose: SKIN CHANGES Erythema/hair loss/ulceration CATARACTS A clouding that develops in the lens of the eye or its envelope TERATOGENESIS The development of defects in an embryo

Radiation Risks: Stochastic Genetic Severity of condition independent of dose: GENETIC MUTATION A permanent change in the DNA sequence that makes up a gene GENOMIC INSTABILITY Failure to transmit an accurate copy of the entire genome CANCER INDUCTION Process by which normal cells are transformed into cancer cells Non-threshold, increasing probability with dose

Genetic Effects of Radiation Exposure Linear, nonthreshold response All mutations are harmful Exclusively naturally occurring mutations Females are less radiosensitive than males Most mutations are recessive Dependent on: FRACTIONATION When a certain quantity of a mixture is divided up in a number of smaller quantities PROTRACTION Anterior movement of the arms at the shoulders

It is possible to inflict damage during radiology procedures! A subtle and disturbing aspect of radiation damage can be the delay in its manifestation. One cannot automatically assume that when such damage occurs long after a fluoroscopy study, that it's cause will be associated with the study. It is highly probable that there are fluoroscopists who have inadvertently caused radiation burns to a patient and are not aware of injury inflicted. 16-21 weeks post- fluoroscopic procedure 18-21 months post procedure Close-up Courtesy FDA Web Site: http://www.fda.gov/cdrh/rsnaii.html

Patient Dose Factors / Considerations Fluoroscopy exposure time or # of radiographic exposures Beam Parameters: Intensity Penetration Distance from x-ray tube Beam Size Sensitivity of exposed organs (damage threshold) It is the responsibility of the fluoroscopist to minimize fluoroscopic exposure within clinical limits as well as to understand the associated risks to the patient Fortunately many of the issues just discussed which reduce operator exposure also reduce patient exposure. Although some actions reduce both patient and operator exposure and improve image quality, unfortunately, some actions which reduce patient exposure also degrade the image quality. The principle source of radiation to patients is the primary beam, radiation coming directly from the x-ray tube. Exposure for a particular patient depends upon the beam's intensity, the length of time the beam is on, the distance of the patient from the x-ray tube, the collimation of the x-ray beam. Different organs exhibit different sensitivities to radiation. Damage thresholds to various organs can be exceeded. In fluoroscopy skin is often the critical organ in terms of the amount of radiation received and the threshold for damage.

Risk Estimates Relative Risk = Observed cases/Expected cases Excess Risk = Observed cases/Expected cases Absolute Risk = # cases/106 persons/rad/year

Radiation-Induced Leukemia Years

Radiation Induced Cancers Observed in Irradiated Populations THYROID CANCER Thymus irradiation Rongelap Atoll nuclear test BREAST CANCER Tb treatment A-bomb survivors BONE CANCER Radium watch dial painters Radium salt treatment LUNG CANCER Uranium miners SKIN CANCER Orthovoltage radiation therapy LIVER AND SPLEEN CANCER Thorotrast

Effects of 200 rad in Utero

Expected Days of Life Lost Risky Condition Expected Days of Life Lost Being male rather than female 2800 Heart disease 2100 Being unmarried 2000 One pack of cigarettes a day 1600 Working as a coal miner 1100 Cancer 980 30 pounds overweight 900 Stroke 520 All accidents 435 Service in Vietnam 400 Motor vehicle accidents 200 Average occupational accidents 74 Speed limit increase from 55 to 65 mph 40 Radiation worker 12 Airplane crashes 1 “Radiologic Science for Technologists, Physics, Biology and Protection” Stewart Bushong (2008).  

Please close this PowerPoint presentation, and continue the lesson. What’s Next? Please close this PowerPoint presentation, and continue the lesson. Presented by Elsevier items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.