Anatomy

Body

Understanding Radiation Examinations

The ionizing effects of radiation increase the risks of developing cancer. It is believed by many that the proper precautions for radiographing fetuses, infants, and pediatrics may not be appropriately utilized and emphasized. Depending on the facility, the proper precautions may or may not be followed. Sixty five to seventy five percent of Computed Tomography (CT) examinations performed may be necessary. However, it is not uncommon for a doctor to order a CT examination 'just in case'. To elaborate, twenty five to thirty five percent of these examinations are done more as an insurance policy than because of actual necessity. Radiography, Fluoroscopy, Computed Tomography and Mammography are all forms of diagnostic radiation. Each examination uses a different amount of ionizing radiation. The more ionizing radiation the body absorbs the more likely it becomes to suffer the hazardous effects. Radiographs may be used to diagnose broken bones, pathology, soft tissue damage, as well as other things. Mammography is similar to radiography except that it is specific to breast tissue. Fluoroscopy is a real time radiograph of the patient and delivers a much higher dose than a single radiograph does. Fluoroscopy is best defined as an ongoing radiograph that gives the radiologist the ability to actual see the body's internal organs perform their functions. In general computed tomography delivers a much higher dose than fluoroscopy. CT examinations take pictures of the body from left to right and top to bottom. It has a starting point and an ending point. CT examinations are used on patient, who have possible skull fracture, or to see internal functions of the organs by injecting contrast intravenously or orally, or simply to get more detail than could have been acquired on a radiograph. Nuclear medicine involves the injection of radiopharmaceuticals which are detected circulating throughout the body. This is known as scintigraphy, and can provide images involving circulation and locating severe infections. (Furlow, Neonatal Imaging)

There are several other examinations that produce similar result and do not use ionizing radiation. Ultrasound is one possible alternative instead of performing an examination that is detrimental to a patient's health. Ultrasound uses high frequency sound waves to create pictures of tissue along different body planes. Research at Yale University recently discovered that the high frequency sound waves used during an ultrasound actually cause damage to the cerebral cortex of mice embryos. This does not mean that the use of ultrasound of fetuses should be abandoned for it is still a far safer option than a CT examination. This research only suggests that again no examination should be performed without proper cause. Ultrasounds should not be taken for granted. (Orenstein, "Ultrasound Check")

"Magnetic Resonance Imaging (MRI) is a digital imaging technique" used to reconstruct an image using protons, or magnetic dipoles. The movement of the fetus within the womb previously prevented the use of MRI examinations. MRI examination use to require the patient to remain still for a longer period of time, making it nearly impossible to acquire adequate images to be used for diagnosis. Recently the time it would take to acquire an image has bee decreased to less than one second. MRI examinations can be safely performed throughout pregnancy however; doctors tend to avoid these examinations during the first trimester of pregnancy simply because this is when the fetus is most sensitive to damage by outside forces. (Harvey) Both ultrasounds and MRIs will be discussed again later in this paper.

Cell Sensitivity to Radiation

"Radiation's benefits to diagnostic and therapeutic medicine are undisputed, yet always must be weighed against the potential dangers that overexposure to ionizing radiation presents." (Brusin) Health care workers are responsible for explaining the health risks of ionizing radiation to their patients. The number one priority of every radiographic technologist and radiologist is to keep the exposure levels to the minimum required for the examination being performed. The reason this is done is to stop ionizing energy in x-rays from entering the body and causing molecular changes in the cells. These molecular changes damage the cells and impede their ability to function property and may eventually cause the cell to die. Radiobiologist are responsible for studding the radiosensitivity of different tissues.(Burke) The radiosensitivity of cells is based on how often the cells renew themselves. Radiosensitivity within the tissues of the body varies a great deal. (See Illustrations I, p. 8.)

Stem cells, reproductive cells, and blood cells are very radiosensitive. The tissues and organs found in fetuses, infants, and children are among the most radiosensitive because the cells are dividing more rapidly. Fetuses, infants and children are more likely to develop cancer from exposure to ionizing radiation than adults. Mature cells become more resistant to radiation as they grow older. Tissues with less demand for renewal are more resistant to the harmful effects of radiation. "Evidence has long suggested that developing embryo or fetus is especially radiosensitive." (Brusin)

Early Effects of Ionizing Radiation on Fetuses, Infants, and Children

The early effects of ionizing radiation during pregnancy can be fatal to the fetus. "...Mortality due to x-ray irradiation was pronounced in the early 1900s. X-ray induced anemia, radiation burns on skin and hair loss were widely reported, and the first documented fatality from radiation exposure occurred in the United States in 1904." (Furlow) The risk of developing cancer from radiation exposure accumulates with every examination. Children have a longer life expectancy than adults. Furthermore, children have a longer amount of time to develop the cancers. Despite the knowledge that ionizing radiation is more harmful to younger people, there is a reported increase in the number of examinations involving ionizing radiation in children. It has been recorded that there is a six hundred percent increase in computed tomography within the last forty years. Studies have determined that a single CT examination produces enough radiation to dramatically increase the risk of fatal cancer due to radiation exposure. (Minigh)

Radiation is known to cause birth defects. An agent that causes birth defects is known as a teratogen. Radiation doses during pregnancy can induce a number of birth defects. Some examples are embryonic, fetal, of neonatal