Radiation Dose Reduction in Imaging Modalities
In recent years much discussion around CT dosages has forced manufacturers to provide data and safe guards for all exams. ‘Excessive radiation exposure’ has been life changing for many patients but many organizations are working to implement standards to reduce radiation dosage through the use of medical equipment. To learn more check out the infographic below created by ADU Online’s Bachelor of Science in Radiologic Sciences
There are two basic types of radiation; ionizing and non-ionizing radiation. The former is the most commonly used type of radiation. It is a high-energy form of radiation that can separate electrons from molecules and atoms, which often leads to ionization and causes structural changes in a catalystic manner, leaving behind radiation particles. Non-ionizing radiation, on the other hand, is low-energy and generally harmless as it only generates heat and produces light, as opposed to dislodging electrons. This type of radiation can only cause a small amount of movement in atoms and electrons, which cannot lead to ionization.
Types of Medical Imaging that Produce Radiation
Some common medical equipment known to produce radiation include; X-ray machines, CT scans, angiography and mammography. Molecular imaging procedures normally require injection of radiopharmaceuticals into the human body to show biological processes in real-time. These radiopharmaceuticals normally produce radiation.
Breakdown of Radiation Exposure Levels
A typical X-ray exposes the patient to 10 mrem of radiation while abdominal X-ray and abdominal CT scan expose the patient to 120 mrem and 1,000 mrem of radiation respectively. On the other hand, a mammogram exposes the patient to 200-300 mrem of radiation. CAT scans and radiation therapy have the highest exposure levels of 2,000-10,000 mrem and 5 million mrem of radiation respectively. It is important to note that the acceptable level of radiation exposure for the general population is 500 mrem/year while the exposure limit for radiation workers is 5,000 mrem/year. Unfortunately, medical radiation exposure levels in the recent years have been increasing to unsafe levels. This can be attributed to higher ionizing radiation scans.
Medical Equipment with the Highest Ionizing Radiation Exposure Levels
Flouroscopy, PET and CT scans are popular in the medical imaging industry because they produce real-time images, which are incredibly helpful in medical diagnostics. While the three scans only account for a quarter of all medical imaging procedures in the U.S., they can be blamed for nearly 90 percent of all medically-related radiation exposure.
Between 1989-2009, radiation exposure levels in the United States increased significantly because of these three scans. In 2006, it was reported that man-made radiation exposure levels were six times the levels recorded in the 1980s. A survey in 2007 revealed that 20 percent of patients in over 60 medical organizations underwent duplicate scans.
In 2011, 85 million CT scans were done in the United States. While new technologies, such as multidetector CT scanners offer higher resolution, they expose the patient to 30-50% more radiation. In the future, it is expected that the number of CT and PET scans, among other type of medical imaging procedures, will continue to increase.
Possible Risks Associated with Increased Low-Dose Radiation Exposure
Radiation exposure from CT scans and medical imaging for heart disease can cause cell damage. Cell mutations can also occur as a result of DNA damage, and this may lead to development of cancerous cells, or tumor cells. It is estimated that out of the 72 million CT scans done in 2007, 29,000 may lead to new cancer cases in the future.
Radiation Dose Reduction
In a bid to reduce radiation exposure levels, doctors are required to keep radiation dose as low as reasonably achievable (ALARA). This can be achieved through a number of deliberate measures. For instance, medical professionals can use alternative imaging equipment which do not produce any radiation, such as MRIs and ultrasound, instead of using CT scans and X-ray machines. Updating equipment with sophisticated image processing software can also help to reduce exposure levels by eliminating the need to repeat procedures or increasing the radiation dose. Before performing an imaging procedure, medical professionals should ensure patients are well positioned and instruct them not to move. This will help to reduce the number of repeat procedures.
Doctors who are treating cancer patients should administer chemical barriers, such as Amisfosfostine. Medical professionals are also advised to personalize CT scans to suit their patients’ health, age, weight, status and demographics among other factors.
Radiation Dose Reduction Best Practices
Medical professionals should position the patient properly for best view before performing the procedure. Radiation dose for patients with BMI less than 30 should also be reduced. Medical professionals should also learn how to control radiation exposure levels by adjusting the current and voltage. Reducing the voltage (kVp) and current (mA) can reduce exposure levels by over 40%. Scans should only target the area of interest to prevent other parts of the body from getting exposed. Bowtie filters should be used to prevent scattering of X-rays while CT scanners should be set to filter out cardiac noise. Most importantly, however, physical barriers should be used to reduce radiation exposure. For instance, medical imaging equipment should only be used in a building surrounded by concrete walls. Leaded plexiglass should also be used to keep scattering radiation at bay. Leaded thyroid shields, gloves and aprons should also be worn inside the radiation area.
Physician education is an important requirement in radiation dose reduction. According to a recent survey, 85% of physicians underestimated the risks/effects of radiograph-related radiation exposure. Only 20% of physicians had radiation safety training while 25% of physicians did not know that MRIs do not use radiation. Therefore, physician education is important. That said, following the recommended safety protocols and observing best practices can help to reduce radiation exposure levels significantly.
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