Radio Frequency Burns - Coursework Example

Radio Frequency Burns Student’s name: Institution: Date: 1. Introduction Magnetic resonance imaging (MRI) or magnetic resonance tomography (MRT) refers to a medical imaging procedure applied in radiology to look into the body’s function and anatomy in terms of both health and diseases. The Magnetic resonance imaging (MRI) scanners often use strong magnetic fields as well as radio waves to create images from the body (Bushong, 2009). The technique has been applied for a long time, since the early 1980s and has proven to be secure and also the most effective means of investigating the anatomy and functionality of body organs. Among all the body-imaging scanners, MRI has been the most preferred since it does not use ionizing radiation during imaging. MRI, however, is safe, but not safe all the time since the magnetic fields created while, the scanner is at work often has diverse effects on different types of people. Some of the most common risks attached to the MRI scanner include the risks associated with metallic substances on the body; the radiofrequency effects, and radio frequency burns that are usually caused to patients (Bronson, 2006, August 1). These risks are not always normal or frequent but are likely to occur under certain circumstances. This paper will discuss the radio frequency burns, how they occur, their causes and how to prevent them. Radio frequency in MRI machine under perspective The MRI radio frequency system comprise of several components, which help in transmission and reception of radio frequencies that act to excite the nuclei, applying gradients, selecting slices and acquiring signals. Among the radio frequency system components are the coils, which play a very vital role in the performance of the entire system. During the transmission, the aim is always to distribute equal transmission throughout the volume under scan (Abel, 2013). The coil also needs to be sensitive during reception and ensure the best signal to noise ratio (SNR) is maintained. The procedure for Magnetic Resonance Imaging (MRI) engages the use of strong magnetic fields as well as radio waves to generate cross-sectional images of the organs under study. The signal detected by an MRI may vary and largely depends on the local magnetic properties and water content in that region. The local magnetic properties described above are created by electric current passed across the coils. After establishment of the magnetic field around the body, the machine can then acquire the preferred images through transmission and reception of radio waves sent through the transmitter. The signals are then used to generate images that will help with the desired analysis. The magnetic force produced by the MRI often induce the hydrogen atoms within the body tissues to line up in a given direction. The radio frequency used in the MRI machines are always specifically meant for hydrogen atoms, thus when the radio frequency pulse is released directed towards a specific area, the protons within that area absorb energy, which causes them to spin in some direction (Weekly News, 2014, February 27&Robitaille & Berliner, 2009). One property of the Radiofrequency (RF) is that they do not have a tendency of penetrating deeper into the electrical conductors; however, they always flow along their surfaces causing what is known as skin effect. Thus, when human body gets in contact with the high power radiofrequencies, they can cause surface burns otherwise known as RF burns on the skin of the affected patient. Turning off the radio frequency pulse causes the hydrogen protons to gain their natural alignment slowly in the magnetic field. At the same time, they release the excess energy stored in them, and during this time, the MRI picks up signals given by the protons and sends them to the computer (Bendel, 2008). The computer system upon reception of the data can convert the data into an image, which can be put on film. 2. Radio frequency effects As discussed above, the effects of radiofrequency are often minimal, but their occurrence cannot be assumed. There are two ways through which radiofrequencies effects may resurface on the patient’s body, these are in the deposition of energy produced by the radio frequencies into the tissues, as well as the possibility of the patients developing burns (Fayad, 2007). Radiofrequency usually produces heat during its transmission. The radiofrequency power transmitted causes a series of activities, which include fast spin of echo pulse sequences and transfer of magnetic pulses; these activities are translated into heat in the body of the patient. This heating can be dangerous if not controlled and can cause adverse effects to the patient if no special care is taken. Different health conditions are likely affect the ability of an individual’s body to tolerate thermal changes. Such conditions may include hypertension, fever, diabetes, cardiovascular disease, skin disease, obesity and other forms of medication can effectively alter the body’s thermoregulatory abilities therefore their bodies may not respond appropriately to the heat produced (Stokar, 2007). The presence of any of the above health conditions makes the patient vulnerable to the effects resulting from the MRI radiofrequencies. A patient should therefore be examined for the presence of any of the above health conditions before they are placed under the MRI machine for imaging. Most energy transmitted by the radiofrequency pulse is often absorbed into the body tissues of the patient mainly in the form of heat. However, the body naturally responds to this by dispersing the extra heat through radiation, convection and conduction to help in maintaining a normal body temperature (Durbridge, 2011). The sum of energy deposited per unit mass is referred to as specific absorption rate (SAR), and is calculated in Watts per kilogram (W/kg). The MRI system is tuned to perform the specific absorption rate (SAR) for every patient that is in the machine and this helps in regulating the energy deposited in the body tissues. Many clinical scanners have been installed with configurations that enable them give a warning when the normal SAR levels are exceeded. These are most importantly helpful in ensuring that such heat absorption does not rise above the temperatures that can easily harm the body. Nonetheless, there are certain patients that have thermoregulatory systems that can easily be compromised. Such patients always sensitive and form the highest percentage of people affected by the heat energy produced by the radiofrequency pulse. In this effect, most of these persons develop fever, dizziness or nausea. Such high temperatures can also result in weakening of the body and lead to further complications that the patient may not be in a position to handle (Hernes, 2008) 3. Radio frequency burns The radiofrequency coil transmits the pulses directly to the body of the patient. The pulses have the capacity of inducing electric currents in the presence of conducting materials; then induced heating of the body tissues of the patient. This can result into superficial skin burning. The conducting materials in this case may not only be limited to things that people wear on their bodies, but also to substances that form part of the exam such as electrodes, leads and cables Fig. 1.0 Picture showing Radiofrequency burns (Image from www.accessdata.fda.gov) Many patients have reported instances of third degree burns during their MRI examinations and these are mainly attributed to the cables, sensors, or other devices that are usually brought to contact with the patient’s skin during the scanning process (Perrin, 2012). The electrical currents occurring in this case are induced through two magnetic fields; these are the radiofrequency field and the pulsed magnetic gradient. Every time there is an intersection of these two magnetic fields in the presence of an electrically conductive substance, there is a tendency of electromotive force forming (EMF). This will result into heating that will cause the skin burns (Bendel, 2008). 4. Specific absorption rates (SAR) Specific absorption rate (SAR) in Magnetic resonance imaging (MRI) refers to the quantity of the heat absorption rate by the human body during exposure to MRI electromagnetic field (Olsen et al. 2008). It can as well be known as the amount of power absorbed in per unit mass of the body tissues. It is measured in watts per kilogram. The SAR can be calculated for a small portion of the body tissues or over the whole body depending on the levels of exposure (Truong et al. 2009). There are standard limits for SAR and these are defined by FDA and IEC. The SAR limits for FDA Area Dose Time SAR (W/Kg) Entire body Average 15 4 Head Average 10 3 Head or torso Exposure per gram tissue 5 8 Extremities Exposure per gram tissue 5 12 SAR limits for International Electro-technical Commission Levels Whole body head Head or torso Extremities Level 0 2W/Kg 3.2 W/Kg 10 W/kg 20W/kg Level 1 4W/Kg 3.2W/Kg 10W/Kg 20W/kg NB- for level 11 is a controlled operating mode and all the values used are above the level 1 values (MRI Database, 2012, February 9). 5. Causes of Radiofrequency burns and how prevent each The radiofrequency burns are often caused by a number of factors most of which revolve around the machine and the individual livelihood. Some of these may include burns caused by cabling, skin to skin contact during MRI, tattoos and metallic substances in the body. Below is an in-depth analysis of each of the above mentioned causative factors. 5.1 Radiofrequency burns from cabling As mentioned previously, the MRI machine induces two magnetic fields; these are the pulses resulting from radio frequency and pulses resulting from magnetic gradient. Whenever these two magnetic fields intersect in the presence of cables used in the MRI machine, Electromotive force is formed causing heat (Durbridge, 2011). The heating of the cable results into skin burn. Most instances that have been reported of RF burns are always caused through these procedures. The picture below demonstrates some of the burns caused by cabling. The cables came in contact with the patient’s skin and resulted into the reddish burns on the skin. One such instance was witnessed at the UBC research centre where Dr. Zamboni discovered that a patient had developed burns on the body due to contact with cables during the imaging process (Health and beauty close-up, 2010, November 30). (Photo courtesy http://www.canstockphoto.com) How to prevent RF burns caused by cabling RF cabling burns can be prevented in a number of ways; most of these include making choice of the perfect length and the thickness of the cable. The larger the cable, the greater the magnetic strength of the current and the more likely it is to produce a high amount of heat. Therefore, the cables used during MRI should be sized and should not be very long. Doctors often know the ideal cable shape and position that should be used during the examination (Kanal & Wolf, 2008). The patient’s body should also not touch the transmit RF coil, for this reason, an insulating material should be used, at least 1 cm in thickness (Kanal & Wolf, 2008). As well, finding the ideal position for the cable and shape during examination can significantly help in reducing the radiofrequency burns. The patient should, therefore, be positioned in a manner that will prevent any skin contacts with the loop formation points (Kuperman, 2009). There must also not be skin to skin contact between the elements on the patient’s body; hands resting on thighs or crossed ankles should be avoided by all means. The cables used should also not be looped; this means that they should not be circular or U shaped. At the same time, the cables should not be in contact with any metal or cables or should not cross each other. This will prevent instances of RF burns occurring on the skin. The patient should also be monitored at all times to ensure that the coils and the radiofrequency pulse do not affect them in any way (Durbridge, 2011). Most patients may not be in a position to tell whether their bodies are reacting to the RF burns or not, therefore, they should be closely monitored to ensure that the occurrence of such is limited and not affecting the process. Finally, the cable should be checked prior to the examination process for any form of cut or damage. Damage to any part of these cables may result to severe thermal induction to the cables and pose a great threat to the patients (Li et al. 2007). Such damages may also remove insulation from the cables leaving the patient exposed to the thermal injuries. Regular maintenance should therefore be performed to ensure that all the cables within the MRI machine are well insulated and none poses a threat to patients. This important consideration must always be made prior to any MRI procedure (Perrin, 2012). Radio frequency burns from skin to skin contact Skin to skin contacts of the body parts is highly not recommended since they provide points through the resulting head produced accumulate and cause pain. Skin to skin contact often results into creation of a partial vacuum between the skin surfaces in contact (Hernes, 2008). When heat is trapped between these surfaces, they result to burns. The figure below shows burns caused by skin to skin contact during the MRI process. In this case, the patients hands were closely tucked together hence leading to the burns. Fig. Radiofrequency burns from skin to skin contact (Courtesy of http://alhamora.hubpages.com/) How to prevent Radiofrequency burns from skin to skin contact In order to prevent the occurrence of radiofrequency burns from skin to skin contact, the patient and the staff should take appropriate measures. Some of these measures include the following: Ideal position of the patient during the exam: The patient should be put in a position that will prevent the body parts from coming in contact with each other. The hands must not rest on the thighs or any other part. The same should apply to the ankles, which should not touch one another (Stokar, 2007) Increase the staff awareness about skin - skin contact burn and RF pulse burn: by educating the staff members on the effects of skin-to-skin contact during MRI. This will limit the instances of neglect that may occur in the course of duty by the staff members (Kuperman, 2009). There should be notices in the scan room reminding the staff of taking the appropriate precautions when using the MRI machines with the patients. Staff should also be educated about patient positioning and the side effects of musing wrong positions in the MRI machine. This education can be done periodically ensure that the health professionals are updated on the most advanced methods of using an MRI machine. As well, the education should be comprehensive and cover every aspect of positioning since it can be quite challenging for these persons. 5.2 Radiofrequency burns from tattoos Radiofrequency burns can also be caused by the presence of permanent cosmetic marks or tattoos. Certain inks used in creating the tattoos are ferrous and contain iron oxide or some other metallic pigments which when exposed to the magnetic field environment produces a burning sensation, swelling or even skin irritation (Journal of Engineering., 2012, September 12). The risk in this case becomes more obvious when the location of the tattoo is within the region that is under examination. Despite the risks levels attached to performing MRI on these patients, certain measures should be placed under consideration to ensure that the effects are significantly reduced (Jin, 2007). How to prevent Radiofrequency burns from tattoos: To prevent radiofrequency burns from tattoos there are certain steps that can be taken to facilitate this. Some of these may include the following: Providing the staff members with education regarding preparation of patients, especially those having tattoos in their bodies. The education should also include various types of tattoos and best ways through which they can be handled in cases where the patient has to go through MRI examination. Before to the examination, patients should fill in scanning questionnaire (Durbridge, 2011). This is meant to find more personal information about their experiences and health information. The questionnaire will be helpful in making the patient provide more information that is necessary for patient preparation for the scanning (Maya, 2008). At the same time, the questionnaire may help in bringing to light certain past medical scan examination and how the tattooed region was handled during the entire process. Below is a sample of the questionnaire that is to be filled by the patient (pls leave this one highlighted I will add the sample of questionnaire) The most common way of preventing the occurrence of Radiofrequency burns is through application of a wet cloth on the area to be scanned (Durbridge, 2011). Other cool substances can be used to prevent the occurrence of these and may include items such ice block pieces. Most MRI machines also have alarm systems and microphones through which the patients can raise alarm in case he/ she feels unnecessary heat. This is meant to alert the technician of any impending danger (Kuperman, 2009). 5.3 Radiofrequency burns from Jewellery and metallic substances Jewellery and metallic substances can heat up and cause motion when the radiofrequency pulse is applied on them. This heating up and motion is very dangerous to the patients and can cause adverse results in terms of thermal injury (Gellissen et al. 2009). The process of heating up causes burns and soreness on the skin, which in the long run affects the patients. How to prevent Radiofrequency burns from Jewellery and metallic substances: There are certain ways through which these radiofrequency burns from jewellery and metallic substances can be reduced. They include the following: The staff must be educated on the correct patient preparation procedures in cases where jewellery and metallic substances are found in the body. Relatively, the education of staff should involve the best ways to keep the jewellery and metallic substances that are found with the patients (Bendel, 2008). A number of patients often complain of losing their expensive and costly jewelleries while undergoing MRI tests Similarly, keeping them safe will shield them from the magnetic attraction inside the MRI room hence preventing any looming danger that they may cause to people working or patients in the room. Patients intending to go for MRI should complete the scanning questionnaire. In cases involving children and elderly people, consent from parents or a relative should be sought and such should help them fill out the questionnaire. A short interview should also follow the questionnaire and should focus mainly on the medical history of the patient (Hall, 2008). There are however instances where a patient may be having metallic substances in the body which cannot permit performance of MRI procedures. For instance, the patient may have cardiac pacemaker, in such a case, the technician may recommend x-ray or other scan procedure since the radiofrequency pulse would affect such gadgets in the body (Shellock, 2007). To prevent the occurrence of radiofrequency burns, caution needs to be taken depending on the nature of metallic substance on the body and the ability to remove such. In case the metallic substance or the jewellery cannot be removed from the patients’ body, insulation of the substance is recommended so as to detach it, separate from the other parts of the body (Shellock, 2007). They should be wrapped as much as possible with an insulating material that will prevent the effects of the radiofrequency pulses from causing them to heat up. 6. Conclusion Despite the MRI processes and procedures being safe, certain cautions need to be taken since the process may not guarantee total safety under certain circumstances. Radiofrequency burns are prevalent during MRI scans and the patients need to take extreme caution to ensure that such do not affect them. References Abel, G. (2013). Radiofrequency in MRI machine. Nature, 501(7466), 138-139. Bendel, P. (2008). Method to eliminate the effects of magnetic field inhomogeneities in NMR imaging and apparatus therefor. Magnetic Resonance Imaging, 5(5), IV-V. Bronson, J. G. (2006, August 1). 3T MRI: ready for prime time? The benefits of 3-Tesla MRI have been established, but its physics mandate protocol revisions.(Magnetic resonance imaging). Medical Imaging, 3, 5. Bushong, S. C. (2009). Magnetic resonance imaging: physical and biological principles (2nd ed.). St. Louis: Mosby. Drobnjak, I., Pell, G. S., & Jenkinson, M. (2010). Simulating the effects of time-varying magnetic fields with a realistic simulated scanner. Magnetic Resonance Imaging, 28(7), 1014-1021. Durbridge, G. (2011). Magnetic Resonance Imaging: Fundamental Safety Issues. Journal of Orthopaedic and Sports Physical Therapy, 41(11), 820. Fayad, Z. A. (2007). Magnetic Resonance Imaging . Topics in magentic resonance imaging and causes of RF burns, 18(5), 317. Gellissen, J., Axmann, C., Prescher, A., Bohndorf, K., & Lodemann, K. (2009). Extra- and intracellular accumulation of ultra small super paramagnetic iron oxides (USPIO) in experimentally induced abscesses of the peripheral soft tissues and their effects on magnetic resonance imaging. Magnetic Resonance Imaging, 17(4), 557-567. Hall, W. A. (2008). Magnetic Resonance Imaging in Neurointervention. Topics in magnetic resonance imaging, 19(4), 177. Health and beauty close-up. (2010, November 30). Positive and negative MRI effects on patients. UBC Research Centre . Health and Beauty Close-Up, 2, 6. Hernes, P. (2008). Magnetic Resonance Imaging and effects of Radiofrequency pulses. Topics in magnetic resonance imaging, 5(2), 69. Jin, J. (2007). Electromagnetic analysis and design in magnetic resonance imaging. Boca Raton: CRC Press. Journal of Engineering. (2012, September 12). Patent Issued for Superconductor Magnetic Resonance Imaging System and Method (Super-MRI). Journal of Engineering, 6, 6. Kanal, E., & Wolf, G. L. (2008). Heat deposition effects in nuclear magnetic resonance imaging in 550 patients. Magnetic Resonance Imaging, 4(2), 139. Kuperman, V. (2009). Magnetic resonance imaging physical principles and applications. San Diego: Academic Press. Li, G., Ng, M. C., Wong, K. K., Luk, K. D., & Yang, E. S. (2007). Spinal effects of acupuncture stimulation assessed by proton density-weighted functional magnetic resonance imaging at 0.2 T. Magnetic Resonance Imaging, 23(10), 995-999. Maya, B. (2008). Functional MRI and effects of Radiofrequency pulses. London: Enslow Publishers. MRI Database. (2012, February 9). MRI Database. Magnetic Resonance TIP -. Retrieved April 22, 2014, from http://www.mr-tip.com/serv1.php?type=db1&dbs=Specific+Absorption+Rate Olsen, R. G., Schneider, J. B., & Tell, R. A. (2011). Radio Frequency Burns in MRI machines. Magnetic Resonance Imaging effects, 26(1), 352-359. Perrin, A. (2012). Electromagnetic fields, environment and health. Paris: Springer. Robitaille, P., & Berliner, L. J. (2009). Ultra high field magnetic resonance imaging. New York, NY: Springer. Shellock, F. G. (2007). Magnetic Resonance Procedures Health Effects and Safety.. Hoboken: CRC Press. Stokar, S. (2007). Reducing the effects of coherence in magnetic resonance imaging. Magnetic Resonance Imaging, 10(4), II. Truong, T., Chakeres, D. W., Beversdorf, D. Q., Scharre, D. W., & Schmalbrock, P. (2009). Effects of static and radiofrequency magnetic field inhomogeneity in ultra-high field magnetic resonance imaging. Magnetic Resonance Imaging, 24(2), 103-11 Read More

The local magnetic properties described above are created by electric current passed across the coils. After establishment of the magnetic field around the body, the machine can then acquire the preferred images through transmission and reception of radio waves sent through the transmitter. The signals are then used to generate images that will help with the desired analysis. The magnetic force produced by the MRI often induce the hydrogen atoms within the body tissues to line up in a given direction.

The radio frequency used in the MRI machines are always specifically meant for hydrogen atoms, thus when the radio frequency pulse is released directed towards a specific area, the protons within that area absorb energy, which causes them to spin in some direction (Weekly News, 2014, February 27&Robitaille & Berliner, 2009). One property of the Radiofrequency (RF) is that they do not have a tendency of penetrating deeper into the electrical conductors; however, they always flow along their surfaces causing what is known as skin effect.

Thus, when human body gets in contact with the high power radiofrequencies, they can cause surface burns otherwise known as RF burns on the skin of the affected patient. Turning off the radio frequency pulse causes the hydrogen protons to gain their natural alignment slowly in the magnetic field. At the same time, they release the excess energy stored in them, and during this time, the MRI picks up signals given by the protons and sends them to the computer (Bendel, 2008). The computer system upon reception of the data can convert the data into an image, which can be put on film. 2. Radio frequency effects As discussed above, the effects of radiofrequency are often minimal, but their occurrence cannot be assumed.

There are two ways through which radiofrequencies effects may resurface on the patient’s body, these are in the deposition of energy produced by the radio frequencies into the tissues, as well as the possibility of the patients developing burns (Fayad, 2007). Radiofrequency usually produces heat during its transmission. The radiofrequency power transmitted causes a series of activities, which include fast spin of echo pulse sequences and transfer of magnetic pulses; these activities are translated into heat in the body of the patient.

This heating can be dangerous if not controlled and can cause adverse effects to the patient if no special care is taken. Different health conditions are likely affect the ability of an individual’s body to tolerate thermal changes. Such conditions may include hypertension, fever, diabetes, cardiovascular disease, skin disease, obesity and other forms of medication can effectively alter the body’s thermoregulatory abilities therefore their bodies may not respond appropriately to the heat produced (Stokar, 2007).

The presence of any of the above health conditions makes the patient vulnerable to the effects resulting from the MRI radiofrequencies. A patient should therefore be examined for the presence of any of the above health conditions before they are placed under the MRI machine for imaging. Most energy transmitted by the radiofrequency pulse is often absorbed into the body tissues of the patient mainly in the form of heat. However, the body naturally responds to this by dispersing the extra heat through radiation, convection and conduction to help in maintaining a normal body temperature (Durbridge, 2011).

The sum of energy deposited per unit mass is referred to as specific absorption rate (SAR), and is calculated in Watts per kilogram (W/kg). The MRI system is tuned to perform the specific absorption rate (SAR) for every patient that is in the machine and this helps in regulating the energy deposited in the body tissues. Many clinical scanners have been installed with configurations that enable them give a warning when the normal SAR levels are exceeded. These are most importantly helpful in ensuring that such heat absorption does not rise above the temperatures that can easily harm the body.

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