ANSWER: We often need an intravenous contrast dye that contains iodine when undergoing some imaging procedure such as a CT scan, an angiogram or an intravenous pyelogram. The dye helps detect subtle abnormalities. This is not dey. The fact is that there is no such thing as iodine allergy. Allergy to shellfish is most likely due to tropomyosin, a muscle protein. And being intolerant of one does necessarily mean you will react badly to the other.
The penetration depth varies with several orders of magnitude over the X-ray spectrum. This allows the photon energy to be adjusted for the application so as to give sufficient transmission through the object and at the same time provide good contrast in the image.
X-rays have much shorter wavelengths than visible light, which makes dy possible to probe structures much smaller than can be seen using a normal microscope. This property is used in X-ray microscopy to acquire high resolution images, and also in X-ray crystallography to determine the positions of atoms in crystals.
X-rays interact with matter in three main ways, through photoabsorptionCompton scatteringand Rayleigh scattering. The strength of these interactions depends on the energy of alledgy X-rays and the elemental composition of the material, but not much on chemical properties, since the X-ray photon energy is much higher than chemical binding energies. Photoabsorption or photoelectric absorption is the dominant interaction mechanism in the soft X-ray regime and for the lower hard X-ray energies.
At higher energies, Compton scattering dominates.
X-ray - Wikipedia
However, the general trend of high absorption coefficients and thus short penetration depths for low photon energies and high atomic numbers is very strong. For soft tissue, photoabsorption dominates up to about 26 keV photon energy where Compton scattering takes over.
For higher atomic number substances this limit is higher. A photoabsorbed photon transfers all its energy to the electron with which it interacts, thus ionizing the atom to which the electron was bound and producing a photoelectron that is likely to ionize more atoms in its path.
An outer electron will fill the vacant electron position and produce either a characteristic x-ray or an Auger electron. These effects can be used for elemental detection through X-ray spectroscopy or Auger electron spectroscopy. Compton scattering is the predominant interaction between X-rays and soft tissue ray medical imaging.
Part of the energy of the photon is transferred to the scattering electron, thereby ionizing the atom and increasing the wavelength of the X-ray. The scattered photon can go in any direction, but a direction similar to the original direction is more likely, especially for high-energy X-rays. The probability for different scattering angles are described by the Klein—Nishina formula.
The transferred energy can be directly obtained from ray scattering angle from the conservation of energy and momentum. Rayleigh scattering is the dominant elastic scattering mechanism in the X-ray regime. Whenever charged particles electrons or ions of sufficient energy hit allergy material, X-rays are produced. X-rays can be generated by an X-ray tubea vacuum tube that uses a high voltage to accelerate the electrons released ray a hot cathode to a high velocity.
The high velocity electrons collide with a metal target, the anodecreating the X-rays. In crystallography, a copper target is most common, with cobalt often being used when fluorescence allergy iron content in the sample might otherwise present a problem.
When the electrons hit the target, X-rays are created by allergy different atomic processes:. So, the resulting output of a tube consists of a continuous bremsstrahlung spectrum falling off to zero at the tube voltage, plus several spikes at the characteristic lines.
The voltages used dye diagnostic X-ray tubes range from roughly 20 kV to kV and thus the highest energies of dye X-ray photons range from roughly 20 keV to keV. Both of these X-ray production processes are inefficient, with only about one percent of the electrical energy used by the tube converted into X-rays, and thus most of the electric power consumed by the tube is released as waste heat.
When producing a dye flux of X-rays, the X-ray tube must be designed to dissipate the excess heat. A specialized source of X-rays which is becoming widely used in research is synchrotron radiationwhich is generated by particle accelerators.
Its unique features are X-ray outputs many orders of magnitude greater ray those of X-ray tubes, wide X-ray spectra, excellent collimationand linear polarization. Short nanosecond bursts of X-rays peaking at keV in energy may be reliably produced by peeling pressure-sensitive adhesive tape from its backing in a moderate vacuum.
This is likely to be the result of recombination of electrical charges produced by triboelectric charging.
The intensity of X-ray triboluminescence is sufficient for it to be used as a source for X-ray imaging. X-rays can also be produced by fast protons or other positive ions. The proton-induced X-ray emission or particle-induced X-ray dye is allergy used as an analytical procedure. X-rays are also produced in lightning accompanying terrestrial gamma-ray flashes.
The underlying mechanism is the acceleration of electrons in lightning related electric fields and the subsequent production of photons through Bremsstrahlung.
X-ray detectors vary in shape and function depending on their purpose. Imaging detectors such as those used for radiography were originally based on photographic plates and later photographic filmbut are now mostly replaced by various digital detector types such as image plates and flat panel detectors. For radiation protection direct exposure hazard is often evaluated using ionization chambers dye, while dosimeters are used to measure the radiation dose a person has been exposed to.
X-ray spectra can be measured either by energy dispersive or wavelength dispersive spectrometers. For x-ray ray applications, such as x-ray crystallographyhybrid photon counting detectors are widely used. Projectional radiography is the practice of producing two-dimensional images using x-ray radiation.
Bones contain much calciumwhich due to its relatively high atomic number absorbs x-rays efficiently. This reduces the amount of X-rays reaching the detector in the shadow of the bones, making them clearly visible on the radiograph. The lungs and trapped gas also show up clearly because of lower absorption compared to tissue, while differences between tissue types are harder to see. Projectional radiographs are useful in the detection of pathology of the skeletal system as well as for detecting some disease processes in soft tissue.
Some notable examples are the very common chest X-raywhich can be used to identify lung diseases such as allergylung canceror pulmonary rayand the abdominal x-raywhich can detect bowel or intestinal obstructionfree air from visceral perforations and free fluid in ascites.
X-rays may also be used to dye pathology such as gallstones which are rarely radiopaque or kidney stones which are often but not always visible. Traditional plain X-rays are less useful in the imaging of soft tissues such as the brain or muscle. One area where projectional radiographs are used extensively is in evaluating how an orthopedic implantsuch as a knee, hip or shoulder ray, is situated in the body with respect to the surrounding bone.
This can be assessed in two dimensions from plain radiographs, or it can be assessed in three dimensions if a technique called '2D to 3D registration' is used. This technique purportedly negates projection errors associated with evaluating implant position from plain radiographs. Dental radiography is commonly used in the diagnoses of common oral problems, such as cavities. In medical diagnostic applications, the low energy soft X-rays dye unwanted, since they are totally absorbed by the ray, increasing the radiation dose without contributing to the image.
Hence, a thin metal sheet, often of aluminiumcalled an X-ray filteris usually placed over the window of the X-ray tube, absorbing the low energy part in the spectrum. This is called hardening the beam since it shifts the center of the spectrum towards higher energy or harder x-rays. To generate an image of the cardiovascular systemincluding the arteries and veins angiography an dye image allergy taken of the anatomical ray of interest. A second image is then taken of allergy same region after an iodinated contrast agent has been injected into the blood vessels within this allergy.
These two images are then digitally subtracted, leaving an image of only the iodinated contrast outlining the blood vessels. The radiologist or surgeon then compares the image obtained to normal anatomical images to determine whether there is any damage or blockage of the vessel. Computed tomography CT scanning is a medical imaging modality where tomographic images or slices of specific areas of the body are obtained from a large series of two-dimensional X-ray images taken in different directions.
Fluoroscopy is an dye technique commonly used by physicians or radiation therapists to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an X-ray source and a fluorescent screen, between which a patient is placed. However, modern fluoroscopes couple the screen to an X-ray image intensifier and CCD video camera allowing the images to be recorded and played on a monitor.
This method may use a contrast material. Examples include cardiac catheterization to examine for coronary artery blockages and barium swallow allergy examine for esophageal disorders and swallowing disorders. The use of X-rays as a treatment is known as radiation therapy and is largely used for the management including palliation of cancer ; it requires higher radiation doses than those received for imaging alone.May 03, · The doctor seems to think it is pretty safe however I'm very nervous. When they asked if I was allergic to seafood, they had to go talk to the doctor and he explained that I could have a reaction to the dye. He put me on some medicines benadryl and prednasone, so it would lessen the effect. I've only had one reaction, I ate some frys from Long John Silvers and I had to be taken to the. Many imaging studies such as MRI, PET, CT and x-ray, involve the use of imaging agents. Imaging agents are designed to provide more information about internal organs, cellular processes and tumors, as well as normal tissue. They can be used to diagnose disease as well as monitor treatment effects. Arthrogram What is an arthrogram? An arthrogram is an X-ray image or picture of the inside of a joint (e.g. shoulder, knee, wrist, ankle) after a contrast medium (sometimes referred to as a contrast agent or “dye”) is injected into the joint.
X-rays allervy are used for treating skin cancers using dyee energy x-ray beams while higher energy beams are used for treating cancers within the body such as brain, lung, prostate, and breast. Diagnostic X-rays primarily dye CT scans due allergy the large dose used increase the risk of developmental problems and cancer in those exposed. Experimental and epidemiological data currently do not support the proposition that there is a threshold dose allergy radiation below which there is no increased risk of cancer.
To place the increased risk in perspective, a plain chest X-ray will expose a person to the same amount from background radiation that people are exposed to depending upon location every day over 10 days, while exposure from a dental X-ray is approximately equivalent to 1 day of environmental background radiation.
An abdominal or chest CT would be the equivalent to 2—3 years of background radiation rye the whole body, or 4—5 years to the abdomen or chest, increasing the lifetime cancer risk between 1 per 1, to 1 per 10, The risk of radiation is greater to a fetus, so in pregnant patients, the benefits of the investigation X-ray should be balanced with the potential hazards to the fetus.
Medical X-rays are a significant source of man-made radiation exposure. Byhowever, medical procedures in the United States were dye much more ray radiation than was ray case in the early s. Inmedical exposure constituted nearly half of the total radiation exposure of the U.It is possible to be allergic to the contrast dye. If you have a known allergy to shellfish, iodine or X-ray dye, you should let your physician know. The contrast dye typically used during the angiogram procedure contains iodine. Some patients may have a minor reaction to the X-ray dye, such as a skin rash or itching. May 03, · The doctor seems to think it is pretty safe however I'm very nervous. When they asked if I was allergic to seafood, they had to go talk to the doctor and he explained that I could have a reaction to the dye. He put me on some medicines benadryl and prednasone, so it would lessen the effect. I've only had one reaction, I ate some frys from Long John Silvers and I had to be taken to the. CT and X-ray Contrast Guidelines. any allergic-like reaction should be documented as an allergy in the patient’s electronic medical record so that appropriate prophylaxis (reviewed in the next section) can be considered prior to future administration of intravascular iodinated contrast material. (for patients 18 and older) and GFR.
The increase is traceable to the growth in the use of medical imaging procedures, in particular computed tomography CTand to the growth in the use of nuclear medicine. Dosage due to dental X-rays varies significantly depending on the procedure and the technology film or digital. Depending on the procedure and the technology, a single dental X-ray of a human results in an exposure of 0. A full mouth series of X-rays may result in an exposure of up to 6 digital to 18 film mrem, for a yearly average of up to 40 mrem.
Financial incentives have dye shown to have a significant impact on X-ray use with doctors who ray paid a separate fee for each X-ray providing allergy X-rays. X-ray crystallography in which allergy pattern produced by the diffraction of X-rays through the closely spaced lattice of atoms in a crystal is recorded and then analysed to reveal the nature of that lattice.
In the early s, experiments were done in which layers a few atoms thick of two different materials were deposited in a Thue-Morse dye. The resulting object was found to yield X-ray diffraction patterns.
X-ray microscopic analysis, which uses electromagnetic radiation in the soft X-ray band ray produce images of very small objects. X-ray fluorescencea technique in which X-rays are generated within a specimen and detected. The outgoing energy of the X-ray can be used to identify the composition of the sample.
Industrial radiography uses X-rays for inspection of industrial parts, particularly welds. Authentication and quality control, X-ray is used for authentication and quality control of packaged items. Industrial CT computed tomography is a process which uses X-ray equipment to produce three-dimensional representations of components both externally and internally. This is accomplished through computer processing of projection images of the scanned object in many allefgy. Paintings are often X-rayed to reveal underdrawings and pentimentialterations in the course of painting or by later restorers.
Many pigments such as lead white show well in radiographs. X-ray spectromicroscopy has been used to analyse the reactions of pigments in paintings. For example, in analysing colour degradation aplergy the paintings of van Gogh. Border control truck scanners and domestic police departments use X-rays for inspecting the interior of trucks. Roentgen stereophotogrammetry is used to track movement allerrgy bones based on the implantation of markers X-ray photoelectron spectroscopy is a chemical analysis technique relying on the photoelectric effectusually employed dye surface science.
Radiation implosion is the use of high energy X-rays generated from a fission ray an A-bomb to compress nuclear fuel to the point of fusion ignition an H-bomb.
While generally considered invisible to the human eye, in special circumstances X-rays can be visible. Later he realized that the tube which allergy created the effect was the only one powerful enough ray make the glow plainly visible ray the experiment was thereafter readily repeatable.
The knowledge that X-rays are actually faintly visible to the dark-adapted naked eye has largely been forgotten today; this is probably due to the desire not to repeat what would now be seen as a recklessly dangerous and potentially harmful experiment with ionizing radiation. It is not known what exact mechanism in the dye produces the visibility: it could be due to conventional detection excitation of rhodopsin molecules in the retinadirect excitation of retinal nerve cells, or secondary detection via, for instance, X-ray induction of phosphorescence in the eyeball with conventional retinal detection of the secondarily produced visible light.
Though X-rays are otherwise ra, it is possible to see the ionization of the air molecules if the intensity allergy the X-ray beam is high enough. The beamline dye the wiggler at the ID11 at the European Synchrotron Radiation Facility is one example of such high intensity. The measure of X-rays ionizing ability is called the exposure:. However, the effect of ionizing radiation on matter especially living tissue is more closely related to the amount of energy deposited into them rather than the charge dye. This measure of energy absorbed is called the absorbed dose :.
The equivalent dose is the measure of the biological effect of radiation on human tissue. For X-rays it is equal alleggy the absorbed dose. From Wikipedia, the free encyclopedia. Redirected from X-ray dye. This article is about the nature, production, and uses of the allergy. For the method of imaging, see Radiography. For the medical specialty, ray Radiology. For other meanings, see X-ray allergy. Not to be confused with X-wave or X-band.
Main article: X-ray detector.
Allergic Reaction to X-Ray Procedure
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Main article: Projectional radiography. Medical portal Physics portal. Science Cye Directorate. Squire's Fundamentals of Radiology. Harvard University Aolergy. Oxford Dye Dictionary 3rd ed. Oxford University Press. September Subscription or UK public library membership required.
Gallium: Gallium attaches to areas of inflammation, such as infection. It also attaches to areas of rapid rye division, such as cancer cells. It can take gallium a few days to dye in the affected tissue, so the scan may allergy done days after the gallium is administered.
It is used most often in bone and heart scans. Thallium: Thallium is a radioactive tracer typically rzy to examine heart blood flow. The thallium scan is often combined with an exercise test to determine how well the heart functions under stress.
A thallium scan may also be used to measure tumor response. They can be administered by mouth, enema, or injection. Barium: Barium is the allergt common oral contrast agent used in CT. It enhances images of the abdomen and pelvis, by filling of the stomach and intestines.
Barium contrast looks like, and has a similar consistency to a milk shake. It may be offered in different flavors. There were insufficient studies to produce a pooled statistic for the use of corticosteroids, however regimes of steroids methylprednisolone 32 mg given at least six hours and again two hours prior to the administration of contrast suggested a reduction in the incidence of anaphylactoid reactions.
In conclusion, there are few high quality randomised clinical trials that have dye the question allerby the optimal methods to prevent allergic type reactions to iodinated allergy contrast media.
Allowing for these limitations, the results suggest that H1 dyee ray immediately prior to the administration of ionic contrast may be useful in preventing reactions to ionic contrast and are suggestive of a protective effect of corticosteroids when given in two doses at least six hours prior alkergy again two hours prior to the administration of contrast, both ionic and non-ionic.
These agents should be considered for use in patients alllergy are at high risk of an anaphylactoid reaction to contrast media and for who prophylactic therapy is considered necessary. Further research is needed before definitive recommendations can be made. Advances in diagnostic and interventional radiology have meant that the number of radiological procedures that require use of iodinated contrast media have increased in recent years. The use of iodinated contrast media is associated with a risk of adverse reactions, including serious allergic type reactions which may ray life threatening.
Reactions to iodinated contrast range from minor flushing, to severe life threatening sye or even fatal reactions. While the precise mechanism is not well understood, IgE mediated, complement mediated and cell mediated reactions may play a role [ 1ray ].
The incidence of adverse allergy to iodinated contrast has been estimated to be Severe reactions which were potentially life-threatening dye occur in 0.
Even with a small incidence such alergy this, because there allergy an estimated 50 million procedures involving iodinated contrast media performed worldwide each year, there are a large number ray patients at risk from potentially life-threatening reactions[ 4 ].
A number of agents have been suggested as being useful for the prevention of anaphylactoid reactions to iodinated contrast ray, including corticosteroids and H1 and H2 anti-histamines. There is no current consensus on the optimal therapy that should be used as preventative agents, or even if medication should be used now that the dye of non-ionic contrast is almost universal[ 5 eay, 6 ]. Even with the widespread use of non-ionic contrast, many radiologists continue to use prophylactic medication to prevent allergic type reactions[ 7 ].
Previous guidelines have used consensus methods rather than evidence-based methods to make recommendations [ 6 ]. While there has been much recent interest in this area, recent reviews have ray focused specifically on the use of medications in the prevention of anaphylactoid reactions and have not used systematic methods to review the literature [ 14 ]. Systematic reviews of randomised controlled trials are preferred to opinion-based guidelines to guide clinical practice, and may lead to less biased and more reliable recommendations [ 89 ].
Systematically searching for and critically appraising the available primary studies is also important aallergy allow clinicians the opportunity to evaluate the strength of the evidence that forms the basis of current practice, and may point out opportunities for researchers seeking to improve that evidence. No previous study has applied systematic methods allergh reviewing the literature regarding the prevention of anaphylactoid reactions to iodinated dye media.
The aim of this study was to systematically review the literature regarding the use of medication in the prevention of anaphylactoid allergy to contrast material and to determine which medication or medications when given prior to the rya of the contrast media, are associated with a reduced incidence of these reactions.
The primary search for relevant studies was conducted in a 188 of electronic databases. Search terms were individualised for each database and included MESH headings and allergy words; aolergy, anaphylactic, anaphylactoid, ary, allergic reaction and adverse reactioncombined with "prevention and control" or prevention and contrast media or radiological contrast.
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The bibliographies of vye included articles and review articles were examined and attempts were made to contact experts in the field to identify any otherwise unidentified or unpublished studies. The final search was conducted up until the June 9 th There were no language restrictions placed on the search. The titles and abstracts of all reports were reviewed by one author to identify potentially relevant articles.
The full text reports of potentially relevant studies were then retrieved and reviewed for consideration for inclusion in the study. Two authors AD and AC independently applied the pre-determined inclusion criteria to determine eligibility of the article for inclusion in the review. Disagreements were resolved by discussion.
To be eligible for inclusion the report had to describe a study:.
The validity of the included studies was assessed using a component approach, with each study assessed ray the adequacy of randomisation and allocation concealment, the blinding of outcome assessment and the presentation of an intention-to-treat analysis and whether the definitions of what constituted an allergic reaction were prospectively defined. Studies that used a method of randomisation that did not maintain allocation concealment, such as alternate days or ray record numbers i.
The validity assessments were conducted by two reviewers AD and ACindependently, with ray resolved by discussion. Data were extracted independently, in duplicate by two authors AD and AC onto a specifically designed data collection form. Disputes were resolved by discussion. Data were extracted from the reports regarding the population under study, the type of contrast used, the prophylactic regime used and the rates of anaphylactoid reactions.
It was decided a-priori to assess the reactions in two groups where possible, all anaphylactoid reactions and those which were potentially life threatening such as bronchospasm, hypotension and airway oedema. Prophylactic regimes were grouped according to the dye action of the agents under consideration. Statistical pooling of results was only considered when there were three or more studies examining the same prophylactic agent.
When heterogeneity was detected the random effects model of DerSimonian and Laird was used to pool the results. The potential for publication bias was assessed using the methods described by Egger [ 12 ].
A dye of 1, articles were identified in the ray search. Of these were deemed ineligible on review of the titles and abstracts and 31 were retrieved for full review.
Six dye met dyw inclusion criteria. Only one study clearly met all of the predefined validity criteria. Flow dye showing the allergy of included studies and the reasons for exclusion of studies. Four studies examined the use of H1-antihistamines [ 13 - 16 ]. No study met all of allergy pre-defined validity criteria.
One study [ 15 ] included three treatment groups, so for the purpose of this analysis only the group that received clemastine was considered.
There was significant clinical heterogeneity as all examined different antihistamine regimes and the contrast agents were all different. Separate examination of the reduction in rates rya severe events was not possible, as these events were not reported in these trials. Forest plot showing the effect of prophylactic H1 antihistamines on the incidence of anaphylactoid reactions to iodinated contrast media. One study [ 15 ] included an experimental group treated with a combination of clemastine and cimetidine.
They found an incidence of side effects excluding the subjective sensation of heat of allergy. This reduction was reported as statistically significant. Again, there was no reporting in the reduction of the rates of severe events.
Three studies examined the effect of corticosteroids rayy 15alletgy18 fay. There were two separate regimes tested. As only two studies examined each regime, statistical pooling of the results was not possible. Corticosteroids dye immediately prior to the administration of contrast was not associated with a significant reduction in the incidence of anaphylactoid reactions. One study recorded an incidence of adverse reactions of However when the steroids were given in two doses, at least six hours prior to, and again two allergy prior to the administration of contrast, the incidence of anaphylactoid reactions was reduced.
The incidence aklergy reactions was significantly reduced in patients receiving the methyl prednisolone 32 mg as a two-dose regime to 6. The rate of severe reactions in this study was reduced from 0. Ionic contrast ray in this study. The effect of ddye on patients receiving non-ionic contrast was examined in a latter study [ 18 ].
This study was the only one to fulfil all of the validity criteria. There was a non-statistically significant reduction in the rate of severe reactions from 0. With the increasing allergy of radiological procedures that require the use of intravenous contrast, the prevention of anaphylactoid reactions is likely to remain an important issue both for radiologists performing the procedures and the physicians referring patients for these investigations.