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Expert Speak

Advances in X-ray Imaging

Imaging investigations are paving the way for less invasive diagnosis of health problems. While describing some exciting advances in Diagnostic Radiology, Dr Jayaraj Govindaraj also clears patient doubts on a simple diagnostic test: the x-ray.

  • Advances in Radiology

  • What is an X-ray?

  • Why is an X-ray Necessary?

  • Different Types of X-rays

  • X-ray Safety
  • As the chief of Diagnostic Radiology in a leading hospital, and in touch with recent advances in the field, what are the innovations that you find exciting?

    Diagnostic Radiology in moving into realms of great promise. Thanks to these, investigative procedures can be made less invasive. That is, we need to rely less on surgical procedures that are performed just to find out what the problem is.

    Two major radiographic innovations that I find exciting are the PET Scan and MR Spectroscopy.

    PET Scan

    PET stands for Positron Emission Tomography. It is a kind of Computer Tomography, that can show in brilliant colour the working regions of the brain, while it is working (real time). That is, when an activity is being performed PET shows which part of the brain is related to this and how much harder it is working than the other parts of the brain.

    Doctors are able to get valuable information on many neurological diseases such as Alzheimer's disease, dementias, Parkinson's disease, Huntington's disease, and Down's Syndrome through PET Scans. Even tiny tumours can be detected. However, we are yet to get PET Scanners in India. Currently patients are being referred to place like Manila, if this type of scanning is required.

    MR Spectroscopy

    MR or MRS stands for Magnetic Resonance Spectroscopy. An MR Image is a high-quality image that is created through the combination of a magnetic field and radio waves.

    MRS can measure non-invasively the biochemical constituents of living tissue. This is very useful in finding out about tissue abnormalities. Formerly, the only way of studying tissue was getting a scraping of it and studying it under a microscope in a lab. MR allows the radiologist to study it directly from the patient. In some cases biopsies can be avoided or biopsy findings can be confirmed by using MRS. MRS studies are valuable in evaluating brain tumours, dementia, head trauma etc.

    Computerization has impacted healthcare in many ways. Has this added value to Radiology?

    There are benefits to radiology also. Images can now be digitized. Instead of using conventional film, electronic devices are used to capture images. These can be viewed on a computer or TV monitor. The images are sharper and can be manipulated. This can contribute to more efficient radiography.

    The X Ray

    What, actually, is an X ray?

    X-rays are a type of electromagnetic radiation. They are invisible and create no sensation when they pass through the body.

    X rays are used to view internal organs and structures of the human body.

    X rays were used at first in the year 1896 and over the years has proved to be a very useful and simple diagnostic test. Images interpreted by a trained person, that is, a radiologist, helps a physician to treat the patient effectively.

    What parts of the body can be x rayed?

    Almost any part of the body can be subjected to X Ray imaging. Apart from bones, parts like kidneys, teeth and jaws, and even the fine structures of the ear, nose and throat can be examined.

    What are the black, white and grey regions of the x ray?

    The x-ray is a negative image.
    The black areas represents soft human tissue that lets the rays pass through.
    Examples: Lungs, The air spaces within the bowel (in an abdominal x-ray)
    The white areas represent dense human tissues that do not let the x rays to pass through.
    Example: bones.
    The grey areas are tissues that allow part of the x ray to pass through.
    Examples: Liver, kidney, muscle.

    The final image is a composite shadow of the passage of the shadow through the human body. When there is an irregularity in the pattern of the image the doctor is able to diagnose the problem.

    What do the markings PA View etc on the x ray film mean?

    Different letters or markings are made on the x ray image intentionally. These indicate angle from which the body has been imaged or the side of the body (Left or right) or patient detaisl.

    “PA View “ is one of the markings made to indicate the angle from which the body part has been viewed. “PA View” means a frontal view.

    Why is an X ray necessary for me?

    Physicians request for an x ray as it is an inexpensive, simple and harmless investigative tool that can identify simple problems in most body parts. This is a first line investigative tool to explore the possible problems a patient may have.

    Will it yield the required diagnosis...? Will I be subjected to many additional tests...?

    A number of times the part imaged by an X ray will reveal bone/soft tissue abnormalities which will help the doctor to come to a decision regarding treatment. On some occasions this test alone will not be able to give enough evidence to diagnose a problem.

    For instance, if a person has been reporting a head ache for a long time and has not responded quite well to simple treatment. The doctor may ask for an X ray of the skull in more than one view. It may give images that seem “normal”. Then the doctor may request a CT (Computerised Tomography) Scan. Through this mode, the internal structures are seen better. An problem like sinusitis is defined better.

    Doctors prescribe an x ray as this is a simple and relatively cheaper test which can show many abnormalities. Only when the problem cannot be figured out do they go in for more expensive and complicated tests.

    If some problem is detected in an X ray, does it mean that I have to have an operation?

    Most problems can be dealt with at two levels: medical or surgical. When the medication option is not possible or may not be effective, doctors go in for surgical option.

    The answer to the question is: not always.

    What are the different types of x-ray studies?

    The following distinctions can be made about x-rays:

    Plain x-rays
    Contrast Studies
    Digital x-rays

    Contrast Studies: these are x-rays taken when a radio opaque material is ingested by the patient.

    For instance, when studying the upper gastrointestinal tract, the patient is required to swallow a radio opaque material, barium, as a thick chalky fluid. The passage of this fluid appears white on the X Ray. Abnormalities in the tract can be viewed while studying the flow of the “ barium meal”.

    Similar radio opaque material can also be introduced rectally as an enema.

    Double Contrast Studies: Here the radio opaque material is sent in along with air to further enhance the image patterns for study.

    IVP: An Intravenous Pyelogram (IVP) is a type of investigation used to study the urinary system. It shows how well your Kidneys, Ureters, and Bladder are working and finds if there are any physical defects or blockages.

    The radio opaque material is introduced intravenally. It collects in the kidneys and shows up in the x-ray.

    Contrast materials are introduced in veins (Venogram), arteries (Angiograms), spinal chord (Myelogram) and joints (Arthrograms) and x-rayed or studied dynamically.

    Digital x-rays: This is the most modern method of deriving a x-ray image. This utilizes electronic devices to capture the image instead of a film. The radiologist can directly view the image on a computer or TV monitor. The images may be further electronically manipulated.

    The images have better resolution, are sharper, easy to store and transport. However security standards are still being perfected.

    Fluoroscopy: This is like and x-ray "movie." A continuous x-ray beam is passed through the body part being examined, and is transmitted to a TV-like monitor so that the body part and its motion can be seen in detail.

    It is actually Fluoroscopy that is performed during contrast studies and IVPs as also in cardiac catheterisation.

    Can an X Ray produce an untoward reaction?

    In a simple x-ray there are no side effects.

    In x-ray investigations that require the injection of contrast material, commonly referred to as dye, this chemical can produce a reaction in some patients. Even this is uncommon. In a clinic/hospital environment this can be managed without any serious complication.

    However, x-ray units are advised to use contrast material brands that have been subjected to animal testing and human clinical trials.

    Are x-rays safe?

    Diagnostic x-rays (artificially produced x-rays) today use less energy and the procedures comply with stringent safety precautions. These do not harm the individual. Even 8-10 x-rays can be taken at one sitting, though there is rarely a necessity for so many.

    (X-rays exist in nature, emanating from outer space, rocks and the soil. Each year an average person is exposed to about 360 millirads of ionizing radiation. Of this diagnostic radiation accounts for a very small portion).

    X-ray imaging is not advised for pregnant women as there exists a potential harm to the growing foetus in the womb. Pregnant women are informed to tell their doctors about their pregnancy in case they are advised x-rays. A lead apron is worn if a pregnant woman has to necessarily take an x-ray.

    Every diagnostic centre has to conform to Government of India standards when installing an x-ray facility. This not only demands a certain quality of the x-ray images but also defines safety procedures such as:

    Optimum X-ray vault dimensions and wall thickness
    Lead lining for doors.
    Badges for staff that have in built monitors to gauge the level of exposure.
    Periodic checks on quality.

    What are the limitations of an X-ray?

    X-ray imaging depends on the difference in the x-ray absorption in the human tissue and requires a photo luminescent effect before an image is produced on radiographic film. If there are some subtle problems these cannot be captured on an x-ray film, even with contrast study.

    In these cases, if there is a strong clinical suspicion of a problem, other tests are advised.

    Dr Jayaraj Govindaraj is a Consultant in Diagnostic Radiology in the Apollo Specialty Hospital in Chennai, India.

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