Radiology – College Essay

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Humanity, constantly learning, growing,

and facing more challenges each second

of the day. Whether the challenges

are mental or purely physical. We have found more

efficient, safer, and easier ways of doing

the tasks we may face. From moving cargo, to

sending information via the Internet.

Probably the greatest accomplishments we have

made, are in the studies of medicine/treatment.

And to be specific, the study of radiology.

Radiology, the process of working and viewing

inside the human body without breaking the skin. By using radiant

energy, which may take the form of x rays or other types of radiation,

we are able to diagnose and treat many diseases and injuries. Both

diagnostic and therapeutic radiology involve the use of ionizing radiation

( Beta, Alpha, Gamma, and x rays), with the exception of the MRI, which

uses a magnetic field rather then radiation.

Radiology is classified as being either

diagnostic or therapeutic. Diagnostic radiology is an evaluation

of the body, by means of static or dynamic images or anatomy, physiology,

and alterations caused by injury or disease. A majority of these

pictures are formed by passing a low or high level of x rays through the

part of the body being examined, producing the static image on film.

This image is called a radiograph or x ray picture. The image it’s

self may have many forms. It could be a common radiograph, such as

a chest x ray; a tomograph (Greek for “section”), which is a radiograph

obtained by timing the x ray exposure to correspond with the movement of

the x ray tube and film in opposite directions around the plane of the

body; or, finally, a computerized axial tomography (CAT or CT) scan.

Which is a computer analysis of a sharply limited, thin x ray beam passed

circumferentially through an area of the body, giving the doctor of Technician

a cross-sectional image. Much like that of slicing a loaf of bread

into sections.

Other images may be obtained by using ultrasound

or MRI, or by recording the activity of isotopes internally administered

and deposited in certain parts of our body. This practice is called

nuclear radiology or nuclear medicine. This include such techniques

as a PET scan, or positron emission tomography, which uses patterns of

the positron decaying to study metabolism reactions in the body. PET requires

a cyclotron as an on-site source of short-lived, positron-emitting isotopes.

The isotopes are injected into the patient along with a glucose related

compound, and the positrons collide with the electrons in the body

to produce photons. The photons are then tracked by a tomographic

scintillation counter, and the information is processed by a computer to

provide both image and data on blood flow and metabolic processes within

bodily tissues. PET scans are particularly useful for diagnosing

brain tumor and the effects of strokes on the brain, along with various

mental illnesses. They are also used in brain research and in mapping of

brain functions.

Another form of imaging is ultrasound.

Ultrasound, which uses very high frequency sound, is directed into the

body. And because the tissue interference’s reflect sound, doctors

are able to produce, by use of a computer, a photograph or moving image

on a television. Ultrasound has many application uses on the body,

but is more commonly used in examinations of the fetus during pregnancy,

because use of radiation may affect the outcome of the baby. Some

other practices for ultrasound include examination of the arteries, heart,

pancreas, urinary system, ovaries, brain, and spinal cord. And because

sound travels well through fluids it is a very useful technique for diagnosing

cysts( which are filled with fluid), and fluid filled structures such as

the bladder. And since sound is absorbed by air and bone it is impossible

to use a ultrasound on bones or lungs.

The sound waves are produced by a random

oscillating crystal, and are inaudible to humans. A instrument called

a transducer is used to transmit the sound waves and receive the echoes.

The transducer must be in close contact with the skin, and a jelly like

substance is used to improve the quality of the transmission.

And last of the diagnostic imaging tools

is the MRI. MRI, which stands for Magnetic Resonance Imaging.

Was a technique developed in the 1950’s by Felix Bloch, and is the most

versatile, powerful, and sensitive tool in use. The process of MRI

was originally called NRI (Nuclear Resonance Imaging), but was found to

be to confusing due to the fact that MRI’s don’t use radioactivity and

ionizing radiation. The MRI generates a very powerful electromagnetic

field, which allows the radiologist to generate thin-section images of

any part of the body. Also it can take these images from any direction

or angle, and is done without and surgical invasion. Another plus

side to the MRI is The time it take to perform, where as a CAT scan may

take 30-60 min. A MRI may only take 15 minutes max. The

MRI also creates ‘maps’ of biochemical compounds within a cross-section

of the body. These maps give basic biomedical and anatomical information

that provides new knowledge and may allow early diagnosis of many diseases.

The MRI is possible in the human body

because our bodies are filled with small biological ‘magnets’, the most

abundant and responsive of these are the protons (in the nucleus of the

hydrogen atom). The principal of the MRI, utilizes the random distribution

of protons, which have basic magnetic properties. Once the patient

is placed in the cylindrical magnet, the diagnosis process follows 3 steps.

First, MRI creates a steady state of magnetism in the body, that is 30,000

time greater then that of the earth’s own magnetic field. The rate

of absorption in the body is measure in megahertz and gigahertz ranges.

Then MRI stimulates the body with radio waves to change the steady-state

orientation of the hydrogen protons. It then Stops the radio waves

and ‘listens’ to the bodies electromagnetic transmissions at the selected

frequency. The transmitted signal is used to create images much like

those of the CAT scans, but are far more accurate and much easier to interpret.

In current practice, the MRI is preferred

for diagnosing most diseases of the brain and central nervous system.

And is the best diagnostic technique we know. It’s images, information,

and other vital information surpass that of its relatives the CAT scans,

x rays, PET scans, etc. The MRI has yet another distinguishing feature

it can determine between soft tissue in both normal and diseased states.

The only drawback to the MRI is that is relatively expensive ($2,000 dollars

session), but that may not be so bad when you account for all the money

and time you save by getting treatment and diagnosis sooner. Because

the MRI uses no radiation what-so-ever the only risk it presents is to

people who have one or more of the following: A pacemaker, neurostimulator,

implanted electrodes, pumps, or electrical devices, diabetic insulin pumps,

aneurysm clips, shunt, seizures, heart bypass surgery, abdominal injuries,

eye prosthesis, hearing aid, dentures, middle ear prosthesis, metal mesh,

wire sutures, war injuries or gunshot wounds, other known metal fragments

in head, eye, or body, known possible pregnancy, IUD’s, penile prosthesis,

joint or limb replacement, fractured bones treated with metal rods, plates,

pins, screws, nails, or clips, any other for of prosthesis, permanent eye

liner, wig, or make-up with metallic fragments.

Many organs that may not be visible by

routine radiographic methods may become visible by ingesting, installing,

injecting, or inhalation of substances. These substances are called

contrast media, which are impenetrable by radiation. Exams involving

a contrast include the upper intestine, the colon, a arthrogram ( a injection

into a joint), myelogram ( an injection into the spinal canal), and an

angiogram ( a injection of the contrast into an artery, vein, or lymph

vessel). These procedures may be observed while the they are taking

place, by fluoroscopy. Which is a movable, radiation sensitive screen.

Now That I have described static images

and the processes used to create them let me explain dynamic images and

how they are manufactured. Dynamic images, which record movement

of organs or the flow of contrast material through blood vessels or spinal

canal, may be obtained be recording the image by fluoroscopy, or by recording

on to video tape or movie film (cineradiography). Both film and the

video tape are permanent recording media. The fluoroscopic image

on the other hand isn’t. However, these images can be made permanent

( film spots), and can be made at any time during the examination.

The use of ionizing radiation in

the assessment of a disease is similar to the use of drugs and medication

in treatment of the disease. For the simple reason that radiographic

exams should only be performed for specific medical indications and only

on the direct request of a physician or another skilled professional.

And although diagnostic radiation dose levels do have a small risk potential,

no current evidence shows that properly conducted diagnostic exams have

no detectable adverse effects on our bodies. Dynamic images are used

quite frequently, but not as often as static images.

As I mentioned at the beginning of my report,

there are 2 sections of radiology. And since I just discussed diagnostic

radiology, it is time to explain a little about therapeutic radiology.

Therapeutic Radiology is used in the treatment of malignant diseases with

ionizing radiation, either alone or with drugs. This practice branches

off from the discovery of elements that occur naturally in the late 19th

century. Such treatment is often described in terms of energy of

the beam being used: superficial(less then 120 Kilovolts, orthovoltage

(l20 to 1000 kV), megavoltage (Greater then 1000 kV) Superficial

radiation is used in treatment of diseased skin, eye, or other parts of

the bodies surface. Orthovoltage therapy has almost been completely

replaced megavoltage(cobalt, linear accelerator, and betatron). Because

it provides more efficient delivery of the intended dose to tumors deep

within the body, sparing the skin and surrounding tissues as much as possible.

Radiation therapy may be used alone as

the treatment of choice in most cases of cancer of the skin; in certain

stages of cancers involving the cervix, uterus, breast, and prostate; and

in some types of leukemia and lymphoma, particularly Hodgkin’s Disease.

In such instances, radiation therapy is intended to effect a cure.

But when is use with cancer-treatment drugs it may only pose as a relief

of symptoms. Radiation therapy is commonly used before and after

surgical removal of certain tumors, in order to provide a better chance

of cure.

The idea of radiation therapy is that normal

tissues have a greater ability to recover from the effects of the radiation

more so then tumor and tumor cells. Thus, a radiation dose sufficient

to destroy tumor cells will only temporally injure adjacent normal cell.

And if the ability of normal tissue to recover from a given amount of radiation

is known to be the same as or less then that of the cancer tissues, the

tumor is described as being radio-resistant. Such forms of therapy

are not considered an appropriate form of treatment.

Well, as you can see radiology is a field

of study that deserves our uttermost attention. For the future of

humanity may one day totally rely on these processes.

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