Medical Uses

There are many uses of radiation in medicine.  The most well known is using x rays to see whether bones are broken.  The broad area of x-ray use is called radiology.  Within radiology, we find more specialized areas like mammography, computerized tomography (CT), and nuclear medicine (the specialty where radioactive material is usually injected into the patient).  Another big area of x-ray use is called cardiology – where special x-ray pictures are taken of the heart.

There are additional areas in medicine using radiation or radioactive material.  These are for treatment of disease or cancer and are commonly called therapy.  A subspecialty in nuclear medicine is nuclear medicine therapy.  A common example of nuclear medicine therapy is the use of radioactive iodine to treat thyroid problems, including thyroid cancer.  A subspecialty of oncology (the study and treatment of cancer) is radiation oncology.  As the name suggests, this area of oncology focuses on the use of radiation to treat cancer.

We’re going to take a short look at each of these with some common examples.  Something to keep in mind is that there is no limit on the number of doctor-prescribed medical exams involving radiation that a person can have.  Medical exams involving radiation are considered beneficial to the individual.  This is where you can take an active role.  It is important that you know what the exam is, what it is for, and how the results will be important to what is needed for you medically.

Radiology

Chest X Ray

A chest x ray is probably one of the most common diagnostic exams used to look at the chest, ribs, lungs, and heart.  We use the chest x ray to assure, perhaps, that the person is healthy enough to undergo surgery or to look for certain diseases like emphysema, pneumonia, or lung cancer.

Barium Enema

A barium enema helps us look at the large intestine or colon.  Most often, a barium enema is performed by putting barium into the large intestine so it can be seen on x rays.  Barium is a contrast material that is not radioactive, but simply allows the intestine to be visible on the x ray.  Watching the barium go through the intestine allows doctors to see if there are blockages or other issues.  Sometimes, after most of the barium is removed, air is put into the intestine.  The air helps fill out the intestine and with the little bit of barium still coating the intestine wall, even some small obstructions will now be visible.

Mammogram

Mammography is a type of x-ray imaging used most often to look for or diagnose breast cancer or other breast disease.  A mammogram can show even very small abnormalities and, in individuals with very dense breast tissue, these small masses can be seen up to two years before the individual can feel them.

CT Exam

Computerized tomography (CT) imaging is a technique using x rays and computer processing to generate two-dimensional pictures of the inside of the body.  The images are called “CT slices” because one image will show all things in the body in that one location.  Picture a loaf of bread.  Now picture that loaf of bread having a heart, lungs, stomach and other organs inside of it.  Take one slice of it out of the center – what do you see?  If that is a CT slice of the center of the body, we will likely see a section of the stomach, maybe some small intestine, a section of the spine, maybe some liver, and other tissues that are in the center of the body.  When more than one body slice is created, the doctor can see through an entire organ enabling the doctor to find the cause of many types of abdominal pain.

Nuclear Medicine and Nuclear Cardiology

Nuclear medicine differs from general radiology in the following respects: you are not exposed to radiation from a machine outside the body, you are administered (intravenously or by mouth) a liquid substance that is radioactive, you become radioactive for a short time, and with this radioactive substance in your body, we can actually determine if organs in the body are functioning like they should be.  In addition to organ function, we can use tests like this to look at blood flow, check respiratory function, look for infections, measure organ functions, and many other functionally related issues.

Within nuclear medicine is a group of tests that use certain types of radioactive materials and the images that are obtained from these tests are call PET scans.  PET stands for positron-emission tomography.  A positron is similar to a beta particle.  This is a specialized type of imaging that can be used for cancer detection, memory disorders, and even measuring how well certain drugs are doing to get rid of cancer. 

Cardiology

In cardiology, the most common x-ray exam is the angiogram.  During an angiogram, contrast material that is not radioactive is injected into the heart arteries so the arteries can be seen by the x rays.  The angiogram is used to find out whether there are issues with these arteries like a blockage.  In some cases, if narrowed or blocked arteries are found during the exam, a procedure called angioplasty might be done to clean out the blockage and a metal stent placed in the artery to hold it open.

Radiation Oncology

Brachytherapy

Brachytherapy is a procedure where small metal implants (usually about the size of a piece of rice) are put inside the body in or near a cancerous tumor.  Inside the small implant is some radioactive material.  The radioactive material is sealed inside the implant and cannot get out.  The implant stays in the location where it was positioned and exposes the tumor to a constant stream of radiation until the radioactivity decays away.  Sometimes the implants are temporary – the implant is inside the body only for a short period of time (24-48 hours) while the patient is hospitalized and is then removed – or it can be permanently placed in the tumor and it is safe for the patient to go home. 

Cs-137 Tubes
picture
Ir-192 ribbons
picture

I-125 seeds
picture

Linear Accelerators

A linear accelerator (also called a LINAC) is a very large device that emits high-energy x rays and electron beams.  It is the most common device used in radiation oncology for cancer treatment.  The linear accelerator x-ray or electron beam can be highly collimated so the energy is delivered to the tumor while sparing normal tissues.  A specialized type of treatment that is becoming more common with linear accelerators is called intensity modulated radiation therapy (IMRT).  The intent of IMRT is to do a better job of delivering the beam to diseased tissue without harming surrounding tissues.

Gamma Knife

The gamma knife is a highly specialized piece of equipment.  Very high doses of radiation are delivered to very small diseased areas within the head. These units are typically used to treat or reduce the effects of tumors, blood vessel defects, motor issues (like face tics), epilepsy, and Parkinson’s disease.