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Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special camera that detects radioactivity.

Before the test, you receive a small amount of radioactive material. You may get it as an injection. Sometimes you swallow it or inhale it. Then you lie still on a table while the camera makes images. Most scans take 20 to 45 minutes.

Nuclear scans can help doctors diagnose many conditions, including cancers, injuries, and infections. They can also show how organs like your heart and lungs are working.

Angina is chest pain or discomfort you feel when there is not enough blood flow to your heart muscle. Your heart muscle needs the oxygen that the blood carries. Angina may feel like pressure or a squeezing pain in your chest. It may feel like indigestion. You may also feel pain in your shoulders, arms, neck, jaw, or back.

Angina is a symptom of coronary artery disease (CAD), the most common heart disease. CAD happens when a sticky substance called plaque builds up in the arteries that supply blood to the heart, reducing blood flow.

There are three types of angina:

• Stable angina is the most common type. It happens when the heart is working harder than usual. Stable angina has a regular pattern. Rest and medicines usually help.
• Unstable angina is the most dangerous. It does not follow a pattern and can happen without physical exertion. It does not go away with rest or medicine. It is a sign that you could have a heart attack soon.
• Variant angina is rare. It happens when you are resting. Medicines can help.

Not all chest pain or discomfort is angina. If you have chest pain, you should see your health care provider.

NIH: National Heart, Lung, and Blood Institute

Radiation is energy. It travels in the form of energy waves or high-speed particles. Radiation can occur naturally or be man-made. There are two types:

• Non-ionizing radiation, which includes radio waves, cell phones, microwaves, infrared radiation and visible light
• Ionizing radiation, which includes ultraviolet radiation, radon, x-rays, and gamma rays

Background radiation is all around us all the time. Most of it forms naturally from minerals. These radioactive minerals are in the ground, soil, water, and even our bodies. Background radiation can also come from outer space and the sun. Other sources are man-made, such as x-rays, radiation therapy to treat cancer, and electrical power lines.

Radiation has been around us throughout our evolution. So our bodies are designed to deal with the low levels we're exposed to every day. But too much radiation can damage tissues by changing cell structure and damaging DNA. This can cause serious health problems, including cancer.

The amount of damage that exposure to radiation can cause depends on several factors, including:

• The type of radiation
• The dose (amount) of radiation
• How you were exposed, such as through skin contact, swallowing or breathing it in, or having rays pass through your body
• Where the radiation concentrates in the body and how long it stays there
• How sensitive your body is to radiation. A fetus is most vulnerable to the effects of radiation. Infants, children, older adults, pregnant women, and people with compromised immune systems are more vulnerable to health effects than healthy adults.

Being exposed to a lot of radiation over a short period of time, such as from a radiation emergency, can cause skin burns. It may also lead to acute radiation syndrome (ARS, or "radiation sickness"). The symptoms of ARS include headache and diarrhea. They usually start within hours. Those symptoms will go away and the person will seem healthy for a little while. But then they will get sick again. How soon they get sick again, which symptoms they have, and how sick they get depends on the amount of radiation they received. In some cases, ARS causes death in the following days or weeks.

Exposure to low levels of radiation in the environment does not cause immediate health effects. But it can slightly increase your overall risk of cancer.

Before they start treatment, health care professionals need to figure out how much radiation your body absorbed. They will ask about your symptoms, do blood tests, and may use a device that measures radiation. They also try get more information about the exposure, such as what type of radiation it was, how far away you were from the source of the radiation, and how long you were exposed.

Treatment focuses on reducing and treating infections, preventing dehydration, and treating injuries and burns. Some people may need treatments that help the bone marrow recover its function. If you were exposed to certain types of radiation, your provider may give you a treatment that limits or removes the contamination that is inside your body. You may also get treatments for your symptoms.

There are steps you can take to prevent or reduce radiation exposure:

• If your health care provider recommends a test that uses radiation, ask about its risks and benefits. In some cases, you may be able to have a different test that does not use radiation. But if you do need a test that uses radiation, do some research into the local imaging facilities. Find one that monitors and uses techniques to reduce the doses they are giving patients.
• Reduce electromagnetic radiation exposure from your cell phone. At this time, scientific evidence has not found a link between cell phone use and health problems in humans. More research is needed to be sure. But if you still have concerns, you can reduce how much time you spend on your phone. You can also use speaker mode or a headset to place more distance between your head and the cell phone.
• If you live in a house, test the radon levels, and if you need to, get a radon reduction system.
• During a radiation emergency, get inside a building to take shelter. Stay inside, with all of the windows and doors shut. Stay tuned to and follow the advice of emergency responders and officials.

Environmental Protection Agency

Your liver makes a digestive juice called bile. Your gallbladder stores it between meals. When you eat, your gallbladder pushes the bile into tubes called bile ducts. They carry the bile to your small intestine. The bile helps break down fat. It also helps the liver get rid of toxins and wastes.

Bile duct cancer is rare. It can happen in the parts of the bile ducts that are outside or inside the liver. Cancer of the bile duct outside of the liver is much more common. Risk factors include having inflammation of the bile duct, ulcerative colitis, and some liver diseases.

Symptoms can include:

• Jaundice
• Itchy skin
• Fever
• Abdominal pain

Tests to diagnose bile duct cancer may include a physical exam, imaging tests of the liver and bile ducts, blood tests, and a biopsy.

Treatments include surgery, radiation therapy, and chemotherapy.

NIH: National Cancer Institute

Your liver makes a digestive juice called bile. Your gallbladder stores it between meals. When you eat, your gallbladder pushes the bile into tubes called bile ducts. They carry the bile to your small intestine. The bile helps break down fat. It also helps the liver get rid of toxins and wastes.

Different diseases can block the bile ducts and cause a problem with the flow of bile:

• Gallstones, which can increase pressure in the gallbladder and cause a gallbladder attack. The pain usually lasts from one to several hours.
• Cancer
• Infections
• Birth defects, such as biliary atresia. It is the most common reason for liver transplants in children in the United States.
• Inflammation, which can cause scarring. Over time, this can lead to liver failure.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

The bladder is a hollow organ in your lower abdomen that stores urine. Many conditions can affect your bladder. Some common ones are:

• Cystitis - inflammation of the bladder, often from an infection
• Urinary incontinence - loss of bladder control
• Overactive bladder - a condition in which the bladder squeezes urine out at the wrong time
• Interstitial cystitis - a chronic problem that causes bladder pain and frequent, urgent urination
• Bladder cancer

Doctors diagnose bladder diseases using different tests. These include urine tests, x-rays, and an examination of the bladder wall with a scope called a cystoscope. Treatment depends on the cause of the problem. It may include medicines and, in severe cases, surgery.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases

Your gallbladder is a pear-shaped organ under your liver. It stores bile, a fluid made by your liver to digest fat. As your stomach and intestines digest food, your gallbladder releases bile through a tube called the common bile duct. The duct connects your gallbladder and liver to your small intestine.

Your gallbladder is most likely to give you trouble if something blocks the flow of bile through the bile ducts. That is usually a gallstone. Gallstones form when substances in bile harden. Rarely, you can also get cancer in your gallbladder.

Many gallbladder problems get better with removal of the gallbladder. Fortunately, you can live without a gallbladder. Bile has other ways of reaching your small intestine.

Hydrocephalus is the buildup of too much cerebrospinal fluid in the brain. Normally, this fluid cushions your brain. When you have too much, though, it puts harmful pressure on your brain.

Hydrocephalus can be congenital, or present at birth. Causes include genetic problems and problems with how the fetus develops. An unusually large head is the main sign of congenital hydrocephalus.

Hydrocephalus can also happen after birth. This is called acquired hydrocephalus. It can occur at any age. Causes can include head injuries, strokes, infections, tumors, and bleeding in the brain. Symptoms include:

• Headache
• Vomiting and nausea
• Blurry vision
• Balance problems
• Bladder control problems
• Thinking and memory problems

Hydrocephalus can permanently damage the brain, causing problems with physical and mental development. If untreated, it is usually fatal. With treatment, many people lead normal lives with few limitations. Treatment usually involves surgery to insert a shunt. A shunt is a flexible but sturdy plastic tube. The shunt moves the cerebrospinal fluid to another area of the body where it can be absorbed. Medicine and rehabilitation therapy can also help.

NIH: National Institute of Neurological Disorders and Stroke

The urinary system is the body's drainage system for removing wastes and extra water. It includes two kidneys, two ureters, a bladder, and a urethra. Urinary tract infections (UTIs) are the second most common type of infection in the body.

You may have a UTI if you notice:

• Pain or burning when you urinate
• Fever, tiredness, or shakiness
• An urge to urinate often
• Pressure in your lower belly
• Urine that smells bad or looks cloudy or reddish
• Pain in your back or side below the ribs

People of any age or sex can get UTIs. But about four times as many women get UTIs as men. You're also at higher risk if you have diabetes, need a tube to drain your bladder, or have a spinal cord injury.

If you think you have a UTI it is important to see your doctor. Your doctor can tell if you have a UTI with a urine test. Treatment is with antibiotics.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases