Name: PET Scan
Creator: Dr Roger Henderson
Published: 2021-07-15T09:18:03.963Z

The scanner is large and white with a hole in the middle where the bed (and patient) passes through. You are laid down on the bed for a PET scan and the bed will move you through the scanner. The radiotracer will be injected into your arm and should not be painful. The scan usually takes up to an hour to complete and you will need to try to lie as still as possible during this time.

What is the machine like?

The amount of radiation from the radioactive tracer is very small and your body will excrete the substance over the course of a couple of hours but it can give an extremely small increased risk of developing cancer in the future. It is also best avoided in people who are pregnant unless it is an emergency situation.

What about the radioactive tracer?

A memory test gives a snapshot of different aspects of how you process and remember things.  

There are different types of memory – think of recalling what you watched on TV last night (short-term memory) to reminiscing about a childhood holiday (long-term memory) or adding up your share of a restaurant bill (working memory). The memory test may assess other thinking or cognitive skills, such as abstract representation using shapes, language and communication skills, your concentration and attention skills and general knowledge questions. 

Some of the questions can seem quite basic or easy and some seem confusing – just go with the flow, great if you know the answer, and don’t worry if you don’t. 

An X-ray is a type of scan that uses very small amounts of radiation to create a 2D black and white image of the inside of your body. X-rays send small amounts of radiation energy through the body and detect the amount that has passed through to the other side. Different tissues block or absorb different amounts of the X-rays depending on how dense they are. The more dense the matter, the more radiation it will block and the lighter it will appear. For example, bone shows up as white as it blocks a large amount of the radiation, whereas, air in the lungs allows more to pass through and shows up as much darker.

CT stands for computerised tomography and it is a way of scanning that uses multiple X-rays to create accurate 3D images of the inside of your body. X-rays send small amounts of radiation energy through though the body and detect the amount that has passed through to the other side. 

Different tissues block or absorb different amounts of the X-rays depending on how dense they are. The more dense the matter, the more radiation it will block and so the whiter it appears on the image. So, for example bone shows up as bright white as it blocks a large amount of the radiation, whereas air such in the lungs allows more to pass through and shows up as much darker. 

Lower back pain is a very common symptom. Up to 80% of us will experience it at some time, with men and women being equally affected. It occurs most often between ages 30 and 50, due in part to the ageing process but also as a result of sedentary lifestyles with too little exercise– but fortunately in most cases it’s not serious and typically gets better on its own within a few weeks.

Low back pain can often occur for no obvious reason – you can simply wake up with it, or it can happen during the day out of the blue – but it can also occur after lifting a heavy object or moving awkwardly. Other common reasons for back pain include [slipped discs](https://www.healthwords.ai/condition/disc-herniation-causes-symptoms-and-treatment), muscle spasm and some conditions and diseases, such as [arthritis](https://www.healthwords.ai/condition/arthritis-380), spinal stenosis and [fibromyalgia](https://www.healthwords.ai/condition/fibromyalgia-845).

In the majority of cases, lower back pain is typically on one side of your back and can spread down into the cheeks of your bottom or into your thighs. It’s often eased or helped by lying down flat, and made worse by moving, sneezing or coughing.

You can reduce your risk of making your low back pain worse or preventing it flaring up again, by maintaining a healthy weight, or losing weight if you’re overweight, [giving up smoking](https://www.healthwords.ai/article/quitting-smoking-how-to) if relevant, taking regular low-impact exercise and keeping your [stress](https://www.healthwords.ai/article/stress) levels to a minimum. If your job or hobby involves regular lifting, make sure you learn how to do this properly to protect your back, as this can leave it prone to injury.

Dr Kandi - Back Pain

Every woman in the UK is entitled to breast cancer screening. This starts from the age of 50, and continues up to your 71st birthday. You’ll be invited every three years by the local health authority, and they'll use your age and contact details from your doctor's records.

Breast cancer is the most common cancer in the UK, and every 1 in 8 women is diagnosed in their lifetime. The risk grows with age, hence the screening starting at 50. It can occur in men, as they have breast tissue too, but it’s much more rare, so they are not included in the screening programme.

The letters MRI stand for magnetic resonance imaging and it is a way of scanning that uses a magnetic field and radio waves to create accurate images of the inside of your body. The different densities in your body show up as different shades of grey to white in the images produced. MRI is one of the safest forms of scanning and is pain-free. Unlike [X-ray](https://www.healthwords.ai/article/x-ray-scan) and [CT scans](https://www.healthwords.ai/article/ct-scan), it does not cause any radiation exposure. It can be used to look at any part of the body but is particularly useful for looking at the brain, spine, blood vessels, and heart.

Cancer occurs when cells in our body multiply out of control, producing lots of abnormal cells. These abnormal cells don't function like they should and can invade tissues or organs and can sometimes spread to other parts of the body. Different cancers are due to different types of cells multiplying out of control. The most common types in the UK are breast, prostate, lung and bowel cancer, but there are many other types of cancer.

1 in 2 people will develop cancer in their lifetime, which is a scary fact but the treatments for cancer have improved massively over the years. Many cancers are able to be cured completely, particularly if caught early, so it’s important to know about the signs to look out for and to seek medical advice early if you notice these.

Any cancer fits into four stages, depending on the size of the tumour and whether it has spread and by how far. These are used to guide what treatment would be best. In Stage 1, the cancer is small and has not spread anywhere. Stage 2 is when the cancer is larger but hasn't spread. In Stage 3, the cancer is larger and has spread to areas close by. Stage 4 is when the cancer has spread to other parts of the body and is known as metastatic cancer.

An ultrasound scan (USS) uses sound waves to create accurate 3D images of small areas of the inside of your body. The sound waves bounce off tissues inside your body and it is how the sound waves bounce back from surfaces that are measured creating the image. The sound waves are extremely high frequency so you will not be able to hear them.

Ultrasound scanning is extremely safe, pain-free, and does not use any radiation (unlike [X-ray](https://www.healthwords.ai/article/x-ray-scan), PET, and [CT scan](https://www.healthwords.ai/article/ct-scan). Ultrasound scanning can be used for looking at many areas of the body, in particular, monitoring a baby’s progression in pregnancy, looking at certain organs or lumps to help with diagnosing, and looking at muscle, joint, and tendon injuries.

A brain tumour occurs when a cluster of cells grow abnormally in the brain and this can affect people in different ways. A brain tumour may be benign (it’s not cancer) but may still grow to a size where it presses on important parts of the brain and causes symptoms as a result. Alternatively, it may have cancer cells in it that disrupt the normal functioning of an area of the brain (even if it is a small size) and this is called a malignant tumour. Brain tumours are more common in older people. 

If a benign tumour remains small and slow-growing, it may not cause any symptoms at all. Almost 6,000 people in the UK are diagnosed with a benign brain tumour every year.  

Malignant brain tumours usually grow faster than benign ones, and every year about 5,500 people in the UK are diagnosed with one. They’re more likely to come back after treatment than benign ones, as well as being more likely to spread to other parts of the brain. 

Sarcoma is a rare cancer affecting any part of the body. The most common type are soft tissue sarcomas which develop in muscle, nerves, fatty tissue and blood vessels. The other types are bone sarcoma and gastrointestinal stromal tumours.

**Around 3,000 people a year in the UK** are diagnosed with sarcoma, making it a rare cancer, and it affects men and women equally.

## Types of Sarcomas

### Bone Sarcomas

Bone sarcomas are a diverse group of malignancies that originate from bone tissue, comprising several distinct subtypes with varying characteristics and treatment approaches. The main types of bone sarcomas include osteosarcoma, Ewing sarcoma, and chondrosarcoma.

**Osteosarcoma** is the most common type of primary bone cancer, typically arising in the long bones of the arms and legs. It predominantly affects children and young adults, with a peak incidence during adolescence. Osteosarcoma often presents as a painful swelling or mass near the affected bone and may be associated with pathological fractures. Diagnosis is confirmed through imaging studies, such as [X-rays](https://www.healthwords.ai/article/x-ray-scan), [CT scans](https://www.healthwords.ai/article/ct-scan), or [MRI](https://www.healthwords.ai/article/mri-scan-696), followed by biopsy for histological examination. Treatment typically involves a combination of surgery, chemotherapy, and sometimes radiation therapy, aimed at achieving local control and preventing metastasis.

**Ewing sarcoma** is a rare type of bone cancer that primarily affects children and young adults. It commonly arises in the pelvis, femur, or ribs, although it can occur in any bone. Ewing sarcoma is characterised by aggressive growth and a propensity for metastasis to other bones or organs. Symptoms may include pain, swelling, and occasionally, fever. Diagnosis involves imaging studies and biopsy for histological analysis. Treatment usually consists of chemotherapy, surgery, and/or radiation therapy, depending on the extent of the disease and the presence of metastasis.

**Chondrosarcoma** is a malignant tumour that arises from cartilage cells within bones. It typically occurs in older adults and commonly affects the pelvis, femur, or shoulder. Chondrosarcoma is characterised by slow growth and a tendency to recur locally, although it has a lower risk of metastasis than osteosarcoma and Ewing sarcoma. Diagnosis is established through imaging studies and biopsy. Treatment involves surgical resection of the tumour, with adjuvant therapy such as chemotherapy or radiation therapy in some cases.

### Soft Tissue Sarcomas

Soft tissue sarcomas are a diverse group of cancers that arise from various soft tissues in the body, including muscles, fat, nerves, blood vessels, and connective tissues. These tumours encompass a wide range of subtypes, each with unique histological, molecular, and clinical features.

**Liposarcoma** is the most common type of soft tissue sarcoma, arising from fat cells (adipocytes). It typically occurs in the extremities, retroperitoneum, or trunk. Liposarcoma is classified into several subtypes, including well-differentiated, dedifferentiated, myxoid, and pleomorphic variants, each with distinct characteristics and prognosis.

**Leiomyosarcoma** originates from smooth muscle cells and can arise in various locations, including the uterus, gastrointestinal tract, and soft tissues of the extremities. It is characterised by aggressive growth and a propensity for metastasis.

**Fibrosarcoma** arises from fibroblasts, which are cells that produce collagen and other structural proteins in connective tissue. It commonly affects the extremities, trunk, or head and neck region. Fibrosarcoma is characterised by a high recurrence rate and potential for metastasis.

**Synovial sarcoma** is a rare soft tissue sarcoma that typically arises near joints, especially in the extremities. Despite its name, it does not originate from synovial tissue. Synovial sarcoma is characterised by a unique chromosomal translocation and tends to affect young adults. It has a propensity for local recurrence and metastasis.

Dr Roger Henderson

Chief Content Officer

PET stands for positron emission tomography, and it is a way of creating 3D images of the inside of your body as well as images to show how well certain parts of the body are working. During the scan a slightly radioactive substance (known as a radiotracer) is injected into your bloodstream that can then be detected as it moves around your body and is taken up by different cells or parts of your body. It shows which cells are more active and which are less. It is usually used in combination with CT or MRI scanning to provide detailed images. 

Your body then excretes the radiotracer over the course of a couple of hours after the scan so it does not stay in your system. PET scanning is particularly useful for helping diagnose cancer, looking at its spread or response to treatment as well as looking at conditions that affect the brain.

PET Scan

What is the machine like?

What about the radioactive tracer?

Related topics

Memory Test - What happens?

X-ray Scan

CT Scan

Lower back pain

Breast cancer screening

MRI scan

Cancer

Ultrasound Scan

Brain tumour in adults

Sarcoma