Tag Archives: Absorbed dose

Radiotherapy

Definition:
Radiotherapy is a way of treating or managing cancer using radiation. It works by damaging cells in the area being treated. Normal cells are able to repair this damage, but cancer cells can’t and are destroyed.
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Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of exposed tissue, furthermore, it is believed that cancerous cells may be more susceptible to death by this process as many have turned off their DNA repair machinery during the process of becoming cancerous. To spare normal tissues (such as skin or organs which radiation must pass through in order to treat the tumor), shaped radiation beams are aimed from several angles of exposure to intersect at the tumor, providing a much larger absorbed dose there than in the surrounding, healthy tissue. Besides the tumour itself, the radiation fields may also include the draining lymph nodes if they are clinically or radiologically involved with tumor, or if there is thought to be a risk of subclinical malignant spread. It is necessary to include a margin of normal tissue around the tumor to allow for uncertainties in daily set-up and internal tumor motion. These uncertainties can be caused by internal movement (for example, respiration and bladder filling) and movement of external skin marks relative to the tumor position.

Radiation oncology is the medical specialty concerned with prescribing radiation, and is distinct from radiology, the use of radiation in medical imaging and diagnosis). Radiation may be prescribed by a radiation oncologist with intent to cure (“curative”) or for adjuvant therapy. It may also be used as palliative treatment (where cure is not possible and the aim is for local disease control or symptomatic relief) or as therapeutic treatment (where the therapy has survival benefit and it can be curative). It is also common to combine radiation therapy with surgery, chemotherapy, hormone therapy, Immunotherapy or some mixture of the four. Most common cancer types can be treated with radiation therapy in some way. The precise treatment intent (curative, adjuvant, neoadjuvant, therapeutic, or palliative) will depend on the tumor type, location, and stage, as well as the general health of the patient. Total body irradiation (TBI) is a radiation therapy technique used to prepare the body to receive a bone marrow transplant. Brachytherapy, in which a radiation source is placed inside or next to the area requiring treatment, is another form of radiation therapy that minimizes exposure to healthy tissue during procedures to treat cancers of the breast, prostate and other organs.

Radiation therapy has several applications in non-malignant conditions, such as the treatment of trigeminal neuralgia, severe thyroid eye disease, pterygium, pigmented villonodular synovitis, and prevention of keloid scar growth, vascular restenosis , and heterotopic ossification. The use of radiation therapy in non-malignant conditions is limited partly by worries about the risk of radiation-induced cancers.

Method of radiotherapy
Radiotherapy can be given as teletherapy (also known as external beam radiotherapy), when a beam of radiation is aimed at the area to be treated from a machine located away from the patient.

Other forms of radiotherapy are high or low-dose brachytherapy, which involves a radioactive source being placed on or in a tumour.

Dose:
The amount of radiation used in photon radiation therapy is measured in gray (Gy), and varies depending on the type and stage of cancer being treated. For curative cases, the typical dose for a solid epithelial tumor ranges from 60 to 80 Gy, while lymphomas are treated with 20 to 40 Gy.

Preventative (adjuvant) doses are typically around 45 – 60 Gy in 1.8 – 2 Gy fractions (for Breast, Head, and Neck cancers.) Many other factors are considered by radiation oncologists when selecting a dose, including whether the patient is receiving chemotherapy, patient comorbidities, whether radiation therapy is being administered before or after surgery, and the degree of success of surgery.

Delivery parameters of a prescribed dose are determined during treatment planning (part of dosimetry). Treatment planning is generally performed on dedicated computers using specialized treatment planning software. Depending on the radiation delivery method, several angles or sources may be used to sum to the total necessary dose. The planner will try to design a plan that delivers a uniform prescription dose to the tumor and minimizes dose to surrounding healthy tissues.

Treatment planning
All patients who are to have radiotherapy need individually tailored treatment so it is given accurately. A lot of information is needed so the doctor can target the tumour while minimising damage to the healthy tissue. This is called treatment planning and there are a number of ways of doing this.

Simulator planning is done using a specialised x-ray machine that can do the same things as the treatment machines except deliver treatment. The simulator allows the doctor to carefully look at the area that needs treatment and plan it precisely. During the planning, the radiographer will draw some marks on the skin using a pen; when the doctor and radiographer are happy they have an accurate plan, the radiographer may need to make two to three permanent marks called tattoos. These tattoos are the size of a pinhead and are used to ensure the radiotherapy is given to exactly the right place.

ACQSIM planning is done using a scanner. Some patients may need to have an intravenous injection before the scan to show up the area to be treated better. The scan usually takes about 15 minutes and the information from the scan is used to produce a treatment map. Sometimes it’s necessary to take some x-rays and measurements to check the treatment map and this is done on the simulator.

What radiotherapy involves
When radiotherapy treatment is being given by external beam, it’s important the patient is in exactly the same position each time. The radiographers will often use pillows and wedges to make sure the patient is comfortable and in the correct position.

Patients having radiotherapy to the head or neck area may need to have a mould made to keep them in the right position. Moulds are made from clear Perspex after a plaster cast has been made of the head and neck. Once the Perspex mould has been made, the radiotherapy is planned while the patient is wearing the mould and marks are drawn on the mask instead of the skin.

Once the radiographers are happy that the patient is in the correct position they will leave the room to switch the treatment machine on. When the machine is on it makes a buzzing noise. The radiographers watch closely on a television screen. Treatment only lasts a few minutes and does not hurt.

Side effect of radiotherapy
Side effects are different depending on the part of the body being treated. Most side effects are temporary but some may continue for weeks or months after treatment is finished. They include:

•Hair loss (alopecia)
•Cerebral oedema (excess fluid accumulating in the brain) can cause changes in mental state, restlessness, irritability, impaired pupil reactions, headache, increase in blood pressure, decrease in pulse and respiration, and nausea
•Dry or sore mouth or throat, changes in taste sensation, skin thickening
•Inflammation of the gullet, indigestion, nausea, lung inflammation
•Nausea and vomiting, diarrhoea, cystitis
•Sexual dysfunction. In males treatment of the abdomen area can cause impotence, sterility. In females it can cause sterility, loss of sexual desire. Irradiation of the pelvis may cause tightening of the vagina, loss of vaginal lubrication, inflammation or ulceration of the vagina. Some women may find intercourse painful
•Treatment of red bone marrow may cause infection and impaired healing, anaemia, increased tiredness, bruising and bleeding

As well as treating cancer the radiotherapy temporarily damages the outer layers of skin. During treatment the skin cannot repair itself as it normally would and it can become sore. But once treatment has finished the skin generally recovers quite quickly – usually within a month. The level of reaction can depend on your skin type, the type and number of treatments you have, and how you would normally react to the sun.

Skin side effects usually happen later on in the course of radiotherapy treatment or sometimes a few weeks after treatment has finished. Many patients do not have any skin changes at all. Skin care advice will be given to the patients by the staff treating them.

A common side effect of radiotherapy is tiredness and fatigue, which often prevents patients from doing normal everyday activities. Fatigue and tiredness are normal results of having radiotherapy and begin in the first week of treatment, reaching a peak after two weeks of treatment and gradually disappearing a few weeks after treatment has finished.

Radiation therapy accidents:
There are rigorous procedures in place to minimise the risk of accidental overexposure of radiation therapy to patients. However, mistakes do occasionally occur; for example, the radiation therapy machine Therac-25 was responsible for at least six accidents between 1985 and 1987, where patients were given up to one hundred times the intended dose; two people were killed directly by the radiation overdoses. From 2005 to 2010, a hospital in Missouri overexposed 76 patients (most with brain cancer) during a five-year period because new radiation equipment had been set up incorrectly.  Although medical errors are exceptionally rare, radiation oncologists, medical physicists and other members of the radiation therapy treatment team are working to eliminate them. ASTRO has launched a safety initiative called Target Safely  that, among other things, aims to record errors nationwide so that doctors can learn from each and every mistake and prevent them from happening. ASTRO also publishes a list of questions for patients to ask their doctors about radiation safety to ensure every treatment is as safe as possible.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://en.wikipedia.org/wiki/Radiation_therapy
http://www.bbc.co.uk/health/physical_health/conditions/in_depth/cancer/carecancer_radio.shtml
http://www.allvitalpoints.com/2010/how-radiotherapy-is-performed/

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Radiation sickness

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Alternative Names : Radiation poisoning; radiation injury

Definition:
Natural background radiation, known as non-ionizing radiation, such as light, natural radio waves and microwaves generally causes only low levels of damage which can be repaired by the body. However, when the body is exposed to unnaturally high levels of radiation, usually from medical testing and therapy, industrial and manufacturing processes or accidents, and from nuclear weaponry, it cannot combat the damage caused.
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There is great individual variation in how people respond to radiation and the process is not fully understood.Among the cells that are most sensitive to radiation are those that have a high turnover such as cells which line the intestine (crypt cells), white blood cells that fight infection and the cells that make red and white blood cells. The acute impact on these cells leads to the classic early symptoms of radiation sickness. For instance, damage to the intestine cells stimulates nausea, vomiting and dehydration. Chronic radiation exposure leads to an increased risk of cancer and premature ageing.

Radiation penetrates the body and is wholly or partially absorbed by soft and hard tissue.

Radioactive fallout in the form of particulate matter can be swallowed or breathed in.

Symptoms:
There are many symptoms of radiation sickness, and their severity varies greatly depending on the dosage .

The initial symptoms include:

•Nausea
•Vomiting
•Diarrhoea
•Fatigue

These symptoms may be followed by:

•Bleeding from the nose, mouth, gums, and rectum
•Bloody stool
•Bruising
•Confusion
•Dehydration
•Diarrhea
•Fainting
•Fatigue
•Fever
•Hair loss
•Inflammation of exposed areas (redness, tenderness, swelling, bleeding)
•Mouth ulcers
•Nausea and vomiting
•Open sores on the skin
•Skin burns (redness, blistering)
•Sloughing of skin
•Ulcers in the esophagus, stomach or intestines
•Vomiting blood
•Weakness

Your doctor will advise you how best to treat these symptoms. Medications may be prescribed to help reduce nausea, vomiting, and pain. Blood transfusions may be given for anemia. Antibiotics are used to prevent or fight infections.

Causes:
Radiation is the energy released from atoms as either a wave or a tiny particle of matter. Radiation sickness is caused by exposure to a high dose of radiation, such as a high dose of radiation received during an industrial accident. Common exposures to low-dose radiation, such as X-ray examinations, do not cause radiation sickness.

Sources of high-dose radiation :
Possible sources of high-dose radiation include the following:

*An accident at a nuclear industrial facility
*An attack on a nuclear industrial facility
*Detonation of a small radioactive device
*Detonation of a conventional explosive device that disperses radioactive material (dirty bomb)
*Detonation of a standard nuclear weapon
*Radiation sickness occurs when high-energy radiation damages or destroys certain cells in your body. *Regions of the body most vulnerable to high-energy radiation are cells in the lining of your intestinal tract, including your stomach, and the blood cell-producing cells of bone marrow.

Complications:
Radiation-related illnesses tend to show themselves about 10 to 15 years after a radiation disaster. The body’s endocrine, or hormone-secreting, glands appear to be particularly sensitive to radiation.

It is now widely accepted that the Chernobyl nuclear disaster has led to a massive increase in thyroid cancers in the three countries most affected. Already, 680 cases of thyroid cancer have been recorded in Belarus, Russia and Ukraine. Belarus has shown a 100-fold increase, from 0.3 per million in 1981-85 to 30.6 per million in 1991-94.

You may click to see :1 Million Killed in Chernobyl Disaster

Unicef has noted significant increases in many types of health disorders in Belarus since the disaster. For example, problems of the nervous and sensory organs have increased by 43%; disorders of the digestive organs by 28%; and disorders

Diagnosis:
When a person has experienced known or probable exposure to a high dose of radiation from an accident or attack, medical personnel take a number of steps to determine the absorbed radiation dose. This information is essential for determining how severe the illness is likely to be, which treatments to use and whether a person is likely to survive.

Information important for determining an absorbed dose includes:

*Known exposure. Details about distance from the source of radiation and duration of exposure can help provide a rough estimate of the severity of radiation sickness.

*Vomiting and other symptoms. The time between radiation exposure and the onset of vomiting is a fairly accurate screening tool to estimate absorbed radiation dose. The shorter the time before the onset of this sign, the higher the dose is. The severity and timing of other signs and symptoms may also help medical personnel determine the absorbed dose.

*Blood tests. Frequent blood tests over several days enable medical personnel to look for drops in disease-fighting white blood cells and abnormal changes in the DNA of blood cells. These factors indicate the degree of bone marrow damage, which is determined by the level of an absorbed dose.

*Dosimeter. A device called a dosimeter can measure the absorbed dose of radiation but only if it was exposed to the same radiation event as the affected person.Survey meter. A device such as a Geiger counter can be used to survey people to determine the body location of radioactive particles.

*Type of radiation. A part of the larger emergency response to a radioactive accident or attack would include identifying the type of radiation people have been exposed to. This information would guide some decisions for treating people with radiation sickness.

Treatment:
There is no specific treatment once exposure has occurred but management is generally supportive whilst the body recovers from the damage done – anti-nausea drugs and painkillers can be used to relieve symptoms of radiation sickness. Antibiotics may also be needed to fight off secondary infection.

Blood transfusions may be necessary for patients suffering from anaemia

First Aid:
1.Check the person’s breathing and pulse.
2.Start CPR, if necessary.
3.Remove the person’s clothing and place the items in a sealed container. This stops ongoing contamination.
4.Vigorously wash body with soap and water.
5.Dry the body and wrap with soft, clean blanket.
6.Call for emergency medical help or take the person to nearest emergency medical facility if you can do so safely
7.REPORT EXPOSURE TO EMERGENCY OFFICIALS.

If symptoms occur during or after medical radiation treatments:

1.Tell the health care provider or seek medical treatment.
2.Handle affected areas gently.
3.Treat symptoms or illnesses as recommended by the doctor.

DO NOT:
•DO NOT remain in area where exposure occurred.
•DO NOT apply ointments to burned areas.
•DO NOT remain in contaminated clothing.
•DO NOT hesitate to seek emergency medical treatment.

Prevention
•Avoid unnecessary exposure to radiation.
•Persons working in radiation hazard areas should wear badges to measure their exposure levels.
•Protective shields should always be placed over the parts of the body not being treated or studied during x-ray imaging tests or radiation therapy.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.bbc.co.uk/health/physical_health/conditions/radiation_sickness.shtml
http://www.nlm.nih.gov/medlineplus/ency/article/000026.htm
http://www.mayoclinic.com/health/radiation-sickness/DS00432
http://www.thecanadiancharger.com/page.php?id=5&a=92

http://connect.in.com/radiation-sickness/images-radiation-sickness-1-678703799697.html

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Chest X-Ray

Definition:The chest x-ray is the most commonly performed diagnostic x-ray examination. A chest x-ray makes images of the heart, lungs, airways, blood vessels and the bones of the spine and chest.

An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to produce pictures of the inside of the body. X-rays are the oldest and most frequently used form of medical imaging.

Doctors have used x-rays for over a century to see inside the body in order to diagnose a variety of problems, including cancer, fractures, and pneumonia. During this test, you usually stand in front of a photographic plate while a machine sends x-rays, a type of radiation, through your body. Originally, a photograph of internal structures was produced on film; nowadays, the image created by the x-rays goes directly into a computer. Dense structures, such as bone, appear white on the x-ray films because they absorb many of the x-ray beams and block them from reaching the plate (see Figure 16). Hollow body parts, such as lungs, appear dark because x-rays pass through them. (In some other countries, like the United Kingdom, the colors are reversed, and dense structures are black.)

Back x-rays and chest x-rays are among the most common conventional x-ray tests. You should not have an x-ray if you’re pregnant, because radiation can be harmful to a developing fetus.

A chest x-ray provides black-and-white images of your lungs, ribs, heart, and diaphragm.

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Some common uses:
The chest x-ray is performed to evaluate the lungs, heart and chest wall.

A chest x-ray is typically the first imaging test used to help diagnose symptoms such as:

*shortness of breath
*a bad or persistent cough
*chest pain or injury
*fever.
Physicians use the examination to help diagnose or monitor treatment for conditions such as:

*pneumonia
*heart failure and other heart problems
*emphysema
*lung cancer
*other medical conditions.


How should you prepare for the test?

A chest x-ray requires no special preparation.

You may be asked to remove some or all of your clothes and to wear a gown during the exam. You may also be asked to remove jewelry, eye glasses and any metal objects or clothing that might interfere with the x-ray images.

Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to radiation. If an x-ray is necessary, precautions will be taken to minimize radiation exposure to the baby. See the Safety page for more information about pregnancy and x-rays.

You are usually asked to remove all clothing, undergarments, and jewelry above your waist, and to wear a hospital gown.

What does the equipment look like?
The equipment typically used for chest x-rays consists of a wall-mounted, box-like apparatus containing the x-ray film or a special plate that records the image digitally and an x-ray producing tube, that is usually positioned about six feet away.
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The equipment may also be arranged with the x-ray tube suspended over a table on which the patient lies. A drawer under the table holds the x-ray film or digital recording plate.

A portable x-ray machine is a compact apparatus that can be taken to the patient in a hospital bed or the emergency room. The x-ray tube is connected to a flexible arm that is extended over the patient while an x-ray film holder or image recording plate is placed beneath the patient.

What happens when the test is performed?
Chest x-rays usually are taken while you are standing. A technician positions you against the photographic plate (which looks like a large board) to obtain the clearest pictures. He or she takes pictures from the front and from one side while asking you to take in a deep breath just before each picture. The technician leaves the room or stands behind a screen while the x-rays are taken.

How does the procedure work?
X-rays are a form of radiation like light or radio waves. X-rays pass through most objects, including the body. Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small burst of radiation that passes through the body, recording an image on photographic film or a special digital image recording plate.

Different parts of the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air appears black.

On a chest x-ray, the ribs and spine will absorb much of the radiation and appear white or light gray on the image. Lung tissue absorbs little radiation and will appear dark on the image.

Until recently, x-ray images were maintained as hard film copy (much like a photographic negative). Today, most images are digital files that are stored electronically. These stored images are easily accessible and are sometimes compared to current x-ray images for diagnosis and disease management.

How is the procedure performed?

Typically, two views of the chest are taken, one from the back and the other from the side of the body as the patient stands against the image recording plate. The technologist, an individual specially trained to perform radiology examinations, will position the patient with hands on hips and chest pressed the image plate. For the second view, the patient’s side is against the image plate with arms elevated.

 

Patients who cannot stand may be positioned lying down on a table for chest x-rays.

You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image. The technologist will walk behind a wall or into the next room to activate the x-ray machine.

When the examination is complete, you will be asked to wait until the radiologist determines that all the necessary images have been obtained.

The chest x-ray examination is usually completed within 15 minutes.

Additional views may be required within hours, days or months to evaluate any changes in the chest.

What will you experience during and after the procedure?
A chest x-ray examination itself is a painless procedure.

You may experience discomfort from the cool temperature in the examination room and the coldness of the recording plate. Individuals with arthritis or injuries to the chest wall, shoulders or arms may have discomfort trying to stay still during the examination. The technologist will assist you in finding the most comfortable position possible that still ensures diagnostic image quality.
Who interprets the results and how do you get them?
A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.

In an emergency, the results of a chest x-ray can be available almost immediately for review by your physician.
What are the benefits vs. risks?
Benefits:

*No radiation remains in a patient’s body after an x-ray examination.
*X-rays usually have no side effects in the diagnostic range.
*X-ray equipment is relatively inexpensive and widely available in emergency rooms, physician offices, ambulatory care *centers, nursing homes and other locations, making it convenient for both patients and physicians.
*Because x-ray imaging is fast and easy, it is particularly useful in emergency diagnosis and treatment.

Risks:

*There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.

*The chest x-ray is one of the lowest radiation exposure medical examinations performed today. The effective radiation dose from this procedure is about 0.1 mSv, which is about the same as the average person receives from background radiation in 10 days. See the Safety page for more information about radiation dose.

*Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.

How long is it before the result of the test is known?
Although digital images may be available immediately, it will take additional time for a doctor to examine and interpret them. You’ll probably get the results later in the day.

A Word About Minimizing Radiation Exposure:
Special care is taken during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection councils continually review and update the technique standards used by radiology professionals.

State-of-the-art x-ray systems have tightly controlled x-ray beams with significant filtration and dose control methods to minimize stray or scatter radiation. This ensures that those parts of a patient’s body not being imaged receive minimal radiation exposure.

What are the limitations of Chest Radiography?
The chest x-ray is a very useful examination, but it has limitations. Because some conditions of the chest cannot be detected on an x-ray image, this examination cannot necessarily rule out all problems in the chest. For example, very small cancers may not show up on a chest x-ray. A blood clot in the lungs, a condition called a pulmonary embolism, cannot be seen on chest x-rays.

Further imaging studies may be necessary to clarify the results of a chest x-ray or to look for abnormalities not visible on the chest x-ray.

Click for More Additional Information and Resources: ->
*RadiologyInfo: Radiation Therapy for Lung Cancer

*RTAnswers.org: Radiation Therapy for Lung Cancer

Resources:
https://www.health.harvard.edu/diagnostic-tests/chest-x-ray.htm
http://www.radiologyinfo.org/en/info.cfm?PG=chestrad

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