Question:

What is the difference between brachytherapy and teletherapy in radiation therapy?

Answer:

Brachytherapy designates the use of radioactive sources within or in contact with the body as opposed to teletherapy, which is treatment with an external radiation beam. AnswerParty!

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teletherapy Medicine

Radiation therapy (in American English and Canada ), radiation oncology, or radiotherapy (in the UK, and Australia), sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control or kill malignant cells. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers.

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 leading to cellular death. To spare normal tissues (such as skin or organs which radiation must pass through 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.

Medical Physics is generally speaking the application of physics concepts, theories and methods to medicine/healthcare.

Medical physics departments are found in hospitals or universities.

Radiobiology Radioactivity Brachytherapy

Radiation therapy (in American English and Canada ), radiation oncology, or radiotherapy (in the UK, and Australia), sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control or kill malignant cells. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers.

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 leading to cellular death. To spare normal tissues (such as skin or organs which radiation must pass through 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.

External beam radiotherapy or teletherapy is the most common form of radiotherapy. The patient sits or lies on a couch and an external source of radiation is pointed at a particular part of the body. In contrast to internal radiotherapy (brachytherapy), in which the radiation source is inside the body, external beam radiotherapy directs the radiation at the tumour from outside the body. Kilovoltage ("superficial") X-rays are used for treating skin cancer and superficial structures. Megavoltage ("deep") X-rays are used to treat deep-seated tumours (e.g. bladder, bowel, prostate, lung, or brain).

While X-ray and electron beams are by far the most widely used sources for external beam radiotherapy, a small number of centers operate experimental and pilot programs employing heavier particle beams, particularly proton sources.

Ionizing (or ionising) radiation is radiation composed of particles that individually carry enough kinetic energy to liberate an electron from an atom or molecule, ionizing it. Ionizing radiation is generated through nuclear reactions, either artificial or natural, by very high temperature (e.g. plasma discharge or the corona of the Sun), via production of high energy particles in particle accelerators, or due to acceleration of charged particles by the electromagnetic fields produced by natural processes, from lightning to supernova explosions.

When ionizing radiation is emitted by or absorbed by an atom, it can liberate an atomic particle (typically an electron, proton, or neutron, but sometimes an entire nucleus) from the atom. Such an event can alter chemical bonds and produce ions, usually in ion-pairs, that are especially chemically reactive. This greatly magnifies the chemical and biological damage per unit energy of radiation because chemical bonds will be broken in this process. If the atom were inside a crystal lattice in a solid phase, then a "hole" would exist where the original atom was.

Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable (from IAEA definition).

Such contamination presents a hazard because of the radioactive decay of the contaminants, which emit harmful ionising radiation such as alpha or beta particles, gamma rays or neutrons. The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. It is important to be clear that the contamination gives rise to the radiation hazard, and the terms "radiation" and "contamination" are not interchangeable.

Brachytherapy is a type of radiotherapy, or radiation treatment, offered to certain cancer patients. There are two types of brachytherapy – high dose-rate (HDR) and low dose-rate (LDR). LDR brachytherapy is the type that is most commonly used to treat prostate cancer; it may sometimes be referred to as ‘seed implantation’ or it may also be called ‘pinhole surgery’.

In LDR brachytherapy, tiny radioactive particles the size of a grain of rice (see Figure 1) are implanted directly into the site of the tumour. These particles are known as ‘seeds’, and they can be inserted linked together as strands, or individually. Because the seeds are inserted or implanted directly into, or very close to, the tumour, they deliver high doses of radiation to the tumour without affecting the normal healthy tissues around it. This means that the procedure is less damaging than conventional radiation therapy, where the radioactive beam is delivered from outside the body and must pass through other tissues before reaching the tumour.

Acute radiation syndrome (ARS), also known as radiation poisoning, radiation sickness or radiation toxicity, is a constellation of health effects which present within 24 hours of exposure to high amounts of ionizing radiation. The radiation causes cellular degradation due to damage to DNA and other key molecular structures within the cells in various tissues; this destruction, particularly as it affects ability of cells to divide normally, in turn causes the symptoms. The symptoms can begin within one or two hours and may last for several months. The terms refer to acute medical problems rather than ones that develop after a prolonged period.

The onset and type of symptoms depends on the radiation exposure. Relatively smaller doses result in gastrointestinal effects such as nausea and vomiting and symptoms related to falling blood counts such as infection and bleeding. Relatively larger doses can result in neurological effects and rapid death. Treatment of acute radiation syndrome is generally supportive with blood transfusions and antibiotics, with some more exotic treatments such as bone marrow transfusions being required in extreme cases.

Science of drugs including their origin, composition, pharmacokinetics,
pharmacodynamics, therapeutic use, and toxicology.

Pharmacology (from Greek φάρμακον, pharmakon, "poison" in classic Greek; "drug" in modern Greek; and -λογία, -logia "study of", "knowledge of") is the branch of medicine and biology concerned with the study of drug action, where a drug can be broadly defined as any man-made, natural, or endogenous (within the body) molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.

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