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Doctor reviewing a radiation treatment plan. In radiotherapy, radiation treatment planning (RTP) is the process in which a team consisting of radiation oncologists, radiation therapist, medical physicists and medical dosimetrists plan the appropriate external beam radiotherapy or internal brachytherapy treatment technique for a patient with cancer.
An X-ray generator generally contains an X-ray tube to produce the X-rays. Possibly, radioisotopes can also be used to generate X-rays. [1]An X-ray tube is a simple vacuum tube that contains a cathode, which directs a stream of electrons into a vacuum, and an anode, which collects the electrons and is made of tungsten to evacuate the heat generated by the collision.
An x-ray image receptor, containing an anti-scatter grid and three AEC regions (represented by dark grey circles and square) These regions represent anatomical areas, e.g. lungs, spine. They can be selected individually, or all at once depending on the need. Automatic Exposure Control (AEC) is an X-ray exposure termination
Before then hand-held detectors had been used to locate radioactive materials in patients, but the Cassen system (designed for Iodine-131) combined a motor driven photomultiplier tube and printing mechanism. [2] [4] Subsequent developments improved the detection systems, movement, display and printing of images. [5] [6]
Fish bone pierced in the upper esophagus. Right image without contrast medium, left image during swallowing with contrast medium. To obtain an image with any type of image detector the part of the patient to be X-rayed is placed between the X-ray source and the image receptor to produce a shadow of the internal structure of that particular part of the body.
Digital radiography is a form of radiography that uses x-ray–sensitive plates to directly capture data during the patient examination, immediately transferring it to a computer system without the use of an intermediate cassette. [1]
Megavoltage X-rays are produced by linear accelerators ("linacs") operating at voltages in excess of 1000 kV (1 MV) range, and therefore have an energy in the MeV range. The voltage in this case refers to the voltage used to accelerate electrons in the linear accelerator and indicates the maximum possible energy of the photons which are subsequently produced. [1]
Therefore beginning in the 1920s "orthovoltage" 200–500 kV X-ray machines were built. [8] These were found to be able to reach shallow tumors, but to treat tumors deep in the body more voltage was needed. By the 1930s and 1940s megavoltage X-rays produced by huge machines with 3–5 million volts on the tube, began to be employed.