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New X-Ray Presentation
Transcript of New X-Ray Presentation
- is a device that produces visual images generated by electromagnetic radiation which is widely used both on medical expertise and security purposes. - it produces a controlled beam of radiation, which is used to create an image of the inside of your body. This beam is directed at the area being examined. After passing through the body, the beam falls on a piece of film or a special plate where it casts a type of shadow. Different tissues in the body block or absorb the radiation differently. Dense tissue, such as bone, blocks most of the radiation and appears white on the film. Soft tissue, such as muscle, blocks less radiation and appears darker on the film. X-RAY MACHINE X-RAY TIMELINE 1895 All light and radio waves belong to the electromagnetic spectrum, and are all considered different types of electromagnetic waves, including:
- microwaves and infrared bands whose waves are longer than those of visible light (between radio and the visible)
- and UV, EUV, X-rays and g-rays (gamma rays) with shorter wavelengths. Medical X-rays X-rays are capable of penetrating some thickness of matter. Medical x-rays are produced by letting a stream of fast electrons come to a sudden stop at a metal plate; it is believed that X-rays emitted by the Sun or stars also come from fast electrons. The electromagnetic nature of x-rays became evident when it was found that crystals bent their path in the same way as gratings bent visible light: the orderly rows of atoms in the crystal acted like the grooves of a grating. History of X-ray Machine On 8 Nov, 1895, Rector Wilhelm Conrad Röntgen (Roentgen) (accidentally) discovered an image cast from his cathode ray generator, projected far beyond the possible range of the cathode rays (now known as an electron beam). Further investigation showed that the rays were generated at the point of contact of the cathode ray beam on the interior of the vacuum tube, that they were not deflected by magnetic fields, and they penetrated many kinds of matter. Wilhelm Conrad Roentgen (1845–1923). The discovery of X rays in 1895 was the beginning of a revolutionary change in our understanding of the physical world. IN THE WINTER of the year of his fiftieth birthday, and the year following his appointment to the leadership of the University of Würzburg, Rector Wilhelm Conrad Roentgen noticed a barium platinocyanide screen fluorescing in his laboratory as he generated cathode rays in a Crookes tube some distance away. Leaving aside for a time his duties to the university and to his students, Rector Roentgen spent the next six weeks in his laboratory, working alone, and sharing nothing with his colleagues. A strong reason for believing that
the cathode rays were particles was
the observation that they would
not pass through matter that was transparent to ultra-violet light.
When Heinrich Hertz found
that he could pass the rays through metal foil When Heinrich Hertz found that he could pass the rays through metal foil, a fellow German scientist, Philip Lenard, began to study them more
carefully. Lenard designed a tube with a thin aluminum window through which the rays could emerge, and he measured how far
they could travel and still induce fluorescence. Defined in this way, the range of the cathode rays was six to eight centimeters. HOW DID ROENTGEN CAME UP WITH THIS IDEA 1850 As with the invention of incandescent light bulbs, the study of electrical discharge through gases was made possible by the development of improved vacuum technology in the 1850s. Early on, English scientists were investigating the patterns of light and dark that appeared in sealed lead-glass tubes. Heinrich Rudolf Hertz, 1857–1894. Phillip Lenard, 1862–1947 In the course of repeating the experiments of Hertz and Lenard, he happened to notice a glowing fluorescent screen set off quite some distance from the Crookes’ tube he was operating. The screen sat much farther away than the six to eight centimeters that Lenard had found to be the maximum distance for which cathode rays maintain their power to induce fluorescence. Roentgen recognized the effect as worthy of his undivided attention and devoted the next six weeks to its uninterrupted study. CROOKE'S TUBE Forms of tube used by Roentgen
in 1895–1896 for the production
of X rays. Roentgen’s apparatus for studying the
ionization of air by X rays, 1906. Lenard’s experiments inspired Roentgen to wonder if the rays in an attenuated form really traveled farther, and he planned experiments to see if a sensitive electroscope would measure a discharge at four times the distance Lenard had identified. Three days before Christmas he brought his wife into his laboratory, and they emerged with a photograph of the bones in her hand and of the ring on her finger. The Würzburg Physico-Medical Society was the first to hear of the new rays that could penetrate the body and photograph its bones. Roentgen delivered the news on the 28th of December 1895. Emil Warburg relayed it to the Berlin Physical Society on the 4th of January. The next day the Wiener Press carried the news, and the day following word of Roentgen’s discovery began to spread by telegraph around the world. As the physicists wondered about the nature of X rays and used them to probe the structure of crystals and atoms, medical doctors used them to probe the human body and to diagnose and treat disease. Roentgen by presenting an X-ray photograph of his wife’s hand to the Würzburg Physical and Medical Society in January of 1896 began the practice of radiology. A month later a German doctor used an X ray to diagnose sarcoma of the tibia in the right leg of a young boy. The military first used X rays in Naples in May of 1896 to locate bullets in the forearms of two soldiers who had been wounded in Italy’s Ethiopian campaign. 1896 In the first six months after their discovery Viennese mummies were undressed, doctors claimed to have photographed their own brains, and the human heart was uncovered. By 1897 the rays’ dangerous side began to be reported: examples included loss of hair and skin burns of varying severity. 1897 1903 1904 1906 -1908 Charles Barkla conducted a research in the matter of X rays as neutral particles and a professor at the University of Edinburgh who spent over forty years examining the properties of secondary X rays. Between 1906 and 1908 he had noticed that elements emit secondary X rays with a penetrating power in aluminum that is distinct for each element. To distinguish between the hardness of the characteristic rays, he introduced the terminology K and L rays. 1922 1927 1970's to present PARTS OF THE X-RAY MACHINE VACUUM TUBE X-ray tubes are more commonly referred to as vacuum tubes. They are integral parts of the x-ray machine, and work by ionizing radiation with wavelengths shorter than ultraviolet light. A cathode within the machine emits electrons into the vacuum tube, at which point an anode collects the electrodes and establishes an electrical current through the tube. A high voltage is used to accelerate the electrons, and the current flow is pulsed until the required amount of x-ray exposure has occurred. The beams of energy from the tube are focused onto a visible substance, which is where you view the final result. A high voltage power source is required to operate an x-ray machine, usually between 30 and 150 kilovolts depending on the type of x-ray being taken. The voltage is used to accelerate the electrons within the vacuum tube, and is usually pulsed from 1 microsecond to 1 full second. The high voltage power source of an x-ray machine controls the penetration of the x-ray itself, and thus the overall contrast of the image, with the voltage of the current and exposure time affecting the dose and darkness of the image. POWER SOURCE CONTROL UNIT The control unit of the x-ray machine is necessary to manage the current, voltage, and time of exposure. Radiation intensity can change dramatically depending on whether you are using the machine to render x-ray stills of body parts or using it as a security monitor, for example. In addition there is a voltage control with a display, allowing you to make adjustments in the anode itself to change the type of radiation energy being released. The control unit also has a timer to control the pulses and duration of the exposure, shutting the current off when the radiation exposure has been completed. Abdominal X-ray Barium X-ray Chest X-ray Thoracic
Spine Dental X-ray Skull Neck Joint X-ray Lumbosacral spine x-ray HAND X-RAY Pelvis X-ray Bone X-ray PROPERTIES OF X-RAY X-RAY CALIBRATION PROPERTIES & X-RAY
SAFETY MEASURES EXPOSURE CALIBRATION A processor calibration check should be made once a week.
a. Plug the sensitometer into a power outlet in the darkroom and close the darkroom door as though you
were going to process film.
b. Place a processor check film lengthwise as far back as it will go under the metal holding tongue of the
c. Depress the exposure button on the sensitometer momentarily, then release it. Do not hold the exposure
button down; doing so will make multiple exposures.
d. Remove the film and place it lengthwise in the X-omat processor.
e. Meanwhile, insert sensitometer calibration strip into the sensitometer and take a series of 9 readings.
Turn the knob on the sensitometer until the digital readout matches the actual value on the calibration
strip. Repeat for all gradations on the strip.
f. Remove the film from the processor bin and place in the sensitometer and take readings at steps 3 and
7. Also take a background reading on film 1" above densometer imprint and 1" from the border.
g. Compare density readings with densitometer calibration strips obtained the previous week and a
standard strip. If there is a large variation or a trend in values, repeat the calibration.
If the problem persists, inform the MEC manager and the biomedical engineer. Processor Calibration Collimator Check Tube Warmup Procedure
At the beginning of each exam session or any time the x-ray unit has been turned off for two hours or longer, it is necessary to warm up the machine before making full exposures.
a. Set the following exposure factors: 70
kVp, 200 mA, 2 sec.
b.Activate the rotor, and make one
exposure; pause five or ten seconds,
and then make another exposure.
TO GOD BE THE GLORY! On setup day and any other day when the x-ray machine may not be operating properly, a calibration check on exposure factor should be made as follows:
a. Place a 24 x 30 cm cassette in the holder.
b. Attach the step wedge to the image receptor panel, thin side up, in the center of the light field.
c. Make a manual exposure at the following factor: 70 kVp, 200 mA, 3/20 second, 30 mAS.
d. Label the calibration films with the stand number, stand location, date, technician number.
e. Process film.
f. Take densitometer readings at steps 2, 5, and 8 on each film.
g. Compare the density readings with standard film taken at the time of installation. The variation between the shades of gray on a given step should be within one density step. If not, recalibrate. If the problem persists, inform the biomedical engineer in headquarters. A densitometer is used to study the relationship between the intensity of the exposure of the film and the blackness after processing (sensitometry). In order to do this, two pieces of apparatus are needed: an aluminum step wedge, sometimes called a penetrometer, and the densitometer.
a. Place a loaded cassette in the bucky.
b. Make an exposure and process the film. The exposed area on the developed film should be centered on the film so that the unexposed border is even on opposite edges of the film.
If not, inform the biomedical engineer at headquarters.