Biomaterial Database

A megavoltage MTF measurement technique for metal screen-film detectors. 1979

R T Droege

A technique to measure the MTF of metal screen-film detectors at megavoltage x-ray energies has been devised. It employs an exposure through a slit 25 micron wide and a method to average numerous line spread functions from a single film image. That the slit is wide compared to those used at diagnostic x-ray energies serves two purposes: it facilitates the use of a laser alignment procedure designed to ensure correct orientation of the slit-forming tungsten blocks in the x-ray beam, and it also increases the contrast in the slit image, thereby reducing the data analysis problems caused by film noise. Further reduction in the effects of film noise is accomplished by the averaging method. A correction is made to account for the effect of the wide slit on the MTF. The validity of this correction, the laser alignment, and the averaging method have been confirmed by simulations.

UI	MeSH Term	Description	Entries
D007834	Lasers	An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.	Masers,Continuous Wave Lasers,Pulsed Lasers,Q-Switched Lasers,Continuous Wave Laser,Laser,Laser, Continuous Wave,Laser, Pulsed,Laser, Q-Switched,Lasers, Continuous Wave,Lasers, Pulsed,Lasers, Q-Switched,Maser,Pulsed Laser,Q Switched Lasers,Q-Switched Laser
D008962	Models, Theoretical	Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Experimental Model,Experimental Models,Mathematical Model,Model, Experimental,Models (Theoretical),Models, Experimental,Models, Theoretic,Theoretical Study,Mathematical Models,Model (Theoretical),Model, Mathematical,Model, Theoretical,Models, Mathematical,Studies, Theoretical,Study, Theoretical,Theoretical Model,Theoretical Models,Theoretical Studies
D011827	Radiation	Emission or propagation of acoustic waves (SOUND), ELECTROMAGNETIC ENERGY waves (such as LIGHT; RADIO WAVES; GAMMA RAYS; or X-RAYS), or a stream of subatomic particles (such as ELECTRONS; NEUTRONS; PROTONS; or ALPHA PARTICLES).	Radiations
D011856	Radiographic Image Enhancement	Improvement in the quality of an x-ray image by use of an intensifying screen, tube, or filter and by optimum exposure techniques. Digital processing methods are often employed.	Digital Radiography,Image Enhancement, Radiographic,Radiography, Digital,Enhancement, Radiographic Image,Enhancements, Radiographic Image,Image Enhancements, Radiographic,Radiographic Image Enhancements
D011874	Radiometry	The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by SCINTILLATION COUNTING.	Geiger-Mueller Counters,Nuclear Track Detection,Radiation Dosimetry,Dosimetry, Radiation,Geiger Counter,Geiger-Mueller Counter Tube,Geiger-Mueller Probe,Geiger-Mueller Tube,Radiation Counter,Counter Tube, Geiger-Mueller,Counter Tubes, Geiger-Mueller,Counter, Geiger,Counter, Radiation,Counters, Geiger,Counters, Geiger-Mueller,Counters, Radiation,Detection, Nuclear Track,Dosimetries, Radiation,Geiger Counters,Geiger Mueller Counter Tube,Geiger Mueller Counters,Geiger Mueller Probe,Geiger Mueller Tube,Geiger-Mueller Counter Tubes,Geiger-Mueller Probes,Geiger-Mueller Tubes,Probe, Geiger-Mueller,Probes, Geiger-Mueller,Radiation Counters,Radiation Dosimetries,Tube, Geiger-Mueller,Tube, Geiger-Mueller Counter,Tubes, Geiger-Mueller,Tubes, Geiger-Mueller Counter
D011877	Radionuclide Imaging	The production of an image obtained by cameras that detect the radioactive emissions of an injected radionuclide as it has distributed differentially throughout tissues in the body. The image obtained from a moving detector is called a scan, while the image obtained from a stationary camera device is called a scintiphotograph.	Gamma Camera Imaging,Radioisotope Scanning,Scanning, Radioisotope,Scintigraphy,Scintiphotography,Imaging, Gamma Camera,Imaging, Radionuclide
D000497	Alloys	A mixture of metallic elements or compounds with other metallic or metalloid elements in varying proportions.	Alloy
D014414	Tungsten	A metallic element with the atomic symbol W, atomic number 74, and atomic weight 183.85. It is used in many manufacturing applications, including increasing the hardness, toughness, and tensile strength of steel; manufacture of filaments for incandescent light bulbs; and in contact points for automotive and electrical apparatus.	Wolfram
D015502	Absorptiometry, Photon	A noninvasive method for assessing BODY COMPOSITION. It is based on the differential absorption of X-RAYS (or GAMMA RAYS) by different tissues such as bone, fat and other soft tissues. The source of (X-ray or gamma-ray) photon beam is generated either from radioisotopes such as GADOLINIUM 153, IODINE 125, or Americanium 241 which emit GAMMA RAYS in the appropriate range; or from an X-ray tube which produces X-RAYS in the desired range. It is primarily used for quantitating BONE MINERAL CONTENT, especially for the diagnosis of OSTEOPOROSIS, and also in measuring BONE MINERALIZATION.	Absorptiometry, X-Ray,Dual-Photon Absorptiometry,Photodensitometry, X-Ray,Photon Absorptiometry,Single-Photon Absorptiometry,X-Ray Absorptiometry,Absorptiometry, Dual X-Ray,Absorptiometry, Dual-Energy Radiographic,Absorptiometry, Dual-Energy X-Ray,DEXA Scan,DPX Absorptiometry,DXA Scan,Densitometry, X-Ray,Densitometry, Xray,Dual X-Ray Absorptiometry,Dual-Energy Radiographic Absorptiometry,Dual-Energy X-Ray Absorptiometry,Dual-Energy X-Ray Absorptiometry Scan,Radiographic Absorptiometry, Dual-Energy,X-Ray Absorptiometry, Dual-Energy,X-Ray Photodensitometry,Absorptiometries, DPX,Absorptiometry, DPX,Absorptiometry, Dual Energy Radiographic,Absorptiometry, Dual Energy X Ray,Absorptiometry, Dual X Ray,Absorptiometry, Dual-Photon,Absorptiometry, Single-Photon,Absorptiometry, X Ray,DEXA Scans,DXA Scans,Densitometry, X Ray,Dual Energy Radiographic Absorptiometry,Dual Energy X Ray Absorptiometry,Dual Energy X Ray Absorptiometry Scan,Dual Photon Absorptiometry,Dual X Ray Absorptiometry,Photodensitometry, X Ray,Radiographic Absorptiometry, Dual Energy,Scan, DEXA,Scan, DXA,Scans, DEXA,Scans, DXA,Single Photon Absorptiometry,X Ray Absorptiometry,X Ray Absorptiometry, Dual Energy,X Ray Photodensitometry,X-Ray Absorptiometry, Dual,X-Ray Densitometry,Xray Densitometry