(n.) A telescope arranged and used to determine errors of collimation, both vertical and horizontal.
(n.) A tube having a convex lens at one end and at the other a small opening or slit which is at the principal focus of the lens, used for producing a beam of parallel rays; also, a lens so used.
Example Sentences:
(1) The dual-probe system incorporates a central collimated probe for monitoring activity in the LV surrounded by an annular detector collimated in such a manner as to provide simultaneous real-time monitoring of the LV background activity.
(2) The second area of improved SPECT technology is camera collimation and related imaging techniques.
(3) Comparative clinical studies on temporomandibular joints (TMJ) between the LEGP and fan beam collimators also confirm the superior image quality obtained with the fan beam collimator.
(4) In work to determine whether X-radiation could be used to induce tumors of the colon in outbred Holtzman rats, a technique was devised so that only the descending colon could be irradiated with a collimated X-ray beam and tumorigenic exposures in the kilo-Roentgen range were delivered.
(5) In the RAO view with the collimator flat against the chest there was better resolution of the cardiac apex.
(6) As an initial feasibility study of computer-controlled radiation therapy, its application to produce wedge-shaped dose distributions by moving the collimator jaws has been evaluated.
(7) Analysis of the penumbra width of cross dose distributions, as a function of field sizes, allowed us to postulate that the dmax shift could be due to the phantom scattered photons, which in turn were generated by the collimator scattered photons.
(8) Larger detectors with converging collimation result in much higher photon input rates to the scintillation crystal in routine clinical studies than has occurred in the past.
(9) Neutron spectra at various locations in a phantom, irradiated by collimated beams of 14 MeV neutrons and neutrons from 252 Cf and Po-Be sources, were calculated using the Monte Carlo technique.
(10) Without scatter, the resolution was 4.7 mm (full width at half-maximum); in a scatter medium, the resolution was 5.3-10.0 mm with high resolution collimation and 7.7-18.8 mm with general purpose collimation, depending on filtering.
(11) Quantitative measurement of the scatter dose in polystyrene solid phantoms with a Farmer type chamber and effects of shielding blocks under the collimators were studied.
(12) Spatial resolution with parallel-hole or converging collimators was much less satisfactory with Ta-178 because of septal penetration by high-energy photons.
(13) Moving the collimator during imaging will reduce septal aberrations but will not increase resolution.
(14) The nonuniform response inherent in the use of the pinhole collimator has a significant effect, but with computer processing this is readily eliminated.
(15) The exchange of collimator pairs results in significant output differences but has a negligible effect on the depth-dose curves.
(16) This was consistent with the design of the line focus and the beam collimators used in this system.
(17) One-centimeter collimation contiguous scans through the chest were obtained in all patients.
(18) A further increase in photon utization is gained for small-organ imaging with converging collimators, which produce images with superior resolution and sensitivity to that obtained with equivalent parallel-hole collimators.
(19) Normal quantitative circumferential profile limits were established for a 30 degrees bilateral rotating slant-hole (RSH) collimator tomographic system.
(20) Central axis percentage depth doses and off-axis ratios measured with such a collimator show variations with the source-to-surface distance (SSD).
Optical
Definition:
(a.) Of or pertaining to vision or sight.
(a.) Of or pertaining to the eye; ocular; as, the optic nerves (the first pair of cranial nerves) which are distributed to the retina. See Illust. of Brain, and Eye.
(a.) Relating to the science of optics; as, optical works.
Example Sentences:
(1) Following central retinal artery ligation, infarction of the retinal ganglion cells was reflected by a 97 per cent reduction in the radioactively labeled protein within the optic nerve.
(2) This study examined both the effect of variations in optical fiber tip and in light wavelength on laser-induced hyperthermia in rat brain.
(3) The number of axons displaying peptide-like immunoreactivity within the optic nerve, retinal or cerebral to the crush, and within the optic chiasm gradually decreased after 2-3 months.
(4) Once the normal variations are mastered, appreciation of retinal, choroidal, optic nerve, and vitreal abnormalities is possible.
(5) Chromatolysis and swelling of the cell bodies of cut axons are more prolonged than after optic nerve section and resolve in more central regions of retina first.
(6) CW Nd:YAG light transmitted by fiber optic cable and sapphire crystal was applied transsclerally to the ciliary body of pigmented and albino rabbits.
(7) Unlike results seen in the goldfish optic nerve, injury to the rat optic nerve induced no observable increase in laminin content or change in its distribution.
(8) This is the first report of anterior ischemic optic neuropathy as a result of hemodialysis-associated hypotension.
(9) It is shown that, by comparison of a reacting mixture at chemical equilibrium with a non-reacting but equally composed one, the sum of the mean concentrations of the reaction products can immediately be taken from optical absorption or from interferometric measurements.
(10) A television camera scans the spread through microscope optics; computer and special purpose electronics process the video signals to generate run length histograms.
(11) The purity and configuration of each isomer of the free acid and N-chloroacetylated derivative were ascertained by: (a) paper chromatography in five solvent systems, (b) elemental analysis, (c) Van Slyke nitrous acid determination of alpha-carbonyl carbon, and (d) Van Slyke ninhydrin determination of alpha-carbonyl carbon, and (e) optical rotation.
(12) The optical and oxygen binding properties of the reconstituted myoglobins containing two isomeric monoformyl-monovinylhemins were found to be different.
(13) These images were previously determined by using a recently developed hybrid optical-digital method.
(14) The development of optical fibers capable of transmitting laser energy has encouraged the experimental use of laser irradiation for the treatment of acquired cardiovascular disorders.
(15) This technique is sensitive to the optical anisotropy within the muscle, including that due to intrinsic properties of the protein molecules as well as that due to the regular arrangement of proteins in the surrounding medium.
(16) Patients should be evaluated by perimetry using an appropriate strategy and contrast sensitivity testing, along with careful examination of the optic discs.
(17) Thus, during treatment with ethambutol visually (pattern) evoked potentials may reveal a surprisingly high percentage of subclinical optic neuritis.
(18) The optical efficiencies are similar and depend on the match of the excitation characteristics of the stain with the emission spectra of the light source.
(19) Morphological results demonstrated that 30 Gy irradiated animals showed extensive necrosis primarily in the fimbria, which extended into the internal capsule, optic nerve, hippocampus, and thalamus.
(20) A compact attachment for microscope-type instruments is described enabling to introduce, rapidly and qualitatively, minute biological speciments into melted embedding medium and ensuring the safety of optics.