abstract：:The bremsstrahlung spectrum from an 8-MeV linear accelerator has been measured using a NaI(T1) spectrometer system. The spectrum shows a low-energy cutoff at 0.4 MeV and the maximum photon energy to be approximately 6% greater than the nominal energy. The maximum emission of energy fluence was 1.6 and 1.8 MeV for meas...

journal_title：Medical physics

authors： Levy LB,Waggener RG,Wright AE

更新日期：1976-05-01 00:00:00

abstract：:Weighting of given doses from parallel opposed fields is a widespread practice in radiation therapy of cancer in the tonsillar region. In order to determine when weighting is useful, dose distributions on the central axis were calculated for various energies (60Co, 4-, 8-, 15-, and MVp photons), weighting factors, and...

journal_title：Medical physics

authors： Wollin M,Gilbert HA,Kagan AR

更新日期：1976-03-01 00:00:00

abstract：:Permanent implants of 125I seeds at Memorial Sloan-Kettering Cancer Center are performed by the method of "dimension averaging" to determine the total activity to be implanted; that is, the activity (in mCi) is taken to be five times the average dimension (in cm) of the target region. A nomograph has recently been dev...

journal_title：Medical physics

authors： Anderson LL

更新日期：1976-01-01 00:00:00

abstract：:The analysis and understanding of results of computed tomography (CT) require an understanding of photon attenuation in matter. The high sensitivity and resolution of these devices coupled with the use of a polychromatic photon source require a level and breadth of understanding about photon attenuation not usually re...

journal_title：Medical physics

authors： McCullough EC

更新日期：1975-11-01 00:00:00

abstract：:The design and construction of a Styrofoam cutter used in the fabrication of custom shielding blocks is described. ...

journal_title：Medical physics

authors： Sorensen A,Goshaw L

更新日期：1975-11-01 00:00:00

abstract：:Inherent in the line-spread function approach in modulation transfer function (MTF) determinations is the use of a microdensitometer to scan the density pattern resulting from the line exposure. In such a procedure, loss of fidelity in the distribution being scanned is expected. This loss is due in part to the use of ...

journal_title：Medical physics

authors： Villafana T

更新日期：1975-09-01 00:00:00

abstract：:Atomic Energy of Canada Limited 60Co teletherapy units have adjustable collimator hinges to adapt to source diameters from 0.75 to 2.50 cm. Adjustment of the collimator hinge to the manfacturer's settings can cause a loss of radiation field flatness as high as 20% for large fields. The recommended settings appear to c...

journal_title：Medical physics

authors： Heintz PH

更新日期：1975-03-01 00:00:00

abstract：:Interchange or transfer of radiographic techniques through measurement of penetration quality is discussed. The usefulness of this achievement is verified using an aluminum step wedge. Also, the procedure described provides a method for performance evaluation of kVp compensation on diagnostic x-ray installations. ...

journal_title：Medical physics

authors： Lin PJ

更新日期：1975-01-01 00:00:00