摘要:

A digital display plug‐in for use with the Victoreen 555 exposuremeter is described. The device is a readout subsystem for displaying numerical and dimensional information in a clear, legible form, with both probe and range scale factors accounted for in the display itself. In addition to facilitating data gathering with the 555, the device circumvents nonlinearity in the analog meter movement. Minor modifications required of the 555 mainframe are described.

ISSN:0269-3127    

DOI:10.1118/1.594241

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

Scatter–air ratios are tabulated quantities which are based on measurement and which are used to calculate the dose to points in the body of a patient exposed to radiation fields of arbitrary shape. For computing purposes it is convenient to represent these quantities by an equation. We have found a nine‐parameter empirical function which expresses scatter–air ratio data for60Co γ rays and for 4‐ and 6‐MV x rays. To test the equation it was used to calculate tissue–air ratios for a range of rectangular fields. The results are in good agreement with published values.

ISSN:0269-3127    

DOI:10.1118/1.594265

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

The Keithley model 602 electrometer–Farmer ionization chamber combination has served as the standard dosimetry system for calibration measurements made by the AAPM Radiological Physics Center at 156 different institutions. The constancy of this system is compared to that for the Baldwin–Farmer Secondary Standard Dosemeter type 2502, and is based on measurements made over a 3‐yr period on a Cobalt‐60 γ‐ray source. A Strontium‐90 check source is also shown to be a reliable standard, and frequent checks with such a source can prevent serious calibration errors.

ISSN:0269-3127    

DOI:10.1118/1.594266

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

A third‐degree polynomial and power‐law analysis with the method of least‐squares fit are computed for backscatter factor with a continuous variation of field size and different beam quality of radiation from 1.0‐mm Al external x ray to60Co γ ray. Three coefficients are required for a third‐degree polynomial and two coefficients for power law method of each beam quality.

ISSN:0269-3127    

DOI:10.1118/1.594242

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

Iodine‐123 has such great potential to nuclear medicine that all possible production methods should be considered. In this report an experimental study related to123l production at a high‐intensity fast flux reactor using the reaction124Xe(n,2n)123Xe is considered. The conclusion is that123l could be made in small quantities and the cost would be higher than the cyclotron methods presently used.

ISSN:0269-3127    

DOI:10.1118/1.594243

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

The total effects of the cavity displacement and the perturbation of the field by the cavity in thimble‐chamber measurements of absorbed dose were investigated for electron beams of energy 15, 20, 30, and 39 MeV and for60CO γ radiation by LiF dosimeter rods of diameter 1 mm and length 6 mm. The measurements were carried out in a polystyrene phantom at recommended reference depths and at the respective electronic equilibrium depths, for cavities of varying sizes. Owing to the cavity effect, the ratio of absorbed dose of a 5‐mm‐diameter cavity to that of a point cavity, at the reference depth, was 1.028 for60Co γ radiation; this ratio varied from 1.022 at 15 MeV to 1.033 for 39‐MeV electrons. Although the cavity effect is present over regions of the depth dose where dose is constant with depth, here it was less dependent on cavity size than when the cavity was positioned at ICRU depths. Both the displacement and perturbation of the radiation field effects are automatically corrected through the experimental arrangement in this work.

ISSN:0269-3127    

DOI:10.1118/1.594267

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1118/1.594244

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1118/1.594268

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1002/j.2473-4209.1976.tb36073.x

出版商:Wiley    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1002/j.2473-4209.1976.tb36074.x

出版商:Wiley    

年代:1998

数据来源: WILEY