摘要:

Photonuclear reactions have been used to calibrate the energy of a Sagittaire clinical electron accelerator between 10 and 30 MeV. Thresholds at 10.8 MeV for the63Cu(γ,n)62Cu reaction and 29.7 MeV for the32S(γ,3p)29Al reaction provided two energy points. The break in the16O(γ,n)15O activation yield curve at 17.3 MeV was determined as an intermediate point. The relationship between electron kinetic energy and current through the energy‐analyzing magnet was found to be linear within 1.0% in this energy range.

ISSN:0269-3127    

DOI:10.1118/1.595062

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

The efficacy of localized current field (LCF) hyperthermia as an adjunct to192Ir interstitial implantation of tumors is currently under investigation. In this article, we describe an experimental LCF system suitable for such investigations, and discuss some of the physical and biological parameters pertinent to its design and safe operation.

ISSN:0269-3127    

DOI:10.1118/1.595223

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

A theoretical analysis of x‐ray tube spectral distributions has been made. Predicted spectra have been calculated for varying kVp and filtration. The analysis is not intended to give absolute tube output but to give accurate relative outputs. Several applications of this analysis are suggested for optimization studies in digital flouroscopy and x‐ray fluorescence analysis.

ISSN:0269-3127    

DOI:10.1118/1.595090

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

In order to produce individualized compensating filters for use with high energy x rays, a study was undertaken to study lead as a filter material using 10‐MV x rays. As was expected, it was found that lead filters could be constructed for 10‐MV x rays by extending concepts developed for cobalt‐60 gamma rays. A quantity called the “effective attenuation coefficient” (μeff) was determined for a range of field sizes, initial depths in water, and lead thicknesses and for 100‐cm SSD and 150‐cm SSD treatment techniques. Slight variations of μeffwith field area and filter thickness were discernable. However, a single value of this parameter could reproduce the original depth of missing tissue data with an rms error of 2 mm. Tests were then performed on filters whose shapes were calculated using the effective attenuation coefficient. Compensating filters restored the flatness of 10‐MV x‐ray beams to better than 5%, which was better than comparable filters using cobalt‐60 gamma rays. The technique is presented as generally reliable for constructing compensating filters for use with high energy linear accelerators.

ISSN:0269-3127    

DOI:10.1118/1.595225

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

A survey of the tissue substitutes, body phantoms, and radiographic test objects used in 98 medical centers in the U.S.A. has recently been completed. The results are presented here and compared with similar surveys undertaken in other countries. Future requirements mentioned by U.S. contributors are discussed.

ISSN:0269-3127    

DOI:10.1118/1.595097

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

摘要:

The formulation, manufacture and testing of an epoxy resin‐based solid substitute for water is presented. This “solid water” has radiation characteristics very close volumetrically to those of water. When it is used as a dosimetry phantom for x‐ and γ‐ray beams in the radiotherapy range, phantom‐to‐water corrections and density corrections are eliminated. Relative transmission measurements have shown that the transmission through 10 cm of solid water is within 0.2% of that through an equal thickness of water for x and γ rays. The use of this material for calibration phantoms can help achieve the goal of radiotherapy beam calibrations within ±1.0% of the true dose rate, easier to achieve.

ISSN:0269-3127    

DOI:10.1118/1.595063

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1118/1.595064

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1118/1.595227

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1118/1.595069

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY

ISSN:0269-3127    

DOI:10.1118/1.595070

出版商:American Association of Physicists in Medicine    

年代:1998

数据来源: WILEY