The effect of boron-containing layers on the yield of secondary gamma radiation

Atomic Energy ◽  
1961 ◽  
Vol 8 (1) ◽  
pp. 42-43 ◽  
Author(s):  
D. L. Broder ◽  
A. P. Kondrashov ◽  
A. A. Kutuzov ◽  
A. I. Lashuk
Keyword(s):  
Gamma Radiation ◽  
Secondary Gamma Radiation

Secondary gamma radiation from neutral particle beams

1991 ◽  
Vol 2 (2-3) ◽  
pp. 199-208
Author(s):  
Guy A. Letteer ◽  
John A. Jungerman ◽  
Carlos M. Castaneda
Keyword(s):  
Gamma Radiation ◽  
Neutral Particle ◽  
Particle Beams ◽  
Secondary Gamma Radiation

Problems of secondary gamma radiation in reactor shields

1975 ◽  
Vol 38 (6) ◽  
pp. 520-523
Author(s):  
A. A. Abagyan ◽  
T. A. Germogenova ◽  
A. A. Dubinin ◽  
V. I. Zhuravlev ◽  
V. A. Klimanov ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Secondary Gamma Radiation

scholarly journals Photoneutrons for Radiation Therapy and Radionuclide Production

2018 ◽  
Vol 3 (3) ◽  
pp. 41
Author(s):  
H. A. Onischuk ◽  
Yu. A. Kurachenko ◽  
Yu. G. Zabaryansky
Keyword(s):  
Gamma Radiation ◽  
Electron Energy ◽  
Electron Accelerator ◽  
Spectral Characteristics ◽  
Liquid Gallium ◽  
Output Unit ◽  
Output Beam ◽  
Radionuclide Production ◽  
Neutron Therapy ◽  
Secondary Gamma Radiation

The possibility of organizing neutron therapy with a photoneutron beam produced by the electron accelerator target, and ensuring the required dose at the tumor at a reasonable exposure time and with minimal impact on patients investigated. Generation of neutrons from the target of electron accelerator takes place in two stages: e- ® γ ® n, and in the selected electron energy range of 20-100 MeV, the bremsstrahlung gamma radiation in many times (~ 3 orders of magnitude) offers more than “useful” neutron yield. This raises the problem of the selective control of the “harmful” for radiotherapy secondary gamma radiation while providing the minimum attenuation of the neutron flux in the output beam. In order to solve the general problem of the formation of a neutron beam with necessary spectral characteristics having sufficient intensity, there has been resolved a number of computational tasks of the selection of the optimal configuration of the output beam unit and its composition. The matter of high importance is to minimize additional irradiation of the patient from the bremsstrahlung (generated by electrons) and secondary gamma radiation (generated by neutrons) from the accelerator target as well as from output unit’s materials. On the other hand, at a generation stage e- ® γ the bremsstrahlung beam could be applied for effective radionuclide production by reactions (γ,n) and (γ,p) due to high leak intensity ~ 1.3·1017 photon/s. By the Mo100(γ,n)99Mo reaction the main diagnostic nuclide 99Tc could be produced sufficiently for the clinical needs. The resulting configuration of the output unit provides the required beam quality for the neutron capture therapy (NCT), which commonly assumed to be the only competitive technology of neutron therapy on the background of the massive invasion of proton therapy and other highly selective techniques that ultimately damage the target sparing the surrounding tissues and organs. For the accessible accelerator (average current 4 mA and electron energy 35 MeV) the flux density of epithermal photoneutrons (they required for NCT) in the beam at the output is of the order of magnitude or more higher than the typical yield from existing and planned reactors' beams. The proposed scheme of generation and extraction of photoneutrons for NCT has a number of strong advantages over traditional techniques: a) the applying of electron accelerators for neutron production is much safer and cheaper than conventional reactor beams in use; b) accelerator with the target, the beam output unit with the necessary equipment can be placed on the territory of the clinic without any problems of radiation safety; c) the proposed target – liquid gallium, which also serves as a cooler, is an “environmentally friendly” material due to low activation which rapidly (in ~ 4 days) falls to the background level.

Effects of sterilization modes on the mechanical strengths of plaster of paris implants

1989 ◽  
Vol 47 ◽  
pp. 890-891
Author(s):  
K. Cowden ◽  
B. Giammara ◽  
T. Devine ◽  
J. Hanker
Keyword(s):  
Gamma Radiation ◽  
Calcium Sulfate ◽  
Significant Loss ◽  
Potassium Sulfate ◽  
Limiting Factors ◽  
Radiation Sterilization ◽  
Plaster Of Paris ◽  
Hardness Tester ◽  
Dry Heat ◽  
Calcium Sulfate Hemihydrate

Plaster of Paris (calcium sulfate hemihydrate, CaSO4. ½ H2O) has been used as a biomedical implant material since 1892. One of the primary limiting factors of these implants is their mechanical properties. These materials have low compressive and tensile strengths when compared to normal bone. These are important limiting factors where large biomechanical forces exist. Previous work has suggested that sterilization techniques could affect the implant’s strength. A study of plaster of Paris implant mechanical and physical properties to find optimum sterilization techniques therefore, could lead to a significant increase in their application and promise for future use as hard tissue prosthetic materials.USG Medical Grade Calcium Sulfate Hemihydrate Types A, A-1 and B, were sterilized by dry heat and by gamma radiation. Types A and B were additionally sterilized with and without the setting agent potassium sulfate (K2SO4). The plaster mixtures were then moistened with a minimum amount of water and formed into disks (.339 in. diameter x .053 in. deep) in polyethylene molds with a microspatula. After drying, the disks were fractured with a Stokes Hardness Tester. The compressive strengths of the disks were obtained directly from the hardness tester. Values for the maximum tensile strengths σo were then calculated: where (P = applied compression, D = disk diameter, and t = disk thickness). Plaster disks (types A and B) that contained no setting agent showed a significant loss in strength with either dry heat or gamma radiation sterilization. Those that contained potassium sulfate (K2SO4) did not show a significant loss in strength with either sterilization technique. In all comparisons (with and without K2SO4 and with either dry heat or gamma radiation sterilization) the type B plaster had higher compressive and tensile strengths than that of the type A plaster. The type A-1 plaster however, which is specially modified for accelerated setting, was comparable to that of type B with K2SO4 in both compressive and tensile strength (Table 1).

Use of the comet assay to measure DNA damage in cells exposed to photosensitizers and gamma radiation

1999 ◽  
Vol 96 (1) ◽  
pp. 143-146 ◽  
Author(s):  
J.-P. Pouget ◽  
J.-L. Ravanat ◽  
T. Douki ◽  
M.-J. Richard ◽  
J. Cadet
Keyword(s):  
Dna Damage ◽  
Comet Assay ◽  
Gamma Radiation ◽  
In Cells
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