<i>Radiation Physics and Chemistry of Polymers</i>

Makhlis, F.A.; Knowles, H. B.

doi:10.1063/1.3023523

Cited by 77 publications

(65 citation statements)

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“…Oxygen can alter the gel sensitivity and depending on amount of contamination and level of irradiation, could retard or inhibit polymerization. This has already been reported by several authors e. g. Hoecker and Watking (1958) and Makhlis (1975). The effect of oxygen is to act as a trap for free radicals (Chrambach and Rodbard 1983).…”

Section: Applicationssupporting

confidence: 48%

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An investigation into the applications of polymer gel dosimetry in radiotherapy

Farajollahi

1999

Medical Physics

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The verification of complex dose distributions produced using novel techniques in radiotherapy requires measurements in three dimensions with high spatial resolution. Recent developments in polymer gel dosimetry employing MRI suggest this may be the best available method. In this work the properties of BANG (bis, acrylamide, nitrogen, and gelatin) polymer gel were investigated. The gel was found to be tissue equivalent and its response to absorbed dose reproducible to within ±4% and linear up to 10–12 Gy. The response of the gel was also found to be independent of energy and dose rate, but dependent on oxygen contamination and gel temperature during MR imaging. The application of BANG gel in different areas of radiotherapy was investigated. In brachytherapy a comparison of the relative dose rate distributions between gel, calculation, and TLDs agreed to within ±5%. The measured dose distributions from complex brachytherapy and multifield external beam irradiations agreed well with the distribution produced by the Helax‐TMS planning system. For external beam irradiation the depth doses measured in the gel showed good agreement with ion chamber measurements to within ±3%. The gel was also used to verify the absorbed dose distribution produced by intensity modulated beam techniques using compensators. The results agreed well with film dosimetry. BANG gel was also found to be an excellent candidate for dynamic measurements and measurements in areas with restricted access. A novel technique for measurements in boron neutron capture therapy using boron‐loaded gel is also described. It was concluded that gel can be used to verify complex dose distributions. [Copies of the thesis are available from Main Library, University of Leicester, University Road, Leicester, LE1 7RH, England.]

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Section: Applicationssupporting

confidence: 48%

“…The change was much more pronounced at higher doses. This may be explained by the release of trapped radicals and further reactions with the monomer (Makhlis 1975). The fate of the trapped radicals depends on the physical state of the polymer.…”

Section: Applicationsmentioning

confidence: 99%

An investigation into the applications of polymer gel dosimetry in radiotherapy

Farajollahi

1999

Medical Physics

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“…From literature, e.g., Charlesby ( 1960), Chapiro ( 1962), Makhblis (1975), and Zosel (1972), as well as from our present investigations [see Fig. 3 (c)l, it is known that polystyrene is rather insensitive towards irradiation: only at very high doses crosslinking will occur.…”

Section: Methodsmentioning

confidence: 84%

Influence of electron beam irradiation on the microrheology of incompatible polymer blends: Thread break‐up and coalescence

Gisbergen¹,

Meijer²

1991

Journal of Rheology

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SynopsisThe microrheology of polymer blends as influenced by crosslinks induced in the dispersed phase via electron beam irradiation, is systematically investigated for the model system polystyrene/low density polyethylene (PWLDPE).Both break-up of threads and coalescence of particles are delayed to a large extent, but are not inhibited completely and occur faster than would be expected for a nonirradiated material with a comparable viscosity. Small amplitude, dynamic rheological measurements indicated that in the irradiated materials a yield stress could exist. In contrast, direct microrheological measurements showed that this yield stress, which would prevent both break-up and coalescence, could not be realized by EB irradiation. Apparently, the direct study of the microrheology of a blend system is important for the prediction of the development of its morphology and it is not possible to rely only on rheological data obtained via other methods.

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“…w i t h i n t h e i r r a d i a t i o n t u b e s were checked w i t h radiochromic f o i l s . I n a r r i v i n g a t t h e s e dose rates i t i s assumed t h a t , f o r a g i v e n gamma r a y f l u x , t h e energy a b s o r p t i o n p e r u n i t mass i n water and i n hydrocarbon materials i s i d e n t i c a l (Makhlis, 1975). S p a t i a l v a r i a t i o n s and a t t e n u a t i o n 2.3 A n a l y t i c a l Procedures 2.3.1 G a s P r e s s u r e and Composition…”

mentioning

confidence: 99%