In this paper, we describe a quantitative evaluation of the dosimetry effect of lack of side-scatter volume (LSSV). MapCheck, an integration diode array, was used to measure dose maps for three large non-IMRT fields (...In this paper, we describe a quantitative evaluation of the dosimetry effect of lack of side-scatter volume (LSSV). MapCheck, an integration diode array, was used to measure dose maps for three large non-IMRT fields (30cm ×30 cm and 40 cm×40 cm open fields, and 30 cm×30 cm wedge field with wedge angle of 60°) and 19 large IMRT fields. For each field, measurement was performed twice, under the conditions of (1) full scatter volume and (2) LSSV. Condition 1 was satisfied by adding PMMA slabs against the side of the MapCheck, and Condition 2, without PMMA slabs. The measured dose maps were compared with pass rate and their difference was scored when the acceptance criterion was set to 0.5%, 1%, 2%, 3%, etc. For very large open fields, the effect of LSSV may be clinically significant, while for large wedge fields and IMRT fields, the effect is negligible.展开更多
The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The p...The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer shows the transition temperatures K52N79I in degreesC, The H-v scattering intensity T(q,t) during the transition I (at 80.2degreesC)-->N (at 75.8degreesC) shows that T(q) is independent of q for all t, and during the initial stage (in 6 s) T(t) increases exponentially with t. In the later stage of the transition T(t) approaches a saturation value in 2 min. This experimental result indicates that the I-->N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.展开更多
文摘In this paper, we describe a quantitative evaluation of the dosimetry effect of lack of side-scatter volume (LSSV). MapCheck, an integration diode array, was used to measure dose maps for three large non-IMRT fields (30cm ×30 cm and 40 cm×40 cm open fields, and 30 cm×30 cm wedge field with wedge angle of 60°) and 19 large IMRT fields. For each field, measurement was performed twice, under the conditions of (1) full scatter volume and (2) LSSV. Condition 1 was satisfied by adding PMMA slabs against the side of the MapCheck, and Condition 2, without PMMA slabs. The measured dose maps were compared with pass rate and their difference was scored when the acceptance criterion was set to 0.5%, 1%, 2%, 3%, etc. For very large open fields, the effect of LSSV may be clinically significant, while for large wedge fields and IMRT fields, the effect is negligible.
基金This work was supported by the National Key Projects for Fundamental Research, "Macromolecular Condensed State" of Ministry of Science and Technology of China.
文摘The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer shows the transition temperatures K52N79I in degreesC, The H-v scattering intensity T(q,t) during the transition I (at 80.2degreesC)-->N (at 75.8degreesC) shows that T(q) is independent of q for all t, and during the initial stage (in 6 s) T(t) increases exponentially with t. In the later stage of the transition T(t) approaches a saturation value in 2 min. This experimental result indicates that the I-->N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.
