Parameters of the photon beams (6 and 20 MV) from a dual-energy linear accelerator (Mevatron-KD, Siemens Medical Laboratories, CA) are presented. The depth dose characteristics of the photon beams are dmax of 1.8 and 3.8 cm and percentage depth dose of 68% and 80% at 10-cm depth and 100-cm source-surface distance for a field size of 10 X 10 cm2 for 6 and 20 MV, respectively. The 6 and 20 MV beams were found to correspond to nominal accelerating potentials of 4.7 and 17 MV, respectively. The stability of output is within +/- 1% and flatness and symmetry are within +/- 3%. These figures compare favorably with the manufacturer's specifications.
Phase contrast, fluorescence and oblique incidence reflection imaging techniques have been used for the purpose of monitoring long-term cellular activity of therapeutically treated cancerous cells in cultures. Morphological changes in living cells that were induced by either irradiation or chemical agent were monitored over several days. Oblique incidence reflection (OIR) microscopy was used to obtain information on cell dynamics with minimal photodamage and sample degradation.Time-lapse imaging and cell culturing techniques used in this study were as described in [1]. Both cell lines for which data are presented were monolayer-adherent type cultures of human origin. With the exception of a few complementary fluorescence frames, the OIR imaging method was used to gather time-lapse information from a targeted cell group.Radiation is commonly and successfully used in the treatment of certain cancers, the dose being delivered in fractions or a sequence of incremental amounts. A preliminary assessment of the effects of irradiation was performed using cancer cells known to be responsive to radiation treatment, and a single dose fraction. A dose of 600cGy was delivered to histone H1-GFP labeled breast cancer cells (MCF-7) using the 6MV therapeutic x-ray beam from a Siemens ONCOR linear accelerator. Phase contrast images of randomly selected cell groups were taken each day for a period of 3 weeks postirradiation. Figure 1 (top) shows representative images of both untreated control (a) and treated (b through d) cells at one-week intervals. Typically, major morphological changes were visible after 4 days; treated cells were many times larger than normal and contained multiple nuclei. Morphologically normal cell colonies began to appear after 1 week and eventually took over the culture after 3 weeks of incubation (untreated control became confluent after 1 week). Figure 1 e) through g) illustrate examples of still frames selected from a time-lapse imaging session performed 6 days post-irradiation. Sequences of oblique images provided clear visualisation of macromolecular streaming, structural movement, nucleoli dynamics, and cell death.Induction of cellular differentiation is a possible treatment of cancers, and clinical trials are underway on several such inducers. Neuroblastoma cell lines have been used as a model to study cell differentiation [2,3]. To induce morphological changes typically seen in differentiation, untagged SK-N-SH neuroblastoma cells were incubated with 5mM sodium butyrate (a histone deacetylase inhibitor known to initiate differentiation in numerous cell lines). Time-lapse OIR imaging experiments of untreated control and treated cells were performed over several days.
Dosimetry measurements have been carried out for the electron beams produced by a linear accelerator at energies 6, 8, 10, 14, 18, and 21 MeV. Characteristic parameters of the central axis dose distributions were derived and compared to corresponding values of electron beams from other accelerators in clinical use where such a comparison is appropriate. A comprehensive set of dosimetric parameters is provided for electron beam treatment planning. The data include central axis depth dose, range-energy parameters, beam penumbra and uniformity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.