Search

Purpose: To investigate the effect of carbon ion irradiation on glioma cell migration., Methods and Materials: U87 and Ln229 glioma cells were irradiated with photons and carbon ions. Migration was analyzed 24 h after irradiation. Fluorescence-activated cell sorting analysis was performed in order to quantify surface expression of integrins., Results: Single photon doses of 2 Gy and 10 Gy enhanced α(ν)β(3) and α(ν)β(5) integrin expression and caused tumor cell hypermigration on both vitronectin (Vn) and fibronectin (Fn). Compared to integrin expression in unirradiated cells, carbon ion irradiation caused decreased integrin expression and inhibited cell migration on both Vn and Fn., Conclusion: Photon radiotherapy (RT) enhances the risk of tumor cell migration and subsequently promotes locoregional spread via photon induction of integrin expression. In contrast to photon RT, carbon ion RT causes decreased integrin expression and suppresses glioma cell migration on both Vn and Fn, thus promising improved local control., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Dynamic beam delivery techniques are being increasingly used for cancer therapy. Scanning ion beams require extensive and time-demanding quality assurance procedures and beam tuning. Accordingly, fast measurement techniques improving the efficiency of the procedures and accommodating the safety requirements are highly desirable. Major requirements for a detector used for beam-shape measurements are high spatial resolution in two dimensions, reusability, online readout and easy handling. At the Heidelberg Ion Beam Therapy Facility (Germany), we examined the performance of the RID 256 L flat-panel detector for beam spot measurements. The two-dimensional beam profiles of proton and carbon ion beams measured were compared to measurements with radiographic films at intermediate energies using the index. The difference to the beam width measured with radiographic films of less than 3% demonstrates sufficient accuracy of ion beam width measurements possible with this detector for both proton and carbon ion beams. The beam shapes were also measured at different beam intensities. At both the highest and lowest energies available at the HIT, no beam spot-shape deformation was found with increasing beam intensities, as long as the boundary of the dynamic range was not exceeded. The signal leak along the readout direction was identified as an undesirable effect. However, due to small amplitudes and static beams, this effect is of minor importance for beam spot measurements. Distortion of results due to detector radiation damage was monitored. No detector radiation damage was observed over the experiments. Moreover, the observed short-time detector response stability (within ±0.1%) as well as medium term stability (within 0.5% in 15 months) was excellent. This flat-panel detector is compact and easy to use. Together with its low weight, this helps to speed up measurement procedures substantially. All these properties make this an ideal detector for the fast, high-resolution imaging of static ion beam spots needed for constancy measurements in daily beam quality assurance and for accelerator tuning. For daily use, radiation damage has to be monitored continuously and corrected for if necessary.

Context: Technological advancements have led craniofacial researchers and clinicians into the era of three-dimensional digital imaging for quantitative evaluation of craniofacial growth and treatment outcomes., Objective: To give an overview of soft-tissue based methods for quantitative longitudinal assessment of facial dimensions in children until six years of age and to assess the reliability of these methods in studies with good methodological quality., Data Source: PubMed, EMBASE, Cochrane Library, Web of Science, Scopus and CINAHL were searched. A hand search was performed to check for additional relevant studies., Study Selection: Primary publications on facial growth and treatment outcomes in children younger than six years of age were included., Data Extraction: Independent data extraction by two observers. A quality assessment instrument was used to determine the methodological quality. Methods, used in studies with good methodological quality, were assessed for reliability expressed as the magnitude of the measurement error and the correlation coefficient between repeated measurements., Results: In total, 47 studies were included describing 4 methods: 2D x-ray cephalometry; 2D photography; anthropometry; 3D imaging techniques (surface laser scanning, stereophotogrammetry and cone beam computed tomography). In general the measurement error was below 1 mm and 1° and correlation coefficients range from 0.65 to 1.0., Conclusion: Various methods have shown to be reliable. However, at present stereophotogrammetry seems to be the best 3D method for quantitative longitudinal assessment of facial dimensions in children until six years of age due to its millisecond fast image capture, archival capabilities, high resolution and no exposure to ionizing radiation.

Purpose: To present the first direct experimental in vitro comparison of the biological effectiveness of range-equivalent protons and carbon ion beams for Chinese hamster ovary cells exposed in a three-dimensional phantom using a pencil beam scanning technique and to compare the experimental data with a novel biophysical model., Methods and Materials: Cell survival was measured in the phantom after irradiation with two opposing fields, thus mimicking the typical patient treatment scenario. The novel biophysical model represents a substantial extension of the local effect model, previously used for treatment planning in carbon ion therapy for more than 400 patients, and potentially can be used to predict effectiveness of all ion species relevant for radiotherapy. A key feature of the new approach is the more sophisticated consideration of spatially correlated damage induced by ion irradiation., Results: The experimental data obtained for Chinese hamster ovary cells clearly demonstrate that higher cell killing is achieved in the target region with carbon ions as compared with protons when the effects in the entrance channel are comparable. The model predictions demonstrate agreement with these experimental data and with data obtained with helium ions under similar conditions. Good agreement is also achieved with relative biological effectiveness values reported in the literature for other cell lines for monoenergetic proton, helium, and carbon ions., Conclusion: Both the experimental data and the new modeling approach are supportive of the advantages of carbon ions as compared with protons for treatment-like field configurations. Because the model predicts the effectiveness for several ion species with similar accuracy, it represents a powerful tool for further optimization and utilization of the potential of ion beams in tumor therapy., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Purpose: Informed consent forms an important part of treatment, especially in the case of elective treatment. The aim of this survey was to establish how much patients can recall of the information given during an informed consent interview before orthognathic surgery. During the consultation, attention was given to all aspects of the treatment. However, because of "insurance-related factors," the need for treatment because of functional reasons was stressed over esthetics. The recall of information given during an informed consent interview before orthognathic surgery was measured using a questionnaire., Materials and Methods: Patients with a mandibular deficiency with a low mandibular plane angle were questioned after an informed consent interview regarding surgical orthodontic treatment., Results: Esthetics were more frequently and functional problems were less frequently recalled as the reason for operation than was expected. The risk of a change in the sensation of the lower lip by surgery was frequently recalled as a reason to refrain from the operation. The overall recall rate of the possible risks and complications of orthodontic surgery was 40%., Conclusions: No reports were found of comparable research on the preoperative recall after consultation before surgical orthodontic surgery. The aspects of communication that can improve recall must be clarified. A recall rate of 100% seems a utopia, although an arbitrary line is needed to determine the quality of an informed consent interview.

The investigation of fragment length distributions of plasmid DNA gives insight into the influence of localized energy distribution on the induction of DNA damage, particularly the clustering of double-strand breaks. We present an approach that determines the fragment length distributions of plasmid DNA after heavy-ion irradiation by using the Local Effect Model. We find a good agreement of our simulations with experimental fragment distributions derived from atomic force microscopy (AFM) studies by including experimental constraints typical for AFM. Our calculations reveal that by comparing the fragmentation in terms of fluence, we can uniquely distinguish the effect of different radiation qualities. For very high-LET irradiation using nickel or uranium ions, no difference between their fragment distributions can be expected for the same dose level. However, for carbon ions with an intermediate LET, the fragmentation pattern differs from the distribution for very high-LET particles. The results of the model calculations can be used to determine the optimal experimental parameters for a demonstration of the influence of track structure on primary radiation damage. Additionally, we compare the results of our model for two different plasmid geometries.

Atomic Force Microscopy of phiX174 plasmids irradiated in vitro was used to visualise the DNA fragmentation induced by heavy ions and to compare it to the fragmentation pattern obtained after X-irradiation. Fragment distributions induced by low ion fuences were found to be much more shifted towards small fragment sizes than the distributions obtained after corresponding doses of X-rays. The average fragment length was found to be significantly smaller than the full plasmid length even for single ion traversals.

Preliminary measurements on the production of single- and double-strand breaks in SV40 and phi X174 plasmid DNA by various heavy ions in radioprotective Tris buffer are presented. The dependence of the recorded yields on the LET of the incoming ions is discussed and shown to be comprehensible within the framework of a model based on the X-ray sensitivity of the exposed DNA and the local dose distribution inside the heavy ion track. The question of the influence of the chemical environment is addressed by comparing the measured cross sections to data recorded previously in more radiosensitive TE buffer. The results indicate that also for systems with high scavenging capacity RBE values larger than unity can be achieved with maximum values in the LET range 100-1000 keV micrometers-1.