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Small changes in container shape or in contact angle can give rise to large shifts of liquid in a microgravity environment. These shifts can be used as a basis for accurate determination of contact angle. The authors describe container shapes, designed for a forthcoming USML-2 experiment, in the form of a circular cylinder with two diametrically opposed ``canonical proboscis`` protrusions. Computational studies indicate that these containers can be designed to have the desirable properties that sufficient liquid will participate in the shift to permit easy observation, but that the change will be abrupt enough to allow precise contact angle determination.

resulting dose plan ‘‘IMRT with PET’’ was used for treatment. For each patient, the 95% isodose curve from the dose plan created without PET was transferred to the target volumes created with the PET-information available. The volume of the 95% isodose curve in ‘‘IMRT without PET’’ was subtracted from the PTV-T from ‘‘IMRT with PET’’ in order to determine the part of the PTV-T treated to an insufficient dose if the target delineation and dose planning had been performed without PET. Standard therapy was IMRT, 68 Gy in 34 fractions to the GTV, nimorazole 1.25 g/m 2 before each fraction, and concomitant cisplatin 40 mg/m 2 weekly. Results: The median tumor volume (GTV) was 71.2 cm 3 (range: 18.1 - 232.9 cm 3 ); 16 patients (80%) were in UICC/AJCC stages III and IV. Addition of PET to CT/MR guided IMRT led to changes in the GTV in 12 patients (60%); the PET-corrected GTV ranged from 67% to 160% of the CT/MR defined volume. In 10 patients (50%) the addition of a PET scan resulted in an expansion of the GTV and in two patients (10%) the GTV was decreased as a result of PET. Changes in GTV occurred in the T-site in 11 patients (55%) and in the N-site in 8 patients (40 %). In 6 patients (30 %) PET resulted in alterations in both T-site and N-site. In 6 patients the PTV-T from ‘‘IMRT with PET’’ was not covered by the 95% isodose curve from ‘‘IMRT without PET’’, indicating that IMRT planning without PET would have resulted in underdosing of PET-positive areas of the GTV. These volumes of PVT-T receiving less than 95% of the specified dose if the PET information had not been included ranged from 0,46 cm 3 to 4.51 cm 3 .I n these volumes the minimal dose ranged from 58.5 Gy to 63.1 Gy in the dose plans from ‘‘IMRT without PET’’. Conclusions: FDG-PET adds important information regarding tumor extension to CT/MRI based IMRT target delineation and dose planning in both T and N sites. Inclusion of PET-positive areas not interpreted as tumor tissue by CT/MR prevents underdosing in critical areas. Planning PET/CT with MRI fusion is recommended for patients with nasopharyngeal carcinoma.

Purpose/Objective(s): The purpose of this study was to present a long-term single institutional experience with the use of daily image-guided radiotherapy (IGRT) for the treatment of head and neck cancer with intensity-modulated radiotherapy (IMRT). We also aimed to determine whether the percentage of weight loss over the course of treatment correlated with changes in positional alignment. Materials/Methods: Between 2005 and 2009, 124 patients with locally advanced head and neck cancer were treated at out our institution using IMRT with daily on-board imaging with megavoltage computed tomography (MVCT). The MVCT images were acquired over a longitudinal field of view that typically ranged from C7 to 2 cm superior to the base of skull using a coarse resolution in-slice thickness and nominal beam energy of 3.5 MV. After the MVCT images were reconstructed, they were fused with the treatment-planning CT images using automated registration bone presets and prepared for realignment if needed. These IGRT image sets were independently reviewed in the sagittal, coronal, and axial planes using the fusion split screen. We examined overall patient set-up shifts in the anterior-posterior (x), right-left (y), and superior-inferior (z) directions for IGRT, and the mean overall shift vector (MOSV) was subsequently calculated to be used as a measure of positional displacement. The percentage of weight loss during the entire course of treatment was determined from a retrospective review of patient records. The Pearson’s Correlation Coefficient, rho (r), was used to determine if a significant correlation existed between percentage weight loss and MOSV. Results: A total of 3,968 fractions were analyzed. The mean systematic alignment errors for all 124 patients were 0.5mm, 1.6mm, and 5.6mm in the x,- y-, z-dimensions with daily IGRT. The mean MOSV for all patients was 8.4mm with a standard deviation of 7.5mm. The mean percentage weight loss for all patients over the course of treatment was 7.2% with a standard deviation of 5.8%. When we compared MOSV to percent weight loss, we failed to detect any correlation between the two groups using the Pearson’s Correlation Coefficient (r=.05). The covariance (r^2) was determined to be 0.002. Conclusions: Although the benefits of daily IGRT have yet to be demonstrated with respect to the clinical endpoints of localregional control and overall survival for patients undergoing IMRT for head and neck cancer, this strategy appears to be a feasible and practical way of minimizing patient set-up error. Notably, the inability to identify any significant correlations between positionalshiftsasmeasuredwithdailyIGRTandvariousweightlossparameterssuggestthattherandomvariationobservedhascauses more complex than simple weight loss.

Misrejoining of double-strand breaks (DSBs) detected with pulsed-field gel electrophoresis (PFGE) after X irradiation of human cells at very high doses (80-160 Gy) is related to dose-response relationships for chromosome aberrations at moderate doses (1-5 Gy) by the Sax-Markov binary eurejoining/misrejoining (SMBE) model. The SMBE model applies Sax's breakage-and-reunion hypothesis to a subset of DSBs active in binary misrejoining and in binary eurejoining (accidental restitution). The model is numerically consistent with both data on chromosome aberrations and the data obtained by PFGE if proximity effects (restrictions on the range of interactions of DSB free ends) are present. Proximity effects are modeled by partitioning the cell's nucleus into approximately 400 interaction sites, with two active DSB free ends capable of rejoining only if they were produced within the same site. Neglecting one-track action, the SMBE model predicts a quadratic-linear dose-response relationship for DSB misrejoining after exposure to low-LET radiation; i.e., there is a quadratic response at moderate doses which becomes linear as the dose becomes large, rather than vice versa. The linear region results because at very high doses almost all of the active DSB free ends misrejoin rather than eurejoin.

With fluorescence in situ hybridization (FISH), many different categories of chromosome aberrations can be recognized-dicentrics, translocations, rings and various complex aberrations such as insertions or three-way interchanges. Relative frequencies for the various aberration categories indicate mechanisms of radiation-induced damage and reflect radiation quality. Data obtained with FISH support a proximity version of the classic random breakage-and-reunion model for the formation of aberrations. A Monte Carlo computer implementation of the model, called the CAS (chromosome aberration simulator), is generalized here to high linear energy transfer (LET) and compared to published data for human cells irradiated with X rays or 238Pu alpha particles. For each kind of radiation, the CAS has two adjustable parameters: the number of interaction sites per cell nucleus and the number of reactive double-strand breaks (DSBs) per gray. Aberration frequencies for various painted chromosomes, of varying lengths, and for 11 different categories of simple or complex aberrations were simulated and compared to the data. The optimal number of interaction sites was found to be approximately 13 for X irradiation and approximately 25 for alpha-particle irradiation. The relative biological effectiveness (RBE) of alpha particles for the induction of reactive DSBs (which are a minority of all DSBs) was found to be approximately 4. The two-parameter CAS model adequately matches data for many different categories of aberrations. It can use data obtained with FISH for any one painting pattern to predict results for any other kind of painting pattern or whole-genome staining, and to estimate a suggested overall numerical damage indicator for chromosome aberration studies, the total misrejoining number.

Many chromosome-type, exchange-type chromosomal aberrations produced by radiation are intrachanges, i.e. involve only one chromosome. It is assumed such intrachanges are formed by illegitimate reunion of two double-strand breaks (DSBs) on the chromosome. The yield of intra-arm intrachanges (acentric rings or paracentric inversions) relative to that of interarm intrachanges (centric rings or pericentric inversions) is larger than would occur if production and illegitimate reunion of DSBs were spatially random. The excess of intra-arm intrachanges is presumably due to proximity effects for illegitimate reunions, i.e. enhancement of the intrachange probability when two DSBs are formed close to one another. Radiation track structure may also play a role. Using a polymer description for "large-scale" chromatin geometry (>2 Mb), and using two alternate (rapid or slow motion) models for the way that DSBs move after they are produced, theoretical estimates are given for size distributions of intrachanges at low or high linear energy transfer (LET). The ratio of intra-arm to interarm intrachanges is derived from the size distribution and compared with data from the literature on centric rings, inversions, interstitial deletions and excess acentric fragments. Proximity effects enhance yields of intra-arm relative to interarm intrachanges at least severalfold and perhaps as much as 10-fold compared to expectations based on spatial randomness. We argue that further measurements of intra-arm and interarm intrachanges would be informative about large-scale chromatin structure and chromosome motion. Because inversions are more frequent than estimates of randomness would indicate, and are transmissible to daughter cells, their size distribution could also help characterize past exposure to high-LET radiation.

BackgroundIn 2012, the United States Preventative Services Task Force issued new guidelines recommending that male U.S. residents, irrespective of race, no longer be screened for prostate cancer. In African American men, the incidence of prostate cancer is almost 60% higher and the mortality rate is two to three times greater than in Caucasians. The purpose of this study is to reduce African American men's prostate cancer burden by demonstrating they need separate screening guidelines.MethodsWe performed a PubMed search using the keywords: African American, Prostate cancer, Outcomes, Molecular markers, Prostate-specific Antigen velocity, PSA density, and to derive data relevant to our hypothesis.ResultsIn our literature review, we identified several aspects of prostate cancer that are different in Caucasian and African American men. These included prostate cancer incidence and outcome, the clinical course of the disease, serum PSA levels, genetic differences, and social barriers. It's also important to note that the USPSTF guidelines were based on two studies, one of which reported that only 4% of its participants were African American. The other did not report demographic information, but used participants from seven European countries with small African American populations.ConclusionGiven the above, we conclude that separate prostate cancer screening guidelines are greatly necessary to help save the lives of African Americans.