Thoracic radiotherapy treatment planning with cine PET/CT

Purpose: Respiratory motion causes substantial uncertainty in radiotherapy treatment planning. Four-dimensional computed tomography (4D-CT) is a useful tool to image tumor motion during normal respiration. Treatment margins can be reduced by targeting the motion path of the tumor. The expense and complexity of 4D-CT, however, may be cost-prohibitive at some facilities. We developed an image processing technique to produce images from cine CT that contain significant motion information without 4D-CT. The purpose of this work was to compare cine CT and 4D-CT for the purposes of target delineation and dose calculation, and to explore the role of PET in target delineation of lung cancer. Methods: To determine whether cine CT could substitute 4D-CT for small mobile lung tumors, we compared target volumes delineated by a physician on cine CT and 4D-CT for 27 tumors with intrafractional motion greater than 1 cm. We assessed dose calculation by comparing dose distributions calculated on respiratory-averaged cine CT and respiratory-averaged 4D-CT using the gamma index. A threshold-based PET segmentation model of size, motion, and source-to-background was developed from phantom scans and validated with 24 lung tumors. Finally, feasibility of integrating cine CT and PET for contouring was assessed on a small group of larger tumors. Results: Cine CT to 4D-CT target volume ratios were (1.05±0.14) and (0.97±0.13) for high-contrast and low-contrast tumors respectively which was within intraobserver variation. Dose distributions on cine CT produced good agreement (< 2%/1 mm) with 4D-CT for 71 of 73 patients. The segmentation model fit the phantom data with R2 = 0.96 and produced PET target volumes that matched CT better than 6 published methods (-5.15%). Application of the model to more complex tumors produced mixed results and further research is necessary to adequately integrate PET and cine CT for delineation. Conclusions: Cine CT can be used for target delineation of small mobile lesions with minimal differences to 4D-CT. PET, utilizing the segmentation model, can provide additional contrast. Additional research is required to assess the efficacy of complex tumor delineation with cine CT and PET. Respiratory-averaged cine CT can substitute respiratory-averaged 4D-CT for dose calculation with negligible differences.

Partial volume correction incorporating Rb-82 positron range for quantitative myocardial perfusion PET based on systolic-diastolic activity ratios and phantom measurements.

BACKGROUND: Quantitative myocardial PET perfusion imaging requires partial volume corrections. METHODS: Patients underwent ECG-gated, rest-dipyridamole, myocardial perfusion PET using Rb-82 decay corrected in Bq/cc for diastolic, systolic, and combined whole cycle ungated images. Diastolic partial volume correction relative to systole was determined from the systolic/diastolic activity ratio, systolic partial volume correction from phantom dimensions comparable to systolic LV wall thicknesses and whole heart cycle partial volume correction for ungated images from fractional systolic-diastolic duration for systolic and diastolic partial volume corrections. RESULTS: For 264 PET perfusion images from 159 patients (105 rest-stress image pairs, 54 individual rest or stress images), average resting diastolic partial volume correction relative to systole was 1.14 ± 0.04, independent of heart rate and within ±1.8% of stress images (1.16 ± 0.04). Diastolic partial volume corrections combined with those for phantom dimensions comparable to systolic LV wall thickness gave an average whole heart cycle partial volume correction for ungated images of 1.23 for Rb-82 compared to 1.14 if positron range were negligible as for F-18. CONCLUSION: Quantitative myocardial PET perfusion imaging requires partial volume correction, herein demonstrated clinically from systolic/diastolic absolute activity ratios combined with phantom data accounting for Rb-82 positron range.

Detection of enterotoxigenic Escherichia coli in foods by polymerase chain reaction

Enterotoxigenic Escherichia coli (ETEC) causes significant morbidity and mortality in infants of developing countries and is the most common cause of diarrhea in travelers to these areas. Enterotoxigenic Escherichia coli infections are commonly caused by ingestion of fecally contaminated food. A timely method for the detection of ETEC in foods would be important in the prevention of this disease. A multiplex polymerase chain reaction (PCR) assay which has been successful in detecting the heat-labile and heat-stable toxins of ETEC in stool was examined to determine its utility in foods. This PCR assay, preceded by a glass matrix and chaotropic DNA extraction, was effective in detecting high numbers of ETEC in a variety of foods. Ninety percent of 121 spiked food samples yielded positive results. Samples of salsa from Guadalajara, Mexico and Houston, Texas were collected and underwent DNA extraction and PCR. All samples yielded negative results for both the heat-labile and heat-stable toxins. Samples were also subjected to oligonucleotide probe analysis and resulted in 5 samples positive for ETEC. Upon dilution testing, it was found that positive PCR results only occurred when 12,000 to 1,000,000 bacteria were present in 200 mg of food. Although the DNA extraction and PCR method has been shown to be both sensitive and specific in stool, similar results were not obtained in food samples. ^

The status of genetically modified foods internationally and in the United States

Biotechnology refers to the broad set of techniques that allow genetic manipulation of organisms. The techniques of biotechnology have broad implications for many industries, however it promises the greatest innovations in the production of products regulated by the Food and Drug Administration (FDA). Like many other powerful new technologies, biotechnology may carry risks as well as benefits. Several of its applications have engendered fervent emotional reactions and raised serious ethical concerns, especially internationally. ^ First, in my paper I discuss the historical and technical background of biotechnology. Second, I examine the development of biotechnology in Europe, the citizens' response to genetically modified (“GM”) foods and the governments' response. Third, I examine the regulation of bioengineered products and foods in the United States. ^ In conclusion, there are various problems with the current status of regulation of GM foods in the United States. These are four basic flaws: (1) the Coordinated Framework allows for too much jurisdictional overlap of biotechnological foods, (2) GM foods are considered GRAS and consequently, are placed on the market without pre-market approval, (3) federal mandatory labeling of GM foods cannot occur until the question of whether or not nondisclosure of a genetic engineering production processes is misleading or material information and (4) an independent state-labeling scheme of GM foods will most likely impede interstate commerce. ^

Knowledge of exercise recommendations and energy intake from foods and beverages in relation to exercise behaviors within two Hispanic border communities

This research is a secondary analysis of the Qué Sabrosa Vida population-based cross-sectional study of two predominately Mexican American communities located along the Texas-Mexico border in 2000. There were two aims for this research. The first was to determine the relationship between knowledge of exercise and water recommendations, and exercise behavior and water consumption. The second was to determine the relationship between exercise behavior and percentage of energy consumption from beverages. Chi-square analysis revealed the majority of both populations had adequate knowledge about water and exercise recommendations, although significant percentages of the populations (>40%) did not consume water or exercise in adequate amounts. Knowledge was found to be a component of both behaviors, as it was more prevalent in the adults who exercised and consumed water in adequate amounts. Analysis of variance revealed no significant difference between overall beverage calorie percentage and exercise level (all p-values > 0.05); both regions and genders reported ∼18% of total caloric intake from beverages. There was no disproportionate influence of beverage calories on total caloric intake, after controlling for water consumption and independent of exercise behavior. These findings suggest that overall caloric intake, from both foods and beverages, may be the most influential factor to the energy imbalance contributing to the obesity crisis in these Hispanic border populations. ^

An investigation into the relationship between screen time, consumption of advertised foods, and physical activity among Texas 4th grade elementary school children

Background. The high prevalence of obesity among children has spurred creation of a list of possible causative factors, including the advertising of foods of minimal nutritional value, a decrease in physical activity, and increased media use. Few studies show prevalence rates of these factors among large cohorts of children. ^ Methods. Using data from the 2004-2005 School Physical Activity and Nutrition project (SPAN), a secondary analysis of 7907 4th-grade children (mean age 9.74 years) was conducted. In addition, a comic-book–based intervention that addressed advertised food consumption, physical activity, and media use was developed and evaluated using a pre-post test design among 4th-grade children in an urban school district. ^ Results. Among a cohort of 4th-grade children across the state of Texas, children who had more than 2 hours of video game or computer time the previous day were more than twice as likely to drink soda and eat candy or pastries. In addition, children who watched more than 2 hours of TV the previous day were more than three times as likely to consume chips, punch, soda, candy, frozen desserts, or pastries (AOR 3.41, 95% CI: 1.58, 7.37). A comic-book based intervention held great promise and acceptance among 4th-grade children. Outcome evaluation showed that while results moved in a positive direction, they were not statistically significant. ^ Conclusion. Statistically significant associations were found between screen time and eating various types of advertised food. The comic book intervention was widely accepted by the children exposed to it, and pre-post surveys indicated they moved constructs in a positive direction. Further research is needed to look at more specific ways in which children are exposed to TV, and the relationship of the TV viewing time with their consumption of advertised foods. In addition, researchers should look at comic book interventions more closely and attempt to utilize them in more in studies with a longer follow-up time. ^

THE RECOVERY OF ENTEROPATHOGENS FROM CONTAMINATED COOKED FOODS AT HOLDING TEMPERATURES

Hot foods served in foodservice establishments, institutions and homes, have always been regarded as safe, since cooking temperatures are more likely to kill the bacterial agents that may cause foodborne diseases. However, foods that are otherwise served hot have been epidemiologically incriminated for causing foodborne diseases. This situation arises due to the possible post-cooking food contamination. Post-cooking contamination of hot-held food is most threatening for it gives the contaminating agents the possibility of proliferation. On one hand, post-cooking contamination is least understood and on the other, hot-holding of food gives the consumer a false sense of freedom from foodborne diseases. In this study, the dynamics of food contamination before or after cooking and during hot-holding are discussed and a food contamination dynamics model is presented.^ The literature on foodborne cholera, cholera-like diarrhea, shigellosis and E. coli gastroenteritis together with the literature on the occurrence and growth of the causative enteropathogens; 01 V. cholerae, non-01 V. cholerae, S. sonnei, S. flexneri and E. coli were reviewed. The literature on the infective doses of these organisms were also cited.^ In the study, four cooked food types held hot at 40-60(DEGREES)C were deliberately contaminated with 01 V. cholerae, non-01 V. cholerae, S. sonnei, S. flexneri and E. coli, one at a time at each of the hot-holding temperatures. Tested food samples for the recovery of these enteropathogens were withdrawn at various time intervals of hot holding.^ The results showed bacterial recovery to decline with increasing temperature and with increasing hot-holding time within each holding temperature. All the bacterial types except V. cholerae were recovered even after holding the food at 60(DEGREES)C for one hour. V. cholerae was not recovered after hot-holding the food at 50-60(DEGREES)C at certain holding periods. After 48 hrs incubation, V. cholerae was recovered on TCBS agar plates that read negative after the initial 24 hrs of incubation. Effective hot-holding temperatures were determined for each of the food types contaminated by each of the bacterial types.^ Statistical analysis of the collected data showed temperature, bacterial type and their interaction to be significant in enteropathogen recovery. Food type and its interactions with temperature and bacterial type were found not significant. ^

Design, Calibration, and Evaluation of Depth-of-Interaction-Capable PET Detector Modules

High-resolution, small-bore PET systems suffer from a tradeoff between system sensitivity, and image quality degradation. In these systems long crystals allow mispositioning of the line of response due to parallax error and this mispositioning causes resolution blurring, but long crystals are necessary for high system sensitivity. One means to allow long crystals without introducing parallax errors is to determine the depth of interaction (DOI) of the gamma ray interaction within the detector module. While DOI has been investigated previously, newly available solid state photomultipliers (SSPMs) well-suited to PET applications and allow new modules for investigation. Depth of interaction in full modules is a relatively new field, and so even if high performance DOI capable modules were available, the appropriate means to characterize and calibrate the modules are not. This work presents an investigation of DOI capable arrays and techniques for characterizing and calibrating those modules. The methods introduced here accurately and reliably characterize and calibrate energy, timing, and event interaction positioning. Additionally presented is a characterization of the spatial resolution of DOI capable modules and a measurement of DOI effects for different angles between detector modules. These arrays have been built into a prototype PET system that delivers better than 2.0 mm resolution with a single-sided-stopping-power in excess of 95% for 511 keV g's. The noise properties of SSPMs scale with the active area of the detector face, and so the best signal-to-noise ratio is possible with parallel readout of each SSPM photodetector pixel rather than multiplexing signals together. This work additionally investigates several algorithms for improving timing performance using timing information from multiple SSPM pixels when light is distributed among several photodetectors.

Supplemental Nutrition Assistance Program: A policy analysis of restricting foods with minimal nutritional value

In 2011, expenditures for the Supplemental Nutrition Assistance Program (SNAP) reached an all-time high of $72 billion. The goal of SNAP is " to alleviate hunger and malnutrition…by increasing food purchasing power for all eligible households who apply for participation." It has been well established that proper nutrition is essential to good health, making SNAP an important program to public health consumers. Thus, this analysis examined whether SNAP is meeting its stated goal and whether the goal would be reduced if the purchase of foods of minimal nutritional value (FMNV) were restricted. ^ A review of existing literature found that SNAP has been shown to alleviate hunger, but the studies on the nutritional impact of the program were not sufficient to assert whether change is needed. When considering whether limiting FMNV would reduce or improve the effectiveness of SNAP at alleviating hunger and malnutrition, there is very little information on which to base a policy change, particular one that singles out a low income group to restrict purchases. ^ Several states have attempted to restrict the purchase of FMNV but, to date, no such change has been implemented or tested. Conducting pilot studies on the restriction of FMNV, along with better data collection on SNAP purchases, would guide policy changes to the program. Although there are many potential public health benefits to restricting FMNV purchase using SNAP dollars, research is needed to quantify the cost impact of these benefits.^

Student consumption of a la carte foods during school lunch meals

The purpose of this study was to evaluate students' lunch consumption compared to NSLP guidelines, the contribution of competitive foods to calorie intake at lunch, and the differences in nutrient and food group intake between the a la carte food consumers and non- a la carte food consumers.^ In Fall 2011, 1170 elementary and 440 intermediate students were observed anonymously during school lunch. The foods eaten, their source, grade level, and gender were recorded. All a la carte offerings met the Texas School Nutrition Policy.^ Differences in nutrient and food group intake by grade level and between students who consumed a la carte and those who did not were assessed using ANCOVA. A chi-squared analysis was conducted to evaluate differences in a la carte food consumption by grade level, gender, and the school's low income status.^ Average lunch intakes for elementary students were 457 (SD 164) calories for elementary students and 541 calories (SD 188) for intermediate students (p<0.001). 760 students (47%) consumed 937 a la carte foods, with the most often consumed items being chips (32%), ice cream (22%) and snack items (18%). Mean a la carte food intakes were 60 and 98 calories for elementary and intermediate schools respectively (p<0.001). Significantly more (p<0.000) intermediate students (34.3%) consumed a la carte items compared to elementary students (27.5%).^ Students who consumed a la carte foods had significantly higher intakes of calories (p<0.000), fat (p<0.000), sodium (p<0.002), fiber (p<0.000), added sugar (p<0.000), total grains (p<0.000), dessert foods (p<0.000), and snack chips (p<0.000) and lower intakes of vitamin A (p<0.001), iron (p<0.000), fruit (p<0.022), vegetables (p<0.031), milk (p<0.000), and juice (p<0.000) compared to students who did not eat a la carte foods.^ Although previous studies have found that reducing availability of unhealthy items at school decreased student consumption of these items, the results of this study indicate that even the strict guidelines set forth by the state of Texas are not sufficient to prevent increased caloric intake and poor nutrient intake. Strategies to improve student selection and consumption at school lunch when a la carte foods are available are warranted.^