IMPROVING QUANTITATIVE TREATMENT RESPONSE MONITORING WITH DEFORMABLE IMAGE REGISTRATION

Quantitative imaging with 18F-FDG PET/CT has the potential to provide an in vivo assessment of response to radiotherapy (RT). However, comparing tissue tracer uptake in longitudinal studies is often confounded by variations in patient setup and potential treatment induced gross anatomic changes. These variations make true response monitoring for the same anatomic volume a challenge, not only for tumors, but also for normal organs-at-risk (OAR). The central hypothesis of this study is that more accurate image registration will lead to improved quantitation of tissue response to RT with 18F-FDG PET/CT. Employing an in-house developed “demons” based deformable image registration algorithm, pre-RT tumor and parotid gland volumes can be more accurately mapped to serial functional images. To test the hypothesis, specific aim 1 was designed to analyze whether deformably mapping tumor volumes rather than aligning to bony structures leads to superior tumor response assessment. We found that deformable mapping of the most metabolically avid regions improved response prediction (P<0.05). The positive predictive power for residual disease was 63% compared to 50% for contrast enhanced post-RT CT. Specific aim 2 was designed to use parotid gland standardized uptake value (SUV) as an objective imaging biomarker for salivary toxicity. We found that relative change in parotid gland SUV correlated strongly with salivary toxicity as defined by the RTOG/EORTC late effects analytic scale (Spearman’s ρ = -0.96, P<0.01). Finally, the goal of specific aim 3 was to create a phenomenological dose-SUV response model for the human parotid glands. Utilizing only baseline metabolic function and the planned dose distribution, predicting parotid SUV change or salivary toxicity, based upon specific aim 2, became possible. We found that the predicted and observed parotid SUV relative changes were significantly correlated (Spearman’s ρ = 0.94, P<0.01). The application of deformable image registration to quantitative treatment response monitoring with 18F-FDG PET/CT could have a profound impact on patient management. Accurate and early identification of residual disease may allow for more timely intervention, while the ability to quantify and predict toxicity of normal OAR might permit individualized refinement of radiation treatment plan designs.

NEW TOOLS FOR MONITORING GAMMA CAMERA UNIFORMITY

Detector uniformity is a fundamental performance characteristic of all modern gamma camera systems, and ensuring a stable, uniform detector response is critical for maintaining clinical images that are free of artifact. For these reasons, the assessment of detector uniformity is one of the most common activities associated with a successful clinical quality assurance program in gamma camera imaging. The evaluation of this parameter, however, is often unclear because it is highly dependent upon acquisition conditions, reviewer expertise, and the application of somewhat arbitrary limits that do not characterize the spatial location of the non-uniformities. Furthermore, as the goal of any robust quality control program is the determination of significant deviations from standard or baseline conditions, clinicians and vendors often neglect the temporal nature of detector degradation (1). This thesis describes the development and testing of new methods for monitoring detector uniformity. These techniques provide more quantitative, sensitive, and specific feedback to the reviewer so that he or she may be better equipped to identify performance degradation prior to its manifestation in clinical images. The methods exploit the temporal nature of detector degradation and spatially segment distinct regions-of-non-uniformity using multi-resolution decomposition. These techniques were tested on synthetic phantom data using different degradation functions, as well as on experimentally acquired time series floods with induced, progressively worsening defects present within the field-of-view. The sensitivity of conventional, global figures-of-merit for detecting changes in uniformity was evaluated and compared to these new image-space techniques. The image-space algorithms provide a reproducible means of detecting regions-of-non-uniformity prior to any single flood image’s having a NEMA uniformity value in excess of 5%. The sensitivity of these image-space algorithms was found to depend on the size and magnitude of the non-uniformities, as well as on the nature of the cause of the non-uniform region. A trend analysis of the conventional figures-of-merit demonstrated their sensitivity to shifts in detector uniformity. The image-space algorithms are computationally efficient. Therefore, the image-space algorithms should be used concomitantly with the trending of the global figures-of-merit in order to provide the reviewer with a richer assessment of gamma camera detector uniformity characteristics.

Idiographic Self-Monitoring Instruments to Empower Client Participation and Evaluate Outcome in Intensive Family Preservation Services

Intensive Family Preservation Services seek to reflect the values of focusing on client strengths and viewing clients as colleagues. To promote those values, Intensive Family Preservation Programs should include a systematic form of client self monitoring in their packages of outcome measures. This paper presents a model of idiographic self-monitoring used in time series, single system research design developed for Family Partners, a family preservation program of the School for Contemporary Education in Annandale, Virginia. The evaluation model provides a means of empowering client families to utilize their strengths and promote their status as colleague in determining their own goals, participating in the change process, and measuring their own progress.

The Weekly Adjustment Indicators Checklist: An Application in the Child Welfare Field

Research on the effectiveness of various home-based interventions implemented in the 1980s and 1990s indicates that results have been equivocal. Because of the unique and complex behavioral challenges presented by each family and the need for individualized treatments and long-term interventions for these families, group research and evaluation designs are often insufficient in assessing effectiveness of home-based interventions. Alternative evaluation strategies are needed. The purpose of this exploratory study was two-fold: (a) to investigate the applicability and acceptability of the Weekly Adjustment Indicators Checklist (WAIC) in monitoring adult and child behaviors and (b) to monitor, on an on-going basis, the progress of a family referred to an urban family preservation and reunification program. The target family on whom data were collected consisted of a 13-year old girl and her foster parent who was her maternal aunt. The findings of this study indicate that the WAIC is applicable in monitoring the progress of children and adults in care and that it has the endorsement of its user, namely, the direct care provider. Other results of the study, limitations of the study, and future research needs are discussed.

Cultural competence in an HIV dedicated dental clinic: Application of the National Standards for Culturally and Linguistically Appropriate Services in Health Care (CLAS)

This dissertation investigated perspectives on cultural competence among African-American women patients, staff, and the administrator of a dental clinic serving people living with HIV/AIDS; and evaluated the role of the National Standards for Culturally and Linguistically Appropriate Services in Health Care (CLAS) in advancing the provision of culturally competent care in the clinic. ^ The study was qualitative with data collection via focus groups and individual interviews with a sample of African-American women patients, and individual interviews with a sample of staff and the clinic administrator. Transcripts were coded and themes identified using the software program ATLAS.ti. A cultural audit template was developed and applied to evaluate cultural competency. ^ Among attitudes and behaviors that contributed to the provision of culturally competent care at the clinic were respect and empathic communication. Formal cultural competency was not featured strongly in the methods by which the staff learned to work with diverse populations. Instead cultural competence among the staff was based on thoughtful hiring practices, natural aptitude and a climate that encouraged learning through informal sharing of experiences. The staff and administrator felt that an African-American dentist would be an asset in improving culturally competent care at the clinic. Previous research and national policy also promote the provider-patient racial/ethnic concordance to improve care. In this study, however, the patients were happy with the care provided regardless of the race/ethnicity of the staff, probably reflecting the well developed cultural competence skills of clinic staff overall. ^ The clinic administrator was unaware of the CLAS standards although the clinic was implicitly operated under their mandates. This occurred because the clinic is supported by federal funding and the CLAS standards were incorporated into the requirements. Incorporation into and monitoring of the CLAS standards in federally funded programs therefore appears to be an effective means for ensuring that they are implemented. ^ This study illustrates that cultural competence, though not universally understood, can be systematically investigated to identify what constitutes appropriate care and the factors that support or inhibit it. Among important elements of culturally competent care are respect and empathic communication. ^

Evaluation of a solid phase microextraction method for community-based monitoring of 1,3-butadiene and benzene in Houston, Texas

The Houston region is home to arguably the largest petrochemical and refining complex anywhere. The effluent of this complex includes many potentially hazardous compounds. Study of some of these compounds has led to recognition that a number of known and probable carcinogens are at elevated levels in ambient air. Two of these, benzene and 1,3-butadiene, have been found in concentrations which may pose health risk for residents of Houston.^ Recent popular journalism and publications by local research institutions has increased the interest of the public in Houston's air quality. Much of the literature has been critical of local regulatory agencies' oversight of industrial pollution. A number of citizens in the region have begun to volunteer with air quality advocacy groups in the testing of community air. Inexpensive methods exist for monitoring of ozone, particulate matter and airborne toxic ambient concentrations. This study is an evaluation of a technique that has been successfully applied to airborne toxics.^ This technique, solid phase microextraction (SPME), has been used to measure airborne volatile organic hydrocarbons at community-level concentrations. It is has yielded accurate and rapid concentration estimates at a relatively low cost per sample. Examples of its application to measurement of airborne benzene exist in the literature. None have been found for airborne 1,3-butadiene. These compounds were selected for an evaluation of SPME as a community-deployed technique, to replicate previous application to benzene, to expand application to 1,3-butadiene and due to the salience of these compounds in this community. ^ This study demonstrates that SPME is a useful technique for quantification of 1,3-butadiene at concentrations observed in Houston. Laboratory background levels precluded recommendation of the technique for benzene. One type of SPME fiber, 85 μm Carboxen/PDMS, was found to be a sensitive sampling device for 1,3-butadiene under temperature and humidity conditions common in Houston. This study indicates that these variables affect instrument response. This suggests the necessity of calibration within specific conditions of these variables. While deployment of this technique was less expensive than other methods of quantification of 1,3-butadiene, the complexity of calibration may exclude an SPME method from broad deployment by community groups.^