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PurposeThe objective of this study was to determine if exposure to a short-term ultrasound basic biology and anatomy course can promote interest in health careers and other science-related endeavors among DHH students.Design/methodology/approachThis was a single-site, prospective observational study of DHH high school students at a Southern California high school. All participants took a pre-test survey prior to the course. Participants then took part in three teaching sessions which taught basic anatomy using point-of-care ultrasound (POCUS). Following instruction, a post-test survey was performed to determine if students had an increased interest in medicine, science and biology (p = 0.151).Findings28 students were enrolled in the study, with an equal distribution of boys and girls. Initially, subjects reported their interest in medicine at an average of 2.8 ± 1.10. The reported interest in science was 3.0 ± 1.13 and for biology was 3.0 ± 1.19. The change in participants' interest was not statistically significant for medicine (p = 0.791), science (p = 0.225) and biology.Practical implicationsWhile our data did not demonstrate a statistically significant difference in students' interest in STEM fields after the training course, there were several students who were interested in more hands-on shadow experience after the course. Regardless, this study demonstrates persistent barriers that exist for a person who is deaf or hard of hearing to engage in the STEM fields. Future studies are needed to determine the level of instructional activities that may impact the careers of these students.Originality/valuePoint of care ultrasound has been shown to be an effective teaching modality in medical education. However, to date, no studies have been done to assess the utility of ultrasound in teaching the Deaf and Hard of Hearing (DHH) population.

BackgroundOver the past few years, both the scope and utility of point-of-care ultrasound (POCUS) have tremendously expanded in the clinical setting. Despite this growth, few studies have evaluated the compliance, documentation, and billing of POCUS in the emergency department (ED). The objective of this study was to evaluate the compliance of billing and documentation of POCUS and determine if a single, individualized e-mail feedback can help improve billing and documentation.MethodsWe performed a 6-week prospective review of ED POCUSs performed. Following this review, all emergency physicians were sent an individualized e-mail regarding their ultrasound performance including the total number of ultrasounds, ultrasounds per shift, and breakdown of specific ultrasound types. Following this intervention, we collected data from an additional 6 weeks regarding ultrasound billing performance.ResultsA total of 1532 POCUS scans were recorded for data collection. Eight hundred and five scans were enrolled in the preintervention group and 727 scans in the postintervention group. Twelve different types of POCUS scans were recorded. The preintervention group had documented 484/805 scans resulting in a 60.1% (confidence interval [CI] 56.7%-63.5%) documentation ratio. The postintervention group had documented 521/727 resulting in a 71.7% (CI 68.2%-74.9%) documentation ratio.ConclusionThe implementation of timely quality assurance with continuous billing reminders is essential for the maintenance and fiscal sustainability of an emergency medicine ultrasound program. Future studies should further elucidate and quantify the financial impact of modifiable factors within EDs' ultrasound documentation and billing practices.

Author(s): Mazumder, Proma; Al-Khouja, Fares; Moeller, John; Lahham, Shadi | Abstract: Introduction: Point-of-care ultrasound (POCUS) in the emergency department (ED) is being performed with increasing frequency. The objective of this study was to demonstrate how utilization of POCUS can help the emergency physician recognize emphysematous pyelitis (EP) and emphysematous pyelonephritis (EPN). Case Report: A 60-year-old female presented to the ED with normal vital signs and intermittent left-sided flank pain that radiated to her groin. She also had a history of obstructive nephrolithiasis. Within 20 minutes of arrival she became febrile (101.2°Fahrenheit), tachycardic (114 beats per minute), tachypneic (21 breaths per minute), and had a blood pressure of 114/82 millimeters mercury. POCUS was conducted revealing heterogeneous artifact with “dirty shadowing” within the renal pelvis, which was strongly suggestive of air. The emergency physician ordered a computed tomography (CT) to confirm the suspicion for EP and started the patient on broad-spectrum antibiotics. The CT showed a 1.3-centimeter calculus and hydronephrosis with foci of air. The patient received intravenous antibiotics and had an emergent nephrostomy tube placed. Urine cultures tested positive for pan-sensitive Escherichia Coli. Urology was consulted and a repeat CT was obtained to show correct drainage and decreased renal pelvis dilation.Conclusion: Distinctly different forms of treatment are used for EP and EPN, despite both having similar pathophysiology. In EP, air can be seen in the renal pelvis on POCUS, as in this case study, which distinguishes it from EPN. In the case of our patient, the use of POCUS was useful to aid in rapid differentiation between EP and EPN.

Author(s): Lahham, Shadi; Lee, Clifton; Ali, Qumber; Moeller, John; Fischetti, Chanel; Thompson, Maxwell; Saadat, Soheil; Fox, John C. | Abstract: Introduction: Sepsis is a systemic infection that can rapidly progress into multi organ failure and shock if left untreated. Previous studies have demonstrated the utility of point of care ultrasound (POCUS) in the evaluation of patients with sepsis. However, limited data exists on the evaluation of the tricuspid annular plane of systolic excursion (TAPSE) in patients with sepsis.Methods: We prospectively enrolled patients who presented to the emergency department (ED) with concern for severe sepsis or septic shock in a pilot study. In patients that screened positive, the treating physician then performed POCUS to measure the TAPSE value. We compared the intensive care unit (ICU) admission rate, hospital length of stay, and morbidity with their respective TAPSE values.Results: We enrolled 24 patients in the study. Eight patients had TAPSE values less than 16 millimeters (mm), two patients had TAPSE values between 16mm-20mm, and fourteen patients had TAPSE values greater than 20mm. There was no statistically significant association between TAPSE levels and ICU admission (p=0.16), or death (p=0.14). The difference of length of stay (LOS) was not statistically significant in case of hospital LOS (p= 0.72) or ICU LOS.Conclusion: Our pilot data did not demonstrate a correlation between severe sepsis or septic shock and TAPSE values. This may be due to several factors including patient comorbidities, strict definitions of sepsis and septic shock, as well as the absence of septic cardiomyopathy (SCM) in patients with sepsis and septic shock. Future large-scale studies are needed to determine if TAPSE can be beneficial in the ED evaluation of patients with concern for SCM.

Hemiptera, the largest non-holometabolous order of insects, represents approximately 7% of metazoan diversity. With extraordinary life histories and highly specialized morphological adaptations, hemipterans have exploited diverse habitats and food sources through approximately 300 Myr of evolution. To elucidate the phylogeny and evolutionary history of Hemiptera, we carried out the most comprehensive mitogenomics analysis on the richest taxon sampling to date covering all the suborders and infraorders, including 34 newly sequenced and 94 published mitogenomes. With optimized branch length and sequence heterogeneity, Bayesian analyses using a site-heterogeneous mixture model resolved the higher-level hemipteran phylogeny as (Sternorrhyncha, (Auchenorrhyncha, (Coleorrhyncha, Heteroptera))). Ancestral character state reconstruction and divergence time estimation suggest that the success of true bugs (Heteroptera) is probably due to angiosperm coevolution, but key adaptive innovations (e.g. prognathous mouthpart, predatory behaviour, and haemelytron) facilitated multiple independent shifts among diverse feeding habits and multiple independent colonizations of aquatic habitats.

The current study addresses the extent to which diversity in dental attendance across population subgroups exists within and between the USA and selected European countries.The analyses relied on 2006/2007 data from the Survey of Health, Ageing and Retirement in Europe (SHARE) and 2004-2006 data from the Health and Retirement Study (HRS) in the USA for respondents≥51 years of age. Logistic regression models were estimated to identify impacts of dental-care coverage, and of oral and general health status, on dental-care use.We were unable to discern significant differences in dental attendance across population subgroups in countries with and without social health insurance, between the USA and European countries, and between European countries classified according to social welfare regime. Patterns of diverse dental use were found, but they did not appear predominately in countries classified according to welfare state regime or according to the presence or absence of social health insurance.The findings of this study suggest that income and education have a stronger, and more persistent, correlation with dental use than the correlation between dental insurance and dental use across European countries. We conclude that: (i) higher overall rates of coverage in most European countries, compared with relatively lower rates in the USA, contribute to this finding; and that (ii) policies targeted to improving the income of older persons and their awareness of the importance of oral health care in both Europe and the USA can contribute to improving the use of dental services.

What does it mean for an algorithm to be biased? In U.S. law, unintentional bias is encoded via disparate impact, which occurs when a selection process has widely different outcomes for different groups, even as it appears to be neutral. This legal determination hinges on a definition of a protected class (ethnicity, gender, religious practice) and an explicit description of the process. When the process is implemented using computers, determining disparate impact (and hence bias) is harder. It might not be possible to disclose the process. In addition, even if the process is open, it might be hard to elucidate in a legal setting how the algorithm makes its decisions. Instead of requiring access to the algorithm, we propose making inferences based on the data the algorithm uses. We make four contributions to this problem. First, we link the legal notion of disparate impact to a measure of classification accuracy that while known, has received relatively little attention. Second, we propose a test for disparate impact based on analyzing the information leakage of the protected class from the other data attributes. Third, we describe methods by which data might be made unbiased. Finally, we present empirical evidence supporting the effectiveness of our test for disparate impact and our approach for both masking bias and preserving relevant information in the data. Interestingly, our approach resembles some actual selection practices that have recently received legal scrutiny., Comment: Extended version of paper accepted at 2015 ACM SIGKDD Conference on Knowledge Discovery and Data Mining

Dynamic wedge distributions are produced by closing one jaw continuously while simultaneously controlling dose as each position of the jaw. This method of producing wedge distributions requires more frequent Quality Assurance checks, such as verification of wedge profile, wedge factor and verification of the accuracy of the digital position readout for the jaws used for dynamic wedge. “Hard” wedges require only the verification of wedge factor and the verification of reproducibility of mechanical position in the beam. This paper will discuss methods and equipment used for the Quality Assurance of Enhanced Dynamic Wedges.

Purpose : The diffuse shape of the electron beam used for arc therapy requires collimation on the patient's surface to sharply define treatment field edges. The electron beam arcs 10–15° past field edges defined by a custom fitted and manufactured cast which acts as a tertiary collimator. This allows the entire beam profile to be integrated at the field edge. The tertiary collimator is heavy and bulky, requiring two therapists to lift and position the cast. An alternative technique for field edge definition would require the electron arc collimators to dynamically close to zero, while maintaining the projection of the leading edge of the field coincident with the geometric edge of the treatment field. This would allow integration of the entire electron are profile and maintain a sharply defined treatment edge at the medial and lateral margins of the are. The present customized cast could be replaced by generic lead strips at only the superior and inferior treatment field borders. This study investigates the dosimetry of dynamically collimated electron arc treatment volumes at field margins and its potential for eliminating the need for tertiary collimation at the arc field margins. Methods and Materials : Electron arc isodose distributions were calculated using a pencil beam algorithm for treatment volumes defined by tertiary collimation at the surface of a cylindrical phantom and compared to distributions generated by simulating dynamic collimation to define the same field edges. Phantom measurements were performed using film densitometry to verify computer predictions. Results : Penumbra width is one measure of the sharpness of dose fall off at a treatment field edge. We define it as the distance between the 90% and 20% isodose lines at the field edge measured orthogonal to the incident electron beam. Calculations and phantom film densitometry measurements were performed for electron energies from 6–20 MeV. Dynamic and tertiary collimation both reduce penumbra width by approximately 50% compared to no collimation. There is a small advantage in minimizing penumbra width at low electron energy with tertiary collimation. This shifts to a small advantage with dynamic collimation at high electron energy. Conclusion : Dynamic collimation produces a field edge isodose distribution equivalent to tertiary collimation for clinical purposes. These results suggest that tertiary collimation at medial and lateral electron arc treatment field margins can be eliminated with dynamic collimation. This should result in greater clinical acceptance of breast electron arc therapy as the capacity for dynamic collimation is added to the next generation of linear accelerators.

The space of positive definite matrices P(n) is a Riemannian manifold with variable nonpositive curvature. It includes Euclidean space and hyperbolic space as submanifolds, and poses significant challenges for the design of algorithms for data analysis. In this paper, we develop foundational geometric structures and algorithms for analyzing collections of such matrices. A key technical contribution of this work is the use of horoballs, a natural generalization of halfspaces for non-positively curved Riemannian manifolds. We propose generalizations of the notion of a convex hull and a centerpoint and approximations of these structures using horoballs and based on novel decompositions of P(n). This leads to an algorithm for approximate hulls using a generalization of extents.

Objectives: To examine the convergence of an aging population and a decreased availability of dental care coverage using data from the Health and Retirement Study (HRS). Methods: We calculate national estimates of the number and characteristics of those persons age 51 years and above covered by dental insurance by labor force, retirement status, and source of coverage. We also estimate a multivariate model controlling for potentially confounding variables. Results: We show that being in the labor force is a strong predictor of having dental coverage. For older retired adults not in the labor force, the only source for dental coverage is either a postretirement health benefit or spousal coverage. Conclusions: Dental care, generally not covered in Medicare, is an important factor in the decision to seek dental care. It is important to understand the relationship between retirement and dental coverage in order to identify the best ways of improving oral health and access to care among older Americans.

A dynamic field shaping collimation system is evaluated for use in stereotactic radiosurgery of non-spherical lesions. The concept is as follows: (a) use the existing circular collimators to define a cone which encompasses the maximum dimensions of the target volume; (b) position two sets of independent rectangular photon collimators immediately upstream from the circular aperture and allow each collimator to have independent translational and rotational motion in order to define, for each increment of arc, a polygonal field shape having up to four straight and four curved edges which enscribe the beam's eye projection of the target; (c) modify the translational and rotational position of each independent collimator with each change in arc angle to continuously shape the instantaneous field to the target shape. A prototype device has been constructed and uses vane control technology developed in a related research project in electron are therapy. The efficacy of this device is illustrated by dose calculations and measurement based on actual clinical data. Dose volume histograms are used to compare the dose received by three techniques: single isocenter treatment using a single circular aperture, dual isocenter treatment, and single isocenter treatment using dynamically shaped fields. Doses were calculated throughout the brain using a volume grid of 3 mm spacing. Dose volume histograms comparing dose within the target volume and brain volume excluding target volume, as well as computed isodose distributions, demonstrate the possible reduction in normal tissue dose burden while simultaneously preserving dose uniformity throughout the prescribed target volume. This simple four-vane collimation system may provide a viable alternate treatment technique for non-spherical lesions.

Purpose To examine the impact of computerized record and verify (R&V) systems on types of radiotherapeutic error. Methods and materials Radiation therapy treatment errors reported by therapists at the University of Utah between July 1, 1999 and June 30, 2000 were retrospectively reviewed. Results During a 1-year period in which 22,542 external beam radiation therapy treatments were administered, 38 treatment errors (representing 0.17% of external beam treatments administered during this period) were identified and reviewed. Nine cases (0.04% of treatments) representing four types of record and verify (R&V)-related errors were identified, in which the department’s R&V system played a contributory role in the treatment error. Conclusions The common denominator among these R&V-related errors was excessive reliance upon the computer system by therapists. R&V systems eliminate some, but not all, pathways of radiotherapeutic error. Although R&V systems have assumed a crucial role in the precise and reproducible delivery of increasingly complex radiation therapy treatments, their inability to eradicate all radiotherapeutic errors coupled with their parallel ability to facilitate certain mistakes mandates vigilance on the part of the radiation therapy team. Radiation therapy treatment procedures must preserve careful oversight of R&V functions to minimize prospects for treatment error.

Computerized tomography (CT) is used routinely in evaluating radiation therapy isodose plans. With the introduction of 3D algorithms such as the voxel raytrace, which determines inhomogeneity corrections from actual CT Hounsfield numbers, caution must be used when evaluating isodose calculations. Artifacts from contrast media and dental work, radiopaque markers placed by the treatment planner, and changing bowel and rectal air patterns all have the potential to introduce error into the calculation due to inaccurate assessment of high or low density. Radiopaque makers such as x-spot BB's or solder wire are placed externally on the patient. Barium contrast media introduced at the time of simulation may be necessary to visualize specific anatomical structures on the CT images. While these localization and visualization tools may be necessary, it is important to understand the effects they may introduce in the planning process. Other problems encountered are patient specific and out of the control of the treatment planner. These include high- and low-density streaking caused by dental work, which produce computational errors due to overestimation, and small bowel and rectal air, the patterns of which change on a daily basis and may result in underestimation of structure density. It is important for each treatment planner to have an understanding of how this potentially tainted CT information may be applied in dose calculations and the possible effects they may have. At our institution, the voxel raytrace calculation is automatically forced any time couch angle is introduced. Errors in the calculation from the above mentioned situations may be introduced if a heterogeneity correction is applied. Examples of potential calculation errors and the magnitude of each will be discussed. The methods used to minimize these errors and the possible solutions will also be evaluated.

Linear accelerator based stereotactic radiotherapy systems have traditionally utilized rotational arcs with small circular collimators to create relatively conformal dose distributions within a target volume [1,2]. Large or irregularly shaped targets require multiple isocenters to achieve conformality at the expense of dose inhomogeneity within the target volume. The micro-multileaf (MLC) collimator is a recent innovation specifically designed for small-field stereotactic radiotherapy that has improved the conformality of dose delivery to irregularly shaped targets [3–8]. This is accomplished by movement of the narrow-leaf collimators to conform to the shape of the target as seen through a “beams-eye-view” projection during arc rotation. However, neighboring critical structures and physical constraints imposed by patient fixation devices often limit the beam trajectories and geometries available for dose delivery. Dose delivery through limited numbers of fixed fields may be optimal in these situations. However, it is often difficult to achieve a uniform dose distribution using uncompensated or non-intensity modified beams.

Stereotactic radiosurgery has developed into a technique where patient positioning and treatment delivery can be performed with submillimeter precision. Achievement of this level of precision has allowed margins to be significantly reduced, and in some cases, removed altogether. Joined with these reductions in treatment margin has come a desire to shape the radiation beam, further limiting dose to normal tissues. Initial applications of shaped radiosurgery fields utilized circular blocking apertures in an attempt to shape the beam to these small volumes. The resultant dose distributions conformed well to spherical treatment volumes but were inadequate for situations where the volume of interest was irregular in shape. Other techniques, such as applying these circular apertures through multiple isocenter positions to a single volume, have been investigated as possible ways to better conform dose distributions to these irregularly-shaped volumes. Recent technological advances allow the use of micromultileaf collimators which dynamically shape the beam by adjustment of individual leaves as the gantry rotates through the are. With margins potentially so tight, accurate evaluation of these dynamically adjusting treatment parameters becomes critical. Our current treatment planning software evaluates adjustments of the leaf positions in increments of 10 degrees and then does a linear interpolation between increments. Treatment delivery, however, is performed with adjustment in leaf position more consistent with a 1 degree increment. This paper compares the individual position of each leaf as determined for the 10 degrees interpolation to required changes in leaf position when the calculation is performed at increments of less than 10 degrees. Our data suggest that there are instances where improvements can be seen when corrections in leaf positions are made at these smaller increments.

This paper will examine ways that the Shoshone-Bannock Tribe has been integrating science with Native American culture. This paper will explain how and why technology mixed with traditional education can take place in the remote wilderness mountains of Idaho. Finally, we will explain how we are doing this and helping two endangered species at the same time: Salmon/Steelhead and Native American youth. These mountains are our living classroom.

Treatment planning for Enhanced Dynamic Wedge requires a knowledge of the dosimetric parameters of the treatment fields. These dosimetric parameters include depth doses, surface doses, buildup doses, peripheral doses, beam profiles, wedge angles and wedge factors. These parameters and their application to treatment planning are evaluated and compared with standard open field and metal wedge field dosimetric parameters.

The dose to the contralateral breast has been associated with an increased risk of developing a second breast malignancy. Varying techniques have been devised and described in the literature to minimize this dose. Metal beam modifiers such as standard wedges are used to improve the dose distribution in the treated breast, but unfortunately introduce an increased scatter dose outside the treatment field, in particular to the contralateral breast. The enhanced dynamic wedge is a means of remote wedging created by independently moving one collimator jaw through the treatment field during dose delivery. This study is an analysis of differing doses to the contralateral breast using two common clinical set-up techniques with the enhanced dynamic wedge versus the standard metal wedge. A tissue equivalent block (solid water), modeled to represent a typical breast outline, was designed as an insert in a Rando phantom to simulate a standard patient being treated for breast conservation. Tissue equivalent material was then used to complete the natural contour of the breast and to reproduce appropriate build-up and internal scatter. Thermoluminescent dosimeter (TLD) rods were placed at predetermined distances from the geometric beam's edge to measure the dose to the contralateral breast. A total of 35 locations were used with five TLDs in each location to verify the accuracy of the measured dose. The radiation techniques used were an isocentric set-up with co-planar, non divergent posterior borders and an isocentric set-up with a half beam block technique utilizing the asymmetric collimator jaw. Each technique used compensating wedges to optimize the dose distribution. A comparison of the dose to the contralateral breast was then made with the enhanced dynamic wedge vs. the standard metal wedge. The measurements revealed a significant reduction in the contralateral breast dose with the enhanced dynamic wedge compared to the standard metal wedge in both set-up techniques. The dose was measured at varying distances from the geometric field edge, ranging from 2 to 8 cm. The average dose with the enhanced dynamic wedge was 2.7-2.8%. The average dose with the standard wedge was 4.0-4.7%. Thermoluminescent dosimeter measurements suggest an increase in both scattered electrons and photons with metal wedges. The enhanced dynamic wedge is a practical clinical advance which improves the dose distribution in patients undergoing breast conservation while at the same time minimizing dose to the contralateral breast, thereby reducing the potential carcinogenic effects.

Precision and accuracy of a patient's treatment are key advantages of single-fraction stereotactic radiosurgery (SRS) for arteriovenous malformations (AVMS) and some small brain metastases. These advantages are equally valuable in fractionated treatment of the pituitary, brain metastases and brain boost fields. The need to implement the preciseness from stereotactic radiosurgery to fractionated treatments was recognized. Using our experience with single-fraction stereotactic radiosurgery as a model, we developed a multi-fractionated stereotactic radiotherapy technique that allows us to immobilize a patient daily and implement important existing devices such as the Brown-Roberts-Wells (BRW) angiographic localizer, CT scan localizer, and non-coplanar shaped field treatment planning. Development of this technique also allows us to achieve reproducible patient positioning based on immobilization techniques using polyurethane foam immobilization and heat moldable plastic technology without the necessity of the invasive technique of skull fixation. The development, implementation and dosimetry of this technique will be discussed in this paper.

Diseases such as mycosis fungoides require the treatment of a patient's total skin surface with superficial radiation. In a unique clinical situation, a 14-month-old child presented with a need for total skin treatment. A typical total skin technique requires overlapping electron beams, using 6 body positions, each with the gantry rotated for 2 angulations, or '6 positions-12 fields'. Adaptation of this technique for infants is complicated by the small diameter of some body parts, and by the necessity to treat while the patient is anesthetized. Even degraded, low energy electrons can easily penetrate fingers and toes. Therefore, dose from 6 positions becomes additive, and the total dose to small circumferences can be 3 to 4 times more than skin dose on the torso, raising concerns about uneven bone growth in the developing child. Special phantoms were designed for extensive dosimetry needed to determine both dose rate and dose summation from the overlapping beams. Computerized electron pencil beam calculations were compared to TLD measurements. Unique compensating techniques were used to deliver uniform dose. A modification of the 6 position-12 field technique will be described; and accessories used to reduce high dose regions will be illustrated.

Purpose: Five Varian linear accelerators were studied to determine whether their mechanical isocentric accuracies were sufficient for radiosurgery and, if not, if the observed errors were sufficiently consistent and predictable to be correctable by some form of secondary collimator steering device to maintain isocentric alignment. Methods and Materials: A 0.3 mW 670 nm diode laser was mounted in the secondary collimator insert of a radiosurgery extended collimator assembly. A cylindrical lens was used to create a laser fan beam that passed through isocenter and could be oriented parallel or perpendicular to the plane of rotation. A position sensitive photo-diode having an electrical output that varied with the portion of its surface illuminated was mounted at isocenter in a rotational mount. This mount tracked the accelerator gantry such that the surface of the photo-diode remained perpendicular to the laser beam during gantry rotation. An MY recorder was connected to the gantry-angle potentiometer of the accelerator and to the photo-diode and plotted the positional variation from isocenter with gantry rotation. Results: The root-mean-square error for the five machines was ± 0.06 to ± 0.08 mm in the plane of rotation and ± 0.17 to ± 0.35 mm out of (perpendicular to) the plane of rotation. The in-plane-of-rotation errors tended to be maximal near the diagonal gantry angles and the out-of-plane-of-rotation errors were maximal in the over and under vertical positions. Conclusions: Both types of errors were predictable but only the out-of-plane-of-rotation errors were considered large enough to warrant consideration of correction (although the need is debatable). On all the tested machines, the out-of-plane-of-rotation error curve was a relatively smooth bell-shaped function that would be readily amenable to correction. The diode laser/photo-detector system used should prove useful in accurately defining isocenter and facilitating the precise adjustment of the laser isocenter lights.

Brachytherapy dose prescription and treatment planning lag behind the state-of-the-art for external beam therapy. As altered fractionation of external beam therapy improves patient outcome in head and neck cancer, there will be an increased need to compare the two radiotherapy techniques. Currently, implant techniques and dose prescription documentation are not uniform, dose prescription to a target volume is subjective, and implant quality is poorly understood and not routinely assessed. All contribute to a lack of scientifically rigorous brachytherapy clinical trials. Studies designed to combine tumor imaging and dosimetry data are important in the evolution of brachytherapy treatment planning. Head and neck implants, which often require nonparallel, arching, or looping source carriers for all but small tumors in order to encompass the target volume adequately, were used to evaluate the clinical utility and feasibility of computed tomography as a treatment planning tool in brachytherapy. Following placement of plastic afterloading tubes under general anesthesia, orthogonal radiographs with dummy sources in the afterloading tubes are obtained as customary for source localization. With the patient in the same position, axial CT scans are obtained with the dummy seeds still in place for treatment planning. The implant physician, using data from the pre-treatment diagnostic CT scan, outlines target areas on sequential images creating a 3-dimensional target volume. By superimposing anatomic data with isodose curves one can objectively define implant parameters important in clinical trials analysis. These include minimum target absorbed dose, implant uniformity, and treatment to target volume ratio. The results of the first 10 patients are presented and implications of these data regarding the analysis of implant technique, implant quality, and implant optimization are discussed. The technique as performed is laborious but practicable in the clinical research setting of head and neck implant. Further research efforts should improve, simplify, and objectify brachytherapy and hasten the time when rigorous multi-institutional brachytherapy trials will be reality.