bluuebunny/crossref_metadata_2025 huggingface dataset:
Tales of the Bazaar: Interest‐Based Negotiation Across Cultures
Authors: Senger Jeffrey M.
Published: July 2007

Interest‐based negotiation, as popularized by Fisher, Ury, and Patton (1991), is a favored negotiation style of many people in the United States and other parts of the developed world. The authors, an American attorney who has traveled widely, assseses how that approach works in different cultural contexts. Using illustrations from his own experiences, the author shows how interest‐based techniques work successfuly, as well as the limitations of this approach in some situations.
Common Language, Different Meaning: What Meidators Mean When They Talk About Their Work
Authors: Picard Cheryl
Published: July 2007

Mediators, for the most part, descrive their work as “facilitation” but what they actually mean varies considerably. Based on an exploratory study with nealy 90 mediators in Canada (all of whom are also mediation trainers), the author describes the great diversity among mediators’understanding of commonly‐used terms like facilitation, transformative, settlement, and humansitic. She also reports on how such factors as context, gender, and number of years mediating affect mediator perceptions of what they do. In addition, the author shows how perceptions affect the overall philosophy and goal of hte meidation practitioner: One implication of this research is that we can no longer presume to know what people men by “mediation,” nor can we assume mediators are like‐minded in how they understand their work. Thus, practitionsner, scholars and policymakers are encouraged to be purposefully clear when describing and writting about the practice of mediation.
Teaching Negotiation Using Web‐Based Streaming Video
Authors: Peppet Scott R.
Published: July 2007

The brief essay describes the author's experiences using web‐based, streaming video technology in the spring 2002 Legal Negotiation workshop at the University of Colorando's School of Law. He first describes the practical and pedagogical problems with traditional videotaping approaches that led him to consider streaming video. He then explains the project,how it was implemented, and its pedagogical costs and benefits. He also presents the results of a short survey of students indicating how useful the students found this feedback format. Appendix One describes the technical aspects of the project, including startup costs and the software and hardware used.
The Security Council: Adapting to Address Contemporary Conflict
Authors: Malone David M.
Published: July 2007

Throughout the 1990s, with the post‐Cold War era as backdrop, there have been numerous changes in the approach of the United Nations Security Council to conflict between and within nations. The author, using historical incidents for illustration, highlights such topics as: the changing nature of conflicts addressed by the Council; considerations driving Council decision making; developments within the United Nations itself (“institutional”); the cumulative impact of Security Council decision making; and key challenges facing the Council today and in the future.
Realizing the Potential of International Conflict Work: Connections Between Practice and Theory
Authors: Baruch Bush Robert A.
Published: July 2007

The author reviews the insights of four expert practitioners of international conflict resolution, pointing out a common theme that signals a major shift in the way we conduct and conceive of international conflict intervention. In addition to traditional “top‐down” interventions, leading conflict resolution practitioners are advocating a “bottom‐up” approach, a complementary effort that includes development of conflict resolution potential among the parties themselves, without external imposition. This increased emphasis on the kinds of structures, understanding, and relationships that help to transform international conflict situations reflects the impact the developing field of conflict studies has had on practice.
New Problem‐Solving Scholarship: An Historical Tale with a Happy Ending
Authors: Nolan‐Haley Jacqueline
Published: July 2007

The teaching of negotiation in law, business, and other professional schools has greatly increased over the last quarter‐century. The author sets the stage for a review of two negotiation texts and an educational video by opening with an historical overview of the development of negotiation pedagogy, which has been informed by scholars from many different academic disciplines. Teaching negotiation in law schools (which have a long tradition of the “case method” style of teaching, which often encourages an energetic but adversarial approach to problem solving) is still relatively new. The two texts and the educational video examined in this essay offer lessons in a “wide angle” approach to negotiation, which includes (among many other useful topics): ideas fundamental to theory and practice; social and emotional considerations; the role of cultural and gender difference; relationships between principals and representatives; differences among various types of ADR; and applications of various forms of negotiation in many different contexts.
Online Dispute Resolution: Do You Know Where Your Children Are?
Authors: Larson David A.
Published: July 2007

Will we ever see the day when the Internet serves as the primary venue for problem solving and dispute resolution? Social science research suggests that our online communication skills will improve as we learn relational behaviors based upon nonverbal cues available online. Dispute resolution and problem solving will move online, however, whether or not you and I master those skills. Our children already have developed effective online relational behaviors and can establish trust and intimacy online.
Reverse Bargaining: Some Oddities that Illustrate the “Rules”
Authors: Wallihan James
Published: July 2007

Unions striking for lower wages? Buyers seeking higher prices? Such cases of counter‐intuitive or paradoxical bargaining strategy and behavior prove useful in refining the concepts and statement of negotiation theory. Examination of four such instances of apparently nonsensical negotiation reveals the underlying soundness of the distinction between position and interest, once these concepts are specified appropriately. The resulting enrichment of theory, in turn, leads to improved practice, underlining the importance of exploring interests. The argument emphasizes the value of examining the unexpected.
Mediation and Psdychotherapy: Two Sides of the Same Coin?
Authors: Gabel Stewart
Published: July 2007

Some mediators believe that mediation and psychotherapy are quite similar, and that when doing mediation, the mediator also is practicing an art form similar to psychotherapy. On face value, some forms of mediation (e.g., evaluative) and some forms of psychotherapy (e.g., psychoanalysis) are so far apart in theoretical conception and in actual practice that they cannot be compared meaningfully. However, the forms of mediation known as “facilitative” and “transformative” and the forms of brief or focused psychotherapy that often involve families or couples do have considerable similarity. Overall, numerous resonances exist between these two approaches to mediation and to couples or family‐oriented psychotherapies, especially when differences in terminology, licensure, and training requirements are not allowed to obscure commonalities.
Metastasizing malignant pleomorphic adenoma in a young man
Authors: BOURKE JILL L. , LANGER SEPPO W. , JENSEN HELLE L.
Published: July 2007

We present the case of a younger man with metastasizing carcinoma of unknown primary site, where autopsy revealed a malignant pleomorphic adenoma (MPA) of the submandibular gland. MPA is very rare in young persons.
Lethal candida sepsis associated with myeloperoxidase deficiency and pre‐eclampsia
Authors: KALINSKI THOMAS , JENTSCH‐ULLRICH KATHLEEN , FILL SARA , KÖNIG BRIGITTE , COSTA SERBAN‐DAN , ROESSNER ALBERT
Published: July 2007

We report on a 27‐year‐old primipara suffering from pre‐eclampsia who died within 2 days postpartum. Toxemia with disseminated intravascular coagulation (DIC) and acute renal failure had masked the symptoms of invasive candida esophagitis and disseminated candidiasis in both lungs. Candida sepsis was discovered as the cause of death at postmortem examination. Myeloperoxidase (MPO) deficiency was identified as having supported the invasive candida infection. We conclude that a combination of MPO‐deficiency and gestational toxemia may indicate increased susceptibility to severe candida infections.
Validation of the use of Pap‐stained vaginal smears for diagnosis of bacterial vaginosis
Authors: ERIKSSON K. , FORSUM U. , BJØRNEREM A. , PLATZ‐CHRISTENSEN J. J. , LARSSON P. G.
Published: July 2007

Papanicolaou‐stained cervicovaginal smears (Pap smears) are used to screen for cervical cancer. Since there is a lack of consensus in published reports respecting the efficacy of Pap‐stained smears in BV diagnostics, there is a need to validate their use for diagnosis of BV. Slides from the international BV00 workshop were Pap stained and independently analyzed by four investigators under a phase‐contrast microscope. All workshop slides—whether Pap‐stained, Gram‐stained or rehydrated air‐dried smears—were scored according to the same Nugent classification. The diagnostic accuracy of Pap smears for diagnosis of BV had a sensitivity of 0.85 and a specificity of 0.92, with a positive and negative predictive value of 0.84 and 0.93, respectively. The interobserver weighted kappa index was 0.86 for Pap‐stained smears compared to 0.81 for Gram‐stained smears, and 0.70 for rehydrated air‐dried smears using the mean Nugent score as the criterion standard. Provided that the samples are taken from equivalent locations (the vaginal fornix) and analyzed according to the same scoring criteria, there is no discernable difference in the diagnostic accuracy of the three smear‐staining methods. The Pap‐stained vaginal smears can be used as a wholly adequate alternative to Gram‐stained smears for BV diagnosis.
Epithelioid hemangioendothelioma with multiple organ involvement
Authors: CELİKEL CIGDEM , YUMUK P. FULDEN , BASARAN GUL , YİLDİZELİ BEDRETTİN , KODALLİ NİHAT , AHİSKALİ RENGİN
Published: July 2007

Epithelioid hemangioendothelioma is a rare vascular neoplasm of uncertain malignant potential. Various reports document metastatic or concurrent epithelioid hemangioendothelioma in several sites, most commonly with combined lung and liver involvement. The concurrent involvement of multiple sites at presentation may cause diagnostic problems because epithelioid hemangioendothelioma can mimic other neoplastic processes. Although it is a chemoresistant disease, chemotherapy is usually advised for patients with metastatic or concurrent involvement. Here we document the presentation, treatment, and outcome of two cases with concurrent involvement of the lung and liver.
Plexiform schwannoma of the clitoris
Authors: CHUANG WEN‐YU , YEH CHI‐JU , JUNG SHIH‐MING , HSUEH SWEI
Published: July 2007

Only three cases of clitoral schwannoma have been reported in the English language literature, with none of them being a plexiform schwannoma. Here we report the first plexiform schwannoma of the clitoris. A 41‐year‐old woman without neurofibromatosis presented with a 2×2 cm, slowly growing, painless tumor of the clitoris. Simple excision of the tumor was performed, and pathological examination revealed a plexiform schwannoma. No evidence of recurrence was noted after 2 years of follow‐up. Despite its rarity, a schwannoma should be included in the differential diagnosis of a clitoral enlargement or mass. Our case, despite its unique plexiform growth pattern, has clinical features similar to those of other reported cases of clitoral schwannoma.
Analysis of the NADH‐dependent retinaldehyde reductase activity of amphioxus retinol dehydrogenase enzymes enhances our understanding of the evolution of the retinol dehydrogenase family
Authors: Dalfó Diana , Marqués Neus , Albalat Ricard
Published: July 2007

In vertebrates, multiple microsomal retinol dehydrogenases are involved in reversible retinol/retinal interconversion, thereby controlling retinoid metabolism and retinoic acid availability. The physiologic functions of these enzymes are not, however, fully understood, as each vertebrate form has several, usually overlapping, biochemical roles. Within this context, amphioxus, a group of chordates that are simpler, at both the functional and genomic levels, than vertebrates, provides a suitable evolutionary model for comparative studies of retinol dehydrogenase enzymes. In a previous study, we identified two amphioxus enzymes, Branchiostoma floridae retinol dehydrogenase 1 and retinol dehydrogenase 2, both candidates to be the cephalochordate orthologs of the vertebrate retinol dehydrogenase enzymes. We have now proceeded to characterize these amphioxus enzymes. Kinetic studies have revealed that retinol dehydrogenase 1 and retinol dehydrogenase 2 are microsomal proteins that catalyze the reduction of all‐trans‐retinaldehyde using NADH as cofactor, a remarkable combination of substrate and cofactor preferences. Moreover, evolutionary analysis, including the amphioxus sequences, indicates that Rdh genes were extensively duplicated after cephalochordate divergence, leading to the gene cluster organization found in several mammalian species. Overall, our data provide an evolutionary reference with which to better understand the origin, activity and evolution of retinol dehydrogenase enzymes.
Performance evaluation of BC‐3200 hematology analyzer in a university hospital
Authors: PENG L. , BAI L. , NIE L. , WU Z. , YAN C.
Published: July 2007

The BC‐3200 automated hematology analyzer was evaluated and compared with the Beckman‐Coulter AcT (Ac.T diff 2) 3‐part differential hematology analyzer. The BC‐3200 was evaluated according to guidelines published by the International Committee for Standardization in Hematology (ICSH), Clinical and Laboratory Standards Institute (CLSI), and Department of Food and Drug Administration (FDA). The results demonstrated no background, minimal carryover (<0.5%), and excellent linearity for hemoglobin (Hb) level, white blood cell (WBC), red blood cell (RBC), and platelet (PLT) counts (>0.998). Precision was generally acceptable for all complete blood count (CBC) parameters; coefficients of variation (CVs) were within the manufacturer's claims and CVs of CBC parameters, including WBC, RBC and PLT counts, Hb and mean corpuscular volume, were <6%. Correlation between the BC‐3200 and Ac.T diff 2 was excellent (r > 0.98) for all major CBC parameters (WBC, RBC, and PLT counts and Hb). We conclude that the overall performance of the BC‐3200 is excellent and compares well with that of the Coulter Ac.T diff 2.
Finding Water for Growth: New Sources, New Tools, New Challenges1
Authors: Hanak Ellen
Published: July 2007

Abstract:  Rapidly growing regions such as the western United States face difficult challenges in mobilizing new water supplies to meet new demands. Environmental concerns have curtailed the scope for large new surface storage projects, and widespread basin overdraft has limited ground water’s potential as a source of expansion. Drawing on the California experience, this article explores modern water planning approaches, which focus on a portfolio of options including nontraditional sources (recycling, desalination, underground storage) and more efficient use of existing supplies (conservation and water marketing). It reviews the advantages and drawbacks of the elements of the portfolio, provides examples of innovative planning approaches, and assesses the role for supportive government policies.
Restoration of innate host defense responses by oral supplementation of branched‐chain amino acids in decompensated cirrhotic patients
Authors: Nakamura Ikuo , Ochiai Kaori , Imai Yasuharu , Moriyasu Fuminori , Imawari Michio
Published: July 2007

Aim:  It has been reported that host defense responses, such as phagocytic function of neutrophils and natural killer (NK) cell activity of lymphocytes, are impaired in cirrhotic patients. The aim of the present study was to examine the effects of oral supplementation of branched‐chain amino acids (BCAA) on host defense mechanisms in peripheral blood of patients with decompensated cirrhosis.

Methods:  Ten patients with decompensated cirrhosis received 12 g BCAA daily for 3 months. Phagocytic function of neutrophils and NK activity of lymphocytes as well as serum albumin levels and Fisher's ratios were determined before and at 1 and 3 months of BCAA supplementation. For quantification of phagocytic function, fluorescent intensities of cells in the neutrophil region in the cytogram were determined by flow cytometry after incubation of whole blood with fluorescent microspheres. NK activity was estimated by 51Cr release assay using K‐562 cell line as target cells.

Results:  Phagocytic function of neutrophils was significantly improved by 3‐month BCAA supplementation (P < 0.01). Thechanges of NK activity were also significant at 3 months of supplementation compared with before supplementation (P < 0.01). Fisher's ratios were significantly increased at 3 months of BCAA supplementation compared with those before oral supplementation (P < 0.05), although the changes of serum albumin level were not statistically significant.

Conclusions:  BCAA oral supplementation improved phagocytic function of neutrophils and NK activity of lymphocytes in cirrhotic patients. BCAA supplementation may reduce the risk of bacterial and viral infection in patients with decompensated cirrhosis.
A Comparative Study of Formability of Diode Laser Welds in DP980 and HSLA Steels
Authors: Xia M. , Sreenivasan N. , Lawson S. , Zhou Y. , Tian Z.
Published: July 2007

Understanding effects of welding on strength and formability is critical to support wider application of advanced high strength steels in automotive components. In this study, High Strength Low Alloy (HSLA) and DP980 (Dual Phase, 980MPa) sheet steels were welded with a 4kW diode laser. Mechanical properties of welds and parent metals were assessed by tensile and limiting dome height tests, and related to microhardness distribution across the welds. The formability of HSLA welds was insensitive to the welding process and comparable to that of parent metal. For the DP steel, weld formability was much lower than that of corresponding parent metal, which appeared to be due to the formation of soft zones in the outer region of the Heat affected zone (HAZ) of the welds. It was found that increase of welding speed resulted in a slight increase of formability of the DP steel, associated with a reduction in the microhardness difference between base metal and HAZ soft zones.
Physical characterization of a scanning photon counting digital mammography system based on Si‐strip detectors
Authors: Åslund Magnus , Cederström Björn , Lundqvist Mats , Danielsson Mats
Published: July 2007

The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge‐on geometry connected to photon counting electronics. The pixel size is and the field of view . The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a anode‐filter combination with an added filtration.
Resin microsphere activity measurements for liver brachytherapy
Authors: Dezarn William A. , Kennedy Andrew S.
Published: July 2007

The measurement of the radioactivity administered to the patient is one of the major components of microsphere liver brachytherapy. The activity of microspheres in a glass delivery vial was measured in a dose calibrator. The calibration value to use for in the dose calibrator was verified using an activity calibration standard provided by the microsphere manufacturer. This method allowed for the determination of a consistent, reproducible local activity standard. Additional measurements were made to determine some of the factors that could affect activity measurement. The axial response of the dose calibrator was determined by the ratio of activity measurements at the bottom and center of the dose calibrator. The axial response was 0.964 for a glass shipping vial, 1.001 for a glass V‐vial, and 0.988 for a polycarbonate V‐vial. Comparisons between activity measurements in the dose calibrator and those using a radiation survey meter were found to agree within 10%. It was determined that the dose calibrator method was superior to the survey meter method because the former allowed better defined measurement geometry and traceability of the activity standard back to the manufacturer. Part of the preparation of resin microspheres for patient delivery is to draw out a predetermined activity from a shipping vial and place it into a V‐vial for delivery to the patient. If the drawn activity was placed in a glass V‐vial, the activity measured in the dose calibrator with a glass V‐vial was 4% higher than the drawn activity from the shipping vial standard. If the drawn activity was placed in a polycarbonate V‐vial, the activity measured in the dose calibrator with a polycarbonate V‐vial activity was 20% higher than the drawn activity from the shipping vial standard. Careful characterization of the local activity measurement standard is recommended instead of simply accepting the calibration value of the dose calibrator manufacturer.
X‐ray CT dose in normoxic polyacrylamide gel dosimetry
Authors: Baxter P. , Jirasek A. , Hilts M.
Published: July 2007

This study reports on the effects of x‐ray CT dose in CT imaged normoxic polyacrylamide (nPAG) gel dosimeters. The investigation is partitioned into three sections. First, the CT dose absorbed in nPAG is quantified under a range of typical gel CT imaging protocols. It is found that the maximum absorbed CT dose occurs for volumetric imaging and is in the range of /image. This does scales linearly with image averaging. Second, using Raman spectroscopy, the response of nPAG to CT imaging photon energies (i.e., ) is established and compared to the well known dose response of nPAG exposed to photons. It is found that nPAG exhibits a weaker response (per unit dose) to incident photons as compared to incident photons (slopes and ). Finally, using the above data, an induced change in CT number is calculated for nPAG imaged using a range of gel imaging protocols. It is found that under typical imaging protocols (, , image averages) a is induced in active nPAG dosimeters. This is below the current limit of detectability of CT nPAG polymer gel dosimetry. Under expanded imaging protocols (e.g., very high number of image averages) an induced of is possible. In these situations the additional polymerization occurring in nPAG due to the imaging process may need to be accounted for.
Investigation of electron trajectories of an x‐ray tube in magnetic fields of MR scanners
Authors: Wen Zhifei , Fahrig Rebecca , Conolly Steven , Pelc Norbert J.
Published: July 2007

A hybrid x‐ray/MR system combining an x‐ray fluoroscopic system and an open‐bore magnetic resonance (MR) system offers advantages from both powerful imaging modalities and thus can benefit numerous image‐guided interventional procedures. In our hybrid system configurations, the x‐ray tube and detector are placed in the MR magnet and therefore experience a strong magnetic field. The electron beam inside the x‐ray tube can be deflected by a misaligned magnetic field, which may damage the tube. Understanding the deflection process is crucial to predicting the electron beam deflection and avoiding potential damage to the x‐ray tube. For this purpose, the motion of an electron in combined electric and magnetic fields was analyzed theoretically to provide general solutions that can be applied to different geometries. For two specific cases, a slightly misaligned strong field and a perpendicular weak field, computer simulations were performed with a finite‐element method program. In addition, experiments were conducted using an open MRI magnet and an inserted electromagnet to quantitatively verify the relationship between the deflections and the field misalignment. In a strong (; : speed of light) and slightly misaligned magnetic field, the deflection in the plane of and caused by electrons following the magnetic field lines is the dominant component compared to the deflection in the direction due to the drift of electrons. In a weak magnetic field , the main deflection is in the direction and is caused by the perpendicular component of the magnetic field.
On the assay of brachytherapy sources
Authors: Yue Ning J. , Haffty Bruce G. , Yue Jinfeng
Published: July 2007

In many of brachytherapy procedures, a large amount of radioactive sources are used to deliver desired doses to the target volume. It is both the federal regulation recommendation (US Nuclear Regulatory Commission, 10 CFR 35.432) and recommendations of the American Association of Physicists in Medicine (AAPM) [Kutcher et al., Med. Phys. 21, 581–618 (1994); Nath et al., Med. Phys. 24, 1557–1598 (1997)] that users independently verify the sources’ strength. Though the reports of AAPM Task Group 40 [Kutcher et al., Med. Phys. 21, 581–618 (1994)] and 56 [Nath et al., Med. Phys. 24, 1557–1598 (1997)] have made specific recommendations on the assay of brachytherapy sources, the relevant statistical significance of the recommendations remain unanswered. In this study, statistical theories were used and a method was presented to quantify the assay process of brachytherapy sources and to evaluate the recommendations. The results showed that the quality of a source assay process was dependent on the measured source strength deviation and number of assayed sources. Its dependence on the total number of sources becomes statistically insignificant if the total number is large enough. It was concluded that the assay process can be determined by the obtained assay information, instead of a preset percentage of total sources. It was further found that the use of manufacturer's stated strength value may possibly lead to bigger uncertainty in source strength accuracy, unless the manufacturer's stated strength is the measured mean value of all the ordered sources.
Supplement to the 2004 update of the AAPM Task Group No. 43 Report
Authors: Rivard Mark J. , Butler Wayne M. , DeWerd Larry A. , Huq M. Saiful , Ibbott Geoffrey S. , Meigooni Ali S. , Melhus Christopher S. , Mitch Michael G. , Nath Ravinder , Williamson Jeffrey F.
Published: July 2007

Since publication of the 2004 update to the American Association of Physicists in Medicine (AAPM) Task Group No. 43 Report (TG‐43U1), several new low‐energy photon‐emitting brachytherapy sources have become available. Many of these sources have satisfied the AAPM prerequisites for routine clinical use as of January 10, 2005, and are posted on the Joint AAPM/RPC Brachytherapy Seed Registry. Consequently, the AAPM has prepared this supplement to the 2004 AAPM TG‐43 update. This paper presents the AAPM‐approved consensus datasets for these sources, and includes the following sources: Amersham model 6733, Draximage model LS‐1, Implant Sciences model 3500, IBt model 1251L, IsoAid model IAI‐125A, Mentor model SL‐125/SH‐125, and SourceTech Medical model STM1251. The Best Medical model 2335 source is also included. While the methodology used to determine these data sets is identical to that published in the AAPM TG‐43U1 report, additional information and discussion are presented here on some questions that arose since the publication of the TG‐43U1 report. Specifically, details of interpolation and extrapolation methods are described further, new methodologies are recommended, and example calculations are provided. Despite these changes, additions, and clarifications, the overall methodology, the procedures for developing consensus data sets, and the dose calculation formalism largely remain the same as in the TG‐43U1 report. Thus, the AAPM recommends that the consensus data sets and resultant source‐specific dose‐rate distributions included in this supplement be adopted by all end users for clinical treatment planning of low‐energy photon‐emitting brachytherapy sources. Adoption of these recommendations may result in changes to patient dose calculations, and these changes should be carefully evaluated and reviewed with the radiation oncologist prior to implementation of the current protocol.
SU‐DD‐A4‐04: Dosimetry and Image Quality Evaluation of a Dedicated Cone‐Beam CT System for Sinus and Temporal Bone Applications
Authors: Yu L , Vrieze T , Bruesewitz M , Kofler J , McCollough C
Published: July 2007

Purpose: To evaluate the dose and image quality performance of a dedicated cone‐beam CT scanner for sinus and temporal bone applications. Method and Materials: A low‐dose cone‐beam CT system with flat‐panel detector has recently been introduced for high‐contrast applications in the head. Because of the non‐uniform dose distribution throughout the volumetric field of view, the dose in the central plane may not accurately represent the overall dose. In this work, we introduce a novel metric, volumetric average dose, to incorporate the spatial variation of radiation dose in a cone‐beam scan. The definition and measurement of volumetric average dose are analogous to conventional Weighted CTDI, though conceptually different. Using this metric, we evaluated the dose performance of a cone‐beam CT scanner (MiniCAT, Xoran Technologies). Two methods were employed for measurement. One was with a small solid‐state detector (RTI CT‐SD16), the other was with a conventional CT pencil chamber. Both were measured with a standard CTDI head phantom. The low‐ and high‐contrast spatial resolution, and cone‐beam and truncation effects, were also evaluated. Results: The volumetric average doses for sinus and temporal bone studies measured with CT pencil chamber were 5.02 mGy and 4.33 mGy, respectively. With the RTI CT‐SD16 detector, 4.41 mGy and 3.93 mGy were obtained for the two studies. Both are substantially lower than those of conventional adult CT protocols in our practice (58 mGy for sinus and 84 mGy for temporal bone). Isotropic high‐contrast spatial resolution of 16 1p/cm was measured for the temporal bone mode. Low contrast resolution, as anticipated, was inferior to conventional CT. Conclusion: A novel dose metric, volumetric average dose, was used to characterize the dose performance of a cone‐beam CT system. The dose and image quality of the dedicated cone‐beam CT system appear appropriate for sinus and temporal bone applications.
SU‐DD‐A4‐05: Fits of the NT/(Pd2) Shielding Curves in NCRP Report Number 147
Authors: Simpkin D
Published: July 2007

Purpose: The diagnostic x‐ray shielding requirements for Radiographic and R&F rooms presented in Figs. 4.5 through 4.8 in NCRP Report No. 147, and for cardiac angiography labs, have been fit to a three‐parameter equation that relates the barrier thickness x to the value of NT/(Pd2). The locations of the source in the imaging room appropriate to the determination of distance d are also explicitly presented. Methods and Materials: Section 4.2.4 of NCRP‐147 presents lead and concrete shielding requirements for barriers around “representative” Radiographic and R&F rooms that include contributions from all clinical beam locations and directions. The required shielding thickness, x, for the various barriers around each room is presented graphically as a function of NT/(Pd2), where N is the weekly number of patients, T is the occupancy, P is the permitted weekly air kerma, and d is the distance (in m) from an x‐ray source to the occupied area. This method has been applied previously to cardiac angiography labs. Letting η0 be the maximum value of NT/(Pd2) for which no shielding is required, barrier thickness x depends on (NT)/(Pd2) following the equation of Archer et al. (1983):
urn:x-wiley:00942405:media:mp0330:mp0330-math-0001 Results: The values of NT/(Pd2) (mGy−1 m−2) have been fit to Eq. 1 as a function of x for the curves in Figs. 4.5 through 4.8 of NCRP‐147, and for cardiac angiography labs. The resultant values of η0, α, β, and γ for lead and concrete barriers are presented. Conclusions: The use of Eq. 1 with the fitting parameters facilitates the use of the NT/(Pd2) methodology from NCRP‐147 in computer applications. The agreement of the fit and the thicknesses read from the NCRP report is better than 0.026 mm lead and 1.7 mm concrete.
SU‐DD‐A4‐06: Implementation of PACS QA Using AAPM TG‐18 In A Clinical Health Care Center
Authors: Liu Yu
Published: July 2007

Purpose: In the last a few years PACS has been increasingly available and used in clinical care centers. However, there was no standardized quality control for PACS display units, which is the crucial last step in an imaging chain for all diagnostic imaging modalities. In 2005 the final draft of AAPM TG‐18 report was released. The purpose of this work was to implement QA for PACS display utilizing AAPM TG18 report in a tertiary care center. Method and Materials: There are total 66 diagnostic and clinical PACS display monitors located in various areas of the main hospital and 2 satellite clinics. QA procedures were developed using the 2005 final version of AAPM TG‐18 report. VeriLUM (IMAGE Smiths, Inc.) software was installed on all display monitors and a VeriLUM luminance/illuminance spot meter was used for all measurements. Various AAPM TG‐18 report test patterns were used for these evaluations. Results: Quarterly QA including geometric distortion, reflection, luminance response, luminance dependencies, and resolution was performed by a PACS technologist/coordinator. Annual QA including geometric distortion, reflection, luminance response, luminance dependencies, resolution, noise, and veiling glare was performed by a medical physicist. PACS display quality related issues were quantitatively determined using the QA procedures developed from AAPM TG‐18 report. Conclusion: QA for PACS display has been successfully implemented for a year and half in a clinical health care center using AAPM TG‐18 report. It is going to be used for the enterprise wide PACS in the health care system in the near future.
SU‐DD‐A3‐02: Automatic Detection of Positional and Anatomical Setup Errors in CT‐Based Image Guided Radiation Therapy
Authors: Robison B , Seibert R , Ramsey C
Published: July 2007

Purpose: The primary objective of this study was to develop a novel tool using Kernel Classification that could be used to assist in identifying patients with setup issues that result in unacceptable random and systematic errors. Method and Materials: Inter‐Fraction motion was retrospectively analyzed for 30 H&N patients that were positioned for treatment using megavoltage CT (MVCT) images acquired on a helical tomotherapy system. Manual adjustments, in the AP, SI, LAT and Roll planes, were made to ensure correct target alignment from MVCT images acquired on the tomotherapy system. Results: A total of 30 Head and Neck patients were MVCT imaged prior to treatment delivery for a total of 992 imaging sessions. All 30 patients had a decrease in the cross‐sectional volume due to a combination of weight loss and/or tissue response to radiation. Patient errors ranged form incorrect headrest to a shirt and tie that where not removed before treatment. A Principal Component Analysis was performed and showed that there was a relationship present between the stage of the cancer, the patient's overall percent weight loss, and the mean lateral, longitudinal, and vertical shift values.

The kernel classification technique correctly identified 23 out of the 24 Head & Neck patients as either having normal set‐up or problematic setup using their respective shift data sets. These classifications were made using only the shift values from the first 14 treatments. The predictive performance seriously degraded when data from fewer than 14 treatments were used. Conclusion: This study demonstrated that the kernel regression classification method was able to correctly identify the cause behind IGRT positioning problems for individual Head & Neck patients. The study also validated the fact that IGRT positioning problems cause abnormal problem‐specific distributions in the shift data without using the complicated, and generally time‐consuming, statistical distribution tests.
SU‐FF‐I‐22: Scatter Correction for Flat Detector Cone‐Beam CT Based On Simulated Sphere Models
Authors: Bertram M , Hohmann S , Wiegert J
Published: July 2007

Purpose: Uncompensated scattered radiation is one of the major image quality deteriorating factors in flat detector cone‐beam CT. Purpose of this work is to develop a fast, practical, and accurate method for a posteriori correction of X‐ray scatter. Method and Materials: Scatter estimation and correction is carried out using a novel approach based on locally approximating the imaged object by water sphere models. In each projection, the scatter contribution of each ray from the source to the individual detector pixels is derived from a pre‐calculated database of pencil‐beam Monte‐Carlo simulations. The different sphere configurations have the advantage over related existing methods that they allow to accurately reproduce scatter contributions of individual rays regardless of the position of object penetration. Systematic evaluation was carried out by constructing an extensive database of Monte‐Carlo patient simulations, by performing scatter measurements of 15 phantoms on a bench‐top X‐ray system, and based on rotational C‐arm acquisitions from clinical interventional procedures. Results: The novel method was found to produce far superior results than related state‐of‐the‐art approaches. Based on simulated projections of 13 CT data sets of different body regions (head, thorax, abdomen, liver, pelvis), an average reduction of scatter‐caused inhomogeneities from 117 HU to 11 HU per‐voxel deviation from the ground truth was achieved. For individual data sets, the average level of the estimated scatter deviated from the respective optimum by only 5% as compared to a minimum of 14% for tested state‐of‐the‐art approaches. Experimental evaluation and application to clinical data confirmed robustness and efficient reduction of cupping and streak artifacts in reconstructed images. Conclusion: A practical software‐based method was developed allowing to accurately estimate scatter contributions in X‐ray projections. Utilization of this method efficiently reduces scatter‐caused artifacts, and thus substantially improves image quality in flat detector cone‐beam CT.
SU‐FF‐I‐23: Region‐Of‐Interest (ROI) Cone‐Beam Computed Tomography (CBCT) Using Rotational Digital Subtraction Angiography (DSA) Acquisition
Authors: Patel V , More A , Hoffmann K , Bednarek D , Rudin S
Published: July 2007

Purpose: Region‐of‐interest (ROI) cone‐beam computed tomography (CBCT) can reduce dose to the patient. To provide data outside the ROI and overcome the truncation artifacts due to lack of data, we propose a new technique in which a material filter attenuates the beam except in a central ROI. DSA is used to subtract background bone and tissue as well as much of the ROI filter. Method and Materials: A ROI filter was made by making a 1 cm diameter aperture in 0.21 g/cm2 gadolinium screens. The ROI filter was fixed to the x‐ray tube assembly of a standard C‐arm gantry. Mask and contrast acquisitions were performed. Misregistration between the mask and contrast projections were corrected to reduce artifacts at the edge of the ROI. The intensities inside and outside the ROI were further equalized to adjust for the beam hardening effects of the filter outside the ROI. After corrections, reconstruction was performed with the acquisition system's software. Results: DSA‐ROI‐CBCT data were comparable to those obtained with standard DSA‐CBCT with registration and equalization each resulting in artifact reduction at the edge of the ROI. Data outside the ROI was noisier due to fewer photons. Since the x‐ray intensity in the periphery was reduced, the contrast‐to‐noise ratio of the iodinated vessels in the projections inside the ROI was approximately 40% higher than outside. The calculated integral dose reduction for the 12″ acquisition mode with the ROI filter was approximately 85% compared to a full‐field acquisition. Conclusion: By providing data outside the ROI, the new DSA‐ROI‐CBCT technique provides reconstructions inside the ROI comparable to standard DSA‐CBCT with minimal artifacts and significantly reduced integral dose compared to full‐field acquisition. This technique may be easily implemented in the clinical environment for DSA‐ROI‐CBCT reconstruction during ROI image‐guided interventions.

(Support: NIH Grants R01‐NS43924, R01‐EB002873, Toshiba Medical Systems Corporation).
SU‐FF‐I‐24: The Influence of Bowtie Filtration On Cone‐Beam CT Image Quality
Authors: Mail N , Moseley D , Siewerdsen J , Jaffray D
Published: July 2007

Purpose: The large variation of x‐ray fluence at the detector across the imaged field‐of‐view in cone‐beam CT causes the loss of skin‐line and reduces CT number accuracy and image uniformity. We report the performance of a bowtie filter (BTF) as a compensator for improved uniformity, skin‐line and CT number accuracy. Method: Image enhancement is performed using a BT filter with a 20cm collimator. The BTF was inserted 30cm from the x‐ray source on an Elekta Synergy XVI. This filter modulates the 2D x‐ray fluence making it non‐uniform across the field‐of‐view. This compensates for the limited attenuation near the skin, resulting in enhancement of skin‐line and uniformity. Two phantoms (1) CatPhan and 2) CatPhan with irregular acrylic annulus (Cat‐Irreg) were scanned on an Elekta CBCT system. The reconstructed images with and without a BTF were analyzed. The images were transformed into polar coordinates to allow quanitfication of radial lag artifacts (radar artifact) for the Cat‐Irreg phantom. Results: The use of the bowtie filter demonstrated a considerable improvement in CT accuracy in the skin‐line region. The uniformity increases 30% for Cat‐Irreg phantom, and skin‐line edges for both phantoms are visible. CT number accuracy with the BT filter improved by 2% for the CatPhan phantom while no improvement was evident for the Cat‐Irreg phantom. The CT♯ linearity for the catphan phantom with the BT filter improved by 8%. In addition, a 45% reduction in the “radar artifact” was observed in the Cat‐Irreg phantom images acquired with the BT filter. Conclusion: The implemented BTF shows improvement in image quality including uniformity and skin‐line reconstruction. This compensator is static and makes many compromises for anatomical imaging site, patient size, and imaged field‐of‐view. The ideal compensator would optimize the fluence profile to account for numerous properties of the patient and imaging system.

Research sponsored by Elekta.
SU‐FF‐I‐26: A Simple Quantitative Method to Optimize and Monitor Pediatric CT Image Quality
Authors: Goulet P
Published: July 2007

Purpose: To describe a simple quantitative method to optimize and monitor pediatric CT image quality and dose. Method and Materials: Measurements were performed on a multi‐detector CT using helical pediatric brain and body protocols. Water phantoms were used to evaluate HU accuracy and image noise (HU standard deviation) with increasing mAs (dose). A commercial 20‐cm water phantom was used and homemade 15‐cm and 10‐cm diameter water phantoms used to simulate pediatric conditions. Images were inspected for artifacts. Low contrast and noise measurements were performed with the Catphan 15‐cm diameter low contrast module inside and outside the Catphan phantom. Quantitative contrast, noise and contrast‐to‐noise ratio (CNR) measurements were obtained by placing ROIs over the target and background areas. Results: Noise decreased with increasing mAs and was proportional to 1/SQRT (mAs). Noise were strongly dependent on object size. At constant mAs, image noise was 33% and 58% lower in the 15‐cm and 10‐cm objects respectively than in the 20‐cm object. CT number accuracy in the 10‐cm object was outside the ± 5 HU range (AAPM TG‐66). Ring artifacts were observed on the 10‐cm images. Measured contrast was in agreement with the Catphan's nominal contrast. Measured noise in the low contrast module was in agreement with the water‐phantom measurements and provided an independent noise measurement in addition to providing a CNR measurement. At constant technique, CNR increased with decreasing object size. Conclusion: Simple 10‐cm and 15‐cm water phantoms and the 15‐cm Catphan low contrast module can be used to rapidly and quantitatively assess HU accuracy, image contrast, noise and CNR of pediatric CT protocols. Scanning requires less than 15 minutes. Quantitative analysis can be performed rapidly on most CT viewing consoles. This quantitative method can be used to optimize pediatric CT image quality and dose, to monitor pediatric CT scanner performance routinely.
SU‐FF‐I‐27: Optimal CT Imaging Protocol Settings for CT Simulators
Authors: Liu R , Prado K , Wu R , Stevens D , Pan T , Cody D
Published: July 2007

Purpose: It is the expectation of CT simulations to get the best CT images with free breathing scans. CT imaging protocol settings needed to achieve optimal image quality have been identified for every scanner in a Radiation Oncology Department having various makes and models of CT simulators. Method and Materials: A Catphan® phantom was used to evaluate the image quality of 5 different makes/models. Various pitch, detector configuration, and gantry speed parameters were studied, while maintaining constant kVp, effective mAs, head display field of view (DFOV), reconstruction filter, and image thickness settings. Three aspects of image quality were evaluated: 1) helical artifact presence, 2) high contrast resolution, and 3) low contrast resolution. Results: For all CTs, more artifacts appear when the channel width is equal to the image thickness. Less helical artifacts are present if the channel width is half or less of the image thickness. At these settings, however, artifacts are still present in varying degrees depending on pitch. For a 16‐channel CT of one manufacturer, the artifact‐free pitch setting is 1.4 or less, but for their 16‐channel large bore CT, it is 0.9 or less. For another manufacturer's 16‐channel CT, the channel width has to be 1/4 of the image thickness with a pitch of 0.6 to obtain artifact‐free images. The optimal settings for all scanners are different. Only slight differences in high and low contrast resolution are observed, even at varying gantry rotation speeds; these differences seem insignificant at body DFOV (clinical setting). Conclusions: In order to obtain optimal CT image settings, a study should be conducted for each CT model, for there is a vast difference in optimal settings among them. Faster rotation gantry speed should be used as possible, for reduced motion artifact is expected for patient free‐breathing scans.