bluuebunny/crossref_metadata_2025 huggingface dataset:
Does concomitant use of paracetamol potentiate the gastroduodenal mucosal injury associated with aspirin? A prospective, randomised, pilot study
Authors: Boike J. R. , Kao R. , Meyer D. , Markle B. , Rosenberg J. , Niebruegge J. , Stein A. C. , Berkes J. , Goldstein J. L.
Published: June 2012

Background

Paracetamol is commonly prescribed for first‐line symptomatic treatment in patients with osteoarthritis and aspirin is often co‐administered for cardiovascular prophylaxis. It is not known if an interaction exists between aspirin and paracetamol in regards to gastroduodenal mucosal injury.

Aim

To investigate whether or not co‐administered aspirin with paracetamol results in an increased rate of endoscopic gastroduodenal mucosal injury as compared to either agent alone.

Methods

In this prospective, double‐blind, randomised, three‐arm, placebo‐ and active‐controlled, parallel‐group pilot study healthy adult subjects (18–75 years old) with a normal baseline trans‐nasal oesophagogastroduodenoscopy (TN‐EGD), received oral paracetamol 4000 mg q.d.s. (n = 21), aspirin 325 mg q.d.s. (n = 19) or paracetamol 4000 mg q.d.s. and aspirin 325 mg q.d.s. (n = 20). Upper gastrointestinal mucosal injury was evaluated after 7 days of treatment with TN‐EGD.

Results

The rate of gastric ulcers in subjects receiving paracetamol (0/21, 0%) alone or aspirin (3/19, 16%) or both (2/20, 10%) was not different. There were, however, significantly more subjects with one or more lesions (erosion or ulcer) per subject in the paracetamol and aspirin (16/20, 80%) treated subjects as compared to the aspirin (8/19, 42%, P < 0.001) or the paracetamol (3/21, 14%, P < 0.01) exposed subjects. The mean number of lesions per subject was also greater (7.9 vs. 0.7, P < 0.01) in those treated with aspirin and paracetamol compared to paracetamol alone.

Conclusions

Co‐administration of paracetamol and aspirin was not associated with a significant difference in endoscopic ulcer rates compared to either drug alone. There was a strong signal for increased endoscopic erosions and ulcers in the combined group compared to either aspirin or paracetamol alone.
Functional trait divergence of juveniles and adults of nine Inga species with contrasting soil preference in a tropical rain forest
Authors: Palow Danielle T. , Nolting Kristen , Kitajima Kaoru
Published: June 2012

1. Community‐wide studies have shown that functional traits of tropical trees vary with soil‐type preference, but few have examined trait diversification among closely related taxa. In this study, we asked how functional traits of adults and saplings within a speciose genus, Inga, differ in relation to their soil‐type preferences.

2. We quantified soil‐type preference and functional traits of nine Inga species (Fabaceae) in the wet tropical forest at La Selva Biological Station, Costa Rica, where rich alluvial soil and less fertile residual soil of volcanic origin occur in close proximity.

3. From the extensive trail network, we randomly selected 104 trail segments, each 50 m long, along which all Inga individuals >50 cm tall were counted and identified to species. Five and three common species showed significant bias to residual or alluvial soil, respectively, while the remaining one showed no significant bias. For these nine species, we quantified five leaf traits for saplings and adults, as well as wood‐specific gravity (WSG) and three seed traits.

4. For both adults and saplings, leaf mass per area (LMA) and lamina density were higher for residual‐soil specialists than fertile alluvial‐soil specialists. The opposite trend was found for nitrogen (N) and phosphorus (P) concentrations in leaves. Lamina thickness did not differ between soil‐type preference groups. All leaf trait values except N concentration increased from saplings to adults, with adults showing larger interspecific variations in trait values than saplings.

5. Saplings and adults of the single species found on both soils had trait values intermediate between residual and alluvial‐soil specialists.

6. Seed mass and seed N, as well as WSG of adults, were higher in residual‐soil specialists than alluvial‐soil specialists. Higher seed N indicates higher maternal investment of species growing on less fertile soil.

7. These differences in traits among closely related species across continuous soils suggest that habitat filtering has contributed to the evolution of seed, juvenile and adult traits within a speciose tropical tree genus.
Communication and coordination during transition of older persons between nursing homes and hospital still in need of improvement
Authors: Kirsebom Marie , Wadensten Barbro , Hedström Mariann
Published: June 2012

Aim

To investigate registered hospital and nursing home nurses' experiences of coordination and communication within and between care settings when older persons are transferred from nursing homes to hospital and vice versa.

Background

It has previously been reported that transfers to hospital from nursing homes and discharge of patients from hospital are surrounded by communication difficulties. However, studies focusing on both hospital and nursing home registered nurses' experiences of communication and coordination within and between nursing homes and hospitals are uncommon.

Design

A descriptive study design with a qualitative approach was used.

Methods

In 2008, three focus group discussions were conducted with registered nurses from hospitals and nursing homes (n = 20). Data were analysed using content analysis.

Results

Nursing home registered nurses found it difficult to decide whether the older person should be referred to hospital from the nursing home. Hospital registered nurses reported often trying to stop premature discharges or having to carry out the discharge although it had not been fully prepared. Both hospital and nursing home registered nurses suggested increased collaboration to understand each other's work situation better.

Conclusion

Communication and coordination among hospital and nursing home registered nurses need to be furthered improved. Registered nurses' coordination and planning in the nursing home are extremely important to future elder care. We recommend that the medical care plan be regularly updated and meticulously followed, the aim being to reduce the risk of inappropriate medical treatment and nursing care and unnecessary transfer and admission to hospital.
Immunohistochemical features of BK virus nephropathy in renal transplant recipients
Authors: Yamanaka Kazuaki , Oka Kazumasa , Nakazawa Shigeaki , Hirai Toshiaki , Kishikawa Hidefumi , Nishimura Kenji , Kyo Masahiro , Ichikawa Yasuji
Published: June 2012

BK virus nephropathy (BKVN) is one of the factors that reduces renal graft function after transplantation. However, BKVN and rejection present similar pathological findings, as both are accompanied by cellular infiltration to the interstitium and tubulitis, thus they are difficult to distinguish for diagnosis and medical treatment. In the present study, we examined immunohistochemical pathological features of BKVN in four cases treated in our hospital from 2007 to 2010. Common immunohistological finding is that tubulitis in these cases was primarily EMA and 34βE12‐positive and existed predominantly from the collecting duct to the distal convoluted tubule. The majority of infected cells existed in EMA and 34βE12‐positive tubules, which were also located mainly from the collecting duct to the distal tubule. In addition, a large number of SV40‐positive infected cells were similarly seen. Dylon staining clearly revealed eosinophils. We concluded that the main pathological features of BKVN are the presence of tubulitis and infected cells predominantly from the collecting duct to distal tubule and the appearance of eosinophils.
Reviews on mysterious vascular endothelial cells in renal allografts
Authors: Yamaguchi Yutaka
Published: June 2012

Endothelial cells (ECs) are involved in allograft rejection and are prime targets, but also key players. HLA antigens are the most prominent targets of alloantibodies in transplantation. Alloantibodies against other antigens such as ABO blood group antigens and non‐HLA antigens could also be demonstrated. Alloantibodies undoubtedly cause allograft rejection. Activation of ECs by anti‐EC antibodies and direct antibody‐ or complement mediated EC damage may be suggested. However, the mechanisms underlying acute antibody‐mediated rejection (AAMR) and chronic rejection (CR) remain unclear. In this review, the relationship between vascular endothelium and rejection is discussed mainly from our reports, and the mechanism and pathogenesis of CR are discussed.
Dissociation of tone and vowel processing in Mandarin idioms
Authors: Hu Jiehui , Gao Shan , Ma Weiyi , Yao Dezhong
Published: June 2012

Using event‐related potentials, this study measured the access of suprasegmental (tone) and segmental (vowel) information in spoken word recognition with Mandarin idioms. Participants performed a delayed‐response acceptability task, in which they judged the correctness of the last word of each idiom, which might deviate from the correct word in either tone or vowel. Results showed that, compared with the correct idioms, a larger early negativity appeared only for vowel violation. Additionally, a larger N400 effect was observed for vowel mismatch than tone mismatch. A control experiment revealed that these differences were not due to low‐level physical differences across conditions; instead, they represented the greater constraining power of vowels than tones in the lexical selection and semantic integration of the spoken words. Furthermore, tone violation elicited a more robust late positive component than vowel violation, suggesting different reanalyses of the two types of information. In summary, the current results support a functional dissociation of tone and vowel processing in spoken word recognition.
Morphology Control and Self‐Setting Modification of α‐Calcium Sulfate Hemihydrate Bone Cement by Addition of Ethanol
Authors: Pan Zongyou , Yang Guangyong , Lou Yi , Xue Enxing , Xu Huazi , Miao Xigeng , Liu Jianli , Hu Chunfeng , Huang Qing
Published: June 2012

The self‐setting behavior of α‐calcium sulfate hemihydrate is highly dependent on its morphology that is tuned through the addition of ethanol into CaCl2 aqueous solutions during a salt solution method. With the increase of the ethanol/water volume ratios, the mean lengths of the formed crystals decreased from 24 to 19 μm, whereas their mean widths increased from 6 to 18 μm. It is also detected that the setting time of α‐CSH paste reduced from 120 ± 12.3 to 17 ± 2.1 min as the crystal morphology evolved from rod‐like to equiaxial.
Dual infection with Pythium insidiosum and Blastomyces dermatitidis in a dog
Authors: Connolly Sara L. , Frank Chad , Thompson Craig A. , Van Alstine William G. , Gelb Hylton , Heng Hock Gan , Klosterman Emily , Kiupel Matti , Grooters Amy M.
Published: June 2012

A 4‐year‐old male neutered Labrador Retriever with severe gastrointestinal signs, but no respiratory signs, was diagnosed with multifocal pyogranulomatous gastritis, enteritis, and lymphadenitis with intralesional hyphae and multifocal pyogranulomatous pneumonia with intralesional yeast. Based on cytologic evaluation, histologic examination with special stains, and immunohistochemical analysis of tissues collected antemortem or at necropsy, dual infections with Pythium insidiosum and Blastomyces dermatitidis were detected and are reported for the first time.
Increased plasma cardiac troponin I concentration in lambs with myocarditis
Authors: Karapinar Tolga , Eroksuz Yesari , Beytut Enver , Sozdutmaz Ibrahim , Eroksuz Hatice , Dabak Murat
Published: June 2012

Background

Cardiac troponin I (cTnI) is a blood biomarker of myocardial injury. A human cTnI assay may be useful for measuring cTnI concentrations in lambs with naturally occurring myocarditis.

Objective

The aims of this study were to evaluate the utility of a commercially available human chemiluminescent microparticle cTnI immunoassay for measuring plasma cTnI concentrations in lambs with naturally occurring myocarditis from infection with foot and mouth disease virus (FMDV), and to determine cTnI expression in cardiac muscle of affected lambs.

Methods

Ten lambs with myocarditis and 10 clinically healthy lambs (control group) were included. Clinical signs, gross and histologic necropsy findings, and immunoreactivity for cTnI in cardiac tissue were evaluated. Plasma cTnI concentration was determined using the commercial human immunoassay system.

Results

All lambs with myocarditis died within 1 day of clinical signs. Infection with FMDV was confirmed by PCR analysis. Gross cardiac lesions were evident and histologic examination revealed myocarditis. Immunoreactivity for cTnI was absent in cardiac myocytes that were degenerative or necrotic, but was strong in cardiac myocytes from unaffected areas of the myocardium and in all cardiac myocytes of healthy lambs. The geometric mean plasma concentrations of cTnI for lambs in the myocarditis and control groups were 146.78 μg/L (95% confidence interval [CI], 61.90–348.06) and 0.013 μg/L (95% CI, 0.010–0.017), respectively (t‐value 19.27; P < .0001).

Conclusions

A commercial human cTnI assay may be used to detect plasma cTnI concentrations in sheep, and cTnI may be used as a blood‐based biomarker of myocarditis in this species.
Numerical Study of Flow Deflection and Horseshoe Vortices in a Louvered Fin Round Tube Heat Exchanger
Authors: Huisseune H. , T’Joen C. , De Jaeger P. , Ameel B. , Demuynck J. , De Paepe M.
Published: June 2012

In louvered fin heat exchangers, the flow deflection influences the heat transfer rate and pressure drop and thus the heat exchanger’s performance. To date, studies of the flow deflection are two-dimensional, which is an acceptable approximation for flat tube heat exchangers (typical for automotive applications). However, in louvered fin heat exchangers with round tubes, which are commonly used in air-conditioning devices and heat pumps, the flow is three-dimensional throughout the whole heat exchanger. In this study, three-dimensional numerical simulations were performed to investigate the flow deflection and horseshoe vortex development in a louvered fin round tube heat exchanger with three tube rows in a staggered layout. The numerical simulations were validated against the experimental data. It was found that the flow deflection is affected by the tubes in the same tube row (intratube row effect) and by the tubes in the upstream tube rows (intertube row effect). Flow efficiency values obtained with two-dimensional studies are representative only for the flow behavior in the first tube row of a staggered louvered fin heat exchanger with round tubes. The flow behavior in the louvered elements of the subsequent tube rows differs strongly due to its three-dimensional nature. Furthermore, it was found that the flow deflection affects the local pressure distributions upstream of the tubes of the downstream tube rows and thus the horseshoe vortex development at these locations. The results of this study are important because the flow behavior is related to the thermal hydraulic performance of the heat exchanger.
Measuring the Thermal Conductivity of Flowing Liquid Samples Using the Three Omega Method
Authors: Hong Jonggan , Kim Dongsik
Published: June 2012

The thermal conductivity of a liquid is generally measured under conditions that suppress bulk flow in the sample. However, in situ measurement of the thermal conductivity of a flowing liquid would be useful in various scientific and engineering applications. This work demonstrates that a thermal wave technique, such as the three omega method, can effectively measure the thermal conductivity of flowing liquid if the frequency range is adjusted such that the thermal boundary layer is sufficiently thinner than the momentum boundary layer. A new dimensionless number was defined to assess the convection effects, and a criterion for thermal conductivity measurements was obtained for water flowing in a circular tube.
Design and Development of a New Landfill/Biogas Engine Oil for Modern, High BMEP Natural Gas Engines
Authors: Palazzotto John D. , Timar Joseph , Beckman Alan T.
Published: June 2012

The use of higher brake mean effective pressure (BMEP) engines in landfill or alternative gas applications has dramatically increased in the past few years. Operators are using these engines due to their ability to provide lower emissions, coupled with improved economics for the end user due to the higher density or power output capability compared to an engine of similar size and displacement. Landfill gas (LFG) quality can vary greatly, along with the contaminant level due to the composition of the landfill. This environment poses unique challenges to both the engine and the engine oil, including shorter oil drain intervals, corrosive attack of engine components, with increased piston and combustion chamber deposits, to name but a few. Maintaining longer oil drain intervals minimizes unscheduled oil drains, which can decrease the overall cost of the landfill operation. High BMEP engines provide higher power output, however,at the cost of increased maintenance in severe fuel applications. Excessive piston crown and combustion chamber deposits from landfill gas impurities can have a deleterious effect on engine emissions, which may lead to the inability to meet local emissions regulations. Engine lubricants must provide adequate oil life along with minimizing deposit related issues that may negatively impact regular scheduled maintenance cycles, thus reducing engine downtime and increasing revenues. Traditionally, the approach has been that oils formulated for landfill applications used excess base reserve to sufficiently neutralize the acids being formed during the combustion process. Unfortunately, this approach increases the sulfated ash content of the lubricant, which lends itself to increased ash deposits and negatively impacts the combustion dynamics of these high BMEP engines, which are sensitive to ash deposition. Based upon requests for a longer life lubricant without compromising deposit control characteristics to serve landfill applications, a new product development project was specifically targeted for late model, high BMEP engines, which are prone to detonation and sensitive to ash related deposits. This paper presents the development bench testing, and proof of performance field evaluations of a new generation, low ash landfill gas engine oil.
SU‐B‐BRB‐01: Professional Council Symposium: Practice Standards ‐ Driving Forces, Benefits, Potential Pitfalls
Authors: Halvorsen P , Hevezi J , Pizzutiello R , Pacella M
Published: June 2012

Recent coverage in the mainstream media has brought significant attention to the uses of ionizing radiation in medicine. This is not a transient concern, however. Many factors are contributing to this trend, in addition to the general public's concern: ASTRO, ACR and AAPM have advocated clear practice guidelines and mandatory accreditation of all clinical programs in imaging and radiation therapy; payers' requirements and/or assumptions about physicist support for billable procedures, including physicist credentials and supervision; ASTRO's White Paper series on patient safety, which have included a significant focus on staffing; and some states' requirements for external audits of clinical programs

Learning Objectives:

1. Understand the convergence of external factors that are driving the trend toward minimum practice standards, including CMS assumptions about physicist supervision of certain procedures;

2. Understand the effect of this trend in imaging, particularly the impact on community clinics and consulting physicists; and

3. Understand the impact in radiation oncology, particularly on freestanding and small community centers.

4. Understand the AAPM's multi‐faceted approach to ensuring that medical physicists can shape the future of clinical medical physics practice.
SU‐C‐211‐02: A Fast Monte Carlo Dose Algorithm for Radiotherapy Treatment Planning Based on Hybrid Adaptive Meshes
Authors: Yuan J , Brindle J , Zheng Y , Sohn J , Geis P , Yao M , Lo S , Wessels B
Published: June 2012

Purpose: Monte Carlo methods are considered to be the most accurate dose algorithm for radiotherapy. Variance reduction techniques such as history repetition, Russian roulette and photon splitting are employed to improve the calculation efficiency. Generally, it takes a large portion of the simulation time for two inevitable tasks, that is, voxel‐to‐voxel boundary crossing and energy deposition. The purpose of this work is to investigate the potential for additional speedup achieved by reducing the number of boundary crossing based on hybrid adaptive meshes. Method and Materials: A Monte Carlo code was developed to simulate the coupled photon‐electron transport for radiation therapy using a hybrid adaptive mesh. Photon transport was modeled in an analog fashion. The Compton scattering, photoelectric ionization and pair production were considered. For electron transport, a condensed history method was used in which the hard interactions such as inelastic collision and bremsstrahlung were simulated explicitly. The formulation by Kawrakow and Bielajew was used for electron multiple scattering. Photons and electrons were tracked on a hybrid adaptive mesh, which was generated from an initial uniform coarse mesh. The coarse uniform mesh was divided voxel‐by‐voxel into an unstructured finer mesh depending on the splitting criterion such as the density gradient. The resulting adaptive mesh contains larger voxels in smooth density areas and smaller voxels used for density regions with large gradient to retain the accuracy. Results: The speed up observed by varying the splitting level is proportional to N1/3, where N is the total number of the voxels. For the test cases, 30% of the calculation time was saved by using the adaptive meshes starting with 10mm spacing and reduced to 1.25mm voxels for high gradient regions comparing with the 1.25mm uniform meshes. Conclusions: The Monte Carlo simulations can be further accelerated based on these hybrid adaptive meshes.
SU‐C‐211‐05: Evaluation of the Dosimetric Effects of Delivering a VMAT Plan Optimized for a Straight‐Beam Linac on a Bent‐Beam Linac
Authors: Nayebi N , Esquivel C , Patel A , McKinsey R , Papanikolaou N
Published: June 2012

Purpose: To investigate the dosimetric effects of delivering a VMAT plan optimized for a straight‐beam linac on a bent‐beam linac. Methods: When a linac is unavailable to treat, it is common practice to transfer patients to another machine that has been dosimetrically matched. The purpose of this study was to evaluate the changes in the dose to organs at risk (OAR) and planned target volumes (PTV) due to a patient transfer from Clinac 600C/D to Clinac 23EX. The former is a straight beam machine (no bending magnet) and the latter has an achromatic bending magnet. Both machines are equipped with 120 Millennium MLCs. Nine VMAT plans (three treatment sites) originally optimized for the Clinac 600C/D were recalculated for the Clinac 23EX. Each plan was recomputed with the Pinnacle3 treatment planning system to deliver the same dose to the same treatment volume using the same number of monitor units for the entire treatment regime. To quantify the variations, the dose volume histograms (DVHs) for each plan, V50, mean and maximum dose to the OARs and PTV were compared. Results: The V50 of the OARs in the recalculated plan for the Clinac 23EX increased by an average of 15.2% (STD=15.1%). The increases on the maximum and mean dose to the OARs were on average 2.9±1.4% and 5.9±2.7% respectively. The maximum and mean PTV doses also increased for all of the 9 patients by 2.3±1.2% and 2.5±1.0%. Conclusions: The results indicated that the delivery of a VMAT plan for Clinac 600C/D on Clina c23EX will increase the dose to the PTVs and OARs. In cases where a patient is transferred to another machine for a single or small number of fractions, changes in dose distribution may be clinically insignificant; otherwise dosimetric evaluation of the transferred treatment to on another machine is highly recommended.
SU‐C‐BRCD‐02: Sources and Magnitudes of Uncertainties Using the Gamma Knife Extend System
Authors: Schlesinger D , Xu Z , Taylor F , Sheehan J
Published: June 2012

Purpose: The Gamma Knife Extend System uses a vacuum‐assisted dental fixation mounted on a carbon‐fiber frame to achieve non‐invasive immobilization appropriate for multi‐fraction Gamma Knife procedures. At simulation and before each fraction, patient position is determined through the use of high‐precision digital mechanical measurement probes and a reference positioning template (RCT). The objective of this study is to quantify uncertainty in the Extend System from patient setup, intrafraction immobilization, and observer uncertainty in taking positioning measurements. Methods: Positioning measurements for 10 patients/ 36 fractions were used to estimate setup and immobilization uncertainty. Setup uncertainty was quantified by recording the residual difference between pre‐ fraction measurements after repositioning and reference measurements taken at the time of CT imaging. Intrafraction positioning uncertainty was estimated by the difference between post‐fraction and pre‐fraction position measurements. Observer uncertainty was estimated by three observers taking three measurements on each of the 44 measurement holes in the RCT using a phantom as a subject. The distributions of the systematic (Σ) and random (σ) components of the setup and immobilization measurement differences were calculated. The distribution of the random component of the observer measurement variation was determined. Results: The mean radial setup difference from the reference measurements was 0.65mm, SD=0.24mm, Σ = 0.17mm, σ = 0.16mm. The mean intrafractional positional difference was 0.46mm, SD=0.30mm, Σ=0.19mm, s= 0.22mm. The distribution of the random component of observer uncertainty was 0.03mm. Conclusions: The Extend System appears to have uncertainties similar in magnitude to other noninvasive fixation systems. Care should be taken to acquire measurements that can implicitly account for rotations of the patient's head. Further work is required to determine the sensitivity of the vacuum interlock to detect patient motion and to determine the systematic inter/intra‐observer uncertainty. David Schlesinger and Zhiyuan Xu have a grant pending with Elekta, AB for research that is unrelated to the material presented in this abstract. However Elekta, AB is the manufacturer of the treatment device (Gamma Knife) that is related to this material.
SU‐C‐BRA‐06: Monitoring Tumor Motion Using Beam‐Eye‐View EPID Imaging during IMRT: A Gradient‐Based Fiducial Detection Algorithm
Authors: Chen X , Fan J , Chen L , Ma C‐M
Published: June 2012

Purpose: Intrafractional tumor motion introduces significant dose uncertainty for radiotherapy. Using EPID imaging during IMRT delivery will provide a beam‐eye‐view (BEV) tumor motion observation and it also provides a cost‐efficient tumor tracking method, avoiding additional imaging system. The purpose of this study is to develop a fiducial detection algorithm for tumor motion monitoring using beam‐eye‐view (BEV) EPID imaging during external beam IMRT treatment. Methods: A gradient‐based fiducial detection algorithm was developed which includes steps: (1) determine IMRT segment; (2) define a search region; (3) Image gradient, grad(I), within the search region was calculated and a threshold was applied to find candidates; (4) the size and orientation (obtained using radon transform) of each candidate was determined, and compared to expected values (from treatment plan) to find the fiducial. To test this algorithm, external beam breast IMRT fields were delivered to a breast phantom (size: ∼13×10cm) with a gold fiducial (1×5 mm) on the Varian Trilogy. Portal images were acquired using Varian aSi1000 EPID system with the following settings: continuous mode, 3 averages per image, image size 1024×768 with resolution 0.392mm per pixel, EPID at 140cm SID (source‐imager‐ distance). Results: Twenty portal images acquired at different time during IMRT delivery, of which 10 images were with couch shift (4mm), have been tested and initial results show that the algorithm is able to detect the fiducial successfully (100%). The gradient‐based method, which basically uses the edge information, has the advantage over intensity‐based method for MV portal images since generally MV images have lower contrast compared with KV images. Conclusion: A gradient‐based fiducial algorithm has been developed and tested on breast IMRT treatment using a breast phantom. Further studies are warranted for other tumor sites such as prostate IMRT treatment.
SU‐C‐213CD‐03: Significant Inter‐Fractional Variations of Lumpectomy Cavity in Partial Breast Irradiation
Authors: Chen X , White J , Morrow N , Wilson J , Li X
Published: June 2012

Purpose: Inter‐fractional variation in partial breast irradiation (PBI) using external beams is a significant issue. Image guided RT (IGRT), by imaging and repositioning the patient prior to the delivery based on rigid‐body registration, has been introduced to reduce inter‐fractional setup and translational variations. However, IGRT is not capable of addressing organ deformation and rotation. The purpose of this work is to quantitatively characterize those variations in PBI in supine position. Methods: A total of 100 diagnostic‐quality CT sets acquired using an in‐room CT during IGRT at each fraction for 10 breast cancer patients treated with PBI in supine position were analyzed. Targets and organs at risk, including the lumpectomy cavity, treated breast, lung and heart, were delineated by populating the contours from the planning CT to each fraction CT using an auto‐segmentation tool (ABAS, CMS/Elekta) with manual editing. Various parameters, including volume, maximum overlap rate (MOR), dice's coefficient, and distance between centers of mass (COM) were calculated to quantify the inter‐fractional variations. Results: The shape and volume of the lumpectomy cavity in the fractional CTs, particularly in the first fraction CT, change significantly from those in the planning CT. On average, the volume of the lumpectomy cavity decreases by 23%. The MOR varies from 50% to 90% with the mean value of 72%. The dice's coefficient is shown in a similar range. The variation of the treated breast is relatively small. The changes in the distances between the COMs of the lumpectomy cavity and the heart and of the lumpectomy cavity and the treated breast are up to 3 mm. Conclusions: The inter‐fractional lumpectomy cavity deformation is significant during PBI. Strategies that can address not only the translational motion but also the deformation, such as adaptive RT, should be explored for PBI.
SU‐C‐217BCD‐02: Evaluating the Impact of Iterative Reconstruction for Three Major CT Vendors
Authors: Chen J , Yang Z , Samei E , Christianson O , Dima A , Filliben J , Peskin A , Saiprasad G , Siegel E
Published: June 2012

Purpose: Various vendors have promoted iterative reconstruction as an effective way to reduce CT radiation dose while maintaining image quality. The purpose of our exhibit is to demonstrate the effectiveness of various vendor reconstruction approaches on image quality based on a multi‐ institutional study utilizing the ACR phantom as a source of quantitative analysis. Methods: CT scans of the ACR CT QA phantom were acquired using three CT scanners (A: GE Discovery CT750 HD, B: Philips iCT, and C: Siemens FLASH). Images acquired at seven dose levels ranging from 1 to 20 mGy were reconstructed using both FBP and IR. The data acquisition was randomized and duplicated five times to reduce the effect of systematic variations. The images were reconstructed utilizing the kernel of reconstruction recommended by each manufacturer for abdominal CT studies utilizing both filtered back projection and the vendor's iterative reconstruction techniques. The phantom images were quantitatively evaluated for a number of parameters that determined spatial and contrast resolution as well as signal to noise levels. The data were entered into a spreadsheet and subsequently into a statistical package for analysis. Results: The success of iterative reconstruction varied substantially among the three vendors for the low dose CT protocols but did have a positive impact on image quality. The positive impact of iterative reconstruction was greatest for the lowest dose studies. The specific differences will be discussed in detail. Conclusions: In addition to subjective evaluation of image quality which can be affected by many parameters, it is also important to determine the impact of the newly developed CT iterative reconstruction algorithms in a quantitative manner utilizing phantoms. Our study suggests that the quantitative improvements in spatial resolution are modest. However, improvements in contrast to noise ratio are in the neighborhood of 35 to 58% depending on the exact implementation. Funding and Technical Support from National Institute of Standards and Technology is gratefully acknowledged. Technical support from each CT scanner manufacturer is also acknowledged.
SU‐C‐217BCD‐03: CT QA Revisited in Context of Tube Current Modulation and Iterative Reconstruction
Authors: Winslow J , Wilson J , Christianson O , Samei E
Published: June 2012

Purpose: Despite their substantial impact on both patient dose and image quality, automatic‐tube‐current‐modulation (ATCM) and iterative reconstruction (IR) are not typically evaluated or monitored in CT quality assurance (CTQA) programs. A new CT phantom and custom software have been incorporated into the CTQA program at our institution. The purpose of this project was to devise a generic testing platform using these newly designed tools, and introduce this platform as part of regular CTQA testing. Methods: The Mercury Phantom comprises three tapered and four uniform regions of polyethylene (16, 23, 30, and 37cm in diameter), each of which includes four inserts of different materials: air, Polystyrene, Acrylic, and Teflon. Images were acquired using ATCM on three Siemens Flash and three GE 750HD scanners, and iteratively reconstructed (SAFIRE and ASIR). A custom MATLAB software package provided mAs and standard deviation per image, HU, MTF, NPS, and detectability indices for each insert. Results were compared within and across systems, to be used as baseline values for comparison with future system performance testing. Results: For each scanner model, the absolute difference in mAs for corresponding images of the baseline scans had a mean value less than 2 mAs, with a standard deviation of 1.3 mAs. For different phantom diameters, HU measurements for all four inserts varied little between identical systems or reconstruction algorithms. For each reconstruction algorithm used, detectability indices based upon MTF and NPS measurements were very reproducible, averaging less than 5% difference. Different CT models varied substantially in terms of their mAs profile. Conclusions: The Mercury Phantom and data analysis technique can be used to benchmark/monitor CT performance, including ATCM and IR, and identify changes over time and across systems. The methodology can be readily implemented across a fleet of CT scanners at a large academic medical center.
SU‐C‐217A‐01: Digital Breast Tomosynthesis: Is the Room Shielding a Need?
Authors: Zhang J , Garner W , Schlenker G , Szabunio M
Published: June 2012

Purpose: With FDA approval of Digital Breast Tomosynthesis (DBT), a question on its room shielding is raised. According to NCRP147, standard gypsum wallboard construction is adequate to shield the walls of a conventional mammographic unit. This recommendation may not be valid for DBT which acquires data from multiple angles therefore potentially leads to larger scattered radiation. The DBT room shielding may be reconsidered. This study is to investigate if additional room shielding is necessary for DBT. Methods: Room shielding was first calculated following NCRP147 by adjusting recommended air kerma with the ratio of acquisition numbers. We assumed that comparable techniques were used for data acquisition of DBT and conventional mammography. Scattered radiations at locations inside and outside of the door were then measured with Ludlum 9DP survey meter for comparison with shielding design goal, e.g. 0.02 mGy/week. CIRS breast biopsy training phantom was used for the measurements. Two phantoms were overlapped (approximately 6 cm) to simulate a relatively large breast thickness. 150 patients/week was assumed for calculations. Results: Based on both calculation and measurements, the current room without any special shielding is adequate for conventional mammography with 4 images/patient. DBT with 30 to 34 (per patient, tomosythesis vs. combo) radiographic acquisitions requires approximately 20 mm of gypsum wallboard. Standard gypsum wallboard construction may still meet this requirement. However, DBT requires the thickness of solid wood door of approximately 170 mm according to the calculation and approximately 60mm based on the measurements, respectively, with a full occupancy factor. Most current solid wood door cannot meet this requirement. The measurement outside the door also shows high scattered radiation, approximately 0.09mGy/week, which is only acceptable for less occupied areas. Conclusions: With the increasing data acquisitions of DBT, the room shielding needs reconsideration, although both calculation and measurements are very conservative.
SU‐C‐217A‐05: The Design of An Institution Wide Comprehensive Technique Chart for Size‐ Specific Radiography from Pediatrics to Adults
Authors: Bower D , Samei E , Johnson J
Published: June 2012

Purpose: A properly designed projection radiography technique chart enables adherence to maximum Entrance Skin Exposure (ESE) standards, avoidance of improper exposures, and optimization of image quality across devices and patient sizes. The goal of this project was to develop and “field test” a technique chart designed to accomplish these tasks. Methods: All radiographic anatomical examinations at our institution were characterized in terms of average body‐part thickness, kVp, grid use, and field size, across a group of eight patient sizes ranging from neonates to bariatric adults. Wide‐angle transmission fractions (TFs) were measured across a range of thickness, field sizes, and kVp, from which multi‐dimensional fits enabled TF to be estimated for any examination type. For each examination type, target ESE values necessary to deliver manufacturer‐specified detector exposure were determined. The maximum and target ESE values for patients other than average adults were propagated from the average adult values to those for each of the patient size groups using the estimated TFs. For a given x‐ray system, the maximum and the target mAs values were then estimated from the measured mR/mAs for that system for each of the anatomical examinations and patient sizes. Results: Generated mAs values compared reasonably well with empiric values used by technologists for average adult. However, there were notable discrepancies across devices and patient sizes. For large patients, the generated values were in general substantially larger than empiric values. The new technique chart is currently implemented across our institution. Conclusions: Using a universal technique chart enables a reduction in variability of acquisition across the imaging operation at a large medical center. This can substantially aid in improving the consistency of medical imaging and provide important guidance as how image quality and dose can be optimized across patient sizes and age groups.
SU‐C‐218‐02: Real‐Time Adaptive Correction for Varying Source‐To‐Image‐Distance (SID) for a Novel Region of Interest (ROI) Fluoroscopy Dose Reduction Technique Involving Spatially Different Temporal Filtering
Authors: Nagesh S Setlur , Panse A , Jain A , Sharma P , Ionita C , Titus A , Cartwright A , Bednarek D , Rudin S
Published: June 2012

Purpose: A technique is presented to adjust the ROI fluoroscopy equalization mask for changes in the SID and thus to provide boundary‐ artifact‐free brightness and noise equalized images. Methods: Patient dose reduction during x‐ray guided interventions can be achieved by using a combination of ROI fluoroscopy and spatially‐different temporal filtering. ROI fluoroscopy reduces the dose to the patient in the peripheral regions, thus resulting in an image with differential brightness and noise regions. The brightness can be equalized by subtracting a pre‐acquired mask image of the attenuation filter, resulting in an image noisier in the periphery (due to fewer quanta reaching the detector) as compared to the non‐attenuated region. The noise in the periphery region can be reduced by choosing a higher temporal‐ filtering weight using this mask as a reference. However, as source‐to‐ imager‐distance (SID) changes, the mask also needs to be changed due to magnification changes of the ROI‐attenuation filter. To correct for changes in the SID during a procedure, different pre‐acquired masks are used at different SIDs. The SID information is obtained in real‐time from a digital bus on the x‐ray system and, whenever the SID changes, the corresponding mask in the memory is chosen. Although memory inefficient, this implementation is computationally efficient. Results: The technique was implemented and brightness and noise equalized images were obtained without the introduction of boundary artifacts as the SID was changed. The corrections are performed in real‐time without interruption to the interventional procedure. Conclusions: With correction for the change in SID implemented in real‐time, the technique involving the combination of ROI fluoroscopy and spatially‐different temporal filtering can be used in a clinical environment and thus significant patient integral‐dose reduction can be realized during x‐ray guided interventional procedures. Supported in part by: NIH Grants R01‐EB008425, R01‐EB002873 and an equipment grant from Toshiba Medical Systems Corp.
SU‐C‐218‐04: Comparison of Respiratory Gated Micro‐CT in Mechanically Ventilated and Free‐Breathing Rats
Authors: Ford NL , McCaig LA , Lewis JF , Veldhuizen RA , Holdsworth DW , Drangova M
Published: June 2012

Purpose: Lung imaging in preclinical studies can be performed using respiratory‐gated micro‐computed tomography in mechanically ventilated or free‐breathing rodents. In this study, we aim to quantify the differences in lung metrics measured in free‐breathing and mechanically ventilated rodents. Methods: Male sprague‐dawley rats were anaesthetized with ketamine/xylazine and scanned with a retrospective respiratory gating protocol on a GE Locus Ultra micro‐CT scanner (80 kVp, 50 mA, 50 s, 0.28 Gy entrance dose). The rats were free‐breathing and scanned while externally monitoring the respiration. Each animal was intubated and mechanically ventilated (MV) at 56 bpm, 8 mL/kg and PEEP of 5 cm water and rescanned. Images were reconstructed representing peak inspiration and end expiration with 0.15 mm isotropic voxel spacing. Quantitative image‐ based measurements of lung volume and air content were used to calculate the functional residual capacity (FRC) and tidal volume. Measured and calculated values were compared (paired t‐tests). Results: Qualitatively, the images acquired during mechanical ventilation appeared darker in the airspaces and the airways appeared larger. Our image‐based measurements showed an increase in lung volume and air content during mechanical ventilation for both respiratory phases (Free 6.9 mL and MV 12.8 mL for peak inspiration and Free 5.6 mL and MV 10.5 mL at end expiration). Comparisons of the functional metrics showed an increase in both FRC and tidal volumes of mechanically ventilated rats (FRC of 3.2 mL for Free and 8.4 mL for MV, tidal volume of 2.7 mL/kg for Free and 6.1 mL/kg for MV). Conclusions: Although mechanical ventilation may be useful in promoting consistent respiratory patterns, the amount of air in the lungs is higher than in free‐breathing animals. Care should be taken in planning respiratory research to ensure that overinflating the lungs during mechanical ventilation will not compromise the desired measurements or free‐breathing animals should be used.
SU‐D‐211‐03: An Automated Inverse Planning Optimization Approach for Single‐ Fraction and Fractionated Radiosurgery Using Gamma Knife Perfexion
Authors: Ghobadi K , Ghaffari H , Aleman D , Ruschin M , Jaffray D
Published: June 2012

Purpose: The purpose of this work is to develop an automated inverse planning approach to generate singe‐fraction and fractionated stereotactic radiosurgery (SRS) treatment plans for Gamma Knife Perfexion. Methods: Our automated approach consists of two steps: 1) a grassfire‐based algorithm to carefully determine the isocentre locations; 2) a penalty‐based optimization to find the optimal shot shapes and their intensities to minimize the deviation of the delivered dose from the objective dose in all structures. For single‐fraction SRS, a margin‐less approach was taken: conformity of dose to the gross tumor volume (GTV) with a steep dose fall‐off was prioritized. For fractionated radiosurgery, dose homogeneity was given a higher priority since planning target volumes (PTV) were applied to account for daily setup variation, and these PTVs could overlap with organs‐at‐risk (OARs). The two‐step approach was tested on seven clinical cases with PTV sizes of 0.5cm̂3–56.5cm̂3. In the tested cases, the PTV had 0%–38% overlap with OARs. Results: For single‐fraction SRS, the dose to 1mm̂3 brainstem was on average 0.24Gy (range: −2.4Gy to +2.0Gy) lower compared to manually‐generated plans. Beam‐on time varied with the number of isocentres, but on average was 33min longer than manually‐ generated plans. The optimization algorithm took 215min on average, while isocentre selection performed in <10s.For fractionated SRS, the average PTV coverage was V95=94.9% (range: 92.7%–97.6%) and the mean dose to 1 mm̂3 brainstem was 87.8% of the prescription dose (range: 35.4%‐ 108.8%). The mean beam‐on time per fraction per dose‐per‐fraction was 4.8min/Gy (range: 0.9min/Gy‐10.3min/Gy). We observed a tradeoff between conformity and OARs‐sparing in both plans, and added sensitivity to isocentre locations in fractionated plans. In all the cases, GTV received the full prescription dose. Conclusions: The results indicated that automated inverse planning yields improved conformity and OAR‐sparing for single‐ fraction SRS and is capable of generating homogeneous fractionated SRS. This work is partially funded by Elekta Instrument, AB, Stockholm, Sweden.