Relationship of Urethral Dose and Genitourinary Toxicity Among Patients Receiving Vaginal High Dose Rate Interstitial Brachytherapy.

AIMS: Interstitial brachytherapy (ISBT) plays an important role in the management of locally advanced gynaecological malignancies. However, the relationship between urinary toxicity and dose to the urethra is not well understood. We sought to evaluate the correlation between urethral dose and the incidence of genitourinary complications among patients undergoing vaginal high dose rate ISBT. MATERIALS AND METHODS: Eighty-three patients treated with ISBT between August 2014 and April 2018 were retrospectively reviewed. CTCAE version 5.0 was used to grade toxicity. Individual treatment plans were evaluated to collect dose parameters. Urethral contours were added to the structure sets using a uniform 1 cm diameter brush and minimum doses to the hottest 0.1, 0.2 and 0.5 cm3 (D0.1cm3, D0.2cm3 and D0.5cm3) of the urethra were obtained. Total (ISBT ± external beam radiotherapy) equivalent doses in 2 Gy fractions (EQD2) received by the targets and organs at risk were calculated. Numerical counts (%) and medians (interquartile range) were used to characterise the data. Fisher's exact and the Mann-Whitney-Wilcox tests were used as appropriate. Receiver operator curve analysis was used to define the urethral threshold dose that correlated to genitourinary toxicity. RESULTS: The median age and follow-up times were 67 years (59-75) and 25 months (16-37), respectively. Patients had predominantly primary endometrial (49%) and vaginal (37%) cancer, with four (5%) patients with metastatic rectal cancer to the vagina. Twenty-four of 79 (30%) patients experienced acute genitourinary toxicity and 34 of 71 (48%) experienced late genitourinary toxicity. In both analyses, the median urethral dose was significantly higher among those with toxicity. Receiver operator curve analysis indicated that D0.1cm3, D0.2cm3 and D0.5cm3 of the urethra were associated with the development of toxicity at doses >78, >71 and >62 Gy, respectively. CONCLUSION: Urethral dose seems to predict genitourinary toxicity in ISBT of vaginal tumours. Further study with an expanded cohort and longer follow-up is warranted.

Feasibility of using a single MRI acquisition for fiducial marker localization and synthetic CT generation towards MRI-only prostate radiation therapy treatment planning.

Purpose.To investigate the feasibility of using a single MRI acquisition for fiducial marker identification and synthetic CT (sCT) generation towards MRI-only treatment planning for prostate external beam radiation therapy (EBRT).Methods.Seven prostate cancer patients undergoing EBRT, each with three implanted gold fiducial markers, participated in this study. In addition to the planning CT scan, all patients were scanned on a 3 T MR scanner with a 3D double-echo gradient echo (GRE) sequence. Quantitative susceptibility mapping (QSM) was performed for marker localization. QSM-derived marker positions were compared to those from CT. The bulk density assignment technique for sCT generation was adopted. The magnitude GRE images were segmented into muscle, bone, fat, and air using a combination of unsupervised intensity-based classification of soft tissue and convolutional neural networks (CNN) for bone segmentation.Results.All implanted markers were visualized and accurately identified (average error: 0.7 ± 0.5 mm). QSM generated distinctive contrast for hemorrhage, calcifications, and gold fiducial markers. The estimated susceptibility/HU values on QSM/CT for gold and calcifications were 31.5 ± 2.9 ppm/1220 ± 100 HU and 14.6 ± 0.9 ppm/440 ± 100 HU, respectively. The intensity-based soft tissue classification resulted in an average Dice score of 0.97 ± 0.02; bone segmentation using CNN resulted in an average Dice score of 0.93 ± 0.03.Conclusion.This work indicates the feasibility of simultaneous fiducial marker identification and sCT generation using a single MRI acquisition. Future works includes evaluation of the proposed method in a large cohort of patients with optimized acquisition parameters as well as dosimetric evaluations.

Absolute percentage of biopsied tissue positive for Gleason pattern 4 disease (APP4) appears predictive of disease control after high dose rate brachytherapy and external beam radiotherapy in intermediate risk prostate cancer.

BACKGROUND AND PURPOSE: To identify if, in intermediate risk prostate cancer (IR-PCa), the absolute percentage of biopsied tissue positive for pattern 4 disease (APP4) may be a predictor of outcome. MATERIALS AND METHODS: 411 patients with IR-PCa were retrospectively reviewed. APP4 was calculated based on biopsy reports. Multivariable competing risk analysis was then performed on optimized APP4 cutpoints to predict for biochemical failure (BF), androgen deprivation use for BF (ADT-BF) and development of metastases (MD). RESULTS: Median follow-up for the cohort was 5.2 (Inter Quartile Range: 2.9-6.6) years. Median baseline PSA was 7.3 (5.3-9.8) ng/mL. 234 (56.9%) patients had T1 and 177 (43.1%) had T2 disease. Median APP4 was 2.00 (0.75-7.50)%. 38 (9.3%) patients experienced BF. The optimal cutpoint of APP4 for BF was >3.3% with an area under the curve (AUC) of 0.66. 17 (4.1%) received ADT-BF. The ADT-BF cutpoint was >6.6% with an AUC of 0.72. Eight (2.0%) developed MD. The MD cutpoint was >17.5% with an AUC of 0.86. Using APP4 >3.3 vs ≤ 3.3, log-transformed baseline PSA ln(PSA) (HR 2.5, 1.1-6.1; p = 0.037) and APP4 (HR 2.3, 1.1-4.7; p = 0.031) predicted for BF. Using APP4 >6.6 vs ≤ 6.6, ln(PSA) (HR 4.2, 1.4-12.4; p = 0.010) and APP4 (HR 3.7, 1.4-10.0; p = 0.009) were predictive of ADT-BF. APP4 >17.5 vs ≤ 17.5 alone was predictive of MD (HR 25.7, 4.9-135.3; p < 0.001). CONCLUSION: APP4 cutpoints of >3.3%, >6.6% and >17.5% were strongly associated with increased risk of BF, ADT-BF and developing MD respectively. These findings may inform future practice when treating IR-PCa but require external validation.

Acute Upper Gastrointestinal Bleeding in a Tertiary Care Centre of Nepal.

INTRODUCTION: AUGIB is characterized by hematemesis or melena or both. Peptic ulcers and variceal bleed account for majority of cases. Use of proton pump inhibitors in current era is associated with a gradual reduction in burden of peptic ulcer disease. We conducted this study to look into the cause of AUGIB in our community. METHODS: We studied 100 patients in one year period who presented to us with hematemesis or melena. The study was conducted in department of Gastroenterology, Bir hospital, Kathmandu. We identified the culprit lesions by upper gastrointestinal endoscopy. RESULTS: The average age of patients with AUGIB was 51.6 years with 59 (59%) males. Duodenal ulcers are most common 29 (29%), followed by varices 23 (23%) and gastric ulcers 14 (14%). More than one lesion was identified in 38 (38%) patients. Patients with variceal bleed were more likely to present with hematemesis alone as compared to those with ulcer bleed (P=0.005). Variceal bleed patients presented earlier to the hospital (P=0.005), had lower MAP at presentation (P=0.0002), had lower hemoglobin level (P=0.0001) and higher serum creatinine level at presentation (P=0.001). Patients with variceal bleed were more likely to have consumed alcohol 20 (86.9%) and patients with ulcer bleed were more likely to be smokers 29 (67.4%) or consume tobacco 14 (32.5%) (P=0.006). CONCLUSIONS: Ulcer related bleeding is still the most common cause of AUGIB. Many patients with AUGIB have more than one lesions identified during upper gastrointestinal endoscopy.

Colorectal Cancer in Different Age Groups in a Tertiary Hospital in Nepal.

INTRODUCTION: Some studies have suggested that colorectal cancer at a younger age had distinct biological characteristics: different clinical presentations, more advanced stage at time of diagnosis and poorly differentiated carcinoma. The aim of the study is to analyze clinical and histopathological differences between younger (≤40 years of age) and older (>40 years of age) colorectal cancer patients. METHODS: A cross-sectional analysis was conducted amongst the colorectal cancer patients who visited Bir Hospital between July 2015 and April 2017. All colonoscopically diagnosed and histopathologically proven cases of colon cancer were included. Chi-square test and independent t - test was performed to analyze the difference between clinical presentations and histopathological findings among two groups of patients and P value of <0.05 was considered as significant. RESULTS: Thirty younger patients and thirty older patients were enrolled without any differences in gender proportion. There were no statistical differences between clinical presentation and histological grade and type in younger and older patients. The younger patients had more complaints of altered bowel habit (P <0.001) while older patients mostly presented with per rectal bleeding (P< 0.008). CONCLUSIONS: In this study, colorectal cancer at younger ages showed similar characteristics to those of older patients except altered bowel habit was more common in younger patients while per rectal bleeding was more common in older patients. Although colorectal cancer incidence increases with age, younger patients with altered bowel habits, weight loss, anemia and anorexia should also be given due medical attention and undergo evaluation promptly.

Efficacy of Prophylactic use of Ciprofloxacin and Metronidazole in Mild and Moderately Severe Acute Pancreatitis.

INTRODUCTION: There are new concepts and developments in the diagnosis and management of acute pancreatitis. Current evidence suggests that there is no role of prophylactic antibiotics use in acute pancreatitis. However, it is still a common practice to administer prophylactic antibiotics in a country like Nepal. So, we have conducted a study in mild and moderately severe acute pancreatitis to study the efficacy of prophylactic antibiotics. METHODS: A case control study was conducted among 76 patients comparing efficacy of prophylactic antibiotics versus no antibiotics in patients with mild and moderately severe acute pancreatitis. RESULTS: The two most common etiology of acute pancreatitis in AG and NAG were alcohol 21 (55.2%) vs. 24 (63.1%) and biliary 10 (26.3%) vs. 4 (10.5%) respectively. Pancreatic necrosis was seen in five (13.1 %) in AG and four (10.5%) in NAG. Four (10.5%) developed extra pancreatic complications in AG and five (13.1%) in NAG. There was one (2.6%) death in AG and no death in NAG. Abdominal pain improvement seen in AG vs. NAG was 3.2 days vs. 2.4 days (P=0.002). The hospital stay was 7.7±2.23 days in AG and 7.5±1.85 days in NAG (P=0.65). CONCLUSIONS: The routine use of prophylactic antibiotics for mild and moderately severe acute pancreatitis is not associated with improvement in meaningful clinical outcomes.

Pre-fracture individual characteristics associated with high total health care costs after hip fracture.

Older women with pre-fracture slow walk speed, high body mass index, and/or a high level of multimorbidity have significantly higher health care costs after hip fracture compared to those without those characteristics. Studies to investigate if targeted health care interventions for these individuals can reduce hip fracture costs are warranted. INTRODUCTION: The aim of this study is to estimate the associations of individual pre-fracture characteristics with total health care costs after hip fracture, using Study of Osteoporotic Fractures (SOF) cohort data linked to Medicare claims. METHODS: Our study population was 738 women age 70 and older enrolled in Medicare Fee for Service (FFS) who experienced an incident hip fracture between January 1, 1992 and December 31, 2009. We assessed pre-fracture individual characteristics at SOF study visits and estimated costs of hospitalizations, skilled nursing facility and inpatient rehabilitation stays, home health care visits, and outpatient utilization from Medicare FFS claims. We used generalized linear models to estimate the associations of predictor variables with total health care costs (2010 US dollars) after hip fracture. RESULTS: Median total health care costs for 1 year after hip fracture were $35,536 (inter-quartile range $24,830 to $50,903). Multivariable-adjusted total health care costs for 1 year after hip fracture were 14 % higher ($5256, 95 % CI $156 to $10,356) in those with walk speed <0.6 m/s compared to ≥1.0 m/s, 25 % higher ($9601, 95 % CI $3314 to $16,069) in those with body mass index ≥30 kg/m2 compared to 20 to 24.9 mg/kg2, and 21 % higher ($7936, 95 % CI $346 to $15,526) for those with seven or more compared to no comorbid medical conditions. CONCLUSIONS: Pre-fracture poor mobility, obesity, and multiple comorbidities are associated with higher total health care costs after hip fracture in older women. Studies to investigate if targeted health care interventions for these individuals can reduce the costs of hip fractures are warranted.

Nepalese Homebrewed Alcoholic Beverages: Types, Ingredients, and Ethanol Concentration from a Nation Wide Survey.

BACKGROUND: Despite the enormous public health problems related to traditional alcohol consumption practice in Nepal, this area has been ignored and the information at the national level is limited. Thus this study is designed to explore the readily available commonly practiced Nepalese homebrewed alcoholic beverages, the ingredients used and alcohol strength (ethanol concentration). METHODS: This study was carried out as a part of ongoing household survey on "Alcohol consumption practice among married women of reproductive age in Nepal". A total of 284 homebrewed alcoholic beverage (distilled 175, non-distilled:109) samples were collected from the 16 survey districts of Nepal during the period of April to August, 2013. Ethanol percentage was tested in research lab by using standard procedure. RESULTS: Readily available homebrewed alcoholic beverages in practice were mainly of two types "Distilled" (local Raksi) and "Non-distilled" (Jand, Chhyang, Tumba). Rice, wheat, barley, millet, maize, fruits, and pure sugar were the commonly used ingredients to prepare alcohol. Ethanol concentration in homebrewed alcohol was 14.0% (IQR: 10.0-19.0) ranging from 3% to 40% for distilled, and 5.2% (IQR: 3.5-9.8) ranging from 1% to 18.9% for nondistilled. A significant difference (P<0.05) was found in alcohol strength by residence, development regions, types of alcohol, and the ingredients used. CONCLUSIONS: The median concentration of ethanol in readily available home brewed alcoholic beverages in Nepal was more than the strength of factory produced beer. The alcohol strength varies across their types, ingredients used, residence and regions.

Analysis of Health Facility Based Perinatal Verbal Autopsy of Electoral Constituency 2 of Arghakhanchi District, Nepal.

BACKGROUND: Verbal autopsy is a method to diagnose possible cause of death by analyzing factors associated with death through detailed questioning. This study is a part of the operational research program in electoral constituency no. 2 (EC 2) of Arghakhanchi district by MIRA and HealthRight International. METHODS: Two day essential newborn care training followed by one day perinatal verbal autopsy training and later one day refresher verbal autopsy training was given for health staff of EC 2 of Arghakhanchi district in two groups. Stillbirths of >22wks or > 500 gms and Early neonatal deaths (newborns died within7 days of life) were included in this study. The Nepal Government approved verbal autopsy forms were used for performing autopsies. Perinatal deaths were classified according to Wigglesworth's Classification. Causes of Perinatal deaths were analyzed. Data were analyzed in the form of frequencies and tabulation in SPSS 16 . RESULTS: There were 41 cases of perinatal deaths (PND) were identified. Among them, 37 PNDs were from Arghakhanchi district hospital, 2 PNDs from Thada PHC, and one PND each from Subarnakhal and Pokharathok HPs. Among the 41 PNDs, 26 were stillbirths (SB) and 15 were early neonatal deaths (ENND). The perinatal mortality rate (PMR) of Arghakhanchi district hospital was 32.2 per 1,000 births and neonatal mortality rate (NMR) was 9.8 per 1,000 live births. Out of 26 stillbirths, 54% (14) were fresh SBs and 46% (12) were macerated stillbirths. The most common cause of stillbirth was obstetric complications (47%) where as birth asphyxia (53%) was the commonest cause of ENND. According to Wigglesworth's classification of perinatal deaths, Group IV (40%) was the commonest cause in the health facilities. CONCLUSIONS: Obstetric complication was the commonest cause of stillbirth and birth asphyxia was the commonest cause of early neonatal death. This study highlighted the need for regular antenatal check-ups and proper intrapartum fetal monitoring with timely and appropriate intervention to reduce the incidence of stillbirths and intrauterine asphyxia.

Human Immunodeficiency Virus Related Knowledge, Risk Perception and Practices among Married Women of Reproductive Age: A Cross-sectional Study from Mid-western Development Region, Nepal.

BACKGROUND: Despite the implementation of anti-human immunodeficiency virus (HIV) interventions, it has continued to spread from high risk to the low risk population population with the devastating social, economic and health consequences. AIM: The aim of the following study is to identify HIV related knowledge, risk perceptions and practices among married women of reproductive age (MWRA) in Mid-Western Development Region, Nepal. SUBJECTS AND METHODS: A community based, cross-sectional study was conducted during May-December 2010 among 618 MWRA in Mid-western Development Region, Nepal. Multistage random sampling was followed wherein four districts, representing each ecological zone were selected in the first stage. Nine Village Developments Committees with the total 81 clusters were selected in the second and third stages. Finally, 7/8 participants/cluster were selected randomly. Household interviews were conducted using pretested structured questionnaire. Data were analyzed by SPSS 16.0 (SPSS Inc. Chicago, IL, USA). Percentages, mean, Chi-square value and odds ratio were calculated. RESULTS: Nearly three quarters (434/618) of all participants had heard about the HIV. Radio was the most common source of the information 73.3% (318/434) amongst all sources. Unsafe sex 55.3% (240/434), infected blood transfusion 33.2% (144/434), needle sharing 24.7% (107/434) and mother to child transmission 4.1% (18/434) were reported modes of HIV transmission. Condom use during extramarital sex 51.8% (225/434), use of sterilized syringes 24.2% (105/434), restricting sex within couple 22.6% (98/434) and blood safety 20.3% (88/434) were reported HIV preventive measures. Extramarital sex, needle sharing and sharing of the razors/blades were perceived to be the risk behaviors. About 4.9% (30/618) had extramarital sexual experience amongst all participants. Only a quarter (8/30) of those who had extramarital sex used condom regularly. CONCLUSIONS: Almost half of the MWRA had limited awareness on HIV transmission and preventive measures. There was poor HIV preventive practices; indicating knowledge-behavior gaps. Awareness raising and behavior change interventions are recommended.

Evaluation of normalized metal artifact reduction (NMAR) in kVCT using MVCT prior images for radiotherapy treatment planning.

PURPOSE: To evaluate the metal artifacts in kilovoltage computed tomography (kVCT) images that are corrected using a normalized metal artifact reduction (NMAR) method with megavoltage CT (MVCT) prior images. METHODS: Tissue characterization phantoms containing bilateral steel inserts are used in all experiments. Two MVCT images, one without any metal artifact corrections and the other corrected using a modified iterative maximum likelihood polychromatic algorithm for CT (IMPACT) are translated to pseudo-kVCT images. These are then used as prior images without tissue classification in an NMAR technique for correcting the experimental kVCT image. The IMPACT method in MVCT included an additional model for the pair∕triplet production process and the energy dependent response of the MVCT detectors. An experimental kVCT image, without the metal inserts and reconstructed using the filtered back projection (FBP) method, is artificially patched with the known steel inserts to get a reference image. The regular NMAR image containing the steel inserts that uses tissue classified kVCT prior and the NMAR images reconstructed using MVCT priors are compared with the reference image for metal artifact reduction. The Eclipse treatment planning system is used to calculate radiotherapy dose distributions on the corrected images and on the reference image using the Anisotropic Analytical Algorithm with 6 MV parallel opposed 5×10 cm2 fields passing through the bilateral steel inserts, and the results are compared. Gafchromic film is used to measure the actual dose delivered in a plane perpendicular to the beams at the isocenter. RESULTS: The streaking and shading in the NMAR image using tissue classifications are significantly reduced. However, the structures, including metal, are deformed. Some uniform regions appear to have eroded from one side. There is a large variation of attenuation values inside the metal inserts. Similar results are seen in commercially corrected image. Use of MVCT prior images without tissue classification in NMAR significantly reduces these problems. The radiation dose calculated on the reference image is close to the dose measured using the film. Compared to the reference image, the calculated dose difference in the conventional NMAR image, the corrected images using uncorrected MVCT image, and IMPACT corrected MVCT image as priors is ∼15.5%, ∼5%, and ∼2.7%, respectively, at the isocenter. CONCLUSIONS: The deformation and erosion of the structures present in regular NMAR corrected images can be largely reduced by using MVCT priors without tissue segmentation. The attenuation value of metal being incorrect, large dose differences relative to the true value can result when using the conventional NMAR image. This difference can be significantly reduced if MVCT images are used as priors. Reduced tissue deformation, better tissue visualization, and correct information about the electron density of the tissues and metals in the artifact corrected images could help delineate the structures better, as well as calculate radiation dose more correctly, thus enhancing the quality of the radiotherapy treatment planning.

Magnitude and consequences of misclassification of incident hip fractures in large cohort studies: the Study of Osteoporotic Fractures and Medicare claims data.

UNLABELLED: In the Study of Osteoporotic Fractures (SOF), 18.5 % of incident hip fractures identified in Medicare Fee-for-Service claims data were not reported to or confirmed by the cohort. Cognitive impairment was a modest risk factor for false-negative hip fracture ascertainment via self-report. INTRODUCTION: Prospective cohort studies of fractures that rely on participant self-report to be the initial signal of an incident fracture could be prone to bias if a significant proportion of fractures are not self-reported. METHODS: We used data from the SOF merged with Medicare Fee-for-Service claims data to estimate the proportion of participants who had an incident hip fracture identified in Medicare claims that was either not self-reported or confirmed (by review of radiographic reports) in SOF. RESULTS: Between 1/1/1991 and 12/31/2007, 647 SOF participants had a hip fracture identified in Medicare claims, but 120 (18.5 %) were either not reported to or confirmed by the cohort. False-negative hip fracture ascertainment was associated with a reduced modified Mini-Mental State Exam (MMSE) score (odds ratio 1.31 per SD decrease, 95 % C.I. 1.06-1.63). Point estimates of associations of predictors of incident hip fracture were changed minimally when the misclassification of incident hip fracture status was corrected with use of claims data. CONCLUSIONS: A substantial minority of incident hip fractures were not reported to or confirmed in the SOF. Cognitive impairment was modestly associated with false-negative hip fracture ascertainment. While there was no evidence to suggest that misclassification of incident hip fracture status resulted in biased associations of potential predictors with hip fracture in this study, false-negative incident fracture ascertainment in smaller cohort studies with limited power may increase the risk of type 2 error (not finding significant associations of predictors with incident fractures).

Evaluation of metal artifacts in MVCT systems using a model based correction method.

PURPOSE: To evaluate the performance of a model based image reconstruction method in reducing metal artifacts in the megavoltage computed tomography (MVCT) images of a phantom representing bilateral hip prostheses and to compare with the filtered-backprojection (FBP) technique. METHODS: An iterative maximum likelihood polychromatic algorithm for CT (IMPACT) is used with an additional model for the pair∕triplet production process and the energy dependent response of the detectors. The beam spectra for an in-house bench-top and TomoTherapy™ MVCTs are modeled for use in IMPACT. The empirical energy dependent response of detectors is calculated using a constrained optimization technique that predicts the measured attenuation of the beam by various thicknesses (0-24 cm) of solid water slabs. A cylindrical (19.1 cm diameter) plexiglass phantom containing various cylindrical inserts of relative electron densities 0.295-1.695 positioned between two steel rods (2.7 cm diameter) is scanned in the bench-top MVCT that utilizes the bremsstrahlung radiation from a 6 MeV electron beam passed through 4 cm solid water on the Varian Clinac 2300C and in the imaging beam of the TomoTherapy™ MVCT. The FBP technique in bench-top MVCT reconstructs images from raw signal normalized to air scan and corrected for beam hardening using a uniform plexiglass cylinder (20 cm diameter). The IMPACT starts with a FBP reconstructed seed image and reconstructs the final image in 150 iterations. RESULTS: In both MVCTs, FBP produces visible dark shading in the image connecting the steel rods. In the IMPACT reconstructed images this shading is nearly removed and the uniform background is restored. The average attenuation coefficients of the inserts and the background are very close to the corresponding values in the absence of the steel inserts. In the FBP images of the bench-top MVCT, the shading causes 4%-9.5% underestimation of electron density at the central inserts with an average of (6.3 ± 1.8)% for the range of electron densities studied. In the uniform plexiglass background, the shadow creates 0.8%-4.7% underestimation of electron density with an average of (2.9 ± 1.2)%. In the corresponding IMPACT images, the underestimation in the shaded plexiglass background is 0.3%-1.8% with an average of (0.9 ± 0.5)% and 1.4%-6.8% with an average of (2.8 ± 2.7)% in the central insert region. In the FBP images of the TomoTherapy™ MVCT, this shading creates 2.6%-6.7% underestimation of electron density with an average of (3.7 ± 1.4)% at the central inserts and 5.9%-7.2% underestimation in the background with an average of (6.4 ± 0.5)%. In the IMPACT images, the uniform background between the steel rods is restored with 0.3%-1.0% underestimation of electron density with an average of (0.7 ± 0.3)%. The corresponding underestimation at the central inserts of the IMPACT images is -0.4%-0.1% with an average of (-0.1 ± 0.2)%. CONCLUSIONS: The shading metal artifact has been nearly removed in MVCT images using the IMPACT algorithm with the accurate geometry of the system, proper modeling of energy dependent response of detectors, and all relevant photon interaction processes. This results less than 1% difference in electron density in the background plexiglass and less than 3% averaged over the range of electron densities investigated.

SU-E-J-17: Evaluation of Metal Artifact Reduction in MVCTs Using a Model Based Image Reconstruction Method.

PURPOSE: To evaluate the performance of a model based image reconstruction in reducing metal artifacts in MVCT systems, and to compare with filtered-back projection (FBP) technique. METHODS: Iterative maximum likelihood polychromatic algorithm for CT (IMPACT) is used with pair/triplet production process and the energy dependent response of detectors. The beam spectra for in-house bench-top and TomotherapyTM MVCT are modelled for use in IMPACT. The energy dependent gain of detectors is calculated using a constrained optimization technique and measured attenuation produced by 0 - 24 cm thick solid water slabs. A cylindrical (19 cm diameter) plexiglass phantom containing various central cylindrical inserts (relative electron density of 0.28-1.69) between two steel rods (2 cm diameter) is scanned in the bench-top [the bremsstrahlung radiation from 6 MeV electron beam passed through 4 cm solid water on the Varian Clinac 2300C] and TomotherapyTM MVCTs. The FBP reconstructs images from raw signal normalised to air scan and corrected for beam hardening using a uniform plexi-glass cylinder (20 cm diameter). IMPACT starts with FBP reconstructed seed image and reconstructs final image at 1.25 MeV in 150 iterations. RESULTS: FBP produces a visible dark shading in the image between two steel rods that becomes darker with higher density central insert causing 5-8 % underestimation of electron density compared to the case without the steel rods. In the IMPACT image the dark shading connecting the steel rods is nearly removed and the uniform background restored. The average attenuation coefficients of the inserts and the background are very close to the corresponding theoretical values at 1.25 MeV. CONCLUSIONS: The dark shading metal artifact due to beam hardening can be removed in MVCT using the iterative reconstruction algorithm such as IMPACT. However, the accurate modelling of detectors' energy dependent response and physical processes are crucial for successful implementation. Funding support for the research is obtained from "Vanier Canada Graduate Scholarship" and "Canadian Institute of Health Research".

25-Hydroxyvitamin D levels and cognitive performance and decline in elderly men.

OBJECTIVE: To test the hypothesis that lower 25-hydroxyvitamin D [25(OH)D] levels are associated with a greater likelihood of cognitive impairment and risk of cognitive decline. METHODS: We measured 25(OH)D and assessed cognitive function using the Modified Mini-Mental State Examination (3MS) and Trail Making Test Part B (Trails B) in a cohort of 1,604 men enrolled in the Osteoporotic Fractures in Men Study and followed them for an average of 4.6 years for changes in cognitive function. RESULTS: In a model adjusted for age, season, and site, men with lower 25(OH)D levels seemed to have a higher odds of cognitive impairment, but the test for trend did not reach significance (impairment by 3MS: odds ratio [OR] 1.84, 95% confidence interval [CI] 0.81-4.19 for quartile [Q] 1; 1.41, 0.61-3.28 for Q2; and 1.18, 0.50-2.81 for Q3, compared with Q4 [referent group; p trend = 0.12]; and impairment by Trails B: OR 1.66, 95% CI 0.98-2.82 for Q1; 0.96, 0.54-1.69 for Q2; and 1.30, 0.76-2.22 for Q3, compared with Q4 [p trend = 0.12]). Adjustment for age and education further attenuated the relationships. There was a trend for an independent association between lower 25(OH)D levels and odds of cognitive decline by 3MS performance (multivariable OR 1.41, 95% CI 0.89-2.23 for Q1; 1.28, 0.84-1.95 for Q2; and 1.06, 0.70-1.62 for Q3, compared with Q4 [p = 0.10]), but no association with cognitive decline by Trails B. CONCLUSION: We found little evidence of independent associations between lower 25-hydroxyvitamin D level and baseline global and executive cognitive function or incident cognitive decline.

Renal function and rate of hip bone loss in older men: the Osteoporotic Fractures in Men Study.

UNLABELLED: Older men with reduced renal function are at increased risk of hip bone loss. Given the robustness of this association across different measures and a growing body of literature, our findings indicate that clinicians should take into account renal function when evaluating older men for osteoporosis risk and bone loss. Future randomized controlled trials should test whether interventions in this high risk population are effective in preventing bone loss and decreasing fracture incidence. INTRODUCTION: Studies examining whether kidney impairment, not requiring dialysis, is associated with osteoporosis have reported conflicting results. METHODS: We tested the hypothesis that reduced renal function in older men as manifested by higher concentrations of cystatin C or lower levels of estimated glomerular filtration rate (eGFR) is associated with higher rates of bone loss. We measured serum cystatin C, serum creatinine and total hip bone mineral density (BMD) at baseline in a cohort of 404 older men enrolled in the Osteoporotic Fractures in Men (MrOS) Study and followed them prospectively for an average of 4.4 years for changes in BMD. Associations between renal function and change in hip BMD were examined using linear regression. RESULTS: In multivariable analysis, the mean rate of decline in total hip BMD showed an increase in magnitude with higher cystatin C concentration (mean annualized percent change -0.29, -0.34, -0.37 and -0.65% for quartiles 1 to 4; p for trend=0.004). Similarly, adjusted rates of hip bone loss were higher among men with lower eGFR as defined by the modification of diet in renal disease formula (mean annualized percent change -0.58, -0.39, -0.37, and -0.31 for quartiles 1 to 4; p for trend=0.02), but not among men with lower eGFR as defined by the Cockcroft-Gault formula (mean annualized percent change -0.47, -0.44, -0.31 and -0.43 for quartiles 1 to 4; p for trend=0.48). CONCLUSIONS: Older men with reduced renal function are at increased risk of hip bone loss. Our findings suggest that health care providers should consider renal function when evaluating older men for risk factors for bone loss and osteoporosis.

Clinical profile and antibiotics response in typhoid fever.

OBJECTIVE: The objective of this study is to evaluate the clinical profile and drug response in typhoid fever. METHODS: This is a retrospective analysis of paediatric patients suffering from typhoid fever who were admitted at Kathmandu Medical College Teaching Hospital, Sinamangal during the period of two years and nine months. RESULTS: Total numbers of 100 cases of typhoid were studied. Diagnosis of Typhoid fever was based on clinical features, Widal test and blood culture. The sensitivity pattern of drugs in blood culture was recorded. The mode of presentation, treatment history, laboratory investigations reports, antibiotics administered and response to therapy were recorded. CONCLUSION: Quinolone is still the highly sensitive drug and most widely used for Salmonella typhi. Because of the indiscriminate use of these drugs, resistant to ciprofloxacin has been quite high and the duration of the defeverscence period has also been prolonged. But Ofloxacin is still showed highly effective and widely used with good response.