Higher Effective Dose Research Articles

Differential contribution of Gαi/o subunits in the response to food deprivation

Behavioral responses to food deprivation are a fundamental aspect of nervous system function in all animals. Several signaling molecules in the mammalian brain act through G proteins of the Gi/o family to mediate response to food restriction. The present study examined whether food intake changes under a condition of little stimulation to eat, such as that elicited by 4h of food deprivation, was altered by Gi/o isoform silencing induced by intracerebroventricular (i.c.v.) administration of antisense oligodeoxynucleotides (aODN) against the α subunit of Gi1, Gi2, Gi3, Go1 and Go2. The effect of aODN pretreatments on food intake was evaluated 15, 30, 45, and 60min after food re-administration. Selective effects were noted on food intake with anti-Giα1 (3.12–25nmol), Giα3 (1.56–12.5nmol) and Goα2 (3.12–25nmol) aODN exerting increase in food consumption, while anti-Giα2 (3.12–25nmol) and Goα1 (3.12–25nmol) aODN exerting decrease in food consumption. We observed the effect of the α-subunit silencing on food consumption as soon as 15min after food readministration, that was still significant after 60min. At the highest effective doses, different for each anti-Gαi/o subunit, any treatment did not impair motor coordination, nor modified spontaneous mobility and exploratory activity. These results indicate a relevant distinction between Gαi/o subunits on feeding behavior, and suggest that Gi/o proteins are critical for the integrative modulation of normal feeding behavior. Changes in Gi/o protein activity may be associated with modifications of feeding.

Magnolol derivative 002C-3 protects brain against ischemia–reperfusion injury via inhibiting apoptosis and autophagy

Neuroprotective agents can rescue ischemic penumbra in cerebral ischemia. However, the clinically effective neuroprotective agents for cerebral ischemic injury remain deficient in clinic so far. This study was undertaken to investigate the brain protective effect of 002C-3 and its potential mechanisms in rats, and its preliminary toxicity in mice. A transient middle cerebral artery occlusion (tMCAO) model in rats was used to evaluate its effect and mechanism, a dose limited experiment was used to evaluate its preliminary toxicity. 10–50μg/kg of 002C-3 (single iv bolus after reperfusion) significantly reduced neurological scores, infarct volumes and brain water contents, and the effect was more potent than that of magnolol under the same mole dose; 50μg/kg of 002C-3 significantly decreased the number of TUNEL-positive cells, reduced the activity of caspase-3, and lowered the autophagy-related proteins LC3-II and Beclin-1 level in I-R cerebral tissue. At 1000 times’ dose of high effective dose (ip) 002C-3 failed to show evident toxicity in mice, and the mean body weight of mice treated with 002C-3 was almost the same as that of the vehicle control, but magnolol caused evident toxicity and death. In conclusion, 002C-3 has significant protective effect against cerebral ischemia–reperfusion injury; the effect is more potent than magnolol; this effect is maybe associated with its inhibition of both apoptosis and autophagy; its toxicity is greatly reduced compared to magnolol. These results provided data for its further research and development.

Radiation Exposure due to CT of the Scaphoid in Daily Practice

Study background: The aim of this study was to measure radiation exposure including scatter radiation, resulting from CT of the scaphoid in different settings as used in daily practice and to calculate the effective dose (ED) using a wrist phantom. Methods: The radiation exposure was quantified for five different CT protocols, all used in daily practice for the scaphoid CT. Two protocols concerned a CT of the scaphoid with a plaster cast of the hand and three protocols without. For all protocols the Computed Tomographic Dose Index weighted (CTDIw), the scatter dose to the brain and scatter dose to the torso were derived from the CT and measured externally with the Piranha dose meter. Results: The average CTDIw was 2.18 mGy. The average scatter to the brain and torso was 0.011 mSv. The average estimated ED was 0.02 mSv (range 0.02 to 0.04) of which 0.0008 mSv (range 0.0003 to 0.0012) was due to the scatter radiation. The two CT protocols of the scaphoid performed with a plaster cast resulted in a 90% higher ED, although the power of the study was too low to demonstrate this statistically. Conclusion: The CT protocols used for scaphoid analyses in a plaster cast immobilized hand may result in higher radiation exposure than without plaster cast. We therefore recommend, whenever possible, performing CT of the hand and wrist without a plaster cast.

Radiation exposure from diagnostic imaging in young patients with testicular cancer.

Risks associated with high cumulative effective dose (CED) from radiation are greater when imaging is performed on younger patients. Testicular cancer affects young patients and has a good prognosis. Regular imaging is standard for follow-up. This study quantifies CED from diagnostic imaging in these patients. Radiological imaging of patients aged 18-39 years, diagnosed with testicular cancer between 2001 and 2011 in two tertiary care centres was examined. Age at diagnosis, cancer type, dose-length product (DLP), imaging type, and frequency were recorded. CED was calculated from DLP using conversion factors. Statistical analysis was performed with SPSS. In total, 120 patients with a mean age of 30.7 ± 5.2 years at diagnosis had 1,410 radiological investigations. Median (IQR) surveillance was 4.37 years (2.0-5.5). Median (IQR) CED was 125.1 mSv (81.3-177.5). Computed tomography accounted for 65.3 % of imaging studies and 98.3 % of CED. We found that 77.5 % (93/120) of patients received high CED (>75 mSv). Surveillance time was associated with high CED (OR 2.1, CI 1.5-2.8). Survivors of testicular cancer frequently receive high CED from diagnostic imaging, mainly CT. Dose management software for accurate real-time monitoring of CED and low-dose CT protocols with maintained image quality should be used by specialist centres for surveillance imaging. • CT accounted for 98.3 % of CED in patients with testicular cancer. • Median CED in patients with testicular cancer was 125.1 mSv • High CED (>75 mSv) was observed in 77.5 % (93/120) of patients. • Dose tracking and development of low-dose CT protocols are recommended.

Effect of Severe Hypoalbuminemia on Myelosuppression and Other Toxicities of High Dose Melphalan and Autologous Stem Cell Transplantation in AL Amyloidosis Patients

Background: Treatment of AL amyloidosis with high dose intravenous melphalan followed by autologous stem cell transplant (HDM/SCT) is effective in inducing hematologic and clinical remissions associated with prolonged survival. The major toxicities are myelosuppression and GI side effects. Studies have shown that ~75% of melphalan in the blood is bound to plasma proteins, with ~25% free. We hypothesized that AL patients with severe nephrotic syndrome and profound hypoalbuminemia might have a higher fraction of free melphalan, a higher effective dose, and greater toxicity of treatment.Methods: Patients with AL amyloidosis and severe hypoalbuminemia, defined as serum albumin level of < 2 g/dL, treated from 2011 to 2013, were studied retrospectively. The stem cell transplant database was queried for dose of HDM, treatment-related complications, and days of neutrophil and platelet engraftment after SCT.Results: Of 71 patients with AL amyloidosis who underwent HDM/SCT between Jan 2011 and Dec 2013, 12 patients had severe hypoalbuminemia. Of these, 5 received full HDM at 200 mg/m2 and 7 received modified HDM at 140 mg/m2. All patients received GCSF mobilized peripheral blood stem cells following HDM, with a median stem cell dose of CD34+ cells 8.1 x 106/kg (range, 4.0 to 12.2). The median time to engraftment of neutrophils was 11 days, and not statistically different based upon melphalan dose. The median time to platelet engraftment was 13 days, and also did not differ significantly by dose. These times were similar to controls without severe hypoalbuminemia. Grade 4 toxicities were observed in 2 of 7 patients with modified HDM/SCT and 1 of 5 patients with full HDM/SCT.Conclusions: These data suggest that patients with severe hypoalbuminemia do not have more prolonged myelosuppression or increased non-hematologic toxicities compared to other patients. In this retrospective study, we did not measure free melphalan concentrations in the blood. However, these data suggest that patients with severe hypoalbuminemia do not require adjustment of melphalan dosing. DisclosuresNo relevant conflicts of interest to declare.

Factors affecting dispersion of radionuclides in north western coast of Mediterranean Sea, Egypt

This study aims to analyze the principal factors affecting the interaction of 137Cs, 60Co and 89Sr with coastal sediments and their importance for migration of these ions in surface water. The second goal is to assess the acceptability of radiological consequences of proposed routine discharges of nuclear installations for radioactive materials into surface water as well as to confirm the suitability of the site to select and to establish limits for radioactive discharge into water. Uptake of the investigated ions by Mediterranean Sea bottom sediment samples have been studied as a function of liquid to solid ratio (V/m) and contact time using batch technique. The suspended sediment concentration, different discharge rates of radionuclides and the distance between the source point in the sea and the beach were investigated. The obtained results show that Kd of Cs+, Co2+ and Sr2+is 20, 32 and 10 l/g, respectively. The lowest effective dose is for 89Sr, while the highest effective dose is for 137Cs, at the same distances. A mathematical model for the migration of the investigated isotopes in surface water was constructed to predict the concentration of these ions for both different distances and time periods.

Using computed tomography colonography in patients at high risk of colorectal cancer – a prospective study in a university hospital in South America

OBJECTIVES:The purpose of our study was to report the results of the implementation of computed tomography colonography in a university hospital setting serving a Brazilian population at high risk of colorectal cancer.METHODS:After creating a computed tomography colonography service in our institution, 85 patients at high risk of colorectal cancer underwent computed tomography colonography followed by a same-day optical colonoscopy from September 2010 to May 2012. The overall accuracy of computed tomography colonography in the detection of lesions ≥6 mm was compared to that of optical colonoscopy (direct comparison). All colonic segments were evaluated using quality imaging (amount of liquid and solid residual feces and luminal distension). To assess patient acceptance and preference, a questionnaire was completed before and after the computed tomography colonography and optical colonoscopy. Fisher's exact test was used to measure the correlations between colonic distension, discomfort during the exam, exam preference and interpretation confidence.RESULTS:Thirteen carcinomas and twenty-two lesions ≥6 mm were characterized. The sensitivity, specificity and accuracy of computed tomography colonography were 100%, 98.2% and 98.6%, respectively. Computed tomography colonography was the preferred method of investigation for 85% of patients. The preparation was reported to cause only mild discomfort for 97.6% of patients. According to the questionnaires, there was no significant relationship between colonic distension and discomfort (p>0.05). Most patients (89%) achieved excellent bowel preparation. There was a statistically significant correlation between the confidence perceived in reading the computed tomography colonography and the quality of the preparation in each colonic segment (p≤0.001). The average effective radiation dose per exam was 7.8 mSv.CONCLUSION:It was possible to institute an efficient computed tomography colonography service at a university hospital that primarily assists patients from the public health system, with high accuracy, good acceptance and effective radiation doses. Our results seem to be comparable to other centers of excellence and fall within acceptable published guidelines, showing that a successful computed tomography colonography program can be reproduced in a South American population screened in a university hospital.

Abstract 3233: Targeting system xc- in breast cancer cells: Development of novel therapeutics

Abstract Cancer-induced bone pain is a major palliative condition suffered by many afflicted with breast cancer. With current anti-cancer therapeutics prolonging the lives of these patients without eradicating the disease itself, quality of life concerns predominate patient care. A potential mechanism implicates glutamate, and specifically the glutamate-cystine antiporter called system xc-. Due to the accelerated metabolism of cancer cells, this transporter (xCT) is upregulated to supply the cell with adequate cysteine for detoxification of reactive oxygen species via glutathione (GSH) synthesis. We conducted a high-throughput screening of 30,000 compounds to identify novel small molecules capable of reducing glutamate release from MDA-MB-231 cells. Glutamate release was quantified using Amplex Red fluorometric assay after 48 hours incubation with test compounds. Compounds providing the greatest effect were: 4-[2-(Dipropylamino)ethyl]-1,2-benzenediol, SKF 38393, Capsazepine and SPB 05855. Follow-up entailed confirmation of screening results (i.e. inhibition of glutamate secretion) in a dose dependent manner (0-200uM). GSH content of treated cells was also analyzed as it's production is linked to xCT activity. Intracellular GSH levels were analyzed in cell lysates using DNTB. In addition, to further explore mode of action of these compounds, we cloned 2.6 kilobase pairs (-2329 to +278 bp) of the human xCT promoter region from genomic DNA isolated from MDA-MB-231 breast cancer cells. Four truncations were also generated by PCR. Full length and truncated clones were transferred into a luciferase reporter gene construct (PGL3-Basic). This acted as a tool to test whether any of these compounds inhibit glutamate release through transcriptional regulation of xCT. MDA-MB-231 cells were transiently co-transfected with the dual luciferase system and subsequently treated with compounds. Glutamate release data confirmed the results of most positive hits but revealed that SPB 05855 did not meet the original criteria, as it had no effect on inhibition of glutamate release when re-tested. Compound cytotoxicity was assessed using crystal violet staining and dose-response data indicated that a concentration of 50 µM was the highest effective dose that did not result in cytotoxicity for all confirmed compounds. GSH results indicate that only SKF 38393 reduces total GSH levels in a dose-dependent manner. Promoter activity revealed that, of the four compounds, only SKF 38393 significantly affected promoter activity resulting in a 30% reduction in luciferase production. These experiments indicate a series of potent compounds that inhibit glutamate release and have the potential for development into novel therapeutics aimed at the treatment of cancer-induced bone pain. Citation Format: Jennifer Fazzari, Hanxin Lin, Katja Linher-Melville, Gurmit Singh. Targeting system xc- in breast cancer cells: Development of novel therapeutics. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3233. doi:10.1158/1538-7445.AM2014-3233

КОНУСНО-ЛУЧЕВАЯ КОМПЬЮТЕРНАЯ ТОМОГРАФИЯ В ДЕТСКОЙ СТОМАТОЛОГИИ: обзор современной литературы

&lt;p&gt;The use of cone beam computed tomography (CBCT) in paediatric dentistry has been mentioned in numerous publications and case reports. The indications for the use of CBCT in paediatric dentistry, however, have not yet been properly addressed. On the other hand, the three basic principles of radiation protection (justification, limitation and optimisation) should suffice. A review of the current literature was used to assess the indications and contra-indications for the use of CBCT in paediatric dentistry. Paramount is the fact that CBCT generates a higher effective dose to the tissues than traditional dental radiographic exposures do. The effective radiation dose should not be underestimated, especially not in children, who are much more susceptible to stochastic biological effects. The thyroid gland in particular should be kept out of the primary beam as much as possible. As with any other radiographical technique, routine use of CBCT is not acceptable clinical practice. CBCT certainly has a place in paediatric dentistry, but its use must be justified on a patient case individual basis. &lt;/p&gt;

Modulation of gene expression in endothelial cells in response to high LET nickel ion irradiation.

Ionizing radiation can elicit harmful effects on the cardiovascular system at high doses. Endothelial cells are critical targets in radiation-induced cardiovascular damage. Astronauts performing a long-term deep space mission are exposed to consistently higher fluences of ionizing radiation that may accumulate to reach high effective doses. In addition, cosmic radiation contains high linear energy transfer (LET) radiation that is known to produce high values of relative biological effectiveness (RBE). The aim of this study was to broaden the understanding of the molecular response to high LET radiation by investigating the changes in gene expression in endothelial cells. For this purpose, a human endothelial cell line (EA.hy926) was irradiated with accelerated nickel ions (Ni) (LET, 183 keV/µm) at doses of 0.5, 2 and 5 Gy. DNA damage was measured 2 and 24 h following irradiation by γ-H2AX foci detection by fluorescence microscopy and gene expression changes were measured by microarrays at 8 and 24 h following irradiation. We found that exposure to accelerated nickel particles induced a persistent DNA damage response up to 24 h after treatment. This was accompanied by a downregulation in the expression of a multitude of genes involved in the regulation of the cell cycle and an upregulation in the expression of genes involved in cell cycle checkpoints. In addition, genes involved in DNA damage response, oxidative stress, apoptosis and cell-cell signaling (cytokines) were found to be upregulated. An in silico analysis of the involved genes suggested that the transcription factors, E2F and nuclear factor (NF)-κB, may be involved in these cellular responses.

Relationship of Laryngeal Botulinum Toxin Dosage to Patient Age, Vitality, and Socioeconomic Issues

Chemical denervation with botulinum toxin A is the current standard of treatment for spasmodic dysphonia, but dosage is determined individually after a titration period that can take months to years. The objective of this study was to determine if age, body mass index (BMI), overall health, and socioeconomic factors were associated with a patient's optimal dose of botulinum toxin. This retrospective chart review looked at 32 patients with stabilized doses of botulinum toxin. Age and BMI were obtained from patient charts, and overall health was assessed by the Short-Form 36 survey. Analysis showed that BMI was positively correlated with botulinum toxin dose (r=0.42, P=0.02). Overall health showed a positive but nonsignificant association with dose, but subgroup analysis found that adductor spasmodic dysphonia (ADSD) patients without tremor had a significant positive correlation between overall health and dose (r=0.50, P=0.04), whereas tremor-only and mixed dystonia showed a negative nonsignificant correlation. Age was found to have no significant association with dose. Although socioeconomic factors were found to impact the number and frequency of injections, they had no significant impact on the ultimate dosage. BMI and overall health are positively correlated with higher effective dose and may be useful in guiding clinicians during the titration period.

Evaluation of drug--drug interaction potential between DA-9801 and metformin

DA-9801, the mixture extract of Dioscorea rhizoma and Dioscorea nipponica Makino, is a new herbal drug currently being evaluated in a phase II clinical study for the treatment of diabetic peripheral neuropathy. To assess potential drug–drug interactions between DA-9801 and metformin, we investigated the in vitro inhibitory potency of DA-9801 on metformin uptake in HEK293 cells overexpressing organic cation transporter (OCT) 1 and 2. DA-9801 inhibited OCT1- and OCT2-mediated metformin uptake in a concentration dependent manner and IC50 values for OCT1 and OCT2 were 41.8 and 108.9 μg/ml, respectively. Dioscorea nipponica Makino extract showed an inhibitory effect on OCT1- and OCT2-mediated metformin uptake and IC50 values were 33.8 and 87.1 μg/ml, respectively, which were similar to IC50 values of DA-9801. However, Dioscorea rhizoma extract slightly inhibited OCT1- and OCT2-mediated metformin uptake. The results suggest that the inhibitory effect of DA-9801 on OCT1 and OCT2 was attributable to the Dioscorea nipponica Makino extract but not to the Dioscorea rhizoma extract. However, pharmacokinetic properties of metformin measured in rats were unchanged by the co-administration of oral or intravenous DA-9801. In conclusion, DA-9801 moderately inhibited transport activity of OCT1 and OCT2 but did not show significant in vivo drug–drug interaction potential with metformin at its highest effective dose in rats.

Patient Radiation Exposure in a Modern, Large-Volume, Pediatric Cardiac Catheterization Laboratory

Radiation exposure from pediatric cardiac catheterization may be substantial, although published estimates vary. We sought to report patient radiation dose across a range of diagnostic and interventional cases in a modern, high-volume pediatric catheterization laboratory. We retrospectively reviewed diagnostic and interventional cases performed in our pediatric catheterization laboratory from 1 April 2009 to 30 September 2011 for which radiation usage data were available as reported by the Artis Zee(®) (Siemens Medical Solutions) system. Electrophysiology cases were excluded. Radiation dose was quantified as air kerma dose (mGy) and dose-area product (DAP; μGy m(2)). The DAP was converted to an effective dose millisievert (mSv) using the Monte Carlo method. Radiation usage data were available from 2,265 diagnostic and interventional cases with an overall median air kerma dose of 135 mGy [interquartile range (IQR) 59-433], median DAP of 760 μGy m(2) (IQR 281-2,810), of which 75 % (IQR 59-90 %) was derived from fluoroscopy, and median effective dose of 6.2 mSv (IQR 2.7-14.1). Air kerma dose from a single camera >2,000 mGy occurred in 1.8 % of cases. Significant differences in all measures of radiation exposure existed based on procedural and interventional types (p = 0.0001), with interventional cases associated with the highest effective dose after adjusting for patient weight category (p < 0.001). Patient weight, age, fluoroscopy time, and proportional use of digital acquisition were independent predictors of exposure (p ≤ 0.001; R (2) = 0.59-0.64). In a modern, large-volume pediatric catheterization laboratory, the median effective dose is 6.2 mSv with a wide range of exposure based on patient- and procedure-specific factors. Radiation monitoring is an important component of a pediatric laboratory and further dose reduction strategies are warranted.

Ground water contamination with 238U, 234U, 235U, 226Ra and 210Pb from past uranium mining: cove wash, Arizona

The objectives of the study are to present a critical review of the (238)U, (234)U, (235)U, (226)Ra and (210)Pb levels in water samples from the EPA studies (U.S. EPA in Abandoned uranium mines and the Navajo Nation: Red Valley chapter screening assessment report. Region 9 Superfund Program, San Francisco, 2004, Abandoned uranium mines and the Navajo Nation: Northern aum region screening assessment report. Region 9 Superfund Program, San Francisco, 2006, Health and environmental impacts of uranium contamination, 5-year plan. Region 9 Superfund Program, San Franciso, 2008) and the dose assessment for the population due to ingestion of water containing (238)U and (234)U. The water quality data were taken from Sect. "Data analysis" of the published report, titled Abandoned Uranium Mines Project Arizona, New Mexico, Utah-Navajo Lands 1994-2000, Project Atlas. Total uranium concentration was above the maximum concentration level for drinking water (7.410-1 Bq/L) in 19 % of the water samples, while (238)U and (234)U concentrations were above in 14 and 17 % of the water samples, respectively. (226)Ra and (210)Pb concentrations in water samples were in the range of 3.7 × 10(-1) to 5.55 × 102 Bq/L and 1.11 to 4.33 × 102 Bq/L, respectively. For only two samples, the (226)Ra concentrations exceeded the MCL for total Ra for drinking water (0.185 Bq/L). However, the (210)Pb/(226)Ra ratios varied from 0.11 to 47.00, and ratios above 1.00 were observed in 71 % of the samples. Secular equilibrium of the natural uranium series was not observed in the data record for most of the water samples. Moreover, the (235)U/(total)U mass ratios ranged from 0.06 to 5.9 %, and the natural mass ratio of (235)U to (total)U (0.72 %) was observed in only 16 % of the water samples, ratios above or below the natural ratio could not be explained based on data reported by U.S. EPA. In addition, statistical evaluations showed no correlations among the distribution of the radionuclide concentrations in the majority of the water samples, indicating more than one source of contamination could contribute to the sampled sources. The effective doses due to ingestion of the minimum uranium concentrations in water samples exceed the average dose considering inhalation and ingestion of regular diet for other populations around the world (1 μSv/year). The maximum doses due to ingestion of (238)U or (234)U were above the international limit for effective dose for members of the public (1 mSv/year), except for inhabitants of two chapters. The highest effective dose was estimated for inhabitants of Cove, and it was almost 20 times the international limit for members of the public. These results indicate that ingestion of water from some of the sampled sources poses health risks.

Effective dose from chest tomosynthesis in children

Tomosynthesis (digital tomography) is a recently introduced low-dose alternative to CT in the evaluation of the lungs in patients with cystic fibrosis and pulmonary nodules. Previous studies have reported an adult effective dose of 0.12-0.13 mSv for chest tomosynthesis. The aim of this study was to determine the paediatric effective dose from the dose-area-product. During a 3-y period, 38 children with cystic fibrosis and 36 paediatric oncology patients were examined with chest tomosynthesis, totally 169 posteroanterior and 17 anteroposterior examinations (40 boys and 34 girls, mean age 13.7 y, range 7-20 y). Using recently reported paediatric chest tomosynthesis conversion factors (0.23-1.09 mSv Gy cm(-2)) corrected for sex, age and energy, the mean posteroanterior effective dose calculated was 0.17 mSv; using the proposed simplified conversion factors of 0.6 (8-10 y), 0.4 (11-14 y) and 0.3 mSv Gy cm(-2) (15-19 y), the mean posteroanterior effective dose calculated was 0.15 mSv. As the difference in the calculated effective dose was minor, it is recommendable to use the simplified conversion factors. Using the conversion factor for adult chest tomosynthesis (0.26 mSv Gy cm(-2)), the mean effective dose was 0.11 mSv. Anteroposterior exposures had considerably higher effective dose. By using conversion factors adapted for children, the calculated risks from radiologic procedures will be more accurate.

The ratio of ICRP103 to ICRP60 calculated effective doses from CT: Monte Carlo calculations with the ADELAIDE voxel paediatric model and comparisons with published values

The ADELAIDE voxel model of paediatric anatomy was used with the EGSnrc Monte Carlo code to compare effective dose from computed tomography (CT) calculated with both the ICRP103 and ICRP60 definitions which are different in their tissue weighting factors and in the included tissues. The new tissue weighting factors resulted in a lower effective dose for pelvis CT (than if calculated using ICRP60 tissue weighting factors), by 6.5% but higher effective doses for all other examinations. ICRP103 calculated effective dose for CT abdomen + pelvis was higher by 4.6%, for CT abdomen (by 9.5%), for CT chest + abdomen + pelvis (by 6%), for CT chest + abdomen (by 9.6%), for CT chest (by 10.1%) and for cardiac CT (by 11.5%). These values, along with published values of effective dose from CT that were calculated for both sets of tissue weighting factors were used to determine single values for the ratio ICRP103:ICRP60 calculated effective doses from CT, for seven CT examinations. The following values for ICRP103:ICRP60 are suggested for use to convert ICRP60 calculated effective dose to ICRP103 calculated effective dose for the following CT examinations: Pelvis CT, 0.75; for abdomen CT, abdomen + pelvis CT, chest + abdomen + pelvis CT, 1.00; for chest + abdomen CT, and for chest CT. 1.15; for cardiac CT 1.25.

Radiation from CT scans in paediatric trauma patients: Indications, effective dose, and impact on surgical decisions

ObjectivesThe purpose of this study was to determine the effective dose of radiation due to computed tomography (CT) scans in paediatric trauma patients at a level 1 Canadian paediatric trauma centre. We also explored the indications and actions taken as a result of these scans. Patients and methodsWe performed a retrospective review of paediatric trauma patients presenting to our centre from January 1, 2007 to December 31, 2008. All CT scans performed during the initial trauma resuscitation, hospital stay, and 6 months afterwards were included. Effective dose was calculated using the reported dose length product for each scan and conversion factors specific for body region and age of the patient. Results157 paediatric trauma patients were identified during the 2-year study period. Mean Injury Severity Score was 22.5 (range 12–75). 133 patients received at least one CT scan. The mean number of scans per patient was 2.6 (range 0–16). Most scans resulted in no further action (56%) or additional imaging (32%). A decision to perform a procedure (2%), surgery (8%), or withdrawal of life support (2%) was less common. The average dose per patient was 13.5mSv, which is 4.5 times the background radiation compared to the general population. CT head was the most commonly performed type of scan and was most likely to be repeated. CT body, defined as a scan of the chest, abdomen, and/or pelvis, was associated with the highest effective dose. ConclusionsCT is a significant source of radiation in paediatric trauma patients. Clinicians should carefully consider the indications for each scan, especially when performing non-resuscitation scans. There is a need for evidence-based treatment algorithms to assist clinicians in selecting appropriate imaging for patients with severe multisystem trauma.

Antimicrobial efficacy of liposome-encapsulated silver ions and tea tree oil against Pseudomonas aeruginosa ,Staphylococcus aureus and Candida albicans

The activity of alternative antimicrobial agents such as tea tree oil (TTO) and silver ions (Ag(+) ) with multiple target sites impedes the development of antibacterial resistance and might be useful in improving the current treatment strategies for various chronic wound infections. In this study, liposome-encapsulated TTO, Ag(+) and TTO plus Ag(+) were added to suspension cultures of Pseudomonas aeruginosa (Ps.aeruginosa), Staphylococcus aureus (Staph.aureus) and Candida albicans (C.albicans). Treatment of these cultures using the agents in combination at subminimal lethal concentrations resulted in an enhanced loss of viability compared to treatment with individual agents. The effective concentration, elimination time (to the limit of detection, LOD) and fractional lethal concentration index (FLCI) of liposomal agents in combination were as follows: Candida albicans: 0·05% v/v TTO:PVA30-70kDa : 8·9×10(-5) % w/v Ag(+) :PVA30-70kDa : 2·0h, FLCI=0·73 (indifferent), Staphylococcus aureus: 0·05% v/v TTO:PVA30-70kDa : 6·0×10(-4) % w/v Ag(+) :PVA30-70kDa : 1·5h, FLCI=0·38 (synergistic), Pseudomonas aeruginosa: 0·25% v/v TTO:PVA30-70kDa : 3·2×10(-4) % w/v Ag(+) :PVA30-70kDa : 30min, FLCI=0·33 (synergistic). These results show the potential for improving antimicrobial efficacy by delivering lower effective concentrations of alternative agents, via controlled release systems. NB All values denoted as %w/vAg(+) refer to the concentration of silver ions. In this study, we have shown that encapsulating silver (as the ion Ag(+) ) and tea tree oil (singly and in combination) in a controlled release liposomal carrier system can improve their antimicrobial efficacy as well as reduce the effective concentration required. These findings may impact on the problems of agent toxicity caused by the need for high effective doses or microbial resistance where long term application is required.

Acute toxicity profile in prostate cancer with conventional and hypofractionated treatment

PurposeTo compare the acute toxicities in radical treatment of prostate cancer between conventional schedule (C-ARM) with 78 Gy/39 fractions and hypofractionation conformal treatment (H-ARM) with 69 Gy/23 fractions.Methods and materialThis prospective double arm study consisted of 217 patients with prostate cancer, 112 in H-ARM and 105 in C-ARM arm. C-ARM received conventional six- field conformal radiotherapy with 78 Gy in 39 fractions while H-ARM received hypofractionation with 69 Gy in 23 fractions. Weekly assessment of acute reactions was done during treatment and with one, and 3 months using RTOG scale. Univariated analysis was performed to evaluate differences between the incidences of acute reaction in the treatment arms. Variables with p value less than 0.1 were included in the multivariated logistic regression.ResultsThere was no difference between H-ARM versus C-ARM for severity and incidence in genitourinary (GU) and gastrointestinal (GI) acute toxicity. During the treatment comparing H-ARM with C-ARM no differences was observed for GI toxicity (grade 0–3; H-ARM = 45.5%, 34%, 18.7% and 1.8% versus C-ARM = 47.6%, 35.2%, 17.2% and 0). For acute GU toxicity no difference was detected between H-ARM (grade 0–3; 22.3%, 54.5%, 18.7% and 4.5%) and C-ARM (grade 0–3; 25.8%, 53.3%, 17.1% and 3.8%).At the 3- months follow-up, persistent Grade > =2 acute GU and GI toxicity were 2.5% and 1.8% in H-ARM versus 5.7% and 3% in C-ARM (p > 0.05). In univariated and multivariated analyses, there was not any dosimetric predictor for GI and GU toxicity.ConclusionsOur data demonstrate that hypofractionated radiotherapy achieving high biological effective dose using conformal radiotherapy is feasible for prostate cancer, being well tolerated with minimal severe acute toxicity.

Inpatient radiation exposure in patients with spinal trauma

Context/objectiveRadiation exposure from medical imaging is an important patient safety consideration; however, patient exposure guidelines and information on cumulative inpatient exposure are lacking.Design/settingTrauma patients undergo numerous imaging studies, and spinal imaging confers a high effective dose; therefore, we examined cumulative effective radiation dose in patients hospitalized with spinal trauma. We hypothesized that people with spinal cord injury (SCI) would have higher exposures than those with spine fractures due to injury severity.Particpants/interventionsRetrospective data were compiled for all patients with spine injuries admitted to a level I trauma center over a 2-year period.Outcome measuresInjury severity score (ISS) and cumulative radiation exposure were then determined for these patients, including 406 patients with spinal fractures and 59 patients with SCI.ResultsCumulative effective dose was 45 millisieverts (mSv) in SCI patients, compared to 38 mSv in spinal fracture patients (P = 0.01). Exposure was higher in patients with an ISS over 16 (P = 0.001). Mean exposure in both groups far exceeded the European annual occupational exposure maximum of 20 mSv. More than one-third of patients with SCI exceeded the US occupational maximum of 50 mSv.ConclusionPatients with SCI had significantly higher radiation exposure and ISS than those with spine fracture, but the effective dose was globally high. Dose did not correlate with injury severity for patients with SCI. While the benefits of imaging are clear, radiation exposure does involve risk and we urge practitioners to consider cumulative exposure when ordering diagnostic tests.