Image movement of the Elekta EPID during gantry rotation: Effects on the verification of dose distributions.

PURPOSE: The use of Electronic Portal Imaging Devices (EPIDs) to acquire dosimetric information, especially for 3D-back-projection, has been increasingly extended. For a precise back-projection, the accurate knowledge of the movement characteristics of the EPID during gantry rotation is an essential requirement. METHODS AND MATERIAL: Measurements were conducted with different alignments of steel balls, which were mounted on the treatment table to avoid secondary effects such as the mechanical sag of gantry or jaws. The image movement of the EPID was determined by comparing the predicted projections of the phantoms with the EPID acquired image. Effects on dosimetric verifications were evaluated by γ-evaluation. RESULTS: The measurement results showed that the shift of the EPID image is larger in Y direction than in X direction. A maximum rotation of 0.3° and nodding of 2.4° of the detector was calculated. Changes in SDD were found up to 10mm. The angles of nodding are overall higher at discrete gantry angles in comparison to images detected for continuous rotation. Using these results we were able to correct the EPID images used for verification measurements. γ-evaluation revealed a significantly improved agreement between planned and measured EPID signal values. CONCLUSION: The measurement methods and algorithms introduced in this study are simple and comprehensive. Using these methods and algorithms we were able to quantify the major effects on geometrical and dosimetric characteristics. This allows the correction of EPID signal measurements for these effects related to the gantry angle, leading to an improved γ-evaluation for treatment plans.

Characteristics of e-cigarette users and their perceptions of the benefits, harms and risks of e-cigarette use: survey results from a convenience sample in Ottawa, Canada. / Caractéristiques des utilisateurs de cigarettes électroniques et leurs perceptions des avantages, des dangers et des risques de la cigarette électronique : résultats d'un sondage auprès d'un échantillon de commodité à Ottawa (Canada).

INTRODUCTION: Although e-cigarette use ("vaping") is increasing in Canada, few attempts have been made to describe e-cigarette users ("vapers"). In this context, we conducted a study in Ottawa, Canada, to describe e-cigarette users' perceptions of the benefits, harms and risks of e-cigarettes. We also collected information on why, how and where they use e-cigarettes as well as information on side effects. METHODS: A 24-item online survey was administered to individuals who purchased e-cigarettes or e-cigarette-related supplies at one of Ottawa's 17 e-cigarette shops. Descriptive analyses characterized respondents, and logistic regression models were fitted to evaluate the relationship between respondents' characteristics and their perception of e-cigarette harms. RESULTS: The mean age of the 242 respondents was 38.1 years (range: 16-70 years); 66% were male. Nearly all had smoked 100 or more cigarettes in their lifetime (97.9%). More than 80% indicated that quitting smoking was a very important reason for starting to use e-cigarettes and 60% indicated that they intend to stop using e-cigarettes at some point. About 40% reported experiencing some side effects within 2 hours of using e-cigarettes. Those who did not report experiencing any of the listed side effects had approximately 3.2 times higher odds of perceiving e-cigarettes as harmless than those who reported having side effects (odds ratio = 3.17; 95% confidence interval: 1.75-5.73). CONCLUSION: Our findings suggest that most e-cigarette users are using them to reduce or stop smoking cigarettes and perceive them as harmless. Due to our use of convenience sampling, the reader should be cautious in generalizing our findings to all Canadian e-cigarette users.

INTRODUCTION: Bien que l'utilisation de la cigarette électronique (« vapotage ¼) soit en hausse au Canada, peu d'efforts ont été consacrés à la description des utilisateurs de cigarettes électroniques (« vapoteurs ¼). C'est dans ce contexte que nous avons mené une étude à Ottawa (Canada) afin de décrire les perceptions qu'ont les utilisateurs de cigarettes électroniques des avantages, des dangers et des risques de ces dernières. Nous avons également recueilli de l'information pour savoir pourquoi, comment et où ils utilisent la cigarette électronique ainsi que sur les effets secondaires. MÉTHODOLOGIE: Un sondage en ligne de 24 questions a été soumis à des personnes ayant acheté des cigarettes électroniques ou des fournitures connexes dans l'un des 17 commerces de cigarettes électroniques à Ottawa. On a caractérisé les répondants au moyen d'analyses descriptives, puis nous avons appliqué des modèles de régression logistique pour évaluer la relation entre ces caractéristiques et la perception par les répondants des dangers de la cigarette électronique. RÉSULTATS: L'âge moyen des 242 répondants était de 38,1 ans (plage : 16 à 70 ans) et, de ce nombre, 66 % étaient des hommes. Près de la totalité (97,9 %) des répondants avaient fumé 100 cigarettes ou plus au cours de leur vie. Plus de 80 % des répondants ont indiqué que la volonté d'arrêter de fumer constituait l'une des principales raisons de recourir à la cigarette électronique, et 60 % ont mentionné qu'ils avaient l'intention de cesser l'utilisation de la cigarette électronique un jour. Environ 40 % des répondants ont fait état d'effets secondaires au cours des 2 heures suivant l'utilisation des cigarettes électroniques. Les répondants ayant signalé n'avoir ressenti aucun des effets secondaires énumérés étaient environ 3,2 fois plus nombreux à ne percevoir aucun danger dans la cigarette électronique que les personnes ayant signalé des effets secondaires (rapport de cotes = 3,17; intervalle de confiance à 95 % : 1,75 à 5,73). CONCLUSION: D'après nos constatations, la majorité des utilisateurs de cigarettes électroniques ont recours à ces dernières pour réduire ou cesser leur consommation de tabac et ils les perçoivent comme inoffensives. Étant donné que nous avons utilisé un échantillonnage de commodité, le lecteur doit faire preuve de prudence dans la généralisation de nos constatations à tous les utilisateurs de cigarettes électroniques au Canada.

FoxP1 marks medium spiny neurons from precursors to maturity and is required for their differentiation.

Identifying the steps involved in striatal development is important both for understanding the striatum in health and disease, and for generating protocols to differentiate striatal neurons for regenerative medicine. The most prominent neuronal subtype in the adult striatum is the medium spiny projection neuron (MSN), which constitutes more than 85% of all striatal neurons and classically expresses DARPP-32. Through a microarray study of genes expressed in the whole ganglionic eminence (WGE: the developing striatum) in the mouse, we identified the gene encoding the transcription factor Forkhead box protein P1 (FoxP1) as the most highly up-regulated gene, thus providing unbiased evidence for the association of FoxP1 with MSN development. We also describe the expression of FoxP1 in the human fetal brain over equivalent gestational stages. FoxP1 expression persisted through into adulthood in the mouse brain, where it co-localised with all striatal DARPP-32 positive projection neurons and a small population of DARPP-32 negative cells. There was no co-localisation of FoxP1 with any interneuron markers. FoxP1 was detectable in primary fetal striatal cells following dissection, culture, and transplantation into the adult lesioned striatum, demonstrating its utility as an MSN marker for transplantation studies. Furthermore, DARPP-32 expression was absent from FoxP1 knock-out mouse WGE differentiated in vitro, suggesting that FoxP1 is important for the development of DARPP-32-positive MSNs. In summary, we show that FoxP1 labels MSN precursors prior to the expression of DARPP-32 during normal development, and in addition suggest that FoxP1 labels a sub-population of MSNs that are not co-labelled by DARPP-32. We demonstrate the utility of FoxP1 to label MSNs in vitro and following neural transplantation, and show that FoxP1 is required for DARPP-32 positive MSN differentiation in vitro.

Effect of dose reduction on image registration and image quality for cone-beam CT in radiotherapy.

INTRODUCTION: The additional radiation exposure applied to patients undergoing cone-beam computed tomography (CBCT) for image registration in radiation therapy is of great concern. Since a decrease in CBCT dose is linked to a degradation of image quality, the consequences of dose reduction on the registration process have to be investigated. MATERIAL AND METHODS: This paper examines image quality and registration of low-contrast structures on an Elekta XVI for the two treatment areas prostate and chest while gradually decreasing the mAs per frame and the number of projections per CBCT to achieve dose reduction. RESULTS: Ideal results for image quality were obtained for 1.6 mAs/frame and 377 projections in prostate scans and 0.63 mAs/frame and 440 projections in chest images. Lower as well as higher total mAs lead to a decrease in image quality. In spite of poor image quality, registration can be successfully performed even for lowest possible settings. CONCLUSION: The results for registration allow an extensive dose reduction in both treatment areas. Very low mAs, however, do not qualify for clinical use because subjective judgment of the registration process is impossible. Compared to default presets the use of settings for acceptable image quality already permit a decrease in exposure of about 40 % (29.0 to 16.7 mGy) in prostate scans and 60 % (18.3 to 7.7 mGy) in chest scans.

Feasibility study of patient positioning verification in electron beam radiotherapy with an electronic portal imaging device (EPID).

The purpose of this study is to demonstrate the feasibility of verification and documentation in electron beam radiotherapy using the photon contamination detected with an electronic portal imaging device. For investigation of electron beam verification with an EPID, the portal images are acquired irradiating two different tissue equivalent phantoms at different electron energies. Measurements were performed on an Elekta SL 25 linear accelerator with an amorphous-Si electronic portal imaging device (EPID: iViewGT, Elekta Oncology Systems, Crawley, UK). As a measure of EPID image quality contrast (CR) and signal-to-noise ratio (SNR) are determined. For characterisation of the imaging of the EPID RW3 slabs and a Gammex 467 phantom with different material inserts are used. With increasing electron energy the intensity of photon contamination increases, yielding an increasing signal-to-noise ratio, but images are showing a decreasing contrast. As the signal-to-noise ratio saturates with increasing dose a minimum of 50 MUs is recommended. Even image quality depends on electron energy and diameter of the patient, the acquired results are mostly sufficient to assess the accuracy of beam positioning. In general, the online EPID acquisition has been demonstrated to be an effective electron beam verification and documentation method. The results are showing that this procedure can be recommended to be routinely and reliably done in patient treatment with electron beams.

Medical terminations of pregnancy: a viable source of tissue for cell replacement therapy for neurodegenerative disorders.

"Proof-of-principle" that cell replacement therapy works for neurodegeneration has been reported, but only using donor cells collected from fetal brain tissue obtained from surgical terminations of pregnancy. Surgical terminations of pregnancy represent an increasingly limited supply of donor cells due to the tendency towards performing medical termination in much of Europe. This imposes a severe constraint on further experimental and clinical cell transplantation research. Therefore, we explore here the feasibility of using medical termination tissue as a donor source. Products of conception were retrieved from surgical terminations over the last 7 years and from medical terminations over the last 2.5 years. The number of collections that yielded fetal tissue, viable brain tissue, and identifiable brain regions (ganglionic eminence, ventral mesencephalon, and neocortex) were recorded. We studied cell viability, cell physiological properties, and differentiation potential both in vitro and following transplantation into the central nervous system of rodent models of neurodegenerative disease. Within equivalent periods, we were able to collect substantially greater numbers of fetal remains from medical than from surgical terminations of pregnancy, and the medical terminations yielded a much higher proportion of identifiable and dissectible brain tissue. Furthermore, we demonstrate that harvested cells retain the capacity to differentiate into neurons with characteristics appropriate to the region from which they are dissected. We show that, contrary to widespread assumption, medical termination of pregnancy-derived fetal brain cells represent a feasible and more readily available source of human fetal tissue for experimental cell transplantation with the potential for use in future clinical trials in human neurodegenerative disease.

Cervical human papillomavirus infection and squamous intraepithelial lesions in rural Gambia, West Africa: viral sequence analysis and epidemiology.

The development of effective strategies against cervical cancer in Africa requires accurate type specific data on human papillomavirus (HPV) prevalence, including determination of DNA sequences in order to maximise local vaccine efficacy. We have investigated cervical HPV infection and squamous intraepithelial lesions (SIL) in an unselected cohort of 1061 women in a rural Gambian community. Squamous intraepithelial lesions was diagnosed using cytology and histology, HPV was typed by PCR-ELISA of DNA extracts, which were also DNA sequenced. The prevalence of cervical HPV infection was 13% and SIL were observed in 7% of subjects. Human papillomavirus-16 was most prevalent and most strongly associated with SIL. Also common were HPV-18, -33, -58 and, notably, -35. Human papillomavirus DNA sequencing revealed HPV-16 samples to be exclusively African type 1 (Af1). Subjects of the Wolof ethnic group had a lower prevalence of HPV infection while subjects aged 25-44 years had a higher prevalence of cervical precancer than older or younger subjects. This first report of HPV prevalence in an unselected, unscreened rural population confirms high rates of SIL and HPV infection in West Africa. This study has implications for the vaccination of Gambian and other African populations in the prevention of cervical cancer.

The long-term reproductive health consequences of female genital cutting in rural Gambia: a community-based survey.

This paper examines the association between traditional practices of female genital cutting (FGC) and adult women's reproductive morbidity in rural Gambia. In 1999, we conducted a cross-sectional community survey of 1348 women aged 15-54 years, to estimate the prevalence of reproductive morbidity on the basis of women's reports, a gynaecological examination and laboratory analysis of specimens. Descriptive statistics and logistic regression were used to compare the prevalence of each morbidity between cut and uncut women adjusting for possible confounders. A total of 1157 women consented to gynaecological examination and 58% had signs of genital cutting. There was a high level of agreement between reported circumcision status and that found on examination (97% agreement). The majority of operations consisted of clitoridectomy and excision of the labia minora (WHO classification type II) and were performed between the ages of 4 and 7 years. The practice of genital cutting was highly associated with ethnic group for two of the three main ethnic groups, making the effects of ethnic group and cutting difficult to distinguish. Women who had undergone FGC had a significantly higher prevalence of bacterial vaginosis (BV) [adjusted odds ratio (OR)=1.66; 95% confidence interval (CI) 1.25-2.18] and a substantially higher prevalence of herpes simplex virus 2 (HSV2) [adjusted OR=4.71; 95% CI 3.46-6.42]. The higher prevalence of HSV2 suggests that cut women may be at increased risk of HIV infection. Commonly cited negative consequences of FGC such as damage to the perineum or anus, vulval tumours (such as Bartholin's cysts and excessive keloid formation), painful sex, infertility, prolapse and other reproductive tract infections (RTIs) were not significantly more common in cut women. The relationship between FGC and long-term reproductive morbidity remains unclear, especially in settings where type II cutting predominates. Efforts to eradicate the practice should incorporate a human rights approach rather than rely solely on the damaging health consequences.

High-resolution neutron structure of nicotinamide adenine dinucleotide.

The structure of the free-acid form of the coenzyme NAD(+) was determined at 100 K from a single-crystal neutron experiment. NAD(+) is the oxidized form of the coenzyme redox pair NAD(+)/NADH and plays an important role in the catalysis of biological processes. The molecule crystallizes in space group P1 with one NAD(+) and four water molecules per unit cell. The structure is compared with the previous X-ray models of NAD(+) [Reddy et al. (1981), J. Am. Chem. Soc. 103, 907-914; Parthasarathy & Fridey (1984b), Science, 226, 969-971; Guillot et al. (2000), Acta Cryst. C56, 726-728]. The crystal packing and the hydrogen-bond pattern are discussed as well as four short C-H.O contacts involving the pyridine and adenine rings. The structure displays stereochemical distortions owing to the hydrogen bonding and crystal-packing constraints, reflecting the adaptability of the NAD(+) molecule in various chemical environments.

Dose reduction in spiral CT angiography of thoracic outlet syndrome by anatomically adapted tube current modulation.

The aim of this study was to evaluate dose reduction in spiral CT angiography of the thoracic outlet by on-line tube-current control. Prospectively, 114 patients undergoing spiral CT angiography of the subclavian artery for thoracic outlet arterial syndromes were evaluated with and without tube-current modulation at the same session (scanning parameters for the two successive angiograms, one in the neutral position and one after the postural maneuver): 140 kV; 206 mA; scan time 0.75 s; collimation 3 mm; pitch = 1). The dose reduction system was applied in the neutral position in the first 92 consecutive patients and after postural maneuver in the remaining 22 consecutive patients. Dose reduction and image quality were analyzed in the overall study group (group 1; n = 114). The influence of the arm position was assessed in 44 of the 114 patients (group 2), matched by the transverse diameter of the upper thorax. The mean dose reduction was 33% in group 1 (range 22-40%) and 34% in group 2 (range 26-40%). In group 2 the only difference in image quality was a significantly higher frequency of graininess on low-dose scans compared with reference scans whatever the patient's arm position, graded as minimal in 38 of the 44 patients (86%). When the low-dose technique was applied after postural maneuver in group 2: (a) the mean dose reduction was significantly higher (35 vs 32% in the neutral position; p = 0.006); (b) graininess was less frequent (82 vs 91% in the neutral position); and (c) the percentage of graininess graded as minimal was significantly higher (83 vs 70% in the neutral position; p = 0.2027). On-line tube-current modulation enables dose reduction on high-quality, diagnostic spiral CT angiograms of the thoracic outlet and should be applied during data acquisition in the neutral position and after postural maneuver for optimal use.

The burden of reproductive-organ disease in rural women in The Gambia, West Africa.

BACKGROUND: Data on the epidemiology of reproductive-organ morbidity are needed to guide effective interventions, to set health-care priorities, and to target future research. This study aimed to find out the prevalence of reproductive-organ disease in a sample of rural Gambian women. METHODS: A questionnaire on reproductive health was administered by fieldworkers to women aged 15-54 years living in a rural area under demographic surveillance. A female gynaecologist questioned and examined the women (including speculum and bimanual pelvic examinations). Vaginal swabs were taken to test for Trichomonas vaginalis, Candida albicans, and bacterial vaginosis, cervical smears for cytology, cervical swabs for Chlamydia trachomatis PCR and Neisseria gonorrhoeae culture, and venous blood for haemoglobin, HIV, herpes simplex virus 2, and syphilis serology. FINDINGS: 1348 (72.0%) of 1871 eligible women took part. Reproductive-organ symptoms were more likely to be reported to the gynaecologist (52.7% of women) than to the fieldworker (26.5%). Menstrual problems, abnormal vaginal discharge, and vaginal itching were the most commonly reported symptoms. A minority of women said they had sought health care for their symptoms. The frequencies of reproductive-organ morbidity were high: menstrual dysfunction 34.1% (95% CI 29.6-39.1), infertility 9.8% (8.2-11.6), reproductive-tract infections 47.3% (43.7-51.0), pelvic tenderness 9.8% ((7.0-13.5), cervical dysplasia 6.7% (5.2-8.4), masses 15.9% (12.5-20.1), and childbirth-related damage to pelvic structures 46.1% (40.1-52.3). 948 (70.3%) women had at least one reproductive-organ disorder. INTERPRETATION: For these rural women, whose lives depend heavily on their reproductive function, reproductive-organ disease is a large burden. In inadequately resourced rural areas, with poor education, heavy agricultural and domestic labour, and limited access to quality health care, many women are not able to attain and maintain reproductive health and wellbeing.

[Age-related contractility of retinal arterioles during pure oxygen breathing]. / Alterskorrelierte Kontraktilität retinaler Arteriolen bei Sauerstoffatmung.

BACKGROUND: Pure oxygen breathing is a non-invasive method to test the contractility of retinal arterioles. The normal response curve of this provocation method was tested using the Retinal Vessel Analyzer (RVA). Statistical analysis between groups was performed with th Man-Whitney test, correlations were tested with Pearsons' linear function. METHODS: After a 3-min baseline measurement 32 healthy volunteers breathed 100% oxygen for 5 min. The diameter of an retinal arteriole was measured continuously during this provocation by the RVA. Volunteers were separated into four groups according age. RESULTS: All four groups reacted to pure oxygen breathing with significant vasoconstriction of the retinal arteriole: in the youngest group (20-29 years) the reduction was 14.6 +/- 5.2% and the three older age groups 9.4 +/- 5.2%, 4.6 +/- 2.7%, and 2.8 +/- 3.3%. The correlation between vasoconstriction and age was r = 0.73. CONCLUSIONS: Pure oxygen breathing is an easily performed method with minimal invasiveness to the patient. However, the age-correlated response curve must be kept in mind for the clinical use of this method.

Comparison of C-arm CT fluoroscopy and conventional fluoroscopy for percutaneous biliary drainage procedures.

PURPOSE: To conduct a prospective randomized evaluation of C-arm computed tomography (CT) fluoroscopy for external biliary drainage procedures in comparison with conventional fluoroscopic guidance to reduce the number of transhepatic punctures as a primary endpoint. MATERIALS AND METHODS: In 18 patients with biliary obstructions, 20 external percutaneous biliary drainage procedures were prospectively performed with use of either C-arm CT fluoroscopy or conventional fluoroscopy alone. The number of hepatic punctures, procedure time, and fluoroscopy time, were analyzed separately for both methods. RESULTS: C-arm CT fluoroscopy resulted in a reduced number of transhepatic punctures, with decreased procedure and fluoroscopy times (P < .05; t test). When compared with conventional external biliary drainage procedures, a mean of 1.8+/-1 versus 4.8+/-2.8 hepatic punctures at a fluoroscopy time of 3.4+/-1.5 versus 11.4+/-7.4 minutes was required for C-arm CT fluoroscopy, while procedure times were 11+/-3.6 versus 16.2+/-9.3 minutes. CONCLUSIONS: C-arm CT fluoroscopy is associated with decreased procedure and fluoroscopy times, while fewer transhepatic punctures are required to establish external biliary drainage.

Feasibility of C-arm-supported CT fluoroscopy in percutaneous abscess drainage procedures.

PURPOSE: Evaluation of C-arm-supported CT fluoroscopy to facilitate percutaneous abscess drainage procedures. METHODS: Prospectively, 40 percutaneous drainage procedures were performed either with C-arm-supported CT fluoroscopy or with CT fluoroscopy alone. Hybrid imaging was performed on the CT couch after complementing a CT fluoroscopy scanner with a C-arm fluoroscopy unit. Procedure times, drainage revisions during follow-up, and postinterventional drainage periods were analyzed. RESULTS: When compared with exclusive CT fluoroscopic guidance, a median procedure time of 9 +/- 3.7 min versus 14.8 +/- 7.3 min was required for C-arm-supported CT fluoroscopy (p < 0.005, t-test). During follow-up, eight drainage catheters had to be revised within the exclusive CT fluoroscopy group, while only two revisions were necessary within the C-arm-supported CT fluoroscopy group. With C-arm-supported CT fluoroscopy, postinterventional drainage periods were reduced (median 13 vs 19 days; p < 0.001, t-test). CONCLUSION: Compared with exclusive cross-sectional image guidance, C-arm-supported CT fluoroscopy seems to improve placement of abscess drainage catheters to possibly reduce procedure times, drainage catheter revisions, and postinterventional drainage periods.

First experiences in percutaneous arterial chemoembolization of malignant liver lesions by means of real-time CT fluoroscopy.

Computed tomography fluoroscopy (CTF) allows real-time display (continuous imaging) and has been increasingly used in interventional procedures. We wished to demonstrate the usefulness of CTF in chemoembolization of the liver. Twenty-one patients with primary or secondary malignant lesions of the liver underwent CTF-guided chemoembolization after angiographic positioning of a catheter in the hepatic artery. Embolization materials such as Lipiodol and mitomycin C were administered under continuous CT scanning. CTF led to a change of the method (correction of catheter position, application of norepinephrine) in nine of 21 cases. There were no fatal complications.

Immunohistochemical localization of laminin, nidogen, and type IV collagen during the early development of human liver.

There is evidence that basement membrane components control differentiation of liver sinusoids and bile ducts. These processes occur in humans in the 9th gestational week (GW). Distribution of laminin, nidogen, and type IV collagen was studied during human liver development between the 6th and the 10th GW. Laminin and nidogen lined intrahepatic microvessels in the 6th and 7th GW decreasing in quantity at the beginning of the fetal period (9th-10th GW). Type IV collagen was detected in microvessels only from the 9th GW onward. In the early periportal matrix (9th-10th GW) laminin, nidogen, and type IV collagen were diffusely distributed. At these stages, basement membrane zones of larger portal vessels and of early bile ducts were also stained for all three glycoproteins. These results show that laminin and nidogen are localized in microvessels during early human liver development and decrease in concentration at the developmental stage during which microvessels become discontinuous. In contrast, type IV collagen is not present in early microvessels but occurs when laminin and nidogen disappear. The three glycoproteins occur together only in those areas of the developing liver in which, from the 9th GW onward, the differentiation of immature liver cells into biliary epithelium takes place.