An exploration of students' use of digital resources for self-study in anatomy: a survey study.

BACKGROUND: The development of technology has provided new ways for active engagement and for visualizing structures in anatomy education including digital resources that may be used outside of the classroom. To support students' learning, there is a need to better understand students' experiences of using digital resources. This study aimed to identify which resources students use, their preferences, the purpose of using them, and barriers to adopting tools for self-study of anatomy. METHODS: A mixed -methods approach combining qualitative and quantitative data was used to collect and analyse data. Two consecutive cohorts of first-semester medical students (n = 278) were invited to complete an anonymized survey. The survey consisted of itemized questions, free-text space for comments, and one open-ended question. Descriptive statistics were used for demographics and itemized answers. Comments and free-text answers were analysed qualitatively using abductive inference. RESULTS: One hundred and twenty-seven students completed the survey (response rate 45%). Most students (46%) reported that they spend more than 30 h/per week on self-study. They used a variety of digital resources for different purposes. Most students used digital resources to prepare for examinations, when they encountered difficulties and after going through a section. Students reported that they would use digital resources to a greater extent if they were offered an introduction, if resources were more accessible, and if they could interact with a tutor. The free-text responses revealed that digital resources helped students understand anatomy, allowed them to make active choices, provided tools for repetition and memorization, accelerated and simplified the learning process, and complemented other learning resources. CONCLUSIONS: Digital resources may support the understanding of anatomy by offering alternative modes of learning and providing a valuable complement to other learning resources. Educators should consider how digital resources are introduced and offer support and feedback.

How students discern anatomical structures using digital three-dimensional visualizations in anatomy education.

Learning anatomy holds specific challenges, like the appreciation of three-dimensional relationships between anatomical structures. So far, there is limited knowledge about how students construct their understanding of topographic anatomy. By understanding the processes by which students learn anatomical structures in 3D, educators will be better equipped to offer support and create successful learning situations. Using video analysis, this study investigates how students discern anatomical structures. Sixteen students at different levels of education and from different study programs were recorded audiovisually while exploring 3D digital images using a computerized visualization table. Eleven hours of recorded material were analyzed using interaction analysis and phenomenography. Seven categories were identified during data analysis, describing the qualitatively different patterns of actions that students use to make sense of anatomy: decoding the image; positioning the body in space; purposeful seeking, using knowledge and experience; making use of and creating variation; aimless exploration, and arriving at moments of understanding. The results suggest that anatomy instruction should be organized to let the students decide how and at what pace they examine visualized images. Particularly, the discovery process of decoding and positioning the body in space supports a deep learning approach for learning anatomy using visualizations. The students' activities should be facilitated and not directed.

Cohort profile: Nordic Helicobacter Pylori eradication project (NordHePEP).

PURPOSE: This cohort description presents the Nordic Helicobacter Pylori Eradication Project (NordHePEP), a population-based cohort of patients having received eradication treatment for Helicobacter pylori (HP). The cohort is created with the main purpose of examining whether and to what extent HP eradication treatment influences the risk of gastrointestinal cancer. PARTICIPANTS: NordHePEP includes all adults (aged ≥18 years) having been prescribed and dispensed HP eradication treatment according to the nationwide complete drug registries in any of the five Nordic countries (Denmark, Finland, Iceland, Norway, or Sweden) between 1994 and 2020 (start and end year varies between countries). We have retrieved and merged individual-level data from multiple national registries, including drug, patient, cancer, population, and death registries. FINDINGS: The cohort includes 674,771 patients having received HP eradication treatment. During up to 23 years of follow-up, 59,292 (8.8%) participants were diagnosed with cancer (non-melanoma skin cancer excluded), whereof 15,496 (2.3%) in the gastrointestinal tract. FUTURE PLANS: We will analyse HP eradication treatment in relation to gastrointestinal cancer risk. Standardised incidence ratios will be calculated as the observed cancer incidence in the cohort divided by the expected cancer incidence, derived from the background population of the corresponding age, sex, and calendar year.

Foveal and peripheral visual quality and accommodation with multifocal contact lenses.

Multifocal contact lenses are increasingly popular interventions for controlling myopia. This study presents the short-term effects of multifocal contact lenses on foveal and peripheral vision. The MiSight contact lenses designed to inhibit myopia progression and the 1-Day Acuvue Moist contact lenses designed for presbyopia were investigated. The MiSight produced similar foveal results to spectacles despite the increased astigmatism and coma. The MiSight also reduced the low-contrast resolution acuity in the periphery, despite no clear change in relative peripheral refraction. When compared with spectacles, Acuvue Moist decreased accommodative response and reduced foveal high- and low-contrast resolution acuity, whereas peripheral thresholds were more similar to those of spectacles. The most likely treatment property for myopia control by the MiSight is the contrast reduction in the peripheral visual field and the changed accommodation.

A Questionnaire Survey on Long-Term Outcomes in Cats Breed-Screened for Feline Cardiomyopathy.

Feline cardiomyopathy (FCM) is an important contributor to feline morbidity and mortality. This explorative follow-up questionnaire study was aimed at investigating the long-term outcome in cats breed-screened for FCM (BS-FCM) in three Nordic countries. Records of cats with ≥1 BS-FCM between 2004−2015 were included. Of the 1113 included cats, 104/1113 (9.3%) had developed FCM at some time-point. Fifty-nine of the 104 (56.7%) FCM cats were diagnosed within the screening program (ScreenFCM), and 33/59 (55.9%) of these were diagnosed at the first BS-FCM. ScreenFCM cats or with an owner-reported FCM diagnosis at a later time-point had a higher risk of cardiac-related death compared to cats that never developed FCM. A shorter lifespan was found in ScreenFCM cats compared to those with normal screen results (p < 0.001). Times to all-cause mortality were shorter (p < 0.001) in cats that developed FCM at any time-point compared to those that did not. Non-cardiac morbidities were similar in all screen classification groups. The large proportion of cats that developed FCM at a later time-point underscores the need for repeated screenings later in life. Cats that developed FCM at any time-point had a shorter lifespan, with a similar proportion and in line with the nature of non-cardiac morbidities, compared to those without FCM.

Health Care Leaders' Perspectives on How Continuous Professional Development Can Be Promoted in a Hospital Organization.

INTRODUCTION: Leaders play a central role in continuous learning processes aimed to improve health care. However, knowledge of how leaders with power and influence in hospital organizations promote the means for continuous learning in practice is scarce. This study aims to explore how key stakeholders in a hospital organization think about approaches and roles when promoting the reflective practice in small groups as means for continuous professional development in their organizations. METHODS: Six key stakeholders from a regional hospital (two department directors, two ward managers, and two resident supervisors) were recruited through purposive sampling. Semi-structured interviews were conducted, and an abductive content analysis was performed. RESULTS: In the current study, leaders stressed that cultural and structural conditions at all levels in the system were important for the practice of small-group learning. Yet, their suggested approaches referred exclusively to a limited part of the system and were directed to staff at lower hierarchical levels within their jurisdictions. DISCUSSION: The identified gap between the suggested approaches and the claimed conditions for implementing a new strategy for continuous professional development among leaders in a health care organization illuminates difficulties in the implementation process. Providing adequate conditions at all levels of the system demands implementation approaches that include the entire hospital system. This requires that leaders first recognize their need to learn and apply a systemic perspective, and second, that they can create such learning opportunities for themselves.

Three-dimensional visualisation of authentic cases in anatomy learning - An educational design study.

BACKGROUND: Many studies have investigated the value of three-dimensional (3D) images in learning anatomy. However, there is a lack of knowledge about students learning processes using technology and 3D images. To understand how to facilitate and support the learning of anatomy, there is a need to know more about the student perspectives on how they can use and benefit from 3D images. METHODS: This study used designed educational sessions informed by Educational Design Research to investigate the role of technology-enhanced 3D images in students' anatomy learning. Twenty-four students representing different health professions and multiple study levels, and one tutor, participated in the study. A visualisation table was used to display the images of real patient cases related to disorders associated with the abdomen and the brain. Students were asked to explore the images on their own and audio/video capture was used to record their words and actions. Directly following the session, students were interviewed about their perceptions and different ways of learning and studying anatomy. The tutor was interviewed about his reflections on the session and his role as a facilitator on two occasions. Content analysis was used in its manifest and latent form in the data analysis. RESULT: Two main categories describing the students' and tutor's accounts of learning using the visualisation table were identified: 1. Interpreting 3D images and 2. Educational sessions using visualisation tables. Each category had signifying themes representing interpretations of the latent meaning of the students' and tutor's accounts. These were: Realism and complexity; Processes of discernment; References to previous knowledge; Exploring on one's own is valuable; Context enhances learning experiences; Combinations of learning resources are needed and Working together affects the dynamics. CONCLUSIONS: This study identifies several important factors to be considered when designing effective and rewarding educational sessions using a visualization table and 3D images in anatomy education. Visualisation of authentic images has the potential to create interest and meaningfulness in studying anatomy. Students need time to actively explore images but also get tutor guidance to understand. Also, a combination of different resources comprises a more helpful whole than a single learning resource.

Anti-idiotypic antibodies elicit anti-HIV-1-specific B cell responses.

Human anti-HIV-1 broadly neutralizing antibodies (bNAbs) protect against infection in animal models. However, bNAbs have not been elicited by vaccination in diverse wild-type animals or humans, in part because B cells expressing the precursors of these antibodies do not recognize most HIV-1 envelopes (Envs). Immunogens have been designed that activate these B cell precursors in vivo, but they also activate competing off-target responses. Here we report on a complementary approach to expand specific B cells using an anti-idiotypic antibody, iv8, that selects for naive human B cells expressing immunoglobulin light chains with 5-amino acid complementarity determining region 3s, a key feature of anti-CD4 binding site (CD4bs)-specific VRC01-class antibodies. In mice, iv8 induced target cells to expand and mature in the context of a polyclonal immune system and produced serologic responses targeting the CD4bs on Env. In summary, the results demonstrate that an anti-idiotypic antibody can specifically recognize and expand rare B cells that express VRC01-class antibodies against HIV-1.

Anti-HIV-1 B cell responses are dependent on B cell precursor frequency and antigen-binding affinity.

The discovery that humans can produce potent broadly neutralizing antibodies (bNAbs) to several different epitopes on the HIV-1 spike has reinvigorated efforts to develop an antibody-based HIV-1 vaccine. Antibody cloning from single cells revealed that nearly all bNAbs show unusual features that could help explain why it has not been possible to elicit them by traditional vaccination and instead would require a sequence of different immunogens. This idea is supported by experiments with genetically modified immunoglobulin (Ig) knock-in mice. Sequential immunization with a series of specifically designed immunogens was required to shepherd the development of bNAbs. However, knock-in mice contain superphysiologic numbers of bNAb precursor-expressing B cells, and therefore how these results can be translated to a more physiologic setting remains to be determined. Here we make use of adoptive transfer experiments using knock-in B cells that carry a synthetic intermediate in the pathway to anti-HIV-1 bNAb development to examine how the relationship between B cell receptor affinity and precursor frequency affects germinal center (GC) B cell recruitment and clonal expansion. Immunization with soluble HIV-1 antigens can recruit bNAb precursor B cells to the GC when there are as few as 10 such cells per mouse. However, at low precursor frequencies, the extent of clonal expansion is directly proportional to the affinity of the antigen for the B cell receptor, and recruitment to GCs is variable and dependent on recirculation.

Experiences of a One-hour Algorithm in Chest Pain Patients With a Nonelevated Troponin T at Presentation.

BACKGROUND: We aimed to evaluate the use of a 1-hour measurement of high-sensitivity cardiac troponin T (hs-cTnT) in an emergency department (ED) population of chest pain patients with a nonelevated baseline hs-cTnT and to examine the prevalence of early dynamic changes in hs-cTnT and the association with admission rate, diagnosis, and outcome. METHODS: All patients with a chief complaint of chest pain presenting to the ED of Karolinska University Hospital, Solna, Sweden, from December 2014 to September 2015 who had a baseline hs-cTnT of ≤14 ng/L and a second value obtained within >30 to ≤90 minutes were followed for 30 days regarding admission, readmission, myocardial infarction (MI), and death. RESULTS: A total of 1091 patients were included. Dynamic 1-hour changes in hs-cTnT defined as an increase or decrease of ≥3 ng/L occurred in 23 patients (2.1%). Fifteen patients (65.2%) in the dynamic group were admitted, compared with 148 patients (13.9%) in the nondynamic group (P < 0.001). Four of the admitted patients (26.7%) in the dynamic and 1 (0.7%) in the nondynamic group were diagnosed with an MI (P < 0.001). No death or MI occurred within 30 days among those discharged from the ED. CONCLUSIONS: Dynamic 1-hour changes in hs-cTnT were uncommon but associated with a higher rate of admission and of MI in an unselected population of chest pain patients with a nonelevated hs-cTnT at presentation. Lack of dynamic changes makes MI highly unlikely, and a 1-hour measurement may facilitate an early rule out of MI but should be used together with clinical assessment.

Plasma Concentration of Biomarkers Reflecting Endothelial Cell- and Glycocalyx Damage are Increased in Patients With Suspected ST-Elevation Myocardial Infarction Complicated by Cardiogenic Shock.

BACKGROUND: Mortality in ST-elevation myocardial infarction (STEMI) patients developing cardiogenic shock (CS) during hospitalization is high. Catecholamines, ischemia, and inflammation (parameters present in CS) affect the endothelium. We hypothesized that plasma level of biomarkers reflecting endothelial damage would be associated with CS and mortality. METHODS: In 96% of 1467 consecutive patients with suspected STEMI, biomarkers reflecting endothelial cell- (soluble thrombomodulin, sTM) and glycocalyx- (syndecan-1) damage were measured on admission. Patients were stratified by CS development or not. CS-Patients were substratified by CS on admission (admission-CS), CS developed in the catheterization laboratory (cath. lab.-CS), or late CS. RESULTS: STEMI patients with admission-CS (n = 85) and cath.lab.-CS (n = 25) had higher levels of sTM and syndecan-1 compared with no-CS patients (n = 1,299). Late CS-patients (n = 58) had higher levels of sTM (median (25th; 75th percentile) 8.8 (7.0; 11.6) vs. 7.4 (6.0; 9.0) ng/mL, P = 0.0004) but not Syndecan-1 (P = 0.26) compared with no-CS patients. sTM was, however, not independently associated with late CS development (OR (95% CI) 1.07 (0.99-1.16), P = 0.09). Patients with the highest level of sTM and syndecan-1 had the highest 30-day mortality (Plogrank<0.0001). However, neither sTM nor Syndecan-1 was independently associated with 30-day mortality (HR (95% CI) sTM: 1.06 (0.996-1.12), P = 0.07; Syndecan-1: 1.04 (0.99-1.08), P = 0.12). CONCLUSION: Patients with suspected STEMI patients and admission-CS/cath.lab.-CS had elevated admission levels of sTM and Syndecan-1 compared with no CS patients. Patients developing late CS had higher sTM plasma concentration compared with patients without shock. However, the biomarker levels were not independently associated with late CS and mortality.

Physical activity level in people with age related white matter changes correlates to better motor performance, lower comorbidity and higher cognitive level.

BACKGROUND: Physical activity plays a pivotal role in the development of disability and may modify the negative effect of vascular risk factors on progression of both cardio and cerebrovascular disorders. The aim of this study was to evaluate the activity level in people with age-related white matter changes as identified on magnetic resonance imaging (MRI) in relation to motor performance, cognition and perceived health. METHODS: Data came from the first year follow up of one participating centers of the LADIS study. Fifty one subjects were first enrolled in the study. Complete first year follow up data was available for 41 subjects. Information on comorbidity, physical activity level, physical function, cognition, level of white matter changes and perceived health was collected. Physical activity level was classified with a yes or no question and with the Frenchay Activities Index (FAI). RESULTS: Only 36% of the subjects in this study were physically active according to the yes/no question. 27.5% of the subjects were active according to the FAI score which evaluates the everyday activities. Being active discriminated subjects with better physical function. Subjects active according to the FAI score had a higher cognitive level (p ≤ 0.01), lower comorbidity (p = 0.02) and performed better on all motor function tasks as assessed by walking speed (p ≤ 0.01) and the Short Physical Performance battery (SPPB) (p ≤ 0.01). CONCLUSIONS: Being physically active seems to be a long term protective factor. In our study, the majority of subjects with Age Related White Mattter Changes (ARWMC) with no or mild Instrumental Activity of Daily Living (IADL) disability did not attain recommended level of activity at first year follow up. Whether or not increasing physical activity may slow down cognitive decline and lessen development of disability in physically inactive subjects with manifest ARWC remains to be studied. TRIAL REGISTRATION: not applicable.

Physiotherapists' stories about professional development.

INTRODUCTION: A professional career may extend over a period of 40 years. Although learning is a feature of professional competence, little is known about learning and development after professional entry education. METHODS: Narrative inquiry was used to understand how physiotherapists learned and developed over time, and stories from a purposeful sample of 12 physiotherapists were collected. Stories were thematically analyzed with regard to key elements related to learning and development, and common themes were identified across stories. FINDINGS: Four themes emerged from the analysis where physiotherapists learned and developed in working life: (1) facing challenges; (2) contrasting perspectives; (3) drawing on hundreds of educators; and (4) building on personal experience. CONCLUSION: Non-formal ways of learning in working life may help physiotherapists learn and develop confidence, communication strategies and different approaches to treatment. Besides reflection on personal experience and patient encounters, learning and development may be promoted and supported by taking on challenges and changing settings.

Effects of a dietary intervention on gastrointestinal symptoms after prostate cancer radiotherapy: long-term results from a randomized controlled trial.

BACKGROUND AND PURPOSE: To evaluate the long-term effects of dietary intervention on gastrointestinal symptoms after highly dose-escalated radiotherapy for localized prostate cancer, using boost with protons or high-dose-rate brachytherapy. MATERIALS AND METHODS: Patients were randomized to an intervention group (n=64) advised to reduce insoluble dietary fiber and lactose intake, or to a standard care group (n=66) advised to continue their usual diet. Gastrointestinal symptoms, other domains of health-related quality of life (HRQOL), and dietary intake were evaluated for ⩽24months post-radiotherapy with the European Organization for Research and Treatment of Cancer quality-of-life questionnaires QLQ-C30 and QLQ-PR25, Gastrointestinal Side Effects Questionnaire, and Food Frequency Questionnaire. The effect of the intervention on gastrointestinal symptoms was evaluated using generalized estimating equations. RESULTS: Dietary intervention had no obvious effect on long-term gastrointestinal symptoms or HRQOL. The intervention group markedly reduced their dietary fiber and lactose intake during radiotherapy, but adherence tended to decline over time. The vast majority of long-term gastrointestinal symptoms were reported as 'a little', with a noticeable difference from pre-treatment only for unintentional stool leakage, limitations on daily activities, and mucus discharge. CONCLUSION: Long-term gastrointestinal symptoms were predominantly mild, and dietary intervention was not superior to a usual diet in preventing these symptoms.

Assessing patients' perceived bother from the gastrointestinal side effects of radiotherapy for localized prostate cancer: initial questionnaire development and validation.

BACKGROUND: The present study reports on the development and first steps of validation of the Gastrointestinal Side Effects Questionnaire (GISEQ), a measure of patient-reported gastrointestinal symptoms following local radiotherapy to the prostate. The questionnaire design provides a novel approach of assessment of side effects of prostate radiotherapy, by enabling measurement of patient-perceived change in symptoms. MATERIAL AND METHODS: The eight-item GISEQ was administered to 130 prostate cancer patients referred to radiotherapy. Patients completed the GISEQ at four, eight and 15 weeks after start of radiotherapy. The psychometric properties including validity, reliability, responsiveness and feasibility were evaluated. The EORTC QLQ-C30 and QLQ-PR25 were chosen as comparative measures. RESULTS: Expert opinion supported content validity. For concurrent validity, correlation between the GISEQ and matching items in the EORTC questionnaires was moderate but significant (r > 0.41, p < 0.001). The responsiveness was adequate, indicated by changes in GISEQ scores over time corresponding to the effects of radiation. Internal consistency was satisfactory (overall Cronbach's α> 0.70). Sensitivity and specificity for items diarrhea, constipation and blood in stools ranged from 50% to 100% and from 68% to 100%, respectively. All items had a floor effect above 15%. The response rates ranged from 85% to 92% and missing items was < 0.8%, indicating good feasibility. CONCLUSIONS: The GISEQ showed satisfactory internal consistency and adequate content validity, concurrent validity and responsiveness. It is brief, easy to use and can be quickly evaluated, making it useful not only for research but possibly also for clinical settings. Modification of response scale and extension of items are potential improvements. Further work is needed to strengthen the psychometric qualities of the GISEQ and to evaluate its clinical use and potential effects of response shift and recall bias.

Effective treatment of eating disorders: Results at multiple sites.

We report the results of a study based on 1,428 patients with eating disorders treated at 6 clinics. These patients were consecutively referred over 18 years and used inpatient and outpatient treatment. The subjects were diagnosed with anorexia nervosa, bulimia nervosa, or an eating disorder not otherwise specified. Patients practiced a normal eating pattern with computerized feedback technology, they were supplied with external heat, their physical activity was reduced, and their social habits restored to allow them to return to their normal life. The estimated rate of remission for this therapy was 75% after a median of 12.5 months of treatment. A competing event such as the termination of insurance coverage, or failure of the treatment, interfered with outcomes in 16% of the patients, and the other patients remained in treatment. Of those who went in remission, the estimated rate of relapse was 10% over 5 years of follow-up and there was no mortality. These data replicate the outcomes reported in our previous studies and they compare favorably with the poor long-term remission rates, the high rate of relapse, and the high mortality rate reported with standard treatments for eating disorders.

Effects of a dietary intervention on acute gastrointestinal side effects and other aspects of health-related quality of life: a randomized controlled trial in prostate cancer patients undergoing radiotherapy.

PURPOSE: To study the effect of a dietary intervention on acute gastrointestinal side effects and other aspects of health-related quality of life (HRQOL) in prostate cancer patients referred to radiotherapy. MATERIALS AND METHODS: A total of 130 patients were randomly assigned to one of two groups: an intervention group (IG, n=64), instructed to reduce their intake of insoluble dietary fibres and lactose, a standard care group (SC, n=66), instructed to continue their normal diet. Gastrointestinal side effects and other aspects of HRQOL were evaluated from baseline up to 2 months after completed radiotherapy, using the EORTC QLQ-C30 and QLQ-PR25 and the study-specific Gastrointestinal Side Effects Questionnaire (GISEQ). A scale indicating adherence to dietary instructions was developed from a Food Frequency Questionnaire (FFQ), with lower scores representing better compliance. Descriptive and inferential statistical analyses were conducted. RESULTS: There was an interaction effect between randomization and time in the FFQ Scores (p<0.001), indicating that both groups followed their assigned dietary instructions. The dietary intervention had no effect on gastrointestinal side effects or other aspects of HRQOL. During radiotherapy, the percentage of patients with bowel symptoms and bloated abdomen was lower in IG compared to SC, but the between-group differences were not statistically significant. During radiotherapy, the percentage of patients with bowel symptoms, urinary symptoms, pain, fatigue and diminished physical and role functioning increased in both groups. CONCLUSIONS: The dietary intervention had no effect on gastrointestinal side effects or other aspects of HRQOL. The tendency towards lower prevalence of bowel symptoms in IG may indicate some positive effect of the dietary intervention, but methodological refinements, clearer results and longer follow-up are needed before the value of diet change can be established with certainty.

Effects of new, individually adjusted, progressive balance group training for elderly people with fear of falling and tend to fall: a randomized controlled trial.

OBJECTIVE: To evaluate the effects of a new, individually adjusted, progressive and specific balance group training programme on fear of falling, step execution, and gait in healthy elderly people with fear of falling and tend to fall. DESIGN: Randomized controlled trial. SETTING: The study was conducted in Stockholm County, Sweden. SUBJECTS: Fifty-nine community dwelling elderly people were recruited by advertisement, and allocated at random to an intervention group (n = 38) or a control group (n = 21). INTERVENTION: Individually adjusted, progressive and specific balance group training was given three times a week for three months. The training incorporated elements included in, and required for, independent activities of daily living, and for reactions to loss of balance during dual or multiple tasks. MAIN MEASURES: Fear of falling was assessed with Falls Efficacy Scale International (FES-I). The reaction time of step execution was measured with the step-execution test, and gait was measured with GAITRite®. RESULTS: After three months the intervention group showed significant positive changes in the FES-I (P = 0.008), in the step-execution phase of dual-task performance (P = 0.012), and in gait at preferred speed during single-task performance; in cadence (P = 0.030) and, at fast speed, in velocity (P = 0.004) and cadence (P = 0.001). Significant decreases were also found for the likelihood of depression after participating in the training programme. CONCLUSION: This new balance training programme is feasible and leads to decreased fear of falling, decreased time for step execution during dual-task performance and increased velocity during fast walking.

Laser-based standoff detection of explosives: a critical review.

A review of standoff detection technologies for explosives has been made. The review is focused on trace detection methods (methods aiming to detect traces from handling explosives or the vapours surrounding an explosive charge due to the vapour pressure of the explosive) rather than bulk detection methods (methods aiming to detect the bulk explosive charge). The requirements for standoff detection technologies are discussed. The technologies discussed are mostly laser-based trace detection technologies, such as laser-induced-breakdown spectroscopy, Raman spectroscopy, laser-induced-fluorescence spectroscopy and IR spectroscopy but the bulk detection technologies millimetre wave imaging and terahertz spectroscopy are also discussed as a complement to the laser-based methods. The review includes novel techniques, not yet tested in realistic environments, more mature technologies which have been tested outdoors in realistic environments as well as the most mature millimetre wave imaging technique.