Efficacy of the Canadian CT Head Rule in Patients Presenting to the Emergency Department with Minor Head Injury.

Introduction: Approximately, one in three computed tomography (CT) scans performed for head injury may be avoidable. We evaluate the efficacy of the Canadian CT head rule (CCHR) on head CT imaging in minor head injury (MHI) and its association of Glasgow Coma Scale (GCS) and structural abnormality. Materials and methods: We conducted a prospective cross-sectional study from May 2018 to October 2019 in the Department of Emergency Medicine, Pushpagiri Institute of Medical Sciences and Research Centre, Thiruvalla, Kerala. The CCHR is applied to patients with MHIs (GCS 13-15) after initial stabilization and it is ascertained, if they require a non-contrast CT head and imaging is done. For those who do not require CT head as per the CCHR are excluded from this study. After imaging the patients who have a positive finding on CT head are admitted and followed up if they underwent any neurosurgical intervention, those with no findings in CT head are discharged from the hospital. A total of 203 patients were included during study period. Results: A total of 203 patients were included in study with mean age of 49.5 years. Approximately, 70% (142) were male. Sensitivity of CCHR for predicting positive CT finding in the present study sample was 68% and specificity was 42.5%. Conclusion: Canadian CT head rule is a useful tool in the Emergency Department for predicting the requirement of CT in patients with MHI. Canadian CT head rule can reduce the number of CT scans ordered following MHI in ED, thus improving the healthcare costs. How to cite this article: Reddy A, Poonthottathil F, Jonnakuti R, Thomas R. Efficacy of the Canadian CT Head Rule in Patients Presenting to the Emergency Department with Minor Head Injury. Indian J Crit Care Med 2024;28(2):148-151.

Resonant cavities with phase-changing materials.

Phase changing materials are commonly used for optical switching, limiting, and sensing. In many important cases, the change in the transmission characteristics of the optical material is caused by light-induced heating. We demonstrate that the incorporation of such optical materials in judiciously designed photonic structures can dramatically alter the light-induced phase change, as well as the transmission characteristics of the entire photonic structure. Possible practical implications are discussed.

Plasmonic properties of regiospecific core-satellite assemblies of gold nanostars and nanospheres.

Solution-based molecularly-mediated bottom-up assembly of gold nanostars and nanospheres in regiospecific core-satellite nanoarchitectures is reported. The controlled assembly is driven by coupling reactions in solution between small, rigid, Raman-active organic molecules bound to the surface of the nanoparticles, and leads to much narrower interparticle gaps than achievable with DNA-based assembly methods. In the described system, gold nanostars with multiple sharp spikes, ideal for electromagnetic field enhancement, are used as the core particle onto which spherical satellites are assembled. Transmission electron micrographs show that the core-satellite structures assemble with <2 nm interparticle gaps and regiospecific binding of only one sphere per spike, and the process can be followed by monitoring changes in the surface enhanced Raman scattering (SERS) spectra of the Raman active linkers. The assembled structures give rise on average to two orders of magnitude SERS signal enhancement per nanoparticle in comparison to their constituents, which can be attributed to the creation of SERS "hot spots" between the nanostar tip and the satellite sphere. Two dimensional finite element electromagnetic models show strongly confined electromagnetic field intensity in the narrow interparticle gaps of core-satellite assemblies, which is significantly enhanced in comparison to the constituent nanoparticles, thus corroborating the experimental findings. Thus, the assemblies reported here can be envisioned as SERS-tags for imaging purposes as well as a model system for SERS-based chemical sensing with improved sensitivity.

Silicon based plasmonic coupler.

Plasmonics is a field in which the light matter interaction can be controlled at the nanoscale by patterning the material surface to achieve enhanced optical effects. Realisation of micron sized silicon based plasmonic devices will require efficient coupling of light from an optical fibre grating coupler into silicon compatible plasmonic waveguides. In this paper we have investigated a silicon based plasmonic coupler with a very short taper length, which confines and focuses light from a broad input fibre opening into a plasmonic waveguide at the apex of the structure. A simple transfer matrix model was also developed to analyse the transmission performance of the coupler with respect to its key physical parameters. The proposed plasmonic coupler was optimised with respect to its different structural parameters using finite element simulations. A maximum coupling efficiency of 72% for light coupling from a 6.2 µm wide input opening into a 20 nm slit width was predicted. The simulated result also predicted an insertion loss of ≈ 2.0 dB for light coupling into a 300 nm single mode SOI waveguide from a plasmonic structure with a 10.4 µm input opening width and a taper length of only 3.15 µm. Furthermore, the application of the optimised plasmonic coupler as a splitter was investigated, in which the structure simultaneously splits and couples light with a predicted coupling efficiency of ≈ 37 % (or a total coupling efficiency of 73%) from a 6.22 µm input opening into two 50 nm wide plasmonic waveguides.