Radial-mode sensitive probe beam in the rotational Doppler effect.

The rotational Doppler effect (RDE) attracts much attention in various research areas, from acoustics to optics. The observation of RDE mostly depends on the orbital angular momentum of the probe beam, while the impression of radial mode is ambiguous. To clarify the role of radial modes in RDE detection, we reveal the mechanism of interaction between probe beams and rotating objects based on complete Laguerre-Gaussian (LG) modes. It is theoretically and experimentally proved that radial LG modes play a crucial role in RDE observation because of topological spectroscopic orthogonality between probe beams and objects. We enhance the probe beam by employing multiple radial LG modes, which makes the RDE detection sensitive to objects containing complicated radial structures. In addition, a specific method to estimate the efficiency of various probe beams is proposed. This work has the potential to modify RDE detection method and take the related applications to a new platform.

Multi-target object scattering imaging with intensity correlation of structured illumination.

Imaging through scattering layers based on the optical memory effect (OME) concept has been widely investigated in recent years. Among many scattering scenarios, it is very important to recover hidden targets with proper spatial distribution in the scene where multiple targets out of the OME range exist. In this Letter, we put forward a method for multi-target object scattering imaging. With the help of intensity correlation between the structured illumination patterns and recorded speckle images, the relative position of all hidden targets can be obtained and the movement of the targets within the OME range can be tracked. We experimentally implement scattering imaging with 16 targets and the motion tracking of them. Our results present a significant advance in a large field of view scattering imaging with multiple targets.

Dosimetric impact of hollow intraoral stents for head and neck cancer radiotherapy: A phantom study.

PURPOSE: To investigate the dosimetric impact of the calculation boundaries and dose calculation algorithms of radiotherapy in head and neck cancer patients with an opened oral cavity connected to the exterior by a hollow intraoral positioning stent. METHODS AND MATERIALS: A homemade silicone phantom with an opened oral cavity was placed in a CIRS head phantom to model head and neck cancer patients with a hollow intraoral positioning stent. 3D-CRT plans were designed on CT images of the phantom in Monaco and Pinnacle3 treatment planning systems (TPSs) with the same beam parameters. The default boundary and manually extrapolated boundary were both adopted in these two TPSs to explore the dosimetric impact on treatment plans. The nanoDot™ optically stimulated luminescence dosimeters (OSLDs) were chosen to measure the planned dose surrounding the oral cavity of the head phantom after calibration. RESULT: The doses in the air cavity and two measuring points at the joint area were dramatically changed from 0.0, 92.4 and 148.8 cGy to 177.8, 244.2 and 244.1 cGy in Monaco after adopting the extrapolated boundary. While the calculated doses at the same place were changed from 61.2, 143.7 and 198.3 cGy to 175.4, 234.7 and 233.2 cGy in Pinnacle3 with a similar calculation boundary. For the Monaco TPS, the relative errors compared to the OSLD measured doses were 2.94 ± 1.93%, 0.53 ± 8.64%, 2.65 ± 1.87% and 3.93 ± 1.69% at 4 measuring positions. In contrast, the relative errors 4.03 ± 1.93%, 4.85 ± 8.64%, 7.61 ± 1.87% and 5.61 ± 1.69% were observed in Pinnacle3 . CONCLUSION: The boundary setting of an opened oral cavity in TPSs has a significant dosimetric impact on head and neck cancer radiotherapy. An extrapolated boundary should be manually set up to include the whole oral cavity in the dose calculation domain to avoid major dose deviations.

Comparison of geometrical uncertainties in the radiotherapy for various treatment sites with two different immobilization marking methods.

OBJECTIVE: The skin marking method (SMM) and bow-form-ruler marking method (BFRM) are two commonly used patient marking methods in mainland China. This study aims to evaluate SMM and BFRM by comparing the inter-fraction setup errors from using these two methods together with vacuum cushion immobilization in patients underwent radiotherapy for different treatment sites. MATERIALS AND METHODS: Eighteen patients diagnosed with pelvic, abdominal and thoracic malignant tumors (with 6 patients per treatment site) were enrolled in this prospective study. All patients were immobilized with vacuum cushion. Each patient was marked by both SMM and BFRM before computed tomography (CT) simulation. Target location was verified by cone beam CT images with displacements assessed prior to each sampled treatment session. The localization errors in three translational and three rotational directions were recorded and analyzed. RESULTS: Images from 108 fractions in 18 patients produced 324 translational and 324 rotational comparisons for SMM and BFRM. The setup errors of all treatment sites showed no difference in two marking methods in any directions (p > 0.05). In subgroups of treatment site analysis, SMM significantly lessened the lateral and yaw setup errors compared to BFRM in the pelvic sites (0.39±1.85 mm vs -1.28±1.13 mm, p < 0.01 and -0.19±0.59° vs -0.61±0.59°, p < 0.05). However, in the abdominal subgroup, BFRM was superior to SMM for reduced vertical errors (0.17±2.73 mm vs 2.28±3.16 mm, p < 0.05). For the underweight or obese patients (with Body Mass Index, BMI < 18.5 or BMI≥24), SMM resulted in less yaw errors compared to BFRM (-0.05±0.38° vs -0.43±0.48°, p < 0.05). No significant difference between SMM and BFRM in setup errors of normal weighted patients (18.5≤BMI < 24) was observed for all three studied treatment sites. CONCLUSIONS: This study shows no significant difference in patient setup errors for various treatment sites between SMM and BFRM in general. SMM may be suitable for the pelvic tumor and patients with BMI < 18.5 or BMI≥24, while BFRM is recommended for the abdominal tumor sites.

Virtual histological staining of unlabeled autopsy tissue.

Traditional histochemical staining of post-mortem samples often confronts inferior staining quality due to autolysis caused by delayed fixation of cadaver tissue, and such chemical staining procedures covering large tissue areas demand substantial labor, cost and time. Here, we demonstrate virtual staining of autopsy tissue using a trained neural network to rapidly transform autofluorescence images of label-free autopsy tissue sections into brightfield equivalent images, matching hematoxylin and eosin (H&E) stained versions of the same samples. The trained model can effectively accentuate nuclear, cytoplasmic and extracellular features in new autopsy tissue samples that experienced severe autolysis, such as COVID-19 samples never seen before, where the traditional histochemical staining fails to provide consistent staining quality. This virtual autopsy staining technique provides a rapid and resource-efficient solution to generate artifact-free H&E stains despite severe autolysis and cell death, also reducing labor, cost and infrastructure requirements associated with the standard histochemical staining.

Rapid and stain-free quantification of viral plaque via lens-free holography and deep learning.

A plaque assay-the gold-standard method for measuring the concentration of replication-competent lytic virions-requires staining and usually more than 48 h of runtime. Here we show that lens-free holographic imaging and deep learning can be combined to expedite and automate the assay. The compact imaging device captures phase information label-free at a rate of approximately 0.32 gigapixels per hour per well, covers an area of about 30 × 30 mm2 and a 10-fold larger dynamic range of virus concentration than standard assays, and quantifies the infected area and the number of plaque-forming units. For the vesicular stomatitis virus, the automated plaque assay detected the first cell-lysing events caused by viral replication as early as 5 h after incubation, and in less than 20 h it detected plaque-forming units at rates higher than 90% at 100% specificity. Furthermore, it reduced the incubation time of the herpes simplex virus type 1 by about 48 h and that of the encephalomyocarditis virus by about 20 h. The stain-free assay should be amenable for use in virology research, vaccine development and clinical diagnosis.