Path Length Calculation Research Articles

Joint-optimized coverage path planning framework for USV-assisted offshore bathymetric mapping: From theory to practice

Designing effective coverage routes for unmanned surface vehicles (USVs) is crucial to improve the efficiency of offshore bathymetric surveys. However, existing coverage planning methods for practical use are limited, primarily due to the large-scale surveying areas and intricate region geometries caused by coastal features. This study aims to address these challenges by introducing a coverage path planning framework for USV-assisted bathymetric mapping, specifically aimed at the joint optimization of paths to cover numerous complex regions. Initially, we conceptualize the large-scale bathymetric survey mission as an integer programming model. The model uses four distinct decision variables to meticulously formulate length calculations, inter-regional connections, entry and exit point selections, and line sweep direction. Then, a novel hierarchical algorithm is devised to solve the problem. The method first incorporates a bisection-based convex decomposition method to achieve optimal partitioning of complex regions. Additionally, a hierarchical heuristic optimization algorithm that seamlessly integrates the optimization of all influencing factors is designed, which includes order generation, candidate pattern finding, tour finding, and final optimization. The reliability of the framework is validated through semi-physical simulations and lake trials using a real USV. Through comparative studies, our model demonstrates clear advantages in computational efficiency and optimization capability compared to state-of-the-arts, with its superiority becoming more pronounced as the problem scale increases. The results from lake trials further affirm the efficient and reliable performance of our model in practical bathymetric survey tasks.

Laser absorption spectroscopy measurements of different pulmonary oxygen gas concentrations in transmittance and remittance geometry: phantom study.

The gas in scattering media absorption spectroscopy (GASMAS) technique has the potential for continuous, clinical monitoring of preterm infant lung function, removing the need for X-ray diagnosis and reliance on indirect and relatively slow measurement of blood oxygenation. We aim to determine the optimal source-detector configuration for reliable pathlength calculation and to estimate the oxygen gas concentration inside the lung cavities filled with humidified gas with four different oxygen gas concentrations ranging between 21% and 100%. Anthropomorphic optical phantoms of neonatal thorax with two different geometries were used to acquire GASMAS signals, for 30 source-detector configurations in transmittance and remittance geometry of phantoms in two sizes. The results show that an internal light administration is more likely to provide a high GASMAS signal-to-noise ratio (SNR). In general, better SNRs were obtained with the smaller set of phantoms. The values of pathlength and concentrations calculated with signals from the phantoms with optical properties at 820nm exhibit higher variations than signals from the phantoms with optical properties at 764nm. Our study shows that, by moving the source and detector over the thorax, most of the lung volumes can potentially be assessed using the GASMAS technique.

Enhancing remote sensing of water temperature using acoustic tomography and 3-D-RPS algorithm

Remote sensing of water temperature and flow dynamics is of paramount importance for water environment management. Coastal acoustic tomography (CAT), an innovative method for remote sensing in underwater environments, utilizes the dual-way travel time of multiple sound paths to reconstruct the underwater temperature field. However, the transmission experiments are susceptible to data noise caused by station drift and inaccuracies in travel time extraction. In this study, a three-dimensional Rousseeuw Phase-Space (3-D-RPS) thresholding algorithm is proposed to remove outliers in the travel time data obtained from Huangcai Reservoir using three CAT systems on September 16, 2020. Additionally, this work includes grid partitioning based on sound path propagation, calculation of sound path lengths, and reference transmission time within each grid, construction of a sparse matrix, and inversion of the two-dimensional temperature field and its associated inversion error. The accuracy and applicability of the proposed method are confirmed through a comparison with data obtained from temperature–depth (TD) sensors. The results demonstrate the precision and suitability of this approach. By effectively mitigating the impact of station drift and extraction accuracy issues, this method provides a reliable temperature field estimation.

Protocol and application of basal erythrocyte transketolase activity to improve assessment of thiamine status.

Thiamine (vitamin B1) is an essential micronutrient required as a cofactor in many metabolic processes. Clinical symptoms of thiamine deficiency are poorly defined, hence biomarkers of thiamine status are important. The erythrocyte transketolase activity coefficient (ETKac) is a sensitive measure of thiamine status, but its interpretation may be confounded where the availability of the transketolase enzyme is limited. Basal ETK activity per gram of hemoglobin provides a complementary biomarker of thiamine status; however, its measurement and calculation are poorly described. Here, we describe in detail the assessment of basal ETK activity, including the calculation of path length in microplates and the molar absorption coefficient of NADH specific to the assay, and the measurement of hemoglobin in sample hemolysates. To illustrate the application of the methods, we present ETKac and basal ETK activity from women in The Gambia and UK. In conclusion, we present a clear protocol for the measurement of basal ETK activity that will permit the harmonization of methods to improve replication between laboratories.

Towards range-guidance in proton therapy to detect organ motion-induced dose degradations

Introduction. Internal organ motion and deformations may cause dose degradations in proton therapy (PT) that are challenging to resolve using conventional image-guidance strategies. This study aimed to investigate the potential of range guidance using water-equivalent path length (WEPL) calculations to detect dose degradations occurring in PT. Materials and methods. Proton ranges were estimated using WEPL calculations. Field-specific isodose surfaces in the planning CT (pCT), from robustly optimised five-field proton plans (opposing lateral and three posterior/posterior oblique beams) for locally advanced prostate cancer patients, were used as starting points. WEPLs to each point on the field-specific isodoses in the pCT were calculated. The corresponding range for each point was found in the repeat CTs (rCTs). The spatial agreement between the resulting surfaces in the rCTs (hereafter referred to as iso-WEPLs) and the isodoses re-calculated in rCTs was evaluated for different dose levels and Hausdorff thresholds (2–5 mm). Finally, the sensitivity and specificity of detecting target dose degradation (V95% < 95%) using spatial agreement measures between the iso-WEPLs and isodoses in the pCT was evaluated. Results. The spatial agreement between the iso-WEPLs and isodoses in the rCTs depended on the Hausdorff threshold. The agreement was 65%–88% for a 2 mm threshold, 83%–96% for 3 mm, 90%–99% for 4 mm, and 94%–99% for 5 mm, across all fields and isodose levels. Minor differences were observed between the different isodose levels investigated. Target dose degradations were detected with 82%–100% sensitivity and 75%–80% specificity using a 2 mm Hausdorff threshold for the lateral fields. Conclusion. Iso-WEPLs were comparable to isodoses re-calculated in the rCTs. The proposed strategy could detect target dose degradations occurring in the rCTs and could be an alternative to a fully-fledged dose re-calculation to detect anatomical variations severely influencing the proton range.

PO-1461: Benchmarking proton therapy water equivalent path length calculations against TPS algorithms

PO-1461: Benchmarking proton therapy water equivalent path length calculations against TPS algorithms

Network-based analysis of Jinfukang in the treatment of lung cancer

IntroductionJinfukang (JFK), a multi-component herbal formula, has been shown to be effective in clinical practice for the treatment of lung cancer (LC). The purpose of this study was to explore the mechanism of action of JFK against lung cancer using network pharmacology analysis. MethodsIn this study, a network consisting of drugs targets and disease related targets was constructed, and then network analysis was performed to study the anti-LC mechanism of JFK. The information of compounds and their targets of JFK were collected from herbal ingredients' targets database (HIT) and nature product activity & species source database (NPASS). Targets of FDA-approved anti-LC drugs were collected from TTD. The disease-related targets and the drug targets were mapped into the background PPI network. In order to confirm the correlation between drug targets and disease-related targets, the shortest path length between them in the network was calculated. Statistical analysis of KEGG and GO function enrichment of the target profile was performed by Metascape. ResultsTo understand the potential anti-LC mechanism of JFK, 384 direct targets of five Chinese herbal medicines of JFK, which were Astragalus membranaceus, Ophiopogon japonicus, Paris polyphylla, Ligustrum lucidum and Gynostemma pentaphyllum were collected. The result of pathway enrichment of drug targets of JKF showed that JFK acted on cancer-related pathways such as “Pathways in cancer”. Besides, drug targets of JFK were significantly enriched in pathways related to LC. To better display the functional similarity and difference among herbs of JFK, pathways that were significantly enriched were mapped according to the map of KEGG “Small cell lung cancer” and “Non-small cell lung cancer” pathways. The results showed that multiple targets and multiple pathways were involved in the anti-LC effect of JFK. This was mainly related to the inhibition of cell proliferation and the induction of cell apoptosis. The result of network shortest path length calculation showed that drug targets of JFK were closely related to disease-related targets of LC. ConclusionThe therapeutic effect of JFK on LC involved multiple targets and multiple pathways was mainly related to the inhibition of cell proliferation and the induction of cell apoptosis.

Simulation and calibration of a compact millimeter-wavelength Fourier transform spectrometer.

This paper presents the simulation and calibration of a Fourier transform spectrometer (FTS) developed to measure the spectrum of radiation sources between 50 GHz and 330 GHz, such as the cosmic microwave background. The recorded signal is modified from the ideal by properties of the interferometer and the detection system. We have developed a ray-trace-based simulation with which we can model these effects. The model can be verified with measurements and used to understand the instrument's systematic effects and to design new optimized configurations. The optimization comprises parameters of the design, such as large étendu, maximal spectral resolution, compact size, operational simplicity, and light weight, that conflict and need to be balanced. The numerical simulation consists of two parts: time-stream signal analysis and a ray-trace-based simulation that includes polarization and path length calculations and can account for the effects of beam loss and change of focus as the delay-generating mirror travels on its path. The simulation can study the coherence level and frequency resolution of the FTS instrument. While not exercised in this study, the simulation also can be used to study the effect of mirror figure and polarizer non-idealities, walk-off rays in the beam due to the large étendu, as well as misalignment of optical elements. We then present the comparison between simulations of a spectrally unresolved source and measurements by the FTS.

Оценка эффективности пневматического тормоза рельсового автобуса РА-3

Braking system is a very important element of any rolling stock unit, as transportation process safety depends on its efficiency and reliability. Rail buses represent development of diesel trains intended for passenger service on non-electrified track sections. A sudden obstacle on the track requires immediate full stop of the rolling stock, it is urgent to have effective braking which provides the least brake path length. The paper presents results of brake path length calculation for РА-3 rail bus in two-car version with iron and composite brake pads.

Beam angle optimization using angular dependency of range variation assessed via water equivalent path length (WEPL) calculation for head and neck proton therapy

PurposeTo investigate angular sensitivity of proton range variation due to anatomic change in patients and patient setup error via water equivalent path length (WEPL) calculations. MethodsProton range was estimated by calculating WEPL to the distal edge of target volume using planning CT (pCT) and weekly scatter-corrected cone-beam CT (CBCT) images of 11 head and neck patients. Range variation was estimated as the difference between the distal WEPLs calculated on pCT and scatter-corrected CBCT (cCBCT). This WEPL analysis was performed every five degrees ipsilaterally to the target. Statistics of the distal WEPL difference were calculated over the distal area to compare between different beam angles. Physician-defined contours were used for the WEPL calculation on both pCT and cCBCT, not considering local deformation of target volume. It was also tested if a couch kick (10°) can mitigate the range variation due to anatomic change and patient setup error. ResultsFor most of the patients considered, median, 75% quantile, and 95% quantile of the distal WEPL difference were largest for posterior oblique angles, indicating a higher chance of overdosing normal tissues at distal edge with these angles. Using a couch kick resulted in decrease in the WEPL difference for some posterior oblique angles. ConclusionsIt was demonstrated that the WEPL change has angular dependency for the cohort of head and neck cancer patients. Selecting beam configuration robust to anatomic change in patient and patient setup error may improve the treatment outcome of head and neck proton therapy.

EP-2068 Scatter-corrected CBCTs for online water-equivalent path length calculations in proton therapy

EP-2068 Scatter-corrected CBCTs for online water-equivalent path length calculations in proton therapy

A calibration/validation protocol for long/multi‐pathlength capillary waveguide spectrometers

AbstractLong/multi‐pathlength spectrometers are being employed increasingly in ocean science, but detailed calibration/validation protocols for these instruments remain unavailable. The lack of such protocols has led to the collection of absorption data from different instruments that are not always comparable. The goal of this work was to develop procedures that improve inter‐laboratory data reproducibility and accuracy. A World Precision Instrument (WPI) multi‐pathlength liquid capillary waveguide spectrometer along with a Shimadzu dual‐beam spectrometer were employed to evaluate the proposed protocols, which address the following issues: (1) sample cross‐contamination due to improper cell cleaning, (2) nonstandardized sample preparation, (3) errors in effective pathlength determination, and (4) offsets due to refractive index effects (i.e., high‐salinity samples). Effective pathlength calculation is critical given that the measured and manufacturer provided pathlengths can differ significantly, with the provided pathlengths resulting in data with large variation (up to 21%) and percent error (up to 33%) when employing different pathlengths. When these proposed protocols were applied, we found that the WPI spectrometer's precision (measured as a coefficient of variation) was &lt; 0.6% for intra‐day measurements and &lt; 1.5% for inter‐day measurements, and there was &lt; 2% error in absorbance measurements. These procedures allowed for the correction of the significant baseline offsets caused by differences in refractive index between reference and sample, by either subtracting a collected or a generated reference spectrum that matches the offset. Our results indicate that employing the procedures described herein will provide accurate, reproducible, and pathlength‐independent absorption data.

Development and Validation of a Path Length Calculation for Carotid–Femoral Pulse Wave Velocity Measurement

Current distance measurement techniques for pulse wave velocity (PWV) calculation are susceptible to intercenter variability. The aim of this study was to derive and validate a formula for this distance measurement. Based on carotid femoral distance in 1183 whole-body magnetic resonance angiograms, a formula was derived for calculating distance. This was compared with distance measurements in 128 whole-body magnetic resonance angiograms from a second study. The effects of recalculation of PWV using the new formula on association with risk factors, disease discrimination, and prediction of major adverse cardiovascular events were examined within 1242 participants from the multicenter SUMMIT study (Surrogate Markers of Micro- and Macrovascular Hard End-Points for Innovative Diabetes Tools) and 825 participants from the Caerphilly Prospective Study. The distance formula yielded a mean error of 7.8 mm (limits of agreement =-41.1 to 56.7 mm; P<0.001) compared with the second whole-body magnetic resonance angiogram group. Compared with an external distance measurement, the distance formula did not change associations between PWV and age, blood pressure, or creatinine (P<0.01) but did remove significant associations between PWV and body mass index (BMI). After accounting for differences in age, sex, and mean arterial pressure, intercenter differences in PWV persisted using the external distance measurement (F=4.6; P=0.004), whereas there was a loss of between center difference using the distance formula (F=1.4; P=0.24). PWV odds ratios for cardiovascular mortality remained the same using both the external distance measurement (1.14; 95% confidence interval, 1.06-1.24; P=0.001) and the distance formula (1.17; 95% confidence interval, 1.08-1.28; P<0.001). A population-derived automatic distance calculation for PWV obtained from routinely collected clinical information is accurate and removes intercenter measurement variability without impacting the diagnostic utility of carotid-femoral PWV.

Proton radiography for inline treatment planning and positioning verification of small animals

Introduction: As proton therapy becomes increasingly well established, there is a need for high-quality clinically relevant in vivo data to gain better insight into the radiobiological effects of proton irradiation on both healthy and tumor tissue. This requires the development of easily applicable setups that allow for efficient, fractionated, image-guided proton irradiation of small animals, the most widely used pre-clinical model.Material and methods: Here, a method is proposed to perform dual-energy proton radiography for inline positioning verification and treatment planning. Dual-energy proton radiography exploits the differential enhancement of object features in two successively measured two-dimensional (2D) dose distributions at two different proton energies. The two raw images show structures that are dominated by energy absorption (absorption mode) or scattering (scattering mode) of protons in the object, respectively. Data post-processing allowed for the separation of both signal contributions in the respective images. The images were evaluated regarding recognizable object details and feasibility of rigid registration to acquired planar X-ray scans.Results: Robust, automated rigid registration of proton radiography and planar X-ray images in scattering mode could be reliably achieved with the animal bedding unit used as registration landmark. Distinguishable external and internal features of the imaged mouse included the outer body contour, the skull with substructures, the lung, abdominal structures and the hind legs. Image analysis based on the combined information of both imaging modes allowed image enhancement and calculation of 2D water-equivalent path length (WEPL) maps of the object along the beam direction.Discussion: Fractionated irradiation of exposed target volumes (e.g., subcutaneous tumor model or brain) can be realized with the suggested method being used for daily positioning and range determination. Robust registration of X-ray and proton radiography images allows for the irradiation of tumor entities that require conventional computed tomography (CT)-based planning, such as orthotopic lung or brain tumors, similar to conventional patient treatment.

Water equivalent path length calculations using scatter-corrected head and neck CBCT images to evaluate patients for adaptive proton therapy

Proton therapy has dosimetric advantages due to the well-defined range of the proton beam over photon radiotherapy. When the proton beams, however, are delivered to the patient in fractionated radiation treatment, the treatment outcome is affected by delivery uncertainties such as anatomic change in the patient and daily patient setup error. This study aims at establishing a method to evaluate the dosimetric impact of the anatomic change and patient setup error during head and neck proton therapy. Range variations due to the delivery uncertainties were assessed by calculating water equivalent path length (WEPL) to the distal edge of tumor volume using planning CT and weekly treatment cone-beam CT (CBCT) images. Specifically, mean difference and root mean squared deviation (RMSD) of the distal WEPLs were calculated as the weekly range variations. To accurately calculate the distal WEPLs, an existing CBCT scatter correction algorithm was used. An automatic rigid registration was used to align the planning CT and treatment CBCT images, simulating a six degree-of-freedom couch correction at treatments. The authors conclude that the dosimetric impact of the anatomic change and patient setup error was reasonably captured in the differences of the distal WEPL variation with a range calculation uncertainty of 2%. The proposed method to calculate the distal WEPL using the scatter-corrected CBCT images can be an essential tool to decide the necessity of re-planning in adaptive proton therapy.

Calculation of the full-energy peak efficiency of NaI(Tl) detector using the efficiency transfer method for large radioactive cylindrical sources

A new theoretical approach is introduced in this article to calculate the full-energy peak efficiency of cylindrical NaI(Tl) γ-ray detectors. This new approach depends mainly on an analytical calculation of the photon average path lengths inside the source-to-detector system. The effective solid angle Ω join mathematically with the efficiency transfer method (ET) to obtain a simple formula for the detection efficiency. The self attenuation factor of the source (with a radius greater than the detector's radius) matrix is also considered. In addition, the attenuation factors of the source container, the detector housing and any absorbing materials during the measurement are also included. Results are compared with those obtained from ETNA program and those measured by two different cylindrical NaI(Tl) detectors with resolution (FWHM) at 662 keV equal to 7.5% and 8.5%, respectively. 152Eu aqueous radioactive cylindrical sources covering the energy range from 121 keV up to 1408 keV are used. The measured and the calculated with ETNA program efficiencies are compared with those calculated with this new approach. The results are found satisfactory with negligible discrepancies.

MO-FG-CAMPUS-JeP1-05: Water Equivalent Path Length Calculations Using Scatter-Corrected Head and Neck CBCT Images to Evaluate Patients for Adaptive Proton Therapy

Purpose: To establish a method to evaluate the dosimetric impact of anatomic changes in head and neck patients during proton therapy by using scatter-corrected cone-beam CT (CBCT) images. Methods: The water equivalent path length (WEPL) was calculated to the distal edge of PTV contours by using tomographic images available for six head and neck patients received photon therapy. The proton range variation was measured by calculating the difference between the distal WEPLs calculated with the planning CT and weekly treatment CBCT images. By performing an automatic rigid registration, six degrees-of-freedom (DOF) correction was made to the CBCT images to account for the patient setup uncertainty. For accurate WEPL calculations, an existing CBCT scatter correction algorithm, whose performance was already proven for phantom images, was calibrated for head and neck patient images. Specifically, two different image similarity measures, mutual information (MI) and mean square error (MSE), were tested for the deformable image registration (DIR) in the CBCT scatter correction algorithm. Results: The impact of weight loss was reflected in the distal WEPL differences with the aid of the automatic rigid registration reducing the influence of patient setup uncertainty on the WEPL calculation results. The WEPL difference averaged over distal area was 2.9 ± 2.9 (mm) across all fractions of six patients and its maximum, mostly found at the last available fraction, was 6.2 ± 3.4 (mm). The MSE-based DIR successfully registered each treatment CBCT image to the planning CT image. On the other hand, the MI-based DIR deformed the skin voxels in the planning CT image to the immobilization mask in the treatment CBCT image, most of which was cropped out of the planning CT image. Conclusion: The dosimetric impact of anatomic changes was evaluated by calculating the distal WEPL difference with the existing scatter-correction algorithm appropriately calibrated. Jihun Kim, Yang-Kyun Park, Gregory Sharp, and Brian Winey have received grant support from the NCI Federal Share of program income earned by Massachusetts General Hospital on C06 CA059267, Proton Therapy Research and Treatment Center.

SU‐E‐T‐455: Impact of Different Independent Dose Verification Software Programs for Secondary Check

Purpose:There have been many reports for different dose calculation algorithms for treatment planning system (TPS). Independent dose verification program (IndpPro) is essential to verify clinical plans from the TPS. However, the accuracy of different independent dose verification programs was not evident. We conducted a multi‐institutional study to reveal the impact of different IndpPros using different TPSs.Methods:Three institutes participated in this study. They used two different IndpPros (RADCALC and Simple MU Analysis (SMU), which implemented the Clarkson algorithm. RADCALC needed the input of radiological path length (RPL) computed by the TPSs (Eclipse or Pinnacle3). SMU used CT images to compute the RPL independently from TPS). An ion‐chamber measurement in water‐equivalent phantom was performed to evaluate the accuracy of two IndpPros and the TPS in each institute. Next, the accuracy of dose calculation using the two IndpPros compared to TPS was assessed in clinical plan.Results:The accuracy of IndpPros and the TPSs in the homogenous phantom was +/−1% variation to the measurement. 1543 treatment fields were collected from the patients treated in the institutes. The RADCALC showed better accuracy (0.9 ± 2.2 %) than the SMU (1.7 ± 2.1 %). However, the accuracy was dependent on the TPS (Eclipse: 0.5%, Pinnacle3: 1.0%). The accuracy of RADCALC with Eclipse was similar to that of SMU in one of the institute.Conclusion:Depending on independent dose verification program, the accuracy shows systematic dose accuracy variation even though the measurement comparison showed a similar variation. The variation was affected by radiological path length calculation. IndpPro with Pinnacle3 has different variation because Pinnacle3 computed the RPL using physical density. Eclipse and SMU uses electron density, though.

On the complexity of average path length for biological networks and patterns

Path length calculation is a frequent requirement in studies related to graph theoretic problems such as genetics. Standard method to calculate average path length (APL) of a graph requires traversing all nodes in the graph repeatedly, which is computationally expensive for graphs containing large number of nodes. We propose a novel method to calculate APL for graphs commonly required in the studies of genetics. The proposed method is computationally less expensive and less time-consuming compared to standard method.

Calculation and control of flow path length in superelevation sections

For the sake of researching the drainage on superelevation section, according to the character of the superelevation gradient process, the calculation models of flow path length for superelevation gradient sections with the same change direction and the opposite are built by FDM and multiple linear regression method. Then, Considered traffic safety and unfavorable drainage combination state with the critical water film thickness, the formula of the flow path maximum control length is deduced based on flow continuity and momentum theory. The maximum length of flow path should not exceed 41 m for highway in 80 km/h. Finally, the calculation model is verified to be workable and reasonable by the engineering example, and flow path length can be reduced by setting appropriate longitudinal slope or superelevation to improve the road surface drainage condition.