Automatic Extraction of Power Lines from Aerial Images of Unmanned Aerial Vehicles.

Automatic power line extraction from aerial images of unmanned aerial vehicles is one of the key technologies of power line inspection. However, the faint power line targets and complex image backgrounds make the extraction of power lines a greater challenge. In this paper, a new power line extraction method is proposed, which has two innovative points. Innovation point one, based on the introduction of the Mask RCNN network algorithm, proposes a block extraction strategy to realize the preliminary extraction of power lines with the idea of "part first and then the whole". This strategy globally reduces the anchor frame size, increases the proportion of power lines in the feature map, and reduces the accuracy degradation caused by the original negative anchor frames being misclassified as positive anchor frames. Innovation point two, the proposed connected domain group fitting algorithm solves the problem of broken and mis-extracted power lines even after the initial extraction and solves the problem of incomplete extraction of power lines by background texture interference. Through experiments on 60 images covering different complex image backgrounds, the performance of the proposed method far exceeds that of commonly used methods such as LSD, Yolact++, and Mask RCNN. DSCPL, TPR, precision, and accuracy are as high as 73.95, 81.75, 69.28, and 99.15, respectively, while FDR is only 30.72. The experimental results show that the proposed algorithm has good performance and can accomplish the task of power line extraction under complex image backgrounds. The algorithm in this paper solves the main problems of power line extraction and proves the feasibility of the algorithm in other scenarios. In the future, the dataset will be expanded to improve the performance of the algorithm in different scenarios.

Influence of the Integral Quality Monitor transmission detector on high energy photon beams: A multi-centre study.

PURPOSE: The influence of the Integral Quality Monitor (IQM) transmission detector on photon beam properties was evaluated in a preclinical phase, using data from nine participating centres: (i) the change of beam quality (beam hardening), (ii) the influence on surface dose, and (iii) the attenuation of the IQM detector. METHODS: For 6 different nominal photon energies (4 standard, 2 FFF) and square field sizes from 1×1cm2 to 20×20cm2, the effect of IQM on beam quality was assessed from the PDD20,10 values obtained from the percentage dose depth (PDD) curves, measured with and without IQM in the beam path. The change in surface dose with/without IQM was assessed for all available energies and field sizes from 4×4cm2 to 20×20cm2. The transmission factor was calculated by means of measured absorbed dose at 10cm depth for all available energies and field sizes. RESULTS: (i) A small (0.11-0.53%) yet statistically significant beam hardening effect was observed, depending on photon beam energy. (ii) The increase in surface dose correlated with field size (p<0.01) for all photon energies except for 18MV. The change in surface dose was smaller than 3.3% in all cases except for the 20×20cm2 field and 10MV FFF beam, where it reached 8.1%. (iii) For standard beams, transmission of the IQM showed a weak dependence on the field size, and a pronounced dependence on the beam energy (0.9412 for 6MV to 0.9578 for 18MV and 0.9440 for 6MV FFF; 0.9533 for 10MV FFF). CONCLUSIONS: The effects of the IQM detector on photon beam properties were found to be small yet statistically significant. The magnitudes of changes which were found justify treating IQM either as tray factors within the treatment planning system (TPS) for a particular energy or alternatively as modified outputs for specific beam energy of linear accelerators, which eases the introduction of the IQM into clinical practice.

[The comparison of the micro-syringe with clinical usage].

Micro-syringe as a result of the high frequency of clinical use, direct contact with patients, the failure of its equipment will have a direct impact on the patient's disease status. Researchers in this paper, by simulating the test fluid, electrical safety testing and analysis of statistical methods such as maintenance records, consider six kinds of common injection pump, in terms of performance, safety and the failure rate of three performance. Compared the performance analysis, summarized the various types of injection pump characteristics, researchers make suggestions to clinical departments, equipment procurement and equipment management departments for usage and improvement.

Hydrophobic task-specific ionic liquids: synthesis, properties and application for the capture of SO2.

The capture of SO2 by ionic liquids (ILs) has drawn much attention all over the world. However, ILs can absorb not only SO2 but also water from flue gas. The removal of water from ILs is necessary for reusing the absorbent. In order to reduce the energy costs of removing water, it would be helpful to weaken the interactions between ILs and water. In this work, two kinds of hydrophobic task-specific ILs, 1-(2-diethyl-aminoethyl)-3-methylimidazolium hexafluorophosphate ([Et2NEmim] [PF6]) and 1-(2-diethyl-aminoethyl)-1-methylpyrrolidinium hexafluorophosphate ([Et2NEmpyr][PF6]), were designed and synthesized. Thermal stability and physical properties of the ILs were studied. Furthermore, the application of the ILs for the capture of SO2 and the absorption mechanism were systematically investigated. It has been found that both of the ILs are immiscible with water, and [Et2NEmim][PF6] has much lower viscosity, much higher thermal stability and much higher SO2 absorption rate than [Et2NEmpyr][PF6]. [Et2NEmim][PF6] shows high SO2 absorption capacities up to 2.11 mol SO2 per mole IL (pure SO2) and 0.94 mol SO2 per mole IL (3% SO2) under hydrous conditions at 30 °C. The result suggests that [Et2NEmim][PF6] is a promising recyclable absorbent for the capture of SO2.

[2011 after-service customer satisfaction survey of monitoring devices in Shanghai area].

In 2011, Shanghai Medical Equipment Management Quality Control Center launched the fifth after-sale service satisfaction survey for medical devices in Shanghai area. There are 8 classes medical devices involving in the survey. This paper demonstrates the investigation results of monitoring devices which are from different manufacturers.

Development of XFCT imaging strategy for monitoring the spatial distribution of platinum-based chemodrugs: instrumentation and phantom validation.

PURPOSE: Developing an imaging method to directly monitor the spatial distribution of platinum-based (Pt) drugs at the tumor region is of critical importance for early assessment of treatment efficacy and personalized treatment. In this study, the authors investigated the feasibility of imaging platinum (Pt)-based drug distribution using x-ray fluorescence (XRF, a.k.a. characteristic x ray) CT (XFCT). METHODS: A 5-mm-diameter pencil beam produced by a polychromatic x-ray source equipped with a tungsten anode was used to stimulate emission of XRF photons from Pt drug embedded within a water phantom. The phantom was translated and rotated relative to the stationary pencil beam in a first-generation CT geometry. The x-ray energy spectrum was collected for 18 s at each position using a cadmium telluride detector. The spectra were then used for the K-shell XRF peak isolation and sinogram generation for Pt. The distribution and concentration of Pt were reconstructed with an iterative maximum likelihood expectation maximization algorithm. The capability of XFCT to multiplexed imaging of Pt, gadolinium (Gd), and iodine (I) within a water phantom was also investigated. RESULTS: Measured XRF spectrum showed a sharp peak characteristic of Pt with a narrow full-width at half-maximum (FWHM) (FWHMKα1 = 1.138 keV, FWHMKα2 = 1.052 keV). The distribution of Pt drug in the water phantom was clearly identifiable on the reconstructed XRF images. Our results showed a linear relationship between the XRF intensity of Pt and its concentrations (R(2) = 0.995), suggesting that XFCT is capable of quantitative imaging. A transmission CT image was also obtained to show the potential of the approach for providing attenuation correction and morphological information. Finally, the distribution of Pt, Gd, and I in the water phantom was clearly identifiable in the reconstructed images from XFCT multiplexed imaging. CONCLUSIONS: XFCT is a promising modality for monitoring the spatial distribution of Pt drugs. The technique may be useful in tailoring tumor treatment regimen in the future.

First demonstration of multiplexed X-ray fluorescence computed tomography (XFCT) imaging.

Simultaneous imaging of multiple probes or biomarkers represents a critical step toward high specificity molecular imaging. In this work, we propose to utilize the element-specific nature of the X-ray fluorescence (XRF) signal for imaging multiple elements simultaneously (multiplexing) using XRF computed tomography (XFCT). A 5-mm-diameter pencil beam produced by a polychromatic X-ray source (150 kV, 20 mA) was used to stimulate emission of XRF photons from 2% (weight/volume) gold (Au), gadolinium (Gd), and barium (Ba) embedded within a water phantom. The phantom was translated and rotated relative to the stationary pencil beam in a first-generation CT geometry. The X-ray energy spectrum was collected for 18 s at each position using a cadmium telluride detector. The spectra were then used to isolate the K shell XRF peak and to generate sinograms for the three elements of interest. The distribution and concentration of the three elements were reconstructed with the iterative maximum likelihood expectation maximization algorithm. The linearity between the XFCT intensity and the concentrations of elements of interest was investigated. We found that measured XRF spectra showed sharp peaks characteristic of Au, Gd, and Ba. The narrow full-width at half-maximum (FWHM) of the peaks strongly supports the potential of XFCT for multiplexed imaging of Au, Gd, and Ba ( FWHM(Au,Kα1) = 0.619 keV, FWHM(Au,Kα2)=1.371 keV , FWHM(Gd,Kα)=1.297 keV, FWHM(Gd,Kß)=0.974 keV , FWHM(Ba,Kα)=0.852 keV, and FWHM(Ba,Kß)=0.594 keV ). The distribution of Au, Gd, and Ba in the water phantom was clearly identifiable in the reconstructed XRF images. Our results showed linear relationships between the XRF intensity of each tested element and their concentrations ( R(2)(Au)=0.944 , R(Gd)(2)=0.986, and R(Ba)(2)=0.999), suggesting that XFCT is capable of quantitative imaging. Finally, a transmission CT image was obtained to show the potential of the approach for providing attenuation correction and morphological information. In conclusion, XFCT is a promising modality for multiplexed imaging of high atomic number probes.

[Quality improvement and performance evaluation of Monitoring and Tracking Medical Materials Lot Number].

With various increasing health sector's demand of medical materials, monitoring and tracking medical materials lot number has become the most important thing of hospital's medical materials management. This paper discussed and researched deeply the actual operation problem through data analysis and charts comparison, put forward realizing barcodes wireless scanning, and synchronizing information in local area network, so to improve the barcode input accuracy. Achieve the ultimate goal of completing medical materials lot number traceability.

Improved compressed sensing-based cone-beam CT reconstruction using adaptive prior image constraints.

Volumetric cone-beam CT (CBCT) images are acquired repeatedly during a course of radiation therapy and a natural question to ask is whether CBCT images obtained earlier in the process can be utilized as prior knowledge to reduce patient imaging dose in subsequent scans. The purpose of this work is to develop an adaptive prior image constrained compressed sensing (APICCS) method to solve this problem. Reconstructed images using full projections are taken on the first day of radiation therapy treatment and are used as prior images. The subsequent scans are acquired using a protocol of sparse projections. In the proposed APICCS algorithm, the prior images are utilized as an initial guess and are incorporated into the objective function in the compressed sensing (CS)-based iterative reconstruction process. Furthermore, the prior information is employed to detect any possible mismatched regions between the prior and current images for improved reconstruction. For this purpose, the prior images and the reconstructed images are classified into three anatomical regions: air, soft tissue and bone. Mismatched regions are identified by local differences of the corresponding groups in the two classified sets of images. A distance transformation is then introduced to convert the information into an adaptive voxel-dependent relaxation map. In constructing the relaxation map, the matched regions (unchanged anatomy) between the prior and current images are assigned with smaller weight values, which are translated into less influence on the CS iterative reconstruction process. On the other hand, the mismatched regions (changed anatomy) are associated with larger values and the regions are updated more by the new projection data, thus avoiding any possible adverse effects of prior images. The APICCS approach was systematically assessed by using patient data acquired under standard and low-dose protocols for qualitative and quantitative comparisons. The APICCS method provides an effective way for us to enhance the image quality at the matched regions between the prior and current images compared to the existing PICCS algorithm. Compared to the current CBCT imaging protocols, the APICCS algorithm allows an imaging dose reduction of 10-40 times due to the greatly reduced number of projections and lower x-ray tube current level coming from the low-dose protocol.

Fidelity of dose delivery at high dose rate of volumetric modulated arc therapy in a truebeam linac with flattening filter free beams.

The purpose of this study is to assess fidelity of radiation delivery between high and low dose rates of the flattening filter free (FFF) modes of a new all-digital design medical linear accelerator (Varian TrueBeam™), particularly for plans optimized for volumetric modulated arc therapy (VMAT). Measurements were made for the two energies of flattening filter free photon beams with a Varian TrueBeam™ linac: 6 MV (6 XFFF) at 400 and 1400 MU/min, and 10 MV (10 XFFF) at 400 and 2400 MU/min. Data acquisition and analysis was performed with both ionization chambers and diode detector system Delta(4), for square radiation fields and for 8 VMAT treatment plans optimized for SBRT treatment of lung tumors. For the square fields, a percent dose difference between high and low dose rate of the order of 0.3-0.4% for both photon energies was seen with the ionization chambers, while the contribution to the difference from ion recombination was found to be negligible. For both the VMAT and square-field deliveries, the Delta(4) showed the same average percent dose difference between the two dose rates of ~0.8% and ~0.6% for 10 MV and 6 MV, respectively, with the lower dose rate values giving the greater measured dose compared to the high dose rate. Thus, the VMAT deliveries introduced negligible dose differences between high and low dose rate. Finally, reproducibility of dose measurements was good for both energies.

[2011 Shanghai customer satisfaction report of DSA/X-ray equipment's after-service].

To improve the manufacturer's medical equipment after-sale service, the fifth Shanghai zone customer satisfaction survey was launched by the end of 2011. The DSA/X-ray equipment was setup as an independent category for the first time. From the survey we can show that the DSA/X-ray equipment's CSI is higher than last year, the customer satisfaction scores of preventive maintenance and service contract are lower than others, and CSI of local brand is lower than imported brand.

[Grade III general hospital grade assessment as an opportunity to improve the management level of medical equipment].

In the grade III general hospital reassessment, The department of hospital equipment accords its demand to find the problems and gaps in the actual work, gives modification opinions and programs, and clarifies continuous improved contents in next step, so to improve the management level of medical equipment.

Dose verification for respiratory-gated volumetric modulated arc therapy.

A novel commercial medical linac system (TrueBeam™, Varian Medical Systems, Palo Alto, CA) allows respiratory-gated volumetric modulated arc therapy (VMAT), a new modality for treating moving tumors with high precision and improved accuracy by allowing for regular motion associated with a patient's breathing during VMAT delivery. The purpose of this work is to adapt a previously-developed dose reconstruction technique to evaluate the fidelity of VMAT treatment during gated delivery under clinic-relevant periodic motion related to patient breathing. A Varian TrueBeam system was used in this study. VMAT plans were created for three patients with lung or pancreas tumors. Conventional 6 and 15 MV beams with flattening filter and high-dose-rate 10 MV beams with no flattening filter were used in these plans. Each patient plan was delivered to a phantom first without gating and then with gating for three simulated respiratory periods (3, 4.5 and 6 s). Using the adapted log-file-based dose reconstruction procedure supplemented with ion chamber array (Seven29™, PTW, Freiburg, Germany) measurements, the delivered dose was used to evaluate the fidelity of gated VMAT delivery. Comparison of Seven29 measurements with and without gating showed good agreement with gamma-index passing rates above 99% for 1%/1 mm dose accuracy/distance-to-agreement criteria. With original plans as reference, gamma-index passing rates were 100% for the reconstituted plans (1%/1 mm criteria) and 93.5-100% for gated Seven29 measurements (3%/3 mm criteria). In the presence of leaf error deliberately introduced into the gated delivery of a pancreas patient plan, both dose reconstruction and Seven29 measurement consistently indicated substantial dosimetric differences from the original plan. In summary, a dose reconstruction procedure was demonstrated for evaluating the accuracy of respiratory-gated VMAT delivery. This technique showed that under clinical operation, the TrueBeam system faithfully realized treatment plans with gated delivery. This methodology affords a useful tool for machine- and patient-specific quality assurance of the newly available respiratory-gated VMAT.

Clinical development of a failure detection-based online repositioning strategy for prostate IMRT--experiments, simulation, and dosimetry study.

PURPOSE: To implement and evaluate clinic-ready adaptive imaging protocols for online patient repositioning (motion tracking) during prostate IMRT using treatment beam imaging supplemented by minimal, as-needed use of on-board kV. METHODS: The authors examine the two-step decision-making strategy: (1) Use cine-MV imaging and online-updated characterization of prostate motion to detect target motion that is potentially beyond a predefined threshold and (2) use paired MV-kV 3D localization to determine overthreshold displacement and, if needed, reposition the patient. Two levels of clinical implementation were evaluated: (1) Field-by-field based motion correction for present-day linacs and (2) instantaneous repositioning for new-generation linacs with capabilities of simultaneous MV-kV imaging and remote automatic couch control during treatment delivery. Experiments were performed on a Varian Trilogy linac in clinical mode using a 4D motion phantom programed with prostate motion trajectories taken from patient data. Dosimetric impact was examined using a 2D ion chamber array. Simulations were done for 536 trajectories from 17 patients. RESULTS: Despite the loss of marker detection efficiency caused by the MLC leaves sometimes obscuring the field at the marker's projected position on the MV imager, the field-by-field correction halved (from 23% to 10%) the mean percentage of time that target displacement exceeded a 3 mm threshold, as compared to no intervention. This was achieved at minimal cost in additional imaging (average of one MV-kV pair per two to three treatment fractions) and with a very small number of repositionings (once every four to five fractions). Also with low kV usage (approximation 2/fraction), the instantaneous repositioning approach reduced overthreshold time by more than 75% (23% to 5%) even with severe MLC blockage as often encountered in current IMRT and could reduce the overthreshold time tenfold (to < 2%) if the MLC blockage problem were relieved. The information acquired for repositioning using combined MV-kV images was found to have submillimeter accuracy. CONCLUSIONS: This work demonstrated with a current clinical setup that substantial reduction of adverse targeting effects of intrafraction prostate motion can be realized. The proposed adaptive imaging strategy incurs minimal imaging dose to the patient as compared to other stereoscopic imaging techniques.

Counting the cyclocized polyphenacenes.

In general the cyclocized polyphenacenes have a geometric nonplanar structure. This article gives an explicit expression of the counting formula for the two types of cyclocized polyphenacenes, viz., the belt-type and Möbius type, respectively. The result implies that almost all the belt-type cyclocized polyphenacenes, roughly speaking, are chiral if they are sufficiently large. The numerical results for these two types with the number of phenyl rings from 3 up to 18 are listed, as an example.

Dose reconstruction for volumetric modulated arc therapy (VMAT) using cone-beam CT and dynamic log files.

Volumetric modulated arc therapy (VMAT) has recently emerged as a new clinical modality for conformal radiation therapy. The aim of this work is to establish a methodology and procedure for retrospectively reconstructing the actual dose delivered in VMAT based on the pre-treatment cone-beam computed tomography (CBCT) and dynamic log files. CBCT was performed before the dose delivery and the system's log files were retrieved after the delivery. Actual delivery at a control point including MLC leaf positions, gantry angles and cumulative monitor units (MUs) was recorded in the log files and the information was extracted using in-house developed software. The extracted information was then embedded into the original treatment DICOM-radiation therapy (RT) file to replace the original control point parameters. This reconstituted DICOM-RT file was imported into the Eclipse treatment planning system (TPS) and dose was computed on the corresponding CBCT. A series of phantom experiments was performed to show the feasibility of dose reconstruction, validate the procedure and demonstrate the efficacy of this methodology. The resultant dose distributions and dose-volume histograms (DVHs) were compared with those of the original treatment plan. The studies indicated that CBCT-based VMAT dose reconstruction is readily achievable and provides a valuable tool for monitoring the dose actually delivered to the tumor target as well as the sensitive structures. In the absence of setup errors, the reconstructed dose shows no significant difference from the original pCT-based plan. It is also elucidated that the proposed method is capable of revealing the dosimetric changes in the presence of setup errors. The method reported here affords an objective means for dosimetric evaluation of VMAT delivery and is useful for adaptive VMAT in future.

[2008 Shanghai Customer Satisfaction Survey report of after-sales service for medical imaging equipments].

To improve the after-sales service, a survey aimed at the after-serveis of 3 kinds of medical equipment is applied among 68 hospitals in Shanghai Area in 2008.The Stat. and analysis results are showed in the paper, which will certainly channel off suppliers to set up a harmonious market together.

A small-animal imaging system capable of multipinhole circular/helical SPECT and parallel-hole SPECT.

We have designed and built a small animal single photon emission computed tomography (SPECT) imaging system equipped with parallel-hole and multipinhole collimators and capable of circular or helical SPECT. Copper-beryllium parallel-hole collimators suitable for imaging the ~35 keV photons from the decay of (125)I have been built and installed to achieve useful spatial resolution over a range of object-detector distances and to reduce imaging time on our dual-detector array. To address the resolution limitations in the parallel-hole SPECT and the sensitivity and limited field of view of single-pinhole SPECT, we have incorporated multipinhole circular and helical SPECT in addition to expanding the parallel-hole SPECT capabilities. The pinhole SPECT system is based on a 110 mm diameter circular detector equipped with a pixellated NaI(Tl) scintillator array (1x1x5 mm(3)/pixel). The helical trajectory is accomplished by two stepping motors controlling the rotation of the detector-support gantry and displacement of the animal bed along the axis of rotation of the gantry. Results obtained in SPECT studies of various phantoms show an enlarged field of view, very good resolution and improved sensitivity using multipinhole circular or helical SPECT. Collimators with one, three and five 1 mm diameter pinholes have been implemented and compared in these tests. Our objective is to develop a system on which one may readily select a suitable mode of either parallel-hole SPECT or pinhole circular or helical SPECT for a variety of small animal imaging applications.

A gamma camera re-evaluation of potassium iodide blocking efficiency in mice.

The protection of the thyroid against radioiodine uptake has been an important safety concern for decades. After several studies examined potassium iodide blockade efficacy in the 1960's and 1970's, a standard dosage was prescribed by both the World Health Organization and the U.S. Food and Drug Administration. In this paper, we tested the effectiveness of a scaled version of that standard dosage in comparison to higher doses in mice. A novel gamma camera was employed with a high spatial resolution for precisely quantifying activity within the thyroid and a field of view large enough to image the entire mouse body. Thyroid and whole-body 125I biodistribution was analyzed immediately after exposure and 1 and 7 days later. It was found that 1 h after exposure five times the scaled human dose blocked thyroid uptake about 40% more effectively than the 1X scaled dose. Even after 1 d and 7 d, five times the recommended scaled human dose blocked approximately 10% more effectively than the 1X dose. These data suggest the need for continued evaluation of the effectiveness of KI as a blocking agent and the application of novel, non-invasive technologies to this important human health issue.