Shift Distance Research Articles

Asymmetric Gaussian optical vortex.

We theoretically study a Gaussian optical beam with an embedded off-axis optical vortex. We also experimentally generate such an asymmetric Gaussian optical vortex by using an off-axis spiral phase plate. It is shown that depending on the shift distance the laser beam has the form of a crescent, which is rotated upon propagation. An analytical expression is obtained for the orbital angular momentum of such a beam, which appears to be fractional. When the shift increases, the greater the number of spirality of the phase plate or the "fork" hologram, the slower the momentum decreases. The experimental results are in qualitative agreement with the theory.

Curative effect of minimally invasive puncture and drainage assisted with alteplase on treatment of acute intracerebral hemorrhage

Objective: To investigate the different effects on evacuation of hematoma, the severity of nerve injury, inflammatory reaction and oxidative stress response in the treatment of acute intracerebral hemorrhage by using minimally invasive puncture and drainage assisted with alteplase or urokinase. Methods: A total of 114 patients with acute intracerebral hemorrhage treated with minimally invasive puncture and drainage in our hospital from May 2012 to October 2015 were retrospectively analyzed and divided into alteplase group and urokinase group, which received adjuvant therapy with alteplase and urokinase, respectively. Before and after treatment, CT was used for scanning, and the volume of hematoma and edema and the distance of midline shift were examined. After treatment, serum was collected for detecting the contents of molecular markers of nerve injury, inflammatory reaction and oxidative stress response. Results: On the 3rd day after treatment, the volume of hematoma and edema and the distance of midline shift in minimally invasive group were significantly lower than those of craniotomy group, and incidence of intracranial infection was lower than that of craniotomy group. There was no significant difference of rebleeding incidence compared to craniotomy group. The serum contents of osteopontin, S100β, glial fibrillary acidic protein, neuron-specific enolase, myelin basic protein, neuropeptide Y, ischemia modified albumin, tumor necrosis factor alpha, interleukin-1β, interleukin-6, interleukin-8, soluble intercellular adhesion molecule-1, high- mobility group protein 1, malonaldehyde, advanced oxidation protein products and 8-hydroxy- 2'-deoxyguanosine urine of patients from alteplase group were significantly lower than those of urokinase group. The content of total antioxidant capacity was obviously higher than that of urokinase group. Conclusions: As for the effect on evacuation of hematoma and also the ameliorative effect on nerve injury, inflammatory reaction and oxidative stress response in treatment of acute intracerebral hemorrhage, minimally invasive puncture and drainage assisted with alteplase was superior to adjuvant therapy with urokinase.

Anterior slip phenomenon of the vertebrae after corpectomy surgery and its clinical significance

To investigate the anterior slip phenomenon of the vertebrae after corpectomy surgery and its clinical significance. The clinical data of 164 patients with cervical spondylotic myelopathy treated from January 2010 to April 2013 were retrospectively analyzed. There were 88 males and 76 females, aged from 38 to 74 years old with the mean of 56.2 years. Among them, 31 cases for C₄ corpectomy, 87 cases for C₅ corpectomy, 46 cases for C₆ corpectomy. Preoperative and postoperative distance of posterior wall of vertebral canal to the line of adjacent upper vertebral bodies anterosuperior border and lower vertebral bodies anteroinferior border was measured by CT in cervical sagittal middle layer scanning as the center, anterior slip degree of the vertebrae after operation was evaluated. The fast clustering method was used, the vertebral shift distance as variable, according to the size of the forward distance, 90 cases classified as group 1(forward greatly group), and the 74 cases classified as group 2(forwad short group). The relationships on the anterior slip of the vertebrae and cervical curvature, surgical segment were analyzed. Japanese Orthopaedic Association (JOA) scores and its improvement rate were observed before and after operation, and the relationships on the anterior slip of the vertebrae and sagittal plane diagonal diameter of spinal canal, clinical effect were analyzed. All the patients were followed up from 12 to 48 months with an average of 29.5 months. All operative vertebrae occurred anterior slip with different degree after corpectomy surgery, the maximum was 3.52 mm and minimum was 1.12 mm, with an average of (2.14±1.02) mm. According to the clustering method, the anterior slip distance with (3.07±0.21) mm classified as forward greatly group(90 cases, 54.9%) and the anterior slip distance with (1.55±0.32) mm classified as forwad short group(74 cases, 45.1%). There was no significant difference between anterior slip distance and operation segments(χ²=0.01, P=0.996). Cervical curvature index and anterior slip distance of operated vertebra had a positive correlation (r=0.724). The incidence of reduction of the diagonal diameter of cervical spinal canal in forward greatly group was higher than that of forwad short group(χ²=4.45, P=0.035). The patients with unsatisfactory efficacy appeared obvious anterior slip of the vertebrae after corpectomy than the patients with satisfactory efficacy(P<0.05). Corpectomy of the cervical spine can result in vertebral forward displacement trend, and obvious displacement may cause the secondary compression of the spinal cord.

Three-dimensional analysis of alveolar changes of complete unilateral cleft lip patients after presurgical nasoalveolar molding treatment

This study analyzed the alveolar changes of complete unilateral cleft lip (UCCL) patients after pre-surgical nasoalveolar molding (PNAM) treatment using a three-dimensional method. Palate impressions of thirty UCCL patients who underwent PNAM treatment in the Affiliated Stomatology Hospital of Guangxi Medical University were taken pre- and post-PNAM. The plaster impressions were scanned using cone beam computed tomography (CBCT). The DICOM files were exported and 3D models reconstructed in Mimics 15.0. The following parameters were analyzed in SPSS 17.0: cleft alveolar gap width, alveolar arch end width, upper lip frenulum-median plane distance, alveolar shift distance, and length of alveolar section. After PNAM treatment, the cleft alveolar gap width and upper lip frenulum-median plane distance decreased significantly (P<0.05). No statistically significant change was observed in the alveolar arch end width (P>0.05). Alveolar shift distances for both sides increased significantly (P<0.05), and the shift distance of major alveolar sec-tion had a more significant increase than the minor alveolar section. The lengths of the alveolar section of both sides increased significantly (P<0.05) with the length of the major alveolar section increasing more significantly than the minor alveolar section. The impression-CBCT method supply accurate three-dimensional data of the alveolar process. The PNAM treatment can significantly correct alveolar deformity and improve appearance.

Recognizing nitrogen dopant atoms in graphene using atomic force microscopy

Doping graphene by heteroatoms such as nitrogen presents an attractive route to control the position of the Fermi level in the material. We prepared N-doped graphene on Cu(111) and Ir(111) surfaces via chemical vapor deposition of two different molecules. Using scanning tunneling microscopy images as a benchmark, we show that the position of the dopant atoms can be determined using atomic force microscopy. Specifically, the frequency shift–distance curves f (z) acquired above a N atom are significantly different from the curves measured over a C atom. Similar behavior was found for N-doped graphene on Cu(111) and Ir(111). The results are corroborated by density functional theory calculations employing a van der Waals functional.

Correlation of firing pin impressions based on congruent matching cross-sections (CMX) method

Comparison of firing pin impressions of cartridge cases is an important part of firearms evidence identification. However, compared with breach face impressions, there is only a limited surface area over which firing pin impressions can be compared. Furthermore, the curvature of firing pin impressions makes it difficult to perform automatic correlations of the surfaces. In this study, a new method and related algorithm named congruent matching cross-sections (CMX) are proposed. Each firing pin impression is sliced into layers and the resulting circular cross-sections are converted to two dimensional linear profiles by a polar coordinate transformation. The differential profile extraction method is used for extracting the high frequency micro-features, or the individual characteristics, for accurate correlation. Three parameters are proposed for determining whether these pairwise firing pin impressions are fired from the same firearm. The cross-correlation function (CCF) is used for quantifying similarity of the pairwise profiles which represent the two correlated firing pin images. If the correlated cartridge pair is fired from the same firearm, the maximum CCF value between each of the profile pairs from the reference and the correlated firing pin impressions will be high. The other two parameters relate to the horizontal (or angular) and vertical range of relative shifts that the profiles undergo to obtain the maximum CCF. These shifts are the phase angle θ which corresponds to a horizontal shift of the 2D profiles and the vertical shift distance of slice section, i.e. where the profiles match in the depth of the impression. These shift parameters are used to determine the congruency of the pairwise profile patterns. When these parameter values and their statistical distributions are collected for analysis, the CMX number is derived as a key parameter for a conclusive identification or exclusion. Validation tests using 40 cartridge cases of three different brands fired from 10 firearms produced by three different manufacturers yielded clear separation between known matching (KM) and known non-matching (KNM) image pairs, which strongly supports the effectiveness and feasibility of the proposed CMX method.

An Optimized Air-Core Coil Sensor with a Magnetic Flux Compensation Structure Suitable to the Helicopter TEM System.

The air-core coil sensor (ACS) is widely used as a transducer to measure the variation in magnetic fields of a helicopter transient electromagnetic (TEM) system. A high periodic emitting current induces the magnetic field signal of the underground medium. However, such current also generates a high primary field signal that can affect the received signal of the ACS and even damage the receiver. To increase the dynamic range of the received signal and to protect the receiver when emitting current rises/falls, the combination of ACS with magnetic flux compensation structure (bucking coil) is necessary. Moreover, the optimized ACS, which is composed of an air-core coil and a differential pre-amplifier circuit, must be investigated to meet the requirements of the helicopter TEM system suited to rapid surveying for shallow buried metal mine in rough topography. Accordingly, two ACSs are fabricated in this study, and their performance is verified and compared inside a magnetic shielding room. Using the designed ACSs, field experiments are conducted in Baoqing County. The field experimental data show that the primary field response can be compensated when the bucking coil is placed at an appropriate point in the range of allowed shift distance beyond the center of the transmitting coil and that the damage to the receiver induced by the over-statured signal can be solved. In conclusion, a more suitable ACS is adopted and is shown to have better performance, with a mass of 2.5 kg, resultant effective area of 11.6 m2 (i.e., diameter of 0.496 m), 3 dB bandwidth of 66 kHz, signal-to-noise ratio of 4 (i.e., varying magnetic field strength of 0.2 nT/s), and normalized equivalent input noise of 3.62 nV/m2.

PENGARUH KEBERADAAN OBJEK MANUSIA TERHADAP STABILITAS RECEIVED SIGNAL STRENGTH INDICATOR (RSSI) PADA BLUETOOTH LOW ENERGY 4.0 (BLE)

There are many systems with diverse technologies such as GPS, Wi-Fi, Bluetooth, Zigbee, Ultra Wide Band, Ultrasound, Infrared can be used for location-based services. Of these technologies can be developed several applications for positioning purposes such as monitoring patients in hospitals or elderly people who are undergoing treatment at home. This paper proposes a simple method to estimate the presence of the object / user in a fixed area using parameter Received Signal Strength Indicator (RSSI) on Bluetooth 4.0 Low Energy (BLE). To determine the performance of the RSSI, conducted two experiments in a room scenario dimensions 3 x 2.80 x 2.5 m (present and not present). Two experiments were conducted to test the performance of the RSSI signal. The first experiments with conditions not present showed a good performance. However, in the second experiment (present) with the status of various objects that are in the same room, resulting in poor performance of RSSI, where there is a shift in the RSSI value at the first measurement was obtained average RSSI -73 dBm with a range distance of 2 m, the second measurement obtained an average RSSI value of -85 dBm at a distance of 3 m range. With these results it can be concluded that the human presence in the area of research is very influential on the performance positioning signal strength (RSSI) and the significant impact that the shift distance of up to 1 m.

Development and Application of Blast Casting Technique in Large-Scale Surface Mines: A Case Study of Heidaigou Surface Coal Mine in China

Blast casting is a high-efficiency technique applied in surface mines for overburden removal and results in stripping cost savings. According to ballistic theory and center-of-mass frame basic movement principles, key factors influencing blast casting effect were analyzed, which include bench height and mining panel width, inclined angle of blast holes, explosive unit consumption (EUC), delay-time interval, presplitting, and blast hole pattern parameters. An intelligent design software was developed for obtaining better breaking and casting effect, and the error rates predicted with actual result can be controlled with 10%. Blast casting technique was successfully applied in Heidaigou Surface Coal Mine (HSCM) with more than 34% of material casted into the inner dump. A ramp ditch was set within the middle inner dump for coal transportation. The procedure of stripping and excavating was implemented separately and alternately in the two sections around the middle ramp ditch. An unconstrained-nonlinear model was deduced for optimizing the shift distance of the middle ramp. The calculation results show that optimum shift distance of HSCM is 480 m, and the middle ditch should be shifted after 6 blast casting mining panels being stripped.

The Sensitivity of Phosphocholine 13C Chemical Shifts to pH

Phosphocholine is a useful magnetic resonance (MR) biomarker for cancer. 13C hyperpolarized MR is likely to enhance the detection of this compound by orders of magnitude. The ability to differentiate phosphocholine from its precursor, choline, in live tissues, is unique to MR and depends on the 13C chemical shifts. The dependence of phosphocholine 13C chemical shifts on pH was investigated. We found that under viable physiological conditions of pH > 7, the chemical shift of phosphocholine 13C is stable and the chemical shift distance from the choline 13C signals is preserved. Under acidic intracellular conditions of 6.0 < pH < 7, the pH could be sensed by the phosphocholine 13C chemical shifts. Crucial and damaging pH changes to values lower than 6.0 could be sensed at very high sensitivity. The highest precision for pH determination is obtained when considering the chemical shift difference between positions 1 and 2 of phosphocholine. The solution composition of human plasma did not affect the response of phosphocholine 13C chemical shifts to pH.

Climate Change-Induced Range Expansion of a Subterranean Rodent: Implications for Rangeland Management in Qinghai-Tibetan Plateau.

Disturbances, both human-induced and natural, may re-shape ecosystems by influencing their composition, structure, and functional processes. Plateau zokor (Eospalax baileyi) is a typical subterranean rodent endemic to Qinghai-Tibetan Plateau (QTP), which are considered ecosystem engineers influencing the alpine ecosystem function. It is also regarded as a pest aggravating the degradation of overgrazed grassland and subject to regular control in QTP since 1950s. Climate change has been predicted in this region but little research exists exploring its impact on such subterranean rodent populations. Using plateau zokor as a model, through maximum entropy niche-based modeling (Maxent) and sustainable habitat models, we investigate zokor habitat dynamics driven by the future climate scenarios. Our models project that zokor suitable habitat will increase by 6.25% in 2050 in QTP. The predication indicated more threats in terms of grassland degradation as zokor suitable habitat will increase in 2050. Distribution of zokors will shift much more in their southern range with lower elevation compare to northern range with higher elevation. The estimated distance of shift ranges from 1 km to 94 km from current distribution. Grassland management should take into account such predictions in order to design mitigation measures to prevent further grassland degradation in QTP under climate change scenarios.

Total auricular reconstruction with single big expander at dual plane through incision at remnant ear

To investigate the feasibility and advantages of total auricular reconstruction with single big expander at dual plane through incision at remnant ear. 52 patients with microtia were treated. Through incision at remnant ear, one big expander (150 ml) was implanted in the post-auricular area beneath the superficial facial in the hairless area, and above the superficial fascia in the area with hair. In the second stage, total auricular was reconstructed with autologous cartilage framework and expanded skin. Skin graft was not necessary. Another 32 paitents with single big expander above the superficial fascia were used as control. The downward shift distance of expanders, the appearance of auriculocephalic sulcus and complication were recorded in order to assess the effect of these two methods. The downward shift distance of expanders in the dual plane group (0.7 ± 0.3) cm were lower than that in the control group (1.3 ± 0.4) cm, showing significant difference (P < 0.05). After a follow-up period of 6-12 months, shallow auriculocephalic sulcus was presented in 5 patients of the dual plane group and 12 patient of the control group. The shallow auriculocephalic sulcus was cut to make it deeper and covered with full skin graft. Dual plane skin expansion could reduce the downward shift distance of expander. Adequate skin on the upper part of expander could make satisfactory auriculocephalic sulcus.

SU‐E‐J‐164: Estimation of DVH Variation for PTV Due to Interfraction Organ Motion in Prostate VMAT Using Gaussian Error Function

Purpose:We developed a method to predict the change of DVH for PTV due to interfraction organ motion in prostate VMAT without repeating the CT scan and treatment planning. The method is based on a pre‐calculated patient database with DVH curves of PTV modelled by the Gaussian error function (GEF).Methods:For a group of 30 patients with different prostate sizes, their VMAT plans were recalculated by shifting their PTVs 1 cm with 10 increments in the anterior‐posterior, left‐right and superior‐inferior directions. The DVH curve of PTV in each replan was then fitted by the GEF to determine parameters describing the shape of curve. Information of parameters, varying with the DVH change due to prostate motion for different prostate sizes, was analyzed and stored in a database of a program written by MATLAB.Results:To predict a new DVH for PTV due to prostate interfraction motion, prostate size and shift distance with direction were input to the program. Parameters modelling the DVH for PTV were determined based on the pre‐calculated patient dataset. From the new parameters, DVH curves of PTVs with and without considering the prostate motion were plotted for comparison. The program was verified with different prostate cases involving interfraction prostate shifts and replans.Conclusion:Variation of DVH for PTV in prostate VMAT can be predicted using a pre‐calculated patient database with DVH curve fitting. The computing time is fast because CT rescan and replan are not required. This quick DVH estimation can help radiation staff to determine if the changed PTV coverage due to prostate shift is tolerable in the treatment. However, it should be noted that the program can only consider prostate interfraction motions along three axes, and is restricted to prostate VMAT plan using the same plan script in the treatment planning system.

ORIENTATION SPECTRUM ALGORITHM DEVELOPMENT

Abstract. A morphological orientation spectra is proposed. This spectrum describes basic directions of shape parts. Fast discrete-continuous algorithm for computing orientation spectrum is presented. It is based on usage of continuous skeleton that is constructed from polygonal shape contour. A definition for disc orientation map is given. Comparison experiments for binary shapes with the usage of orientation spectra are carried out. Cyclic shift and EMD-L1 distance are used for spectra comparison. The obtained results indicate that the aggregation of the thickness spectra with orientation spectra increases the quality of inter-class recognition.

Atom-resolved analysis of an ionic KBr(001) crystal surface covered with a thin water layer by frequency modulation atomic force microscopy.

An ionic KBr(001) crystal surface covered with a thin water layer was observed with a frequency modulation atomic force microscope (FM-AFM) with atomic resolution. By immersing only the tip apex of the AFM cantilever in the thin water layer, the Q-factor of the cantilever in probing the solid-liquid interface can be maintained as high as that of FM-AFM operation in air, leading to improvement of the minimum detection of a differential force determined by the noise. Two types of images with atom-resolved contrast were observed, possibly owing to the different types of ions (K(+) or Br(-)) adsorbed on the tip apex that incorporated into the hydration layers on the tip and on the sample surface. The force-distance characteristics at the solid-water interface were analyzed by taking spatial variation maps of the resonant frequency shift of the AFM cantilever with the high Q-factor. The oscillatory frequency shift-distance curves exhibited atomic site dependence. The roles of hydration and the ions on the tip and on the sample surface in the measurements were discussed.

The arthroscopic diagnosis and treatment of acute patellofemoral joint impingement syndrome

Objective To explore the mechanism and characteristics of MRI of acute patellofemoral joint impingement syndrome as well as its arthroscopic diagnosis and treatment. Methods There were a total of 46 cases (9 males and 37 females) with acute patellofemoral joint impingement syndrome from September 2005 to October 2012 in our department, and their average age was 21.6 years old (ranging from 15 to 31 years old). The Q angle, lateral patellofemoral angle (LPA) and lateral shift distance(LSD) of all cases were measured by X-ray and MRI preoperatively. MRI checked the medial patellar retinaculum injury by 4 de-grees: 15 cases of degree Ⅰ, 18 cases of degree Ⅱ, 8 cases of degree Ⅲ, and 5 cases of degree Ⅳ. All operations were monitored under arthroscopy. Firstly, the hemarthrosis was cleared, and secondly arthroscopy was used to explore all around inside joints, the free cartilage and osteochondral fragment were taken out, and the impaired surface of cartilage was repaired. Medial patellar reti-naculum was treated arthroscopically with radio frequency ablation in degree Ⅰ injury. Lateral patellar retinaculum was released when the time of injury was longer than 2 weeks (9 cases), and medial capsule and retinaculum structure were reefed with modified arthroscopy assistance for patients with medial patellar retinaculum injury of degree Ⅱ to Ⅲ with obvious patellar shift. The medi-al capsule and retinaculum structure were strengthened by open surgical method for patients with degree Ⅳ injury. Results Constant findings under arthroscopy were haemarthrosis (46 cases), chondral lesions involved in the lateral femoral condyle and medi-al marginal of patella (37 cases), osteochondral fragments (28 cases), and tear of the medical retinaculum (46 cases). All patients were available at follow-up, the average duration of follow-up was 18.2 months (ranging from 12-36 months). No infection, nerve and blood vessel injury, redislocation or other complications happened. Lysholm, Tegner and AAOS scores were used both preoper-atively and postoperatively, and LPA and LSD were compared. Statistically, the difference between these two scores was significant (P<0.05). The sport ability was improved among all patients. Conclusion Acute patellofemoral joint impingement syndrome can be treated effectively by modified suture of medial capsule and retinaculum structure combined with release of lateral retinacu-lum. The function of knee joint recovered well after operation with satisfactory objective and subjective effects. Key words: Arthroscopy; Patellar; Wounds and injuries

Impact of travel mode shift and trip distance on active and non-active transportation in the São Paulo Metropolitan Area in Brazil

BackgroundChanges in urban mobility play a major role in transforming metropolitan areas into healthier places. This study quantified the impact of changes in travel mode shift and trip distance on active and non-active transportation of working age adult population of São Paulo. Methods and findingsThrough different scenarios, we estimated the daily time spent in transportation per inhabitant (divided in active and non-active transportation time) and the proportion of inhabitants accumulating 30min or more of daily active transportation. The replacement of individual for collective motorized modes in long distance trips (>1000m) in combination with the substitution of long for short trips positively impacted all outcomes. Compared to the current situation, there was an increase in the active transportation time (from 19.4 to 26.7min/inhabitant), which also increased the proportion of adults active for transportation (from 27.6% to 35.4%). Additionally, the non-active transportation time decreased (from 67.0 to 26.2min/inhabitant), which helped to reduce the total time spent in transportation (from 86.4 to 52.9min/inhabitant). ConclusionTransport and urban planning policies to reduce individual motorized trips and the number of long trips might produce important health benefits, both by increasing population levels of active transportation and reducing the non-active and the total time of daily trips.

An Efficient Hybrid Segmentation Algorithm for Computer Tomography Image Segmentation

Medical Image segmentation plays a major role in medical image processing. During last decades, developing robust and efficient algorithms for medical image segmentation has been a demanding area of growing research interest. Extensive research has been done in creating many different approaches and algorithms for image segmentation, but it is still difficult to assess whether one algorithm produces more accurate segmentations than the other. The proposed method utilizes clustering with distance based segmentation approach for Computer tomography image segmentation. This paper provides new hybrid segmentation method based on K-Means, Medoid shift and Signature Quadratic Form Distance algorithm for computer tomography images. We validate the Hybrid segmentation approach with the parameters in terms of sensitivity, specificity, accuracy and number of fragments. The Real time dataset is used to evaluate the performance of the proposed method. The results obtained from the experimentation show that the proposed approach attains reliable segmentation accuracy and also clear that it is more efficient, robust and more appropriate for organ classification.

Automation and uncertainty analysis of a method for in-vivo range verification in particle therapy

We introduce the automation of the range difference calculation deduced from particle-irradiation induced β+-activity distributions with the so-called most-likely-shift approach, and evaluate its reliability via the monitoring of algorithm- and patient-specific uncertainty factors. The calculation of the range deviation is based on the minimization of the absolute profile differences in the distal part of two activity depth profiles shifted against each other. Depending on the workflow of positron emission tomography (PET)-based range verification, the two profiles under evaluation can correspond to measured and simulated distributions, or only measured data from different treatment sessions. In comparison to previous work, the proposed approach includes an automated identification of the distal region of interest for each pair of PET depth profiles and under consideration of the planned dose distribution, resulting in the optimal shift distance. Moreover, it introduces an estimate of uncertainty associated to the identified shift, which is then used as weighting factor to ‘red flag’ problematic large range differences. Furthermore, additional patient-specific uncertainty factors are calculated using available computed tomography (CT) data to support the range analysis. The performance of the new method for in-vivo treatment verification in the clinical routine is investigated with in-room PET images for proton therapy as well as with offline PET images for proton and carbon ion therapy. The comparison between measured PET activity distributions and predictions obtained by Monte Carlo simulations or measurements from previous treatment fractions is performed. For this purpose, a total of 15 patient datasets were analyzed, which were acquired at Massachusetts General Hospital and Heidelberg Ion-Beam Therapy Center with in-room PET and offline PET/CT scanners, respectively. Calculated range differences between the compared activity distributions are reported in a 2D map in beam-eye-view. In comparison to previously proposed approaches, the new most-likely-shift method shows more robust results for assessing in-vivo the range from strongly varying PET distributions caused by differing patient geometry, ion beam species, beam delivery techniques, PET imaging concepts and counting statistics. The additional visualization of the uncertainties and the dedicated weighting strategy contribute to the understanding of the reliability of observed range differences and the complexity in the prediction of activity distributions. The proposed method promises to offer a feasible technique for clinical routine of PET-based range verification.

WE-A-17A-05: Differences in Applicator Configuration and Dwell Loading Between Standard and Image-Guided Tandem and Ring (T&amp;R) HDR Brachytherapy

Purpose: To investigate differences in: (i) relative location of the tandem and the ring compared to a rigid standard applicator model; and (ii) relative loading and changes in loading pattern between standard and image-guided planning. Methods: All T and R insertions performed in 2013 in our institution under CT- or MR-guidance were analyzed. Standard plans were generated using library applicator models with a fixed relationship between ring and tandem, standardized uniform dwell loading and normalization to point A. The graphic plans and the associated standard-plan dwell configurations were compared: the rings were rigidly registered, and the residual tandem shift, rotation and maximum distance between plan tandem dwell and corresponding model tandem dwell were calculated. The normalization ratio (NR = the ratio of graphic versus standard-plan total reference air kerma [TRAK]), the general loading difference (GLD = the difference between graphic and standard ratios of the tandem versus the ring TRAK), and the percent standard deviation (SD% = SD/mean) of the tandem and the ring TRAK for the graphic plan (all standard-plans SD% = 0) were calculated. Results: 71 T and R were analyzed. Residual tandem shift, rotation and maximum corresponding dwell distance were 1.2±0.8mm (0.4±0.4mm lateral, 0.9±0.8mm craniocaudal, 0.4±0.3mm anterior-posterior),more » 2.3±1.9deg and 3.4±2.3mm. NR was 0.86±0.11 indicating a lower overall loading of the graphic compared to the standard plans. GLD was -0.12±0.16 indicating a modest increased ring loading relative to the tandem in the graphic plans. SD% was 2.1±1.6% for tandem and 2.8±1.9% for ring, indicating small deviations from uniform loading. Conclusion: Variability in the relative locations of the tandem and the ring necessitates the independent registration of each component model for accurate digitization. Our clinical experience suggests that graphically planned T and R results on average in a lower total dose to the patient, and in an increased relative loading of the ring component.« less