Breathing Pattern In Patients Research Articles

Characterization of sleep breathing pattern in patients with type 2 diabetes: sweet sleep study.

BackgroundAlthough sleep apnea-hypopnea syndrome (SAHS) is highly prevalent in patients with type 2 diabetes (T2D), it is unknown whether or not subjects with and without T2D share the same sleep breathing pattern.Methodology/Principal findingsA cross-sectional study in patients with SAHS according to the presence (n = 132) or not (n = 264) of T2D. Both groups were matched by age, gender, BMI, and waist and neck circumferences. A subgroup of 125 subjects was also matched by AHI. The exclusion criteria included chronic respiratory disease, alcohol abuse, use of sedatives, and heart failure. A higher apnea hypopnea index (AHI) was observed in T2D patients [32.2 (10.2–114.0) vs. 25.6 (10.2–123.4) events/hours; p = 0.002). When sleep events were evaluated separately, patients with T2D showed a significant increase in apnea events [8.4 (0.1–87.7) vs. 6.3 (0.0–105.6) e/h; p = 0.044), as well as a two-fold increase in the percentage of time spent with oxygen saturation <90% [15.7 (0.0–97.0) vs. 7.9 (0.0–95.6) %; <0.001)], higher rates of oxygen desaturation events, and also higher daily sleepiness [7.0 (0.0–21.0) vs. 5.0 (0.0–21.0); p = 0.006)] than subjects without T2D. Significant positive correlations between fasting plasma glucose and AHI, the apnea events, and CT90 were observed. Finally, multiple linear regression analyses showed that T2D was independently associated with AHI (R2 = 0.217), the apnea index (R2 = 0.194), CT90 (R2 = 0.222), and desaturation events.Conclusions/significanceT2D patients present a different pattern of sleep breathing than subject without diabetes. The most important differences are the severity of hypoxemia and the number of apneas whereas the incidence of hypopnea episodes is similar.

In Vitro Evaluation of Aerosols Delivered via the Nasal Route.

Infants and young children are obligate nose breathers; therefore, a transnasal route seems the logical delivery method of inhaled aerosols. The efficiency of aerosol delivery depends on several factors, such as interface, type of nebulizer, and patient age and breathing pattern. We hypothesized that the use of a vibrating mesh nebulizer, a tight-fitting face mask, and a head model and breathing pattern of an older child would result in a higher lung dose. We also hypothesized that the use of an anatomically correct model would more accurately reflect lung dose than models that do not include airways. A model comprising a breathing simulator and an anatomically correct model of a 7-month-old infant and a 5-y-old child with an interposed collection filter (lung dose) were used. Breathing patterns of a newborn, infant, and child were used with 7 interfaces. A continuous output and a vibrating mesh nebulizer were loaded with albuterol sulfate solution (5 mg/3.5 mL) and operated for 5 min. Albuterol mass was determined via spectrophotometer (276 nm). Lung dose varied between 0 and 3%. The jet nebulizer was more efficient than the vibrating mesh nebulizer. The front-loaded mask was the most efficient interface. We also found that higher tidal volumes were associated with higher lung doses and that the use of a larger airway model resulted in a lower lung dose. Finally, the model showed a good correlation with in vivo data and rendered lung doses severalfold lower than previous data obtained with oral models. Careful pairing of the aerosol generator and interface is very important during transnasal aerosol delivery.

Evaluation of breathing patterns for respiratory-gated radiation therapy using the respiration regularity index

Despite the considerable importance of accurately estimating the respiration regularity of a patient in motion compensation treatment, not to mention the necessity of maintaining that regularity through the following sessions, an effective and simply applicable method by which those goals can be accomplished has rarely been reported. The authors herein propose a simple respiration regularity index based on parameters derived from a correspondingly simplified respiration model. In order to simplify a patient’s breathing pattern while preserving the data’s intrinsic properties, we defined a respiration model as a cos4(ω(t) · t) wave form with a baseline drift. According to this respiration formula, breathing-pattern fluctuation could be explained using four factors: the sample standard deviation of respiration period (sf), the sample standard deviation of amplitude (sa) and the results of a simple regression of the baseline drift (slope as β, and standard deviation of residuals as σr) of a respiration signal. The overall irregularity (δ) was defined as \(\left\| {\vec \omega } \right\|\), where \(\vec \omega \) is a variable newly-derived by using principal component analysis (PCA) for the four fluctuation parameters and has two principal components (ω1, ω2). The proposed respiration regularity index was defined as ρ = ln(1 + (1/δ))/2, a higher ρ indicating a more regular breathing pattern. We investigated its clinical relevance by comparing it with other known parameters. Subsequently, we applied it to 110 respiration signals acquired from five liver and five lung cancer patients by using real-time position management (RPM; Varian Medical Systems, Palo Alto, CA). Correlations between the regularity of the first session and the remaining fractions were investigated using Pearson’s correlation coefficient. Additionally, the respiration regularity was compared between the liver and lung cancer patient groups. The respiration regularity was determined based on ρ; patients with ρ 0.7 was suitable for respiratory-gated radiation therapy (RGRT). Fluctuations in the breathing cycle and the amplitude were especially determinative of ρ. If the respiration regularity of a patient’s first session was known, it could be estimated through subsequent sessions. Notably, the breathing patterns of the lung cancer patients were more irregular than those of the liver cancer patients. Respiration regularity could be objectively determined by using a composite index, ρ. Such a single-index testing of respiration regularity can facilitate determination of RGRT availability in clinical settings, especially for free-breathing cases.

Markerless motion tracking of lung tumors using dual-energy fluoroscopy.

To evaluate the efficacy of dual-energy (DE) vs single-energy (SE) fluoroscopic imaging of lung tumors using a markerless template-based tracking algorithm. Ten representative patient breathing patterns were programmed into a Quasar™ motion phantom. The phantom was modified by affixing pork ribs to the surface, and a cedar insert with a small spherical volume was used to simulate lung and tumor, respectively. Sequential 60 kVp (6 mA) and 120 kVp (1.5 mA) fluoroscopic sequences were acquired. Frame-by-frame weighted logarithmic subtraction was performed resulting in a DE fluoroscopic sequence. A template-based algorithm was then used to track tumor motion throughout the DE and SE fluoroscopy sequences. Tracking coordinates were evaluated against ground-truth tumor locations. Fluoroscopic images were also acquired for two lung cancer patients, neither of which had implanted fiducials. For phantom imaging, a total of 1925 frames were analyzed. The algorithm successfully tracked the target on 99.9% (1923/1925) of DE frames vs 90.7% (1745/1925) SE images (p < 0.01). The displacement between tracking coordinates and ground truth for the phantom was 1.4 mm ± 1.1 mm for DE vs 2.0 mm ± 1.3 mm for SE (p < 0.01). Images from two patients, one with a larger tumor and one with a smaller tumor, were also analyzed. For the patient with the larger tumor, the average displacement from physician defined ground truth was 1.2 mm ± 0.6 mm for DE vs 1.4 mm ± 0.7 mm for SE (p = 0.016). For the patient that presented with a smaller tumor, the average displacement from physician defined ground truth was 2.2 mm ± 1.0 mm for DE vs 3.2 mm ± 1.4 mm for SE (p < 0.01). Importantly, for this single patient with the smaller tumor, 15.6% of the SE frames had >5 mm displacements from the ground truth vs 0% for DE fluoroscopy. This work indicates the potential for markerless tumor tracking utilizing DE fluoroscopy. With DE imaging, the algorithm showed improved detectability vs SE fluoroscopy and was able to accurately track the tumor in nearly all cases.

Generation of fluoroscopic 3D images with a respiratory motion model based on an external surrogate signal

Respiratory motion during radiotherapy can cause uncertainties in definition of the target volume and in estimation of the dose delivered to the target and healthy tissue. In this paper, we generate volumetric images of the internal patient anatomy during treatment using only the motion of a surrogate signal. Pre-treatment four-dimensional CT imaging is used to create a patient-specific model correlating internal respiratory motion with the trajectory of an external surrogate placed on the chest. The performance of this model is assessed with digital and physical phantoms reproducing measured irregular patient breathing patterns. Ten patient breathing patterns are incorporated in a digital phantom. For each patient breathing pattern, the model is used to generate images over the course of thirty seconds. The tumor position predicted by the model is compared to ground truth information from the digital phantom. Over the ten patient breathing patterns, the average absolute error in the tumor centroid position predicted by the motion model is 1.4 mm. The corresponding error for one patient breathing pattern implemented in an anthropomorphic physical phantom was 0.6 mm. The global voxel intensity error was used to compare the full image to the ground truth and demonstrates good agreement between predicted and true images. The model also generates accurate predictions for breathing patterns with irregular phases or amplitudes.

A survey on inhalation effect of essence of peppermint on nausea and vomiting after abdominal surgery in patients who have been admitted to Besaat and Tohid hospitals in Sanandaj

Abstract Background and aim: Nausea and vomiting is among the most common complications in patients recovering from general anaesthesia , 30-70 of patients experience nausea and vomiting after surgery. Although variety of medications have been used to control this complication, it still remains as a problem. Armothpy a non pharmacologic intervention is suggested for treatment of many conditions and Pepprmint may be effectivein treatment of common digestive conditions. This aim of this study was to examine the efficacy of inhaling peppermint essence for prevention of nausea and vomiting after abdominal surgery in patients admitted in Beasssat and Tohid hospitals in Sanandaj in 2011. Method and materials: randomized clinical trial was conducted to examine the efficacy of Peppermint essence inhalation for prevention of post- surgical nausea and sample of the study consisted of 90 patients, which were randomly allocated to receive peppermint inhalation or saline normal. 2 × 2 gauze pad saturated with two drops of pure pharmacy-grade peppermint essence was used for 1 minute in intervention group. For patients in control group a 2 × 2 gauze pad saturated with 0. 9% normal saline was used. visual analog scale was used to rate Patients were followed in recovery and surgical ward for occurrence of nausea and Data were analyzed by SPSS software, version 17. Findings: There was not statistical difference between two groups in terms of confounding variables such as body mass index, length of anesthesia as well as type of anesthesia. 6. 7% of patients in peppermint group and 0% of patients in control group experienced mild Manwitney statistical test, showed no significant difference between the two groups in terms of nausea in recovery room. results indicated there was significant difference between the two groups in the 1392 ناتسمز ،83 هرامش ،23 هرود / 34 ناراکمه و یفجن هراهب severity of nausea in surgical ward. There was not a significant difference between two groups in term of numbers of Conclusion: findings of the study showed no diferrence between peppermint and saline in terms of prevetion of nausea and One reason can either be ineffective breathing patterns of patients after anesthesia or insufficient dose of peppermint which has affected the results of this study. It seems more studies with various shapes and amounts of peppermint are required in this regard. Keywords: Aromaterapy, Nausea & Vomiting, Peppermint REFERENCES Anderson L , Gross B (2004); Aromathrapy with peppermint isopropelalchol ,or placebo is equally effective in reliving post operative nausea. Journal of peri Anesthesia Nursing . 19(1) 35-29. Chadhary S et al (2008); Preoperation intravenous fluid therapy with crystalloid or colloid on post operativenauseav Incidence of post operative nausea and vomiting in patients at a university hospital. Biomed Pap med Fac Unit PalackyOlomuc Czech Repub . 157(1) 69-79. Ferruggiari L et al (2012); The effect of aromatherapy on post operative nausea in women undergoing surgical procedures. Journal of Perianesthesia Nursing . 27(4(246-251. Gan T G et al (2003); Consenus guid lines for managing post operative nausea and vomiting. International Anesthesia Research Society . 97(16) 2-71. Gan T G et al (2007); Societyfor ambulatory anesthesia guid lines for the management of post operative nausea and vomiting. Anesthesia & Analagesia . 105(1)16-25. Hunt R et al (2012); Aromatrapy as treatment for post operative randomized tril. International Anesthisia Analagesia Research Socity . 1(1)1-8. Pellegrin J et al (2009); Comparison of inhalation of isopropyl alcholvsprometazin in the treatment of post operative nausea and vomiting(ponv) in patients identified as at high risk for developing ponv. AANA Journal . 77(4) 293-299. Salehisormaghi MH (2008); Herb and Herbal Therapy . Second ed. Tehran: Doniaetaghzie. Smeltzer S Bare B (2011); Textbook of Medical- Surgical Nursing, Operating Room . Translated by Khachian 1392 ناتسمز ،83 هرامش ،23 هرود / 32 ناراکمه و یفجن هراهب A. Tehran Jameae Negar. (Persian). Shaha PP , Kundnani PKM (2004); A review of medicinal uses and pharmacological effects of menthe pipprita. Natural Product Radiance . 3(4) 214-224. Tate S (1997); Peper mint oilatreatment for postoperative nausea. Journal of Advanced Nursing . 26(1) 584-590.

Analysis of the breathing pattern in elderly patients using the Hurst exponent applied to the respiratory flow signal.

Due to the increasing elderly population and the extensive number of comorbidities that affect them, studies are required to determine future increments in admission to emergency departments. Some of these studies could focus on the relation between chronic diseases and breathing pattern in elderly patients. Variations in the fractal properties of respiratory signals can be associated with several diseases. To determine the relationship between these variations and breathing patterns, and to quantify the fractal properties of respiratory flow signals, we estimated the Hurst exponent (H). Detrended fluctuation analysis (DFA) and discrete wavelet transform-based estimation (DWTE) methods were applied. The estimation methods were analyzed using simulated data series generated by fractional Gaussian noise. 43 elderly patients (19 patients with a non-periodic breathing pattern - nPB, and 24 patients with a periodic breathing pattern - PB) were studied. The results were evaluated according to the length of data and the number of averaged data series used to obtain a good estimation. The DWTE method estimated the respiratory flow signals better than the DFA method, and obtained Hurst values clustered by group. We found significant differences in the H exponent (p = 0.002) between PB and nPB patients, which showed different behavior in the fractal properties.

An initial study on the estimation of time‐varying volumetric treatment images and 3D tumor localization from single MV cine EPID images

In this work the authors develop and investigate the feasibility of a method to estimate time-varying volumetric images from individual MV cine electronic portal image device (EPID) images. The authors adopt a two-step approach to time-varying volumetric image estimation from a single cine EPID image. In the first step, a patient-specific motion model is constructed from 4DCT. In the second step, parameters in the motion model are tuned according to the information in the EPID image. The patient-specific motion model is based on a compact representation of lung motion represented in displacement vector fields (DVFs). DVFs are calculated through deformable image registration (DIR) of a reference 4DCT phase image (typically peak-exhale) to a set of 4DCT images corresponding to different phases of a breathing cycle. The salient characteristics in the DVFs are captured in a compact representation through principal component analysis (PCA). PCA decouples the spatial and temporal components of the DVFs. Spatial information is represented in eigenvectors and the temporal information is represented by eigen-coefficients. To generate a new volumetric image, the eigen-coefficients are updated via cost function optimization based on digitally reconstructed radiographs and projection images. The updated eigen-coefficients are then multiplied with the eigenvectors to obtain updated DVFs that, in turn, give the volumetric image corresponding to the cine EPID image. The algorithm was tested on (1) Eight digital eXtended CArdiac-Torso phantom datasets based on different irregular patient breathing patterns and (2) patient cine EPID images acquired during SBRT treatments. The root-mean-squared tumor localization error is (0.73 ± 0.63 mm) for the XCAT data and (0.90 ± 0.65 mm) for the patient data. The authors introduced a novel method of estimating volumetric time-varying images from single cine EPID images and a PCA-based lung motion model. This is the first method to estimate volumetric time-varying images from single MV cine EPID images, and has the potential to provide volumetric information with no additional imaging dose to the patient.

Capnography during deep sedation with propofol by nonanesthesiologists: a randomized controlled trial.

Propofol, a short-acting hypnotic drug, is increasingly administered by a diverse group of specialists (e.g., cardiologists, gastroenterologists) during diagnostic and therapeutic procedures. Standard monitoring during sedation comprises continuous pulse oximetry with visual assessment of the patient's breathing pattern. Because undetected hypoventilation is a common pathway for complications, capnographic monitoring of exhaled carbon dioxide has been advocated. We examined whether the use of capnography reduces the incidence of hypoxemia during nonanesthesiologist-administered propofol sedation in patients who did not receive supplemental oxygen routinely. An open, stratified, randomized controlled trial was conducted in 427 healthy adult women during minor gynecology procedures in an outpatient clinic in the Netherlands. Patients were randomly assigned to receive either standard respiratory monitoring (standard care) or standard respiratory monitoring combined with capnography (capnography group). To replicate usual clinical practice, capnography monitoring was performed by the same medical team that provided sedation. The primary end point was the incidence of hypoxemia, defined as oxygen saturations <91%. From April 2010 to January 2011, 427 patients were enrolled. In the capnography group, 206 patients and in the standard care group, 209 patients were analyzed. The percentage of patients with a hypoxemic episode was 25.7% (53 of 206) in the capnography group and 24.9% (52 of 209) in the standard care group, resulting in an absolute difference of 0.8% (-7.5 to 9.2%). We were unable to confirm an additive role for capnography in preventing hypoxemia during elective nonanesthesiologist-administered propofol (monotherapy) sedation in healthy women in whom supplemental oxygen is not routinely administered. Based on the confidence interval, the benefit of adding capnography is at most an absolute hypoxemia reduction of 7.5%, suggesting that adding it in this practice setting to the routine monitoring strategy does not necessarily improve patient safety in daily practice.

Oxygen mask capnometry typeR is useful device for continuous CO2 monitoring during different breathing patterns in extubated post abdominal surgical patients: a prospective observational study

Oxygen mask capnometry typeR is useful device for continuous CO2 monitoring during different breathing patterns in extubated post abdominal surgical patients: a prospective observational study

SU‐E‐J‐67: Evaluation of Breathing Patterns for Respiratory‐Gated Radiation Therapy Using Respiration Regularity Index

Purpose:Despite the importance of accurately estimating the respiration regularity of a patient in motion compensation treatment, an effective and simply applicable method has rarely been reported. The authors propose a simple respiration regularity index based on parameters derived from a correspondingly simplified respiration model.Methods:In order to simplify a patient's breathing pattern while preserving the data's intrinsic properties, we defined a respiration model as a power of cosine form with a baseline drift. According to this respiration formula, breathing‐pattern fluctuation could be explained using four factors: sample standard deviation of respiration period, sample standard deviation of amplitude and the results of simple regression of the baseline drift (slope and standard deviation of residuals of a respiration signal. Overall irregularity (δ) was defined as a Euclidean norm of newly derived variable using principal component analysis (PCA) for the four fluctuation parameters. Finally, the proposed respiration regularity index was defined as ρ=ln(1+(1/ δ))/2, a higher ρ indicating a more regular breathing pattern. Subsequently, we applied it to simulated and clinical respiration signals from real‐time position management (RPM; Varian Medical Systems, Palo Alto, CA) and investigated respiration regularity. Moreover, correlations between the regularity of the first session and the remaining fractions were investigated using Pearson's correlation coefficient.Results:The respiration regularity was determined based on ρ; patients with ρ&lt;0.3 showed worse regularity than the others, whereas ρ&gt;0.7 was suitable for respiratory‐gated radiation therapy (RGRT). Fluctuations in breathing cycle and amplitude were especially determinative of ρ. If the respiration regularity of a patient's first session was known, it could be estimated through subsequent sessions.Conclusions:Respiration regularity could be objectively determined using a respiration regularity index, ρ. Such single‐index testing of respiration regularity can facilitate determination of RGRT availability in clinical settings, especially for free‐breathing cases.This work was supported by a Korea Science and Engineering Foundation (KOSEF) grant funded by the Korean Ministry of Science, ICT and Future Planning (No. 2013043498).

SU‐E‐J‐78: Internal Target Volume Delineation for Lung Tumors in Patients Treated with Robotic Radiosurgery

Purpose:To compare different approaches for Internal Target Volume (ITV) delineation for patients treated with fiducial‐free robotic radiosurgery for primary and metastatic lung tumors.Methods:Ten patients undergoing Lung‐Optimized Treatment (LOT) for robotic radiosurgery were imaged with inhale and exhale breath‐hold CT scans and 8‐phase 4DCT scan. We evaluated the differences in internal target volume (ITV) delineated using three approaches: 1) maximum intensity projection (MIP) images reconstructed from 4DCT scan (ITV‐MIP); 2) linear interpolation of Gross Tumor Volumes (GTV) segmented on inhale and exhale breath‐hold scans (ITV‐BH); 3) linear interpolation of GTV segmented on inhale and exhale phases of 4DCT scan (ITV‐2Phase). All contours were independently generated by the same radiation oncologist using lung window settings. Patients had ITV‐MIP volumes ranging from 1.5 to 146.9 cc (mean 36.8 cc) located in various parts of the lung. Volume overlap and matching index (MI) were calculated and compared. The MI between two volumes was defined as the ratio of their intersection to their union. MI of 1 indicates the volumes are identical; MI of 0 indicates that there is no overlap.Results:The three approaches generated very different results. The average (SD) MI for ITV‐MIP and ITV‐BH was 0.52 (0.24); for ITV‐MIP and ITV‐2Phase it was 0.69 (0.13); and for ITV‐BH and ITV‐2Phase was 0.57 (0.21), (ANOVA, p=0.16). Relative to the ITV‐MIP, the percentage of volume overlap was 72% (26%) and 90% (7%) for ITV‐BH and ITV‐2Phase, respectively (t‐test, p=0.05).Conclusion:Differences between ITV‐BH and ITV‐MIP are due to inconsistent lung filling at breath‐hold and nonlinear tumor motion. Therefore, methods to check breath‐hold scanning against regular patient breathing patterns should be developed. Whenever possible, ITV‐BH generated by the LOT workflow should be verified by 4DCT data.

SU-C-9A-06: The Impact of CT Image Used for Attenuation Correction in 4D-PET

Purpose: To evaluate the appropriateness of using 3D non-gated CT image for attenuation correction (AC) in a 4D-PET (gated PET) imaging protocol used in radiotherapy treatment planning simulation. Methods: The 4D-PET imaging protocol in a Siemens PET/CT simulator (Biograph mCT, Siemens Medical Solutions, Hoffman Estates, IL) was evaluated. CIRS Dynamic Thorax Phantom (CIRS Inc., Norfolk, VA) with a moving glass sphere (8 mL) in the middle of its thorax portion was used in the experiments. The glass was filled with 18F-FDG and was in a longitudinal motion derived from a real patient breathing pattern. Varian RPM system (Varian Medical Systems, Palo Alto, CA) was used for respiratory gating. Both phase-gating and amplitude-gating methods were tested. The clinical imaging protocol was modified to use three different CT images for AC in 4D-PET reconstruction: first is to use a single-phase CT image to mimic actual clinical protocol (single-CT-PET); second is to use the average intensity projection CT (AveIP-CT) derived from 4D-CT scanning (AveIP-CT-PET); third is to use 4D-CT image to do the phase-matched AC (phase-matching- PET). Maximum SUV (SUVmax) and volume of the moving target (glass sphere) with threshold of 40% SUVmax were calculated for comparison between 4D-PET images derived with different AC methods. Results: The SUVmax varied 7.3%±6.9% over the breathing cycle in single-CT-PET, compared to 2.5%±2.8% in AveIP-CT-PET and 1.3%±1.2% in phasematching PET. The SUVmax in single-CT-PET differed by up to 15% from those in phase-matching-PET. The target volumes measured from single- CT-PET images also presented variations up to 10% among different phases of 4D PET in both phase-gating and amplitude-gating experiments. Conclusion: Attenuation correction using non-gated CT in 4D-PET imaging is not optimal process for quantitative analysis. Clinical 4D-PET imaging protocols should consider phase-matched 4D-CT image if available to achieve better accuracy.

SU‐D‐18A‐03: Markerless Motion Tracking of Lung Tumors Using Dual‐Energy Fluoroscopy

Purpose:To evaluate the efficacy of dual energy (DE) vs. single energy (SE) fluoroscopic imaging in lung tumors using a markerless template‐based tracking algorithm.Methods:Ten representative patient breathing patterns were programmed into a Quasar™ motion phantom. The phantom was modified by affixing pork ribs to the surface, and a cedar insert with a small spherical volume was used to simulate lung and tumor, respectively. Gated 60kVp(6mA) and 120kVp(1.5mA) fluoroscopic sequences were acquired using the Varian TrueBeam Integrated Imaging Solution. These high and low energy frames were subsequently aligned by phase and amplitude. Frame‐by‐frame weighted logarithmic subtraction was performed resulting in a DE fluoroscopic image sequence that highlighted soft tissue structures. A template‐based algorithm was then used to track tumor motion throughout the sequence for DE and SE images (120kVp). Tracking coordinates were evaluated against ground truth tumor locations as identified by a physician. A displacement of greater than 3 mm was considered a non‐successful track. The same process was also repeated for images obtained from 3 SBRT lung patients, none of which had implanted fiducials.Results:For phantom imaging, a total of 1925 frames were analyzed. The algorithm successfully tracked the target on 91.6%(1763/1925) of DE frames vs. 74.9%(1441/1923) SE images (p&lt;0.001). The displacement between tracking coordinates and ground truth for the phantom was 1.1mm+/−0.7mm for DE and 1.5mm+/− 0.6mm for SE (p&lt;0.001). Images from 3 patients were analyzed with the tumor tracked on 84.9%(478/563) of frames for DE vs. 53.5%(301/563) for SE (p&lt;0.001). The average difference to ground truth for successfully tracked DE frames was 0.6mm+/−0.6mm vs. 1.7mm+/−0.7mm SE (p&lt;0.001).Conclusion:This work indicates the potential for markerless tumor tracking utilizing DE fluoroscopy. With DE imaging, the algorithm showed improved detectability vs. SE fluoroscopy and was able to accurately track the tumor in a majority of cases.This work was supported by Varian Medical Systems

SU‐E‐J‐73: Generation of Volumetric Images with a Respiratory Motion Model Based On An External Surrogate Signal

Purpose:Respiratory motion during radiotherapy treatment can differ significantly from motion observed during imaging for treatment planning. Our goal is to use an initial 4DCT scan and the trace of an external surrogate marker to generate 3D images of patient anatomy during treatment.Methods:Deformable image registration is performed on images from an initial 4DCT scan. The deformation vectors are used to develop a patient‐specific linear relationship between the motion of each voxel and the trajectory of an external surrogate signal. Correlations in motion are taken into account with principal component analysis, reducing the number of free parameters. This model is tested with digital phantoms reproducing the breathing patterns of ten measured patient tumor trajectories, using five seconds of data to develop the model and the subsequent thirty seconds to test its predictions. The model is also tested with a breathing physical anthropomorphic phantom programmed to reproduce a patient breathing pattern.Results:The error (mean absolute, 95th percentile) over 30 seconds in the predicted tumor centroid position ranged from (0.8, 1.3) mm to (2.2, 4.3) mm for the ten patient breathing patterns. The model reproduced changes in both phase and amplitude of the breathing pattern. Agreement between prediction and truth over the entire image was confirmed by assessing the global voxel intensity RMS error. In the physical phantom, the error in the tumor centroid position was less than 1 mm for all images.Conclusion:We are able to reconstruct 3D images of patient anatomy with a model correlating internal respiratory motion with motion of an external surrogate marker, reproducing the expected tumor centroid position with an average accuracy of 1.4 mm. The images generated by this model could be used to improve dose calculations for treatment planning and delivered dose estimates.This work was partially funded by a research grant from Varian Medical Systems.

In vitro evaluation of aerosol delivery by different nebulization modes in pediatric and adult mechanical ventilators.

Aerosol delivery through mechanical ventilation is influenced by the type of aerosol generator, pattern of nebulization, and a patient's breathing pattern. This study compares the efficiency of pneumatic nebulization modes provided by a ventilator with adult and pediatric in vitro lung models. Three pneumatic nebulization modes (inspiratory intermittent [IIM], continuous [CM], and expiratory intermittent [EIM]) provided by the Galileo Gold ventilator delivered medical aerosol to collection filters distal to an endotracheal tube with adult and pediatric test lungs. A unit dose of 5 mg/2.5 mL albuterol was diluted into 4 mL with distilled water and added to a jet nebulizer. The nebulizer was placed proximal to the ventilator, 15 cm from the inlet of the heated humidifier chamber with a T-piece and corrugated aerosol tubing and powered by gas from the ventilator in each of the 3 modes. Time for nebulization was recorded in minutes. Albuterol samples collected in the inhalation filter, nebulizer, T-piece, and corrugated tubing were eluted with distilled water and analyzed with a spectrophotometer. The inhaled drug, as a percentage of total dose in both lung models, was 5.1-7.5%, without statistical significance among the 3 modes. Median nebulization times for IIM, CM, and EIM were 38.9, 14.3, and 17.7 min, respectively, and nebulization time for the 3 modes significantly differed (P < .001). The inhaled drug mass for the 3 modes with the adult lung model was similar to that with the pediatric lung model (7.39 ± 0.76 vs. 6.27 ± 0.69%, P = .77). Aerosol drug delivery with a jet nebulizer placed proximal to the ventilator was not dependent on nebulization mode during simulated pediatric and adult conventional mechanical ventilation. Use of expiratory intermittent mode and continuous nebulization should be considered to reduce treatment time.

A limited‐angle intrafraction verification (LIVE) system for radiation therapy

Currently, no 3D or 4D volumetric x-ray imaging techniques are available for intrafraction verification of target position during actual treatment delivery or in-between treatment beams, which is critical for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. This study aims to develop a limited-angle intrafraction verification (LIVE) system to use prior information, deformation models, and limited angle kV-MV projections to verify target position intrafractionally. The LIVE system acquires limited-angle kV projections simultaneously during arc treatment delivery or in-between static 3D/IMRT treatment beams as the gantry moves from one beam to the next. Orthogonal limited-angle MV projections are acquired from the beam's eye view (BEV) exit fluence of arc treatment beam or in-between static beams to provide additional anatomical information. MV projections are converted to kV projections using a linear conversion function. Patient prior planning CT at one phase is used as the prior information, and the on-board patient volume is considered as a deformation of the prior images. The deformation field is solved using the data fidelity constraint, a breathing motion model extracted from the planning 4D-CT based on principal component analysis (PCA) and a free-form deformation (FD) model. LIVE was evaluated using a 4D digital extended cardiac torso phantom (XCAT) and a CIRS 008A dynamic thoracic phantom. In the XCAT study, patient breathing pattern and tumor size changes were simulated from CT to treatment position. In the CIRS phantom study, the artificial target in the lung region experienced both size change and position shift from CT to treatment position. Varian Truebeam research mode was used to acquire kV and MV projections simultaneously during the delivery of a dynamic conformal arc plan. The reconstruction accuracy was evaluated by calculating the 3D volume percentage difference (VPD) and the center of mass (COM) difference of the tumor in the true on-board images and reconstructed images. In both simulation and phantom studies, LIVE achieved substantially better reconstruction accuracy than reconstruction using PCA or FD deformation model alone. In the XCAT study, the average VPD and COM differences among different patient scenarios for LIVE system using orthogonal 30° scan angles were 4.3% and 0.3 mm when using kV+BEV MV. Reducing scan angle to 15° increased the average VPD and COM differences to 15.1% and 1.7 mm. In the CIRS phantom study, the VPD and COM differences for the LIVE system using orthogonal 30° scan angles were 6.4% and 1.4 mm. Reducing scan angle to 15° increased the VPD and COM differences to 51.9% and 3.8 mm. The LIVE system has the potential to substantially improve intrafraction target localization accuracy by providing volumetric verification of tumor position simultaneously during arc treatment delivery or in-between static treatment beams. With this improvement, LIVE opens up a new avenue for margin reduction and dose escalation in both fractionated treatments and SRS and SBRT treatments.

Dosimetric evaluation of the interplay effect in respiratory-gated RapidArc radiation therapy

Volumetric modulated arc therapy (VMAT) with gating capability has had increasing adoption in many clinics in the United States. In this new technique, dose rate, gantry rotation speed, and the leaf motion speed of multileaf collimators (MLCs) are modulated dynamically during gated beam delivery to achieve highly conformal dose coverage of the target and normal tissue sparing. Compared with the traditional gated intensity-modulated radiation therapy technique, this complicated beam delivery technique may result in larger dose errors due to the intrafraction tumor motion. The purpose of this work is to evaluate the dosimetric influence of the interplay effect for the respiration-gated VMAT technique (RapidArc, Varian Medical Systems, Palo Alto, CA). Our work consisted of two parts: (1) Investigate the interplay effect for different target residual errors during gated RapidArc delivery using a one-dimensional moving phantom capable of producing stable sinusoidal movement; (2) Evaluate the dosimetric influence in ten clinical patients' treatment plans using a moving phantom driven with a patient-specific respiratory curve. For the first part of this study, four plans were created with a spherical target for varying residual motion of 0.25, 0.5, 0.75, and 1.0 cm. Appropriate gating windows were applied for each. The dosimetric effect was evaluated using EDR2 film by comparing the gated delivery with static delivery. For the second part of the project, ten gated lung stereotactic body radiotherapy cases were selected and reoptimized to be delivered by the gated RapidArc technique. These plans were delivered to a phantom, and again the gated treatments were compared to static deliveries by the same methods. For regular sinusoidal motion, the dose delivered to the target was not substantially affected by the gating windows when evaluated with the gamma statistics, suggesting the interplay effect has a small role in respiratory-gated RapidArc therapy. Varied results were seen when gated therapy was performed on the patient plans that could only be attributed to differences in patient respiratory patterns. Patients whose plans had the largest percentage of pixels failing the gamma statistics exhibited irregular breathing patterns including substantial interpatient variation in depth of respiration. The interplay effect has a limited impact on gated RapidArc therapy when evaluated with a linear phantom. Variations in patient breathing patterns, however, are of much greater clinical significance. Caution must be taken when evaluating patients' respiratory efforts for gated arc therapy.

A Pilot Study Comparing 2 Oxygen Delivery Methods for Patients' Comfort and Administration of Oxygen

The traditional oxygen delivery methods for oxygen therapy are continuous flow oxygen (CFO) and demand oxygen delivery (DOD); however, oxygen waste is considerable in CFO, while DOD is uncomfortable for patients. Synchronized DOD (SDOD), which was designed to overcome the drawbacks of both CFO and DOD, supplies oxygen according to the patient's breathing pattern and the desired oxygen saving. This study was conducted to examine the overall performance of SDOD in terms of oxygen saturation (SpO2 ), patients' comfort, and oxygen saving ratio (SR). Study subjects were patients who required oxygen for COPD or pneumonia. Patients received oxygen through nasal prongs by CFO and SDOD for 30 min each. SpO2 was measured every 10 min by pulse oximetry, and subjects recorded their level of comfort after 30 min. The flow of discharged oxygen was recorded to calculate SR. Ten subjects (median age, 68 y; range, 56-86 y) were enrolled. The SpO2 of patients during SDOD (97 ± 2%) was similar to that during CFO (96 ± 3%) with no statistically significant difference (P = .53). Subjects reported SDOD to be more comfortable than CFO. The comfort score of subjects treated with SDOD was 7.05 ± 2.07 (0: very uncomfortable, 10: very comfortable); this was significantly higher (P = .02) than the comfort score (5.20 ± 1.83) of subjects treated with CFO. The SR values set by clinicians were very similar to calculated SR values. SDOD appears to be more suitable for oxygen therapy than CFO when considering SpO2 , patients' comfort, and SR.

The Balance Between Effective Opioid-Based Pain Management and Patient Safety: Can It Be Achieved?

The Balance Between Effective Opioid-Based Pain Management and Patient Safety: Can It Be Achieved?