Verification of surface-guided radiation therapy (SGRT) alignment for proton breast and chest wall patients by comparison to CT-on-rails and kV-2D alignment.

BACKGROUND: Surface-guided radiation therapy (SGRT) systems have been widely installed and utilized on linear accelerators. However, the use of SGRT with proton therapy is still a newly developing field, and published reports are currently very limited. PURPOSE: To assess the clinical application and alignment agreement of SGRT with CT-on-rails (CTOR) and kV-2D image-guided radiation therapy (IGRT) for breast treatment using proton therapy. METHODS: Four patients receiving breast or chest wall treatment with proton therapy were the subjects of this study. Patient #1's IGRT modalities were a combination of kV-2D and CTOR. CTOR was the only imaging modality for patients #2 and #3, and kV-2D was the only imaging modality for patient #4. The patients' respiratory motions were assessed using a 2-min surface position recorded by the SGRT system during treatment. SGRT offsets reported after IGRT shifts were recorded for each fraction of treatment. The agreement between SGRT and either kV-2D or CTOR was evaluated. RESULTS: The respiratory motion amplitude was <4 mm in translation and <2.0° in rotation for all patients. The mean and maximum amplitude of SGRT offsets after application of IGRT shifts were ≤(2.6 mm, 1.6° ) and (6.8 mm, 4.5° ) relative to kV-2D-based IGRT; ≤(3.0 mm, 2.6° ) and (5.0 mm, 4.7° ) relative to CTOR-based IGRT without breast tissue inflammation. For patient #3, breast inflammation was observed for the last three fractions of treatment, and the maximum SGRT offsets post CTOR shifts were up to (14.0 mm, 5.2° ). CONCLUSIONS: Due to the overall agreement between SGRT and IGRT within reasonable tolerance, SGRT has the potential to serve as a valuable auxiliary IGRT tool for proton breast treatment and may improve the efficiency of proton breast treatment.

An evaluation of the use of DirectSPR images for proton planning in the RayStation treatment planning software.

An important source of uncertainty in proton therapy treatment planning is the assignment of stopping-power ratio (SPR) from CT data. A commercial product is now available that creates an SPR map directly from dual-energy CT (DECT). This paper investigates the use of this new product in proton treatment planning and compares the results to the current method of assigning SPR based on a single-energy CT (SECT). Two tissue surrogate phantoms were CT scanned using both techniques. The SPRs derived from single-energy CT and by DirectSPR™ were compared to measured values. SECT-based values agreed with measurements within 4% except for low density lung and high density bone, which differed by 13% and 8%, respectively. DirectSPR™ values were within 2% of measured values for all tissues studied. Both methods were also applied to scanned containers of three types of animal tissue, and the expected range of protons of two different energies was calculated in the treatment planning system and compared to the range measured using a multi-layer ion chamber. The average difference between range measurements and calculations based on SPR maps from dual- and single-energy CT, respectively, was 0.1 mm (0.07%) versus 2.2 mm (1.5%). Finally, a phantom was created using a layer of various tissue surrogate plugs on top of a 2D ion chamber array. Dose measurements on this array were compared to predictions using both single- and dual-energy CTs and SPR maps. While standard gamma pass rates for predictions based on DECT-derived SPR maps were slightly higher than those based on single-energy CT, the differences were generally modest for this measurement setup. This study showed that SPR maps created by the commercial product from dual-energy CT can successfully be used in RayStation to generate proton dose distributions and that these predictions agree well with measurements.

Measurements of fetal dose with Mevion S250i proton therapy system with HYPERSCAN.

PURPOSE: To characterize potential dose to the fetus for all modes of delivery (dynamic adaptive aperture, static adaptive aperture, and no adaptive aperture) for the Mevion S250i Proton Therapy System with HYPERSCAN and compare the findings with those of other available proton systems. MATERIALS AND METHODS: Fetal dose measurements were performed for all three modes of dose delivery on the Mevion S250i Proton therapy system with HYPERSCAN (static aperture, dynamic aperture and uncollimated). Standard treatment plans were created in RayStation for a left-sided brain lesion treated with a vertex field, a left lateral field, and a posterior field. Measurements were performed using WENDI and the RANDO with the detector placed at representative locations to mimic the growth and movement of the fetus at different gestational stages. RESULTS: The fetal dose measurements varied with fetus position and the largest measured dose was 64.7 µSv per 2 Gy (RBE) fraction using the dynamic aperture. The smallest estimated fetal dose was 45.0 µSv per 2 Gy (RBE) at the base of the RANDO abdomen (47 cm from isocenter to the outer width of WENDI and 58.5 cm from the center of the WENDI detector) for the static aperture delivery. The vertex fields at all depths had larger contributions to the total dose than the other two and the dynamic aperture plans resulted in the highest dose measured for all depths. CONCLUSION: The reported doses are lower than reported doses using a double-scattering system. This work suggests that avoiding vertex fields and using the static aperture will help minimize dose to the fetus.

Technical note: Evaluation of a silicone-based custom bolus for radiation therapy of a superficial pelvic tumor.

PURPOSE: Use of standard-of-care radiation therapy boluses may result in air-gaps between the target surface and bolus, as they may not adequately conform to each patient's unique topography. Such air-gaps can be particularly problematic in cases of superficial pelvic tumor radiation, as the density variation may result in the radiation delivered to the target site being inconsistent with the prescribed dose. To increase bolus fit and thereby dose predictability and homogeneity, we designed and produced a custom silicone bolus for evaluation against the clinical standard. METHODS: A custom bolus was created for the pelvic regions of both an anthropomorphic phantom and a pelvic patient with squamous cell carcinoma of the penile shaft. Molds were designed using computed tomography (CT) scans, then 3D-printed and cast with silicone rubber to yield the boluses. Air-gap measurements were performed on custom and standard-of-care Superflab gel sheet boluses by analyzing total volume between the bolus and target surface, as measured from CT scans. Therapeutic doses of radiation were delivered to both boluses. Radiation dose was measured and compared to the expected dose using nine optically stimulated luminescent dosimeters (OSLDs) placed on the phantom. RESULTS: Mean air-gap volume between the bolus and phantom was decreased from 314 ± 141 cm3 with the standard bolus to 4.56 ± 1.59 cm3 using the custom device. In the case of the on-treatment patient, air-gap volume was reduced from 169 cm3 with the standard bolus to 46.1 cm3 with the custom. Dosimetry testing revealed that the mean absolute difference between expected and received doses was 5.69%±4.56% (15.1% maximum) for the standard bolus and 1.91%±1.31% (3.51% maximum) for the custom device. Areas of greater dose difference corresponded to areas of larger air-gap. CONCLUSIONS: The custom bolus reduced air-gap and increased predictability of radiation dose delivered compared to the standard bolus. The custom bolus could increase the certainty of prescribed dose-delivery of radiation therapy for superficial tumors.

Impact of the MLC leaf-tip model in a commercial TPS: Dose calculation limitations and IROC-H phantom failures.

PURPOSE: Treatment planning system (TPS) dose calculation is sensitive to multileaf collimator (MLC) modeling, especially when treating with intensity-modulated radiation therapy (IMRT) or VMAT. This study investigates the dosimetric impact of the MLC leaf-tip model in a commercial TPS (RayStation v.6.1). The detectability of modeling errors was assessed through both measurements with an anthropomorphic head-and-neck phantom and patient-specific IMRT QA using a 3D diode array. METHODS AND MATERIALS: An Agility MLC (Elekta Inc.) was commissioned in RayStation. Nine IMRT and VMAT plans were optimized to treat the head-and-neck phantom from the Imaging and Radiation Oncology Core Houston branch (IROC-H). Dose distributions for each plan were re-calculated on 27 beam models, varying leaf-tip width (2.0, 4.5, and 6.5 mm) and leaf-tip offset (-2.0 to +2.0 mm) values. Doses were compared to phantom TLD measurements. Patient-specific IMRT QA was performed, and receiver-operating characteristic (ROC) analysis was performed to determine the detectability of modeling errors. RESULTS: Dose calculations were very sensitive to leaf-tip offset values. Offsets of ±1.0 mm resulted in dose differences up to 10% and 15% in the PTV and spinal cord TLDs respectively. Offsets of ±2.0 mm caused dose deviations up to 50% in the spinal cord TLD. Patient-specific IMRT QA could not reliably detect these deviations, with an ROC area under the curve (AUC) value of 0.537 for a ±1.0 mm change in leaf-tip offset, corresponding to >7% dose deviation. Leaf-tip width had a modest dosimetric impact with <2% and 5.6% differences in the PTV and spinal cord TLDs respectively. CONCLUSIONS: Small changes in the MLC leaf-tip offset in this TPS model can cause large changes in the calculated dose for IMRT and VMAT plans that are difficult to identify through either dose curves or standard patient-specific IMRT QA. These results may, in part, explain the reported high failure rate of IROC-H phantom tests.

Optimization of a novel large field of view distortion phantom for MR-only treatment planning.

PURPOSE: MR-only treatment planning requires images of high geometric fidelity, particularly for large fields of view (FOV). However, the availability of large FOV distortion phantoms with analysis software is currently limited. This work sought to optimize a modular distortion phantom to accommodate multiple bore configurations and implement distortion characterization in a widely implementable solution. METHOD AND MATERIALS: To determine candidate materials, 1.0 T MR and CT images were acquired of twelve urethane foam samples of various densities and strengths. Samples were precision-machined to accommodate 6 mm diameter paintballs used as landmarks. Final material candidates were selected by balancing strength, machinability, weight, and cost. Bore sizes and minimum aperture width resulting from couch position were tabulated from the literature (14 systems, 5 vendors). Bore geometry and couch position were simulated using MATLAB to generate machine-specific models to optimize the phantom build. Previously developed software for distortion characterization was modified for several magnet geometries (1.0 T, 1.5 T, 3.0 T), compared against previously published 1.0 T results, and integrated into the 3D Slicer application platform. RESULTS: All foam samples provided sufficient MR image contrast with paintball landmarks. Urethane foam (compressive strength ∼1000 psi, density ~20 lb/ft3 ) was selected for its accurate machinability and weight characteristics. For smaller bores, a phantom version with the following parameters was used: 15 foam plates, 55 × 55 × 37.5 cm3 (L×W×H), 5,082 landmarks, and weight ~30 kg. To accommodate > 70 cm wide bores, an extended build used 20 plates spanning 55 × 55 × 50 cm3 with 7,497 landmarks and weight ~44 kg. Distortion characterization software was implemented as an external module into 3D Slicer's plugin framework and results agreed with the literature. CONCLUSION: The design and implementation of a modular, extendable distortion phantom was optimized for several bore configurations. The phantom and analysis software will be available for multi-institutional collaborations and cross-validation trials to support MR-only planning.

Impact of incorporating visual biofeedback in 4D MRI.

Precise radiation therapy (RT) for abdominal lesions is complicated by respiratory motion and suboptimal soft tissue contrast in 4D CT. 4D MRI offers improved con-trast although long scan times and irregular breathing patterns can be limiting. To address this, visual biofeedback (VBF) was introduced into 4D MRI. Ten volunteers were consented to an IRB-approved protocol. Prospective respiratory-triggered, T2-weighted, coronal 4D MRIs were acquired on an open 1.0T MR-SIM. VBF was integrated using an MR-compatible interactive breath-hold control system. Subjects visually monitored their breathing patterns to stay within predetermined tolerances. 4D MRIs were acquired with and without VBF for 2- and 8-phase acquisitions. Normalized respiratory waveforms were evaluated for scan time, duty cycle (programmed/acquisition time), breathing period, and breathing regularity (end-inhale coefficient of variation, EI-COV). Three reviewers performed image quality assessment to compare artifacts with and without VBF. Respiration-induced liver motion was calculated via centroid difference analysis of end-exhale (EE) and EI liver contours. Incorporating VBF reduced 2-phase acquisition time (4.7 ± 1.0 and 5.4 ± 1.5 min with and without VBF, respectively) while reducing EI-COV by 43.8% ± 16.6%. For 8-phase acquisitions, VBF reduced acquisition time by 1.9 ± 1.6 min and EI-COVs by 38.8% ± 25.7% despite breathing rate remaining similar (11.1 ± 3.8 breaths/min with vs. 10.5 ± 2.9 without). Using VBF yielded higher duty cycles than unguided free breathing (34.4% ± 5.8% vs. 28.1% ± 6.6%, respectively). Image grading showed that out of 40 paired evaluations, 20 cases had equivalent and 17 had improved image quality scores with VBF, particularly for mid-exhale and EI. Increased liver excursion was observed with VBF, where superior-inferior, anterior-posterior, and left-right EE-EI displacements were 14.1± 5.8, 4.9 ± 2.1, and 1.5 ± 1.0 mm, respectively, with VBF compared to 11.9 ± 4.5, 3.7 ± 2.1, and 1.2 ± 1.4 mm without. Incorporating VBF into 4D MRI substantially reduced acquisition time, breathing irregularity, and image artifacts. However, differences in excursion were observed, thus implementation will be required throughout the RT workflow.

Automation framework for online review of daily dose distributions using CT on Rails in proton therapy.

PURPOSE: To demonstrate a framework for calculating daily dose distributions for proton therapy in a timeframe amenable to online evaluation using CT-on-Rails. METHODS: Tasks associated with calculation of daily dose are fully automated. A rigid registration between daily and planning images is used to propagate beams and targets for calculation of daily dose; additionally, risk structures are propagated using deformable registration to facilitate online evaluation. An end-to-end constancy test was carried out using a pelvis phantom containing a simulated target and bladder contour. 97 Daily fan-beam CT data sets associated with 10 clinical patients were processed to demonstrate feasibility and utility of online evaluation. Computing times and dosimetric differences are reported. RESULTS: The phantom constancy test took 62 s to complete with no notable discrepancies in the registrations or calculated dose. Max doses were identical for target and bladder contours on initial and repeat scans (359 and 310 cGy (RBE) respectively). Total processing time for 97 daily patient images averaged 154.6 s (73.0 - 222.0 s; SD = 31.8 s). On average, dose calculation accounted for 35 % of total processing time. Average differences in D95 for target contours was 1.5 % (SD = 1.6 %) with a max decrease of 5.9 % on a single daily image. CONCLUSION: Daily dose can be automatically calculated in a timeframe amenable to online evaluation using scanner utilities in conjunction with the scripting API of a commercial treatment planning system. Online evaluation of dose in proton therapy is useful to detect clinically relevant changes, guide setup, and facilitate treatment or replanning decisions.

Isolated lateral-sided knee pain in total knee arthroplasty. A review.

Isolated lateral-sided knee pain is a unique problem following total knee arthroplasty (TKA). Reported causes include soft tissue impingement against extruded cement, an overhanging tibial tray, remnant osteophytes rubbing against the iliotibial band (ITB), popliteal tendon impingement, fabella syndrome, and synovial tissue impingement in the lateral gutter. In addition, iliotibial band traction syndrome secondary to guided motion Bi-cruciate stabilizing knee arthroplasty has been recognized as a new clinical entity. Initial work up should include ruling out the most common causes of painful TKA including infection, aseptic loosening, and instability. Radiographs and CT scan are utilized to identify potential source of pain. Ultrasound evaluation (with elicited probe tenderness) can increase diagnostic accuracy. Ultrasound guided local anesthetic injections can confirm the source of pain. Anti-inflammatory medications, physical therapy with ITB stretches, and therapeutic local steroid injections are initial treatment modalities. Satisfactory resolution of symptoms may require surgical intervention directed at the specific cause and may avoid the morbidity associated with revision TKA.

Adverse Events After Isolated Posterior Cruciate Ligament Reconstruction: A National Database Study.

Background: Optimal management after posterior cruciate ligament (PCL) injury remains an active area of research, as reconstruction is technically challenging and poses unique risks in the posterior knee. Studies have reported variable rates of complications. Purpose: To describe the rates of readmission, emergency department (ED) visits, and postoperative complications within 90 days of isolated PCL reconstruction (PCLR) in a large, national cohort to better understand the perioperative variables that influence a practitioner's decision of whether to pursue operative versus nonoperative management. Study Design: Descriptive epidemiology study. Methods: PCLRs from January 1, 2010, through August 31, 2020, were identified in PearlDiver, a national administrative database. Patients with concomitant ligament surgery and those with fewer than 90 days of postoperative database activity were excluded. Deep vein thromboses, pulmonary embolisms, surgical site infections, compartment syndrome, and vascular events within 90 days of surgery were identified, as were 90-day readmissions and ED visits. Logistic regression models were built in PearlDiver to calculate odds ratios (ORs) for ED utilization. Results: The final cohort consisted of 1154 patients with isolated PCLR (mean age, 34 ± 16 years; 62% male). Most patients were located in the Southern United States (n = 417; 36.1%), and most had commercial insurance (n = 992; 86%). The 90-day rates of adverse events were as follows: deep vein thrombosis (13; 1.1%), pulmonary embolism (19; 1.6%), surgical site infection (<11; <1%), compartment syndrome (<11; <1%), vascular event (<11; <1%), readmission (13, 1.1%), and ED utilization (99; 8.6%). The majority of emergency department visits (52%) occurred in the first 2 weeks postoperatively. Predictive factors for ED utilization included Elixhauser Comorbidity Index score (OR = 1.31 per 2-point increase) and Medicaid insurance (OR = 2.03 relative to commercial insurance). Conclusion: The current study reported rates of adverse events after isolated PCLR in a large, national cohort. The results provide important context for decisions about optimal management of PCL injury.

Insectivorous bat pollinates columnar cactus more effectively per visit than specialized nectar bat.

Plant-pollinator interactions are great model systems to investigate mutualistic relationships. We compared pollinator effectiveness between facultative and obligate nectar-feeding bats to determine how foraging specialization influences mutualistic interactions in a bat-adapted cactus. We predicted that a specialized nectarivorous bat would deliver more pollen than an opportunistic nectar-feeding bat because of specialized adaptations to nectar feeding that indicate close association with their food plants. Counter to our predictions, the opportunistic Antrozous pallidus delivered significantly more pollen grains per visit than the specialized Leptonycteris yerbabuenae. Higher pollinator effectiveness, based on visitation rates and pollen deposition levels, varied between species by site, and although A. pallidus visits flowers much less frequently than L. yerbabuenae over all sites, it is likely an effective and reliable pollinator of Pachycereus pringlei in Baja, Mexico. Our results suggest that morphological adaptations and dietary specialization on nectar do not necessarily confer advantages for pollination over less specialized plant visitors and highlight the reciprocally exploitative nature of mutualisms.

A Novel Positioning Technique for Olecranon Fracture Fixation.

Various positioning techniques have been described for the osteosynthesis of olecranon fractures, each with their own pros and cons. The supine position is time-efficient and better suited in a polytrauma setting but frequently requires an assistant to maintain optimal limb positioning. Also, adequate fluoroscopic imaging is not possible without moving the operative extremity outside the sterile field. We describe a simple and reproducible method addressing these limitations while providing excellent surgical access and intraoperative imaging.

Adipose Tissue Distribution and Body Mass Index (BMI) Correlation With Daily Image-Guided Radiotherapy (IGRT) Shifts of Abdominal Radiation Therapy Patients.

Purpose There are several studies suggesting a correlation between image-guided radiotherapy (IGRT) setup errors and body mass index (BMI). However, abdominal fat content has visceral and subcutaneous components, which may affect setup errors differently. This study aims to analyze a potential workflow for characterizing adipose content and distribution in the region of the target that would allow a quickly calculated metric of abdominal fat content to stratify these patients. Methods IGRT shift data was retrospectively tabulated from daily fan-beam CT-on-rails pre-treatment alignment for 50 abdominal radiation therapy (RT) patients, and systematic and random errors in the daily setup were characterized by tabulating average and standard deviations of shift data for each patient and looking at differences for different distributions of adipose content. Visceral and subcutaneous fat content were defined by visceral fat area (VFA) and subcutaneous fat area (SFA) using a region-growing algorithm to contour adipose tissue on CT simulation scans. All contours were created for a single slice at the treatment isocenter, on which the VFA and SFA were calculated. A log-rank test was used to test trends in shifts over quartiles of adiposity. Results VFA ranged from 1.9-342.8c m2, and SFA from 11.8-756.0 cm2. The standard definition (SD) of random error (σ) in the lateral axis for Q1 vs. Q4 VFA was 0.10cm vs. 0.29cm, 0.12cm vs. 0.28cm for SFA, and 0.12cm vs. 0.31cm for BMI. The percentage of longitudinal shifts greater than 10mm for Q1 vs. Q4 VFA was 0% vs. 9%, 2% vs. 19% for SFA, and 0% vs. 20% for BMI. Statistically significant trends in shifts vs. the BMI quartile were seen for both pitch and the longitudinal direction, as well as for pitch corrections vs. the VFA quartile. Conclusion Within this dataset, abdominal cancer patients showed statistically significant trends in shift probability vs. BMI and VFA. Also, patients in the upper quartiles of all adiposity metrics showed an increased SD of σ in the lateral direction and increased shifts over 10 mm in the longitudinal direction. However, despite these relationships, neither VFA nor SFA offered discernible advantages in their relationship to shift uncertainty relative to BMI.

No Thromboembolic Complications After Facial Feminization Surgery in Transgender Patients Utilizing Estrogen Therapy: A Retrospective Cohort Study.

Purpose: Estrogen therapy is associated with an increased risk of venous thromboembolism (VTE). A large proportion of transfeminine patients use estrogen therapy before undergoing gender-affirming surgery. Many surgeons implement the discontinuation of hormone therapy before surgery. This study sought to evaluate the perioperative risk of VTE in transfeminine patients undergoing the procedure of facial feminization. Methods: Retrospective chart reviews were performed of all patients who underwent facial feminization by a single surgeon at an urban academic institution from 2014 to 2020. Patient characteristics including comorbidities, Caprini score, VTE chemoprophylaxis, and perioperative hormone therapy management were reviewed. The incidences of VTE during perioperative hospital stay and within 1 week and 6 months after the surgical procedure were examined. Results: There were 296 facial feminization procedures performed on 282 distinct patients who met criteria for inclusion in the study. Hormone therapy was prescribed to 83.6% of patients, 69.5% of whom reported that they held these medications before the procedure. Of those holding, 84.1% of patients reported they discontinued these medications between 2 and 4 weeks. No patients received VTE chemoprophylaxis. There were 0 VTE incidents during the patients' perioperative period up to 6 months postprocedure. Conclusion: Our findings support that transfeminine patients who use estrogen hormone therapy are at a minimal risk to experience VTE when undergoing facial feminization procedures. Future directions include evaluating the psychologic effect of discontinuing hormone therapy to help guide perioperative decision making.

High Incidence of Postoperative Nausea and Vomiting in Transgender Women Undergoing Facial Feminization Procedures.

Background: Postoperative nausea and vomiting (PONV) is a significant concern due to its impact on patient comfort, recovery time, and extended hospital stay. Previous research links higher PONV rates in women during their periovulatory phase to estrogen. This study investigates the PONV risk in transgender women after facial feminization surgery. Methods: Retrospective chart reviews of transgender women aged older than 18 undergoing facial feminization from 2014 to 2020 were undertaken. Data included demographics, hormone use history, comorbidities, and PONV history. PONV was classified as any nausea/vomiting episode before discharge. Anesthesia records were examined, and PACU notes were analyzed for PONV indicators. A cis-gender male and female cohort undergoing rhinoplasty served as controls. Results: Of the 282 transgender women receiving facial feminization surgery, 104 experienced PONV, marking a 37% PONV rate. Compared with the 11% PONV rate among cis-gender rhinoplasty patients, this was notably higher. Hormone therapy discontinuation showed no influence on PONV incidence. Conclusions: Transgender women undergoing facial feminization surgery have a 38% PONV rate, surpassing the 11% rate in cis-gender rhinoplasty patients and the general 20%-30% rate for all procedures, including the 25% for oral and maxillofacial surgery. This suggests a heightened PONV risk for transgender women after facial feminization procedures.

Technical note: Clinical evaluation of a newly released surface-guided radiation therapy system on DIBH for left breast radiation therapy.

BACKGROUND: It has been shown that a significant reduction of mean heart dose and left anterior descending artery (LAD) dose can be achieved through the use of DIBH for left breast radiation therapy. Surface-guided DIBH has been widely adopted during the last decade, and there are mainly three commercially available SGRT systems. The reports of the performance of a newly released SGRT system for DIBH application are currently very limited. PURPOSE: To evaluate the clinical performance of a newly released SGRT system on DIBH for left breast radiation therapy. METHODS: Twenty-five left breast cancer patients treated with DIBH utilizing Varian's Identify system were included (total 493-fraction treatments). Four aspects of the clinical performance were evaluated: Identify offsets of free breathing post patient setup from tattoos, Identify offsets during DIBH, Identify agreement with radiographic ports during DIBH, and DIBH reference surface re-capture post patient shifts. The systematic and random errors of free breathing Identify offsets post patient setup were calculated for each patient, as well as for offsets during DIBH. Radiographic ports were taken when the patient's DIBH position was within the clinical tolerance of (± 0.3 cm, ± 30 ), and these were then compared with treatment field DRRs. If the ports showed that the patient alignment did not agree with the DRRs within 3 mm, a patient shift was performed. A new reference surface was captured and verification ports were taken. RESULTS: The all-patient average systematic and random errors of Identify offsets for free breathing were within (0.4 cm, 1.50 ) post tattoo setup. The maximum per-patient systematic and random errors were (1.1 cm, 6.20 ) and (0.9 cm, 20 ), and the maximum amplitude of Identify offsets were (2.59 cm, 90 ). All 493-fraction DIBH treatments were delivered and successfully guided by the Identify SGRT system. The systematic and random errors of Identify offsets for DIBH were within (0.2 cm, 2.30 ). Seven patients needed re-captured surface references due to surface variation or position shifts based on the ports. All patient DIBH verification ports guided by Identify were approved by attending physicians. CONCLUSION: This evaluation showed that the Identify system performed effectively for surface-guided patient setup and surface-guided DIBH imaging and treatment delivery. The feature of color-coded real-time patient surface matching feedback facilitated the evaluation of the patient alignment accuracy and the adjustment of the patient position to match the reference.

Initial clinical evaluation of a novel combined biometric, radio-frequency identification, and surface imaging system.

PURPOSE: To evaluate and characterize the overall clinical functionality and workflow of the newly released Varian Identify system (version 2.3). METHODS: Three technologies included in the Varian Identify system were evaluated: patient biometric authentication, treatment accessory device identification, and surface-guided radiation therapy (SGRT) function. Biometric authentication employs a palm vein reader. Treatment accessory device verification utilizes two technologies: device presence via Radio Frequency Identification (RFID) and position via optical markers. Surface-guidance was evaluated on both patient orthopedic setup at loading position and surface matching and tracking at treatment isocenter. A phantom evaluation of the consistency and accuracy for Identify SGRT function was performed, including a system consistency test, a translational shift and rotational accuracy test, a pitch and roll accuracy test, a continuous recording test, and an SGRT vs Cone-Beam CT (CBCT) agreement test. RESULTS: 201 patient authentications were verified successfully with palm reader. All patient treatment devices were successfully verified for their presences and positions (indexable devices). The patient real-time orthopedic pose was successfully adjusted to match the reference surface captured at simulation. SGRT-reported shift consistency against couch readout was within (0.1 mm, 0.030). The shift accuracy was within (0.3 mm, 0.10). In continuous recording mode, the maximum variation was 0.2 ± 0.12 mm, 0.030 ± 0.020. The difference between Identify SGRT offset and CBCT was within (1 mm, 10). CONCLUSIONS: This clinical evaluation confirms that Identify accurately functions for patient palm identification and patient treatment device presence and position verification. Overall SGRT consistency and accuracy was within (1 mm, 10), within the 2 mm criteria of AAPM TG302.

Mas-related gene X2 (MrgX2) is a novel G protein-coupled receptor for the antimicrobial peptide LL-37 in human mast cells: resistance to receptor phosphorylation, desensitization, and internalization.

Human LL-37 is a multifunctional antimicrobial peptide that promotes inflammation, angiogenesis, wound healing, and tumor metastasis. Most effects of LL-37 are mediated via the activation of the cell surface G protein-coupled receptor FPR2 on leukocytes and endothelial cells. Although LL-37 induces chemotaxis, degranulation, and chemokine production in mast cells, the receptor involved and the mechanism of its regulation remain unknown. MrgX2 is a member of Mas-related genes that is primarily expressed in human dorsal root ganglia and mast cells. We found that a human mast cell line LAD2 and CD34(+) cell-derived primary mast cells, which natively express MrgX2, responded to LL-37 for sustained Ca(2+) mobilization and substantial degranulation. However, an immature human mast cell line, HMC-1, that lacks functional MrgX2 did not respond to LL-37. shRNA-mediated knockdown of MrgX2 in LAD2 mast cell line and primary CD34(+) cell-derived mast cells caused a substantial reduction in LL-37-induced degranulation. Furthermore, mast cell lines stably expressing MrgX2 responded to LL-37 for chemotaxis, degranulation, and CCL4 production. Surprisingly, MrgX2 was resistant to LL-37-induced phosphorylation, desensitization, and internalization. In addition, shRNA-mediated knockdown of the G protein-coupled receptor kinases (GRK2 and GRK3) had no effect on LL-37-induced mast cell degranulation. This study identified MrgX2 as a novel G protein-coupled receptor for the antibacterial peptide LL-37 and demonstrated that unlike most G protein-coupled receptors it is resistant to agonist-induced receptor phosphorylation, desensitization, and internalization.

The incidence of avascular necrosis in children with cerebral palsy after hip containment surgery.

Purpose: To establish the rate of avascular necrosis after hip reconstruction surgery in children with cerebral palsy and to identify risk factors that influence the development of avascular necrosis in this population. Methods: An institutional review board-approved retrospective review was conducted on children with cerebral palsy who underwent hip containment surgery at a single institution. Radiographs were evaluated at three time points. The Reimer's migration percentage, neck shaft angle, epiphyseal shaft angle, acetabular index, center edge angle, and acetabular angle were measured. The presence of avascular necrosis was evaluated and graded by the Bucholz/Ogden and the Kalamchi/MacEwen classification systems. Multivariate logistic regression was performed to identify risk factors associated with the development of avascular necrosis. Results: A total of 154 children with cerebral palsy underwent hip containment surgery on 223 hips. Twenty-nine children (18.8%) underwent both pelvic and femoral procedures; 36 children (23.4%) had only femoral procedures; 47 children (30.5%) had femoral and soft tissue; and 42 children (27.3%) had pelvic, femoral, and soft tissue procedures. Using the Bucholz and Ogden or the Kalamchi classifications, the rate of avascular necrosis was 24.7% (38/154). Of the variables evaluated, preoperative Reimers was found to be significant predictors of avascular necrosis. The rate of avascular necrosis was 26.7% for Gross Motor Functional Classification System level III, 24.1% for Gross Motor Functional Classification System level IV, and 27.3% for Gross Motor Functional Classification System level V. Conclusion: The overall rate of avascular necrosis in children undergoing hip containment surgery was 26.7%. Together, age at surgery, open reduction, previous surgery, preoperative Reimers, and estimated blood loss contributed to the development of postoperative avascular necrosis; however, only preoperative Reimers significantly contributed to the development of avascular necrosis in children with cerebral palsy undergoing hip containment procedures.

Oxygen desaturation in a transgender man: initial concerns and recommendations regarding the practice of chest binding: a case report.

BACKGROUND: Over 1.4 million US adults identify as transgender when gender identity differs from the sex assigned at birth [1]. Although transgender patients face adverse health outcomes, they remain an understudied population [2]. A 2017 study surveyed 411 practicing clinicians and found that 80% had been involved in treating a transgender patient, but 80.6% had never received training on transgender care [3]. The purpose of this report is to describe prolonged desaturation in one case of a transgender patient who wore a chest binder intraoperatively owing to a lack of preoperative recognition. CASE PRESENTATION: A 19-year-old transgender male of African-American descent with anxiety and class 3 obesity presented for an esophagogastroduodenoscopy to evaluate a 2-year history of upper abdominal pain unresponsive to proton pump inhibitor therapy, with a plan for monitored anesthesia care. His medications included sertraline, pantoprazole, zolpidem, ergocalciferol, leuprolide, and testosterone cypionate. Preoperatively, the patient was instructed to remove all clothing and to don a patient gown while in the bathroom. The attending anesthesiologist then conducted the interview and examination in the preoperative holding area. The patient was induced with 250 mg of propofol, and reassuring respirations were noted by capnography. Respirations and oxygen saturation remained stable upon insertion of the endoscope. Four minutes later, the patient's oxygen saturation rapidly decreased to 50% and end-tidal capnography was lost. The endoscope was removed, and the patient was given 200 mg of propofol and 20 mg succinylcholine. His oxygen saturation recovered to 80% and 100% after 2 and 5 minutes, respectively, of ventilation with 100% inspired oxygen. No further oxygen desaturation was noted throughout the procedure, and the patient was closely monitored for signs of respiratory difficulty during an uneventful postoperative course. After full emergence, it was revealed that the patient had been wearing a chest binder throughout the operative procedure. The patient was counseled on the necessity to communicate the presence of this accessory prior to all future procedures. CONCLUSION: In the clinical narrative, a healthy patient was observed to have prolonged oxygen desaturation after induction of anesthesia. Laryngospasm was suspected clinically owing to the sudden absence of end-tidal carbon dioxide. Prolonged oxygen desaturation despite appropriate interventions suggests the contribution of additional factors. We speculate that the presence of a chest binder intraoperatively predisposed the patient to more rapid oxygen desaturation less responsive to typical therapy. A chest binder would introduce mechanical restriction to the patient's breathing owing to its inherent design to compress. Although the patient was asked to remove all clothing, specific instructions were not provided regarding the removal of a chest binder. The presence of chest binding was also absent in the electronic health record, despite the documented presence of the patient's preferred gender, hormonal therapy regimen, and medical history. Ultimately, this case reflects the gap between practitioner knowledge and hospital guidelines and the practices of transgender patients. In reviewing existing literature and the potential for atelectasis with external compression, we would consider that patients refrain from chest binding for 12-24 hours before surgical procedures, resume no sooner than 24 hours after ambulation, and participate in diagnostic incentive spirometry pre- and postoperatively.