The Lifesaving Impact of Transcatheter Interventions in the Early Post-Fontan Palliation Period.

Despite advancements in postoperative outcomes after Fontan surgery, there remains a risk of suboptimal outcomes and significant morbidity in the early postoperative period. Anatomical obstructions in the Fontan pathway can lead to prolonged pleural effusion or ascites, cyanosis, and low cardiac output syndrome (LCOS). Transcatheter interventions offer an alternative to early re-surgery for treating these complications. Over a 13-year period, early catheter angiography, performed within 30 days post-index procedure, was administered to 41 patients, identifying anatomical issues that necessitated re-intervention in 39 cases. This led to transcatheter interventions in 37 (10.4%) of the 344 Fontan surgery patients. The median age was 4.8 years (IQR: 4-9.4), and the median weight was 16.5 kg (IQR: 15-25.2), with females comprising 51.4% (19/37) of this group. The primary indications for the procedures were persistent pleural effusion or ascites in 27 patients (66%), LCOS in 8 patients (20%), and cyanosis in 6 patients (14%). Among the 37 undergoing transcatheter intervention, 30 were treated solely with this method and discharged, three died in ICU follow-up, and four required early re-surgery. No procedural mortality was observed. Our findings demonstrate that transcatheter interventions, including stent implantation, balloon angioplasty, and fenestration dilation, are safe and effective in the early post-Fontan period. Therefore, they should be considered an integral part of the management strategy for this patient group.

Utility of Balloon Occlusion Testing in Determining Fontan Suitability Among Patients with Elevated Pulmonary Artery Pressure and Additional Antegrade Pulmonary Blood Flow.

In individuals with a single ventricle undergoing evaluation before Fontan surgery, the presence of excessive pulmonary blood flow can contribute to increased pulmonary artery pressure, notably in those who had a Glenn procedure with antegrade pulmonary flow. 28 patients who had previously undergone Glenn anastomosis with antegrade pulmonary blood flow (APBF) and with elevated mean pulmonary artery (mPAP) pressure > 15 mmHg in diagnostic catheter angiography were included in the study. After addressing other anatomical factors that could affect pulmonary artery pressure, APBF was occluded with semi-compliant, Wedge or sizing balloons to measure pulmonary artery pressure accurately. 23 patients (82% of the cohort) advanced to Fontan completion. In this group, median mPAP dropped from 20.5 (IQR 19-22) mmHg to 13 (IQR 12-14) mmHg post-test (p < 0.001). Median PVR post-test was 1.8 (IQR 1.5-2.1) WU m2. SpO2 levels decreased from a median of 88% (IQR 86%-93%) pre-test to 80% (IQR 75%-84%) post-test (p < 0.001). In five patients, elevated mPAP post-test occlusion on diagnostic catheter angiography led to non-completion of Fontan circulation. In this group, median pre- and post-test mPAP were 23 mmHg (IQR 21.5-23.5) and 19 mmHg (IQR 18.5-20), respectively (p = 0.038). Median post-test PVR was 3.8 (IQR 3.6-4.5) WU m2. SpO2 levels decreased from a median of 79% (IQR 76%-81%) pre-test to 77% (IQR 73.5%-80%) post-test (p = 0.039). Our study presents a specialized approach for patients initially deemed unsuitable for Fontan due to elevated pulmonary artery pressures. We were able to successfully complete the Fontan procedure in the majority of these high-risk cases after temporary balloon occlusion test.

A Challenging Interventional Procedure: Transcatheter Closure of Tubular Patent Ductus Arteriosus in Patients with Pulmonary Hypertension.

Transcatheter closure of the tubular ducts remains the most challenging procedure, with higher complication rates than other types. This study evaluates the characteristics of transcatheter closure of tubular ducts with pulmonary hypertension. 73 patients with tubular ducts who underwent cardiac catheterization for transcatheter PDA closure were analyzed. The mean age and weight were 1.93 ± 2.68 years and 8.83 ± 6.14 kg, respectively. Transcatheter closure was attempted in 72 patients. Four cases (5.5%) were referred to surgery, while the procedure was completed in the remaining (94.5%). Amplatzer duct occluder (ADO) I or Cardiofix duct occluder (CDO) was the most commonly used devices. However, the use of Amplatzer vascular plug (AVP) II raised in recent years. The most common concern was aortic protrusion/stenosis in ADO I/CDO devices, but most regressed during follow-up. Iatrogenic coarctation of the aorta was observed in two with ADO I/CDO. Embolization of the device to the pulmonary artery was observed in three with CDO, AVP II, and AVP I. Significant left pulmonary artery stenosis requiring stenting developed in one after closure with an MVSDO device. Tubular ducts are highly associated with pulmonary arterial hypertension, and transcatheter closure of them is still challenging despite the developing device armamentarium. Although ADO I or similar devices are widely used, off-label devices are usually needed at increasing rates. The AVP II device is unsuitable for short tubular ducts but seems the best option for long ones.

CD4+CD25+CD127loFOXP3+ cell in food allergy: Does it predict anaphylaxis?

BACKGROUND: Food allergy (FA), hence the incidence of food anaphylaxis, is a public health problem that has increased in recent years. There are still no biomarkers for patients with FA to predict severe allergic reactions such as anaphylaxis. OBJECTIVE: There is limited information on whether regulatory T (Treg) cell levels are a biomarker that predicts clinical severity in cases presenting with FA, and which patients are at a greater risk for anaphylaxis. METHODS: A total of 70 children were included in the study: 25 who had IgE-mediated cow's milk protein allergy (CMPA) and presented with non-anaphylactic symptoms (FA/A-), 16 who had IgE-mediated CMPA and presented with anaphylaxis (FA/A+) (a total of 41 FA cases), and a control group consisting of 29 children without FA. The study was conducted by performing CD4+CD25+CD127loFOXP3+ cell flow cytometric analysis during resting at least 2 weeks after the elimination diet to FA subjects. RESULTS: When the FA group was compared with healthy control subjects, CD4+CD25+CD127loFOXP3+ cell rates were found to be significantly lower in the FA group (p < 0.001). When the FA/A- and FA/A+ groups and the control group were compared in terms of CD4+CD25+CD127loFOXP3+ cell ratios, they were significantly lower in the FA/A- and FA/A+ groups compared to the control group (p < 0.001). CONCLUSIONS: Although there was no significant difference between the FA/A+ group and the FA/A- group in terms of CD4+CD25+CD127loFOXP3+ cells, our study is important, as it is the first pediatric study we know to investigate whether CD4+CD25+CD127loFOXP3+ cells in FA predict anaphylaxis.

Beam commissioning of the first clinical biology-guided radiotherapy system.

This study reports the beam commissioning results for the first clinical RefleXion Linac. METHODS: The X1 produces a 6 MV photon beam and the maximum clinical field size is 40 × 2 cm2 at source-to-axis distance of 85 cm. Treatment fields are collimated by a binary multileaf collimator (MLC) system with 64 leaves with width of 0.625 cm and y-jaw pairs to provide either a 1 or 2 cm opening. The mechanical alignment of the radiation source, the y-jaw, and MLC were checked with film and ion chambers. The beam parameters were characterized using a diode detector in a compact water tank. In-air lateral profiles and in-water percentage depth dose (PDD) were measured for beam modeling of the treatment planning system (TPS). The lateral profiles, PDDs, and output factors were acquired for field sizes from 1.25 × 1 to 40 × 2 cm2 field to verify the beam modeling. The rotational output variation and synchronicity were tested to check the gantry angle, couch motion, and gantry rotation. RESULTS: The source misalignments were 0.049 mm in y-direction, 0.66% out-of-focus in x-direction. The divergence of the beam axis was 0.36 mm with a y-jaw twist of 0.03°. Clinical off-axis treatment fields shared a common center in y-direction were within 0.03 mm. The MLC misalignment and twist were 0.57 mm and 0.15°. For all measured fields ranging from the size from 1.25 × 1 to 40 × 2 cm2 , the mean difference between measured and TPS modeled PDD at 10 cm depth was -0.3%. The mean transverse profile difference in the field core was -0.3% ± 1.1%. The full-width half maximum (FWHM) modeling was within 0.5 mm. The measured output factors agreed with TPS within 0.8%. CONCLUSIONS: This study summarizes our specific experience commissioning the first novel RefleXion linac, which may assist future users of this technology when implementing it into their own clinics.

Treatment planning system commissioning of the first clinical biology-guided radiotherapy machine.

PURPOSE: The RefleXion X1 is a novel radiotherapy machine designed for image-guided radiotherapy (IGRT) and biology-guided radiotherapy (BgRT). Its treatment planning system (TPS) generates IMRT and SBRT plans for a 6MV-FFF beam delivered axially via 50 firing positions with the couch advancing every 2.1 mm. The purpose of this work is to report the TPS commissioning results for the first clinical installation of RefleXion™ X1. METHODS: CT images of multiple phantoms were imported into the RefleXion TPS to evaluate the accuracy of data transfer, anatomical modeling, plan evaluation, and dose calculation. Comparisons were made between the X1, Eclipse™, and MIM™. Dosimetric parameters for open static fields were evaluated in water and heterogeneous slab phantoms. Representative clinical IMRT and SBRT cases were planned and verified with ion chamber, film, and ArcCHECK@ measurements. The agreement between TPS and measurements for various clinical plans was evaluated using Gamma analysis with a criterion of 3%/2 mm for ArcCHECK@ and film. End-to-end (E2E) testing was performed using anthropomorphic head and lung phantoms. RESULTS: The average difference between the TPS-reported and known HU values was -1.4 ± 6.0 HU. For static fields, the agreements between the TPS-calculated and measured PDD10 , crossline profiles, and inline profiles (FWHM) were within 1.5%, 1.3%, and 0.5 mm, respectively. Measured output factors agreed with the TPS within 1.3%. Measured and calculated dose for static fields in heterogeneous phantoms agreed within 2.5%. The ArcCHECK@ mean absolute Gamma passing rate was 96.4% ± 3.4% for TG 119 and TG 244 plans and 97.8% ± 3.6% for the 21 clinical plans. E2E film analysis showed 0.8 mm total targeting error for isocentric and 1.1 mm for off-axis treatments. CONCLUSIONS: The TPS commissioning results of the RefleXion X1 TPS were within the tolerances specified by AAPM TG 53, MPPG 5.a, TG 119, and TG 148. A subset of the commissioning tests has been identified as baseline data for an ongoing QA program.

Early and late outcomes of surgical repair of double-chambered right ventricle: a single-centre experience.

OBJECTIVE: Double-chambered right ventricle is characterised by division of the outlet portion of the right ventricle by hypertrophy of the septoparietal trabeculations into two parts. We aim to report our experiences regarding the presenting symptoms of double-chambered right ventricle, long-term prognosis, including the recurrence rate and incidence of arrhythmias after surgery. METHODS: We retrospectively investigated 89 consecutive patients who were diagnosed to have double-chambered right ventricle and underwent a surgical intervention from 1995 to 2016. The data obtained by echocardiography, cardiac catheterisation, and surgical findings as well as post-operative follow-up, surgical approaches, post-operative morbidity, mortality, and cardiac events were evaluated. RESULTS: Median age at the time of diagnosis was 2 months and mean age at the time of operation was 5.3 years. Concomitant cardiac anomalies were as follows: perimembranous ventricular septal defect (78 patients), atrial septal defect (9 patients), discrete subaortic membrane (32 patients), right aortic arch (3 patients), aortic valve prolapse and/or mild aortic regurgitation (14 patients), and left superior caval vein (2 patients). The mean follow-up period was 4.86 ± 4.6 years. In these patients, mean systolic pressure gradient in the right ventricle by echocardiography before, immediately, and long-term after surgical intervention was 66.3, 11.8, and 10.4 mmHg, respectively. There were no deaths during the long-term follow-up period. Surgical reinterventions were performed for residual ventricular septal defect (2), residual pulmonary stenosis (1), and severe tricuspid insufficiency (1). CONCLUSION: The surgical outcomes and prognosis of double-chambered right ventricle are favourable, recurrence and fatal arrhythmias are unlikely in long-term follow-up.

The assessment of treatment outcomes in patients with acute viral myocarditis by speckle tracking and tissue Doppler methods.

OBJECTIVES: The aim was to evaluate the role of tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE), to identify myocardial dysfunction, and to evaluate myocardial segmental deformation in acute viral myocarditis. METHODS: Twenty-one patients and twelve healthy children were studied prospectively. The TDI and STE were performed before and after treatment. The myocardial velocities (Sm , Em , and Am ) and time intervals (isovolumic contraction, isovolumic relaxation, and ejection times [ET]) at interventricular septum (IVS), left, and right ventricular basal segments were examined by TDI. The left ventricular global longitudinal strain (LVGLS) and strain rate (LVGLSR), left ventricular global circumferential strain (LVGCS) and strain rate (LVGCSR), and right ventricular global longitudinal strain (RVGLS) and strain rate (RVGLSR) were examined by STE. RESULTS: Sm and Em at IVS and at LV, ET at IVS, ET at RV, ET at LV were significantly lower in patients before treatment than controls. LVGLS, LVGLSR, LVGCS, LVGCSR, RVGLS, RVGLSR were significantly decreased in patients before treatment than controls. There was significant improvement for LVGLS, LVGLSR, LVGCS, LVGCSR, and RVGLS in patients after treatment. Sm , Em , and Am at LV were significantly lower in patients before treatment than in patients after treatment. In spite of improvements, Sm , Em , and ET at IVS, LVGLS, LVGLSR, LVGCS, LVGCSR were significantly lower in patients after treatment than controls. CONCLUSIONS: The TDI and STE were useful methods for detection of early myocardial dysfunction and evaluation of treatment outcomes in acute viral myocarditis.

Providing MR Imaging for Cervical Cancer Brachytherapy: Lessons for Radiologists.

Brachytherapy (BT), the use of a locally placed or implanted radioactive source for treatment of an adjacent tumor, is an important component in the treatment of patients with both early- and advanced-stage cervical cancer and is increasingly part of the standard treatment protocol. When it is feasible, many radiation oncologists choose to include a magnetic resonance (MR) imaging examination for planning BT treatment (ie, an MR imaging examination after placement of the applicator but before radiation dosing). MR imaging provides excellent soft-tissue contrast and allows radiation oncologists to individualize the radiation dose to the target volume and minimize the dose to adjacent organs that are at risk for radiation damage. However, traditionally, the radiology department has not performed imaging studies for planning, and the requirements are different compared with those of standard diagnostic imaging. In addition, many applicators are available for use in BT treatment of cervical cancer, and each must considered separately to determine MR safety and to define the best imaging parameters. Starting and supporting a robust gynecologic BT program includes implementing imaging protocols that are helpful to both radiation oncologists and diagnostic radiologists. By becoming more familiar with this treatment modality and the logistics of imaging patients undergoing BT, radiologists can provide imaging support for colleagues in the radiation oncology department and better care for patients. ©RSNA, 2018.

Recovery of myocardial mechanics in Kawasaki disease demonstrated by speckle tracking and tissue Doppler methods.

AIM: To investigate myocardial deformation and function during treatment for Kawasaki disease (KD) in children. METHODS: We performed speckle tracking echocardiography (STE) and tissue Doppler imaging (TDI) in 15 children with KD and 15 healthy children during treatment for KD. STE was performed for longitudinal and circumferential strain (S) and strain rate (SR) at the left ventricle (LV) and for longitudinal S and SR at the right ventricle (RV). TDI was performed at the base of interventricular septum (IVS), LV, and RV. RESULTS: Among TDI parameters, Em and ejection time (ET) at IVS, ET at LV and ET at RV obtained obtained before treatment were significantly lower in patients with KD compared to controls. After treatment, in spite of improvements, ET at IVS and ET at RV remained significantly lower in patients with KD compared to controls. Left ventricular global longitudinal and circumferential S and SR values obtained before treatment were significantly lower in patients with KD compared to controls. Left ventricular S and SR values were found to be increased after treatment. However, left ventricular global circumferential S value remained significantly lower in patients with KD compared to controls. There were no significant differences in right ventricular global longitudinal S and SR values between patients and controls before treatment. CONCLUSION: During acute phase, patients with KD have reduced global left ventricular S and SR which may be more sensitive indicators of myocardial inflammation. This study showed gradual improvements in left ventricular myocardial function during treatment for KD.

The pre-participation screening in young athletes: which protocol do we need exactly?

The aim was to assess the utility and feasibility of a comprehensive cardiac screening protocol in young athletes before participation in sports. A total of 380 athletes referring before participation in sports, between April, 2014 and April, 2015, were included in this study. The mean age was 12.4 years. A screening protocol has been applied to all, including personal and family history, physical examination, 12-lead electrocardiography, transthoracic echocardiography, 24-hour rhythm Holter analysis, and treadmill exercise test. The most frequent complaints were chest pain in 19 (5%), dyspnoea in 13 (3.4%), and dizziness and fainting in five patients (1.3%) on exercise. There was sudden death and arrhythmia in 41 patients (10.7%) owing to family history. Heart murmur was present in 20 (5.2%) and hypertension in 10 patients (2.6%) on physical examination. The 12-lead electrocardiography was abnormal in 9 patients (2.4%). The findings of transthoracic echocardiography were insignificant in 47 patients (12.3%) and in five patients (1.3%) a haemodynamically important condition was detected. The 24-hour rhythm Holter analysis was abnormal in six patients (1.5%). There were significant ST changes in two patients (0.5%) on treadmill exercise test with normal findings on myocardial perfusion scans. No significant relation was present between findings of screening protocol and transthoracic echocardiography, 24-hour rhythm Holter analysis, or treadmill exercise test results. Pre-participation screening in young athletes should consist of a targeted personal history, family history, physical examination, and 12-lead electrocardiography. Other tests should be applied only if the screening indicates the presence of a cardiovascular disease.

Decreased Deformation in Asymptomatic Children with Isolated Left Ventricular Non-compaction and Normal Ejection Fraction.

Echocardiography is the mainstay of screening and disease surveillance in isolated left ventricular non-compaction (iLVNC). The aim of our study is to determine the early regional and global myocardial functional changes and whether the myocardial changes that cannot be detected by conventional echocardiography could be detected by tissue Doppler imaging (TDI) or two-dimensional speckle-tracking echocardiography (STE) in iLVNC cases without symptoms. Longitudinal and circumferential strain (S) and strain rates (SR) as determined by STE in 20 children aged 12.1 ± 3.3 years was compared with those in 20 controls. All children underwent echocardiographic assessment using two-dimensional, tissue Doppler and speckle-tracking echocardiography. iLVNC patients who had normal systolic function by ejection and shortening fractions were included in this study. According to the TDI in all three segments [the non-compacted (NC), neighboring NC (NNC) and compacted (C) segments], isovolumic contraction time, isovolumic relaxation time and myocardial performance index values were significantly higher, while ejection time were significantly lower in the iLVNC group. According to STE in two segments (NC and NNC-segments) longitudinal S and SR values and also circumferential S and SR values were significantly lower in the iLVNC group compared with the control group; whereas, in the global measurements both longitudinal and circumferential S and SR values in all three segments were significantly lower in the iLVNC group compared with the control group. We believe that TDI and STE that evaluates myocardial deformation can be used for the detection of early myocardial dysfunction in the iLVNC patients who are subclinical and whose left ventricular functions were detected as normal by conventional methods with normal ejection and shortening fractions.

A survey on table tolerances and couch overrides in radiotherapy.

The purpose of this study was to survey current departmental policies on treatment couch overrides and the values of table tolerances used clinically. A 25-question electronic survey on couch overrides and tolerances was sent to full members of the American Association of Physicists in Medicine (AAPM). The first part of the survey asked participants if table overrides were allowed at their institution, who was allowed to perform these overrides, and if imaging was required with overrides. The second part of the survey asked individuals to provide table tolerance data for the following treatment sites: brain/head and neck (H&N), lung, breast, abdo-men/pelvis and prostate. Each site was further divided into IMRT/VMAT and 3D conformal techniques. Spaces for free-text were provided, allowing respondents to enter any table tolerance data they were unable to specify under the treatment sites listed. A total of 361 individuals responded, of which approximately half partici-pated in the couch tolerances portion of the survey. Overall, 86% of respondents' institutions allow couch tolerance overrides at treatment. Therapists were the most common staff members permitted to perform overrides, followed by physicists, dosimetrists, and physicians, respectively. Of the institutions allowing overrides, 34% reported overriding daily. More than half of the centers document the over-ride and/or require a setup image to radiographically verify the treatment site. With respect to table tolerances, SRS/SBRT table tolerances were the tightest, while clinical setup table tolerances were the largest. There were minimal statistically significant differences between IMRT/VMAT and 3D conformal table tolerances. Our results demonstrated that table overrides are relatively common in radiotherapy despite being a potential safety concern. Institutions should review their override policy and table tolerance values in light of the practices of other institutions. Careful attention to these matters is crucial in ensuring the safe and accurate delivery of radiotherapy.

Pulmonary arterial hypertension in a child with stage-IV neuroblastoma after autologous hematopoietic stem cell transplantation and review of the literature.

PH is a rare condition with high mortality rate after pediatric HSCT. As clinical presentation is non-specific and may mimic other conditions, a high degree of suspicion is required for diagnosis. Here, we present a patient with stage-IV neuroblastoma who developed PAH after autologous HSCT. After exclusion of other causes of PH, we regarded that this condition was secondary to HSCT.

Protective effect of leflunomide against oxidative intestinal injury in a rodent model of sepsis.

BACKGROUND: Sepsis is defined as an uncontrolled inflammatory response in a host. The process may lead to severe sepsis, multisystem organ failure and even death. Leflunomide has important immunomodulatory and anti-inflammatory effects, which may mitigate host response to bacterial translocation. The goal of our study was to measure the effects leflunomide administration had on a variety of biochemical markers upregulated in systemic inflammatory response syndrome, sepsis, and multiple organ failure syndrome. MATERIALS AND METHODS: Wistar albino type rats were randomly divided into five groups: control, sham, leflunomide, sepsis, and sepsis + leflunomide. Sepsis was achieved by means of the cecal ligation and puncture method. Leflunomide 2 × 10 mg/kg/d was administered before the experiment. At the end of 24 h, the tissue levels of superoxide dismutase, catalase activity, malondialdehyde, nitric oxide, and protein carbonyl were measured. RESULTS: The level of the bowel superoxide dismutase and catalase levels of the sepsis group is significantly lower than those of the control, sham, and leflunomide groups (P < 0.05). Malondialdehyde, nitric oxide, and protein carbonyl levels are significantly higher in sepsis compared with other groups (P < 0.05). CONCLUSIONS: Leflunomide's prevention of protein and lipid peroxidation was observed in septic bowel tissue. Use of leflunomide could have protective effects against both the onset and the progressive stages of sepsis.

A time- and space-saving Monte Carlo simulation method using post-collimation generative adversarial network for dose calculation of an O-ring gantry Linac.

PURPOSE: This study explores the feasibility of employing Generative Adversarial Networks (GANs) to model the RefleXion X1 Linac. The aim is to investigate the accuracy of dose simulation and assess the potential computational benefits. METHODS: The X1 Linac is a new radiotherapy machine with a binary multi-leaf collimation (MLC) system, facilitating innovative biology-guided radiotherapy. A total of 34 GAN generators, each representing a desired MLC aperture, were developed. Each generator was trained using a phase space file generated underneath the corresponding aperture, enabling the generation of particles and serving as a beam source for Monte Carlo simulation. Dose distributions in water were simulated for each aperture using both the GAN and phase space sources. The agreement between dose distributions was evaluated. The computational time reduction from bypassing the collimation simulation and storage space savings were estimated. RESULTS: The percentage depth dose at 10 cm, penumbra, and full-width half maximum of the GAN simulation agree with the phase space simulation, with differences of 0.4 % ± 0.2 %, 0.32 ± 0.66 mm, and 0.26 ± 0.44 mm, respectively. The gamma passing rate (1 %/1mm) for the planar dose exceeded 90 % for all apertures. The estimated time-saving for simulating an plan using 5766 beamlets was 530 CPU hours. The storage usage was reduced by a factor of 102. CONCLUSION: The utilization of the GAN in simulating the X1 Linac demonstrated remarkable accuracy and efficiency. The reductions in both computational time and storage requirements make this approach highly valuable for future dosimetry studies and beam modeling.

Transverse arch stenting and its effect on systemic hypertension.

Background: This study aimed to investigate the safety and efficacy of transverse aortic arch stenting and evaluate the course of hypertension and the act of arch stenting on systemic hypertension. Methods: The transverse aortic arch stenting procedures between January 2007 and May 2023 were retrospectively analyzed. Detailed procedure information, technical aspects, pressure measurements, angiographic data, balloons and stents used, complications, and immediate results were examined. Early and mid-term results were assessed. Results: Eighteen patients (10 males and 8 females; mean age: 14.5±5.3 years; range, 4 to 23 years) were included in the study, all of whom were hypertensive before the procedure. The mean weight was 56.8±19.6 kg. In seven patients, the stent struts had to be dilated due to the stent causing jailing at the entrance of nearby arch vessels. After stenting, there was a significant increase in arch diameter and a decrease in ascending aorta pressure and the pressure gradient across the aorta. There were no early mortality or major complications. Late migration of the stent was observed in one patient. Three patients became normotensive immediately after the intervention, and five became drug-free during the follow-up. The requirement for dual antihypertensive therapy was significantly reduced. Conclusion: Residual transverse arch lesions may contribute to the persistence of systemic hypertension after coarctation treatment. Transverse arch stent implantation can be performed safely with favorable outcomes, facilitating better blood pressure control. However, it should be noted that these patients remain at risk for lifelong hypertension and should be closely monitored in this regard.

First-Year Experience of Stereotactic Body Radiation Therapy/Intensity Modulated Radiation Therapy Treatment Using a Novel Biology-Guided Radiation Therapy Machine.

Purpose: The aim of this study was to present the first-year experience of treating patients using intensity modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT) with a biology-guided radiation therapy machine, the RefleXion X1 system, installed in a clinical setting. Methods and Materials: A total of 78 patients were treated on the X1 system using IMRT and SBRT from May 2021 to May 2022. Clinical and technical data including treatment sites, number of pretreatment kilovoltage computed tomography (kVCT) scans, beam-on time, patient setup time, and imaging time were collected and analyzed. Machine quality assurance (QA) results, machine performance, and user satisfactory survey were also collected and reported. Results: The most commonly treated site was the head and neck (63%), followed by the pelvis (23%), abdomen (8%), and thorax (6%). Except for 5 patients (6%) who received SBRT treatments for bony metastases in the pelvis, all treatments were conventionally fractionated IMRT. The number of kVCT scans per fraction was 1.2 ± 0.5 (mean ± standard deviation). The beam-on time was 9.2 ± 3.5 minutes. The patient setup time and imaging time per kVCT was 4.8 ± 2.6 minutes and 4.6 ± 1.5 minutes, respectively. The daily machine output deviation was 0.4 ± 1.2% from the baseline. The patient QA had a passing rate of 97.4 ± 2.8% at 3%/2 mm gamma criteria. The machine uptime was 92% of the total treatment time. The daily QA and kVCT image quality received the highest level of satisfaction. The treatment workflow for therapists received the lowest level of satisfaction. Conclusions: One year after the installation, 78 patients were successfully treated with the X1 system using IMRT and/or SBRT. With the recent Food and Drug Administration clearance of biology-guided radiation therapy, our department is preparing to treat patients using positron emission tomography-guidance via a new product release, which will address deficiencies in the current image-guided radiation therapy workflow.

Commissioning of a novel PET-Linac for biology-guided radiotherapy (BgRT).

BACKGROUND: Biology-guided radiotherapy (BgRT) is a novel radiotherapy delivery technique that utilizes the tumor itself to guide dynamic delivery of treatment dose to the tumor. The RefleXion X1 system is the first radiotherapy system developed to deliver SCINTIX® BgRT. The X1 is characterized by its split arc design, employing two 90-degree positron emission tomography (PET) arcs to guide therapeutic radiation beams in real time, currently cleared by FDA to treat bone and lung tumors. PURPOSE: This study aims to comprehensively evaluate the capabilities of the SCINTIX radiotherapy delivery system by evaluating its sensitivity to changes in PET contrast, its adaptability in the context of patient motion, and its performance across a spectrum of prescription doses. METHODS: A series of experimental scenarios, both static and dynamic, were designed to assess the SCINTIX BgRT system's performance, including an end-to-end test. These experiments involved a range of factors, including changes in PET contrast, motion, and prescription doses. Measurements were performed using a custom-made ArcCHECK insert which included a 2.2 cm spherical target and a c-shape structure that can be filled with a PET tracer with varying concentrations. Sinusoidal and cosine4 motion patterns, simulating patient breathing, was used to test the SCINTIX system's ability to deliver BgRT during motion-induced challenges. Each experiment was evaluated against specific metrics, including Activity Concentration (AC), Normalized Target Signal (NTS), and Biology Tracking Zone (BTZ) bounded dose-volume histogram (bDVH) pass rates. The accuracy of the delivered BgRT doses on ArcCHECK and EBT-XD film were evaluated using gamma 3%/2 mm and 3%/3 mm analysis. RESULTS: In static scenarios, the X1 system consistently demonstrated precision and robustness in SCINTIX dose delivery. The end-to-end delivery to the spherical target yielded good results, with AC and NTS values surpassing the critical thresholds of 5 kBq/mL and 2, respectively. Furthermore, bDVH analysis consistently confirmed 100% pass rates. These results were reaffirmed in scenarios involving changes in PET contrast, emphasizing the system's ability to adapt to varying PET avidities. Gamma analysis with 3%/2 mm (10% dose threshold) criteria consistently achieved pass rates > 91.5% for the static tests. In dynamic SCINTIX delivery scenarios, the X1 system exhibited adaptability under conditions of motion. Sinusoidal and cosine4 motion patterns resulted in 3%/3 mm gamma pass rates > 87%. Moreover, the comparison with gated stereotactic body radiotherapy (SBRT) delivery on a conventional c-arm Linac resulted in 93.9% gamma pass rates and used as comparison to evaluate the interplay effect. The 1 cm step shift tests showed low overall gamma pass rates of 60.3% in ArcCHECK measurements, while the doses in the PTV agreed with the plan with 99.9% for 3%/3 mm measured with film. CONCLUSIONS: The comprehensive evaluation of the X1 radiotherapy delivery system for SCINTIX BgRT demonstrated good agreement for the static tests. The system consistently achieved critical metrics and delivered the BgRT doses per plan. The motion tests demonstrated its ability to co-localize the dose where the PET signal is and deliver acceptable BgRT dose distributions.

Demonstration of real-time positron emission tomography biology-guided radiotherapy delivery to targets.

BACKGROUND: Biology-guided radiotherapy (BgRT) is a novel technology that uses positron emission tomography (PET) data to direct radiotherapy delivery in real-time. BgRT enables the precise delivery of radiation doses based on the PET signals emanating from PET-avid tumors on the fly. In this way, BgRT uniquely utilizes radiotracer uptake as a biological beacon for controlling and adjusting dose delivery in real-time to account for target motion. PURPOSE: To demonstrate using real-time PET for BgRT delivery on the RefleXion X1 radiotherapy machine. The X1 radiotherapy machine is a rotating ring-gantry radiotherapy system that generates a nominal 6MV photon beam, PET, and computed tomography (CT) components. The system utilizes emitted photons from PET-avid targets to deliver effective radiation beamlets or pulses to the tumor in real-time. METHODS: This study demonstrated a real-time PET BgRT delivery experiment under three scenarios. These scenarios included BgRT delivering to (S1 ) a static target in a homogeneous and heterogeneous environment, (S2 ) a static target with a hot avoidance structure and partial PET-avid target, and (S3 ) a moving target. The first step was to create stereotactic body radiotherapy (SBRT) and BgRT plans (offline PET data supported) using RefleXion's custom-built treatment planning system (TPS). Additionally, to create a BgRT plan using PET-guided delivery, the targets were filled with 18F-Fluorodeoxyglucose (FDG), which represents a tumor/target, that is, PET-avid. The background materials were created in the insert with homogeneous water medium (for S1 ) and heterogeneous water with styrofoam mesh medium. A heterogeneous background medium simulated soft tissue surrounding the tumor. The treatment plan was then delivered to the experimental setups using a pre-commercial version of the X1 machine. As a final step, the dosimetric accuracy for S1 and S2 was assessed using the ArcCheck analysis tool-the gamma criteria of 3%/3 mm. For S3 , the delivery dose was quantified using EBT-XD radiochromic film. The accuracy criteria were based on coverage, where 100% of the clinical target volume (CTV) receives at least 97% of the prescription dose, and the maximum dose in the CTV was ≤130% of the maximum planned dose (97 % ≤ CTV ≤ 130%). RESULTS: For the S1, both SBRT and BgRT deliveries had gamma pass rates greater than 95% (SBRT range: 96.9%-100%, BgRT range: 95.2%-98.9%), while in S2 , the gamma pass rate was 98% for SBRT and between 95.2% and 98.9% for BgRT plan delivering. For S3 , both SBRT and BgRT motion deliveries met CTV dose coverage requirements, with BgRT plans delivering a very high dose to the target. The CTV dose ranges were (a) SBRT:100.4%-120.4%, and (b) BgRT: 121.3%-139.9%. CONCLUSIONS: This phantom-based study demonstrated that PET signals from PET-avid tumors can be utilized to direct real-time dose delivery to the tumor accurately, which is comparable to the dosimetric accuracy of SBRT. Furthermore, BgRT delivered a PET-signal controlled dose to the moving target, equivalent to the dose distribution to the static target. A future study will compare the performance of BgRT with conventional image-guided radiotherapy.