A simulation study of MR-guided proton therapy system using iron-yoked superconducting open MRI: a conceptual study.

Radiotherapy platforms integrated with magnetic resonance imaging (MRI) have been significantly successful and widely used in X-ray therapy over the previous decade. MRI provides greater soft-tissue contrast than conventional X-ray techniques, which enables more precise radiotherapy with on-couch adaptive treatment planning and direct tracking of moving tumors. The integration of MRI into a proton beam irradiation system (PBS) is still in the research stage. However, this could be beneficial as proton therapy is more sensitive to anatomical changes and organ motion. In this simulation study, we considered the integration of PBS into the 0.3-T superconducting open MRI system. Our proposed design involves proton beams traversing a hole at the center of the iron yoke, which allows for a reduced fringe field in the irradiation nozzle while maintaining a large proton scan field of the current PBS. The shape of the bipolar MRI magnets was derived to achieve a large MRI field-of-view. To monitor the beam position and size accurately while maintaining a small beam size, the beam monitor installation was redesigned from the current system. The feasibility of this system was then demonstrated by the treatment plan quality, which showed that the magnetic field did not deteriorate the plan quality from that without the magnetic field for both a rectangular target and a prostate case. Although numerous challenges remain before the proposed simulation model can be implemented in a clinical setting, the presented conceptual design could assist in the initial design for the realization of the MR-guided proton therapy.

Effects of Bifidobacterium-Fermented Milk on Obesity: Improved Lipid Metabolism through Suppression of Lipogenesis and Enhanced Muscle Metabolism.

Obesity is a major global health concern. Studies suggest that the gut microflora may play a role in protecting against obesity. Probiotics, including lactic acid bacteria and Bifidobacterium, have garnered attention for their potential in obesity prevention. However, the effects of Bifidobacterium-fermented products on obesity have not been thoroughly elucidated. Bifidobacterium, which exists in the gut of animals, is known to enhance lipid metabolism. During fermentation, it produces acetic acid, which has been reported to improve glucose tolerance and insulin resistance, and exhibit anti-obesity and anti-diabetic effects. Functional foods have been very popular around the world, and fermented milk is a good candidate for enrichment with probiotics. In this study, we aim to evaluate the beneficial effects of milks fermented with Bifidobacterium strains on energy metabolism and obesity prevention. Three Bifidobacterium strains (Bif-15, Bif-30, and Bif-39), isolated from newborn human feces, were assessed for their acetic acid production and viability in milk. These strains were used to ferment milk. Otsuka-Long-Evans Tokushima Fatty (OLETF) rats administered Bif-15-fermented milk showed significantly lower weight gain compared to those in the water group. The phosphorylation of AMPK was increased and the expression of lipogenic genes was suppressed in the liver of rats given Bif-15-fermented milk. Additionally, gene expression related to respiratory metabolism was significantly increased in the soleus muscle of rats given Bif-15-fermented milk. These findings suggest that milk fermented with the Bifidobacterium strain Bif-15 can improve lipid metabolism and suppress obesity.

Appendiceal neoplasms derived from appendiceal tip remnants following appendectomy: a report of two cases.

BACKGROUND: Neoplasms derived from remnant appendix are rarely described, with most cases arising from the appendiceal "stump". Here, we present two surgical cases of appendiceal neoplasms derived from appendiceal "tip" remnants. CASE PRESENTATION: The first patient was a 71-year-old man who had undergone laparoscopic appendectomy for acute appendicitis 12 years prior. During appendectomy, the appendiceal root was ligated, but the appendix was not completely removed due to severe inflammation. At the most recent presentation, computed tomography (CT) was performed to examine choledocholithiasis, which incidentally revealed a cystic lesion of approximately 90 mm adjacent to the cecum. A retrospective review revealed that the cystic lesion had increased in size over time, and laparoscopic ileocecal resection was performed. Pathology revealed no continuity from the appendiceal orifice to the cyst, and a diagnosis of low-grade appendiceal mucinous neoplasm (LAMN) was made from the appendiceal tip remnant. The patient was discharged without complications. The second patient was a 65-year-old man who had undergone surgery for peritonitis due to severe appendicitis 21 years prior. During this operation, the appendix could not be clearly identified due to severe inflammation; consequently, cecal resection was performed. He was referred to our department with a chief complaint of general fatigue and loss of appetite and a cystic lesion of approximately 85 mm close to the cecum that had increased over time. CT showed irregular wall thickening, and malignancy could not be ruled out; therefore, laparoscopic ileocecal resection with D3 lymph node dissection was performed. The pathological diagnosis revealed mucinous adenocarcinoma (TXN0M0) arising from the remnant appendiceal tip. The patient is undergoing follow-up without postoperative adjuvant chemotherapy, with no evidence of pseudomyxoma peritonei or cancer recurrence for 32 months postoperatively. CONCLUSIONS: If appendicitis-associated inflammation is sufficiently severe that accurate identification of the appendix is difficult, it may remain on the apical side of the appendix, even if the root of the appendix is ligated and removed. If the appendectomy is terminated incompletely, it is necessary to check for the presence of a residual appendix postoperatively and provide appropriate follow-up.

Anterior versus posterior mediastinal reconstruction after esophagectomy in esophageal cancer patients: a systematic review and meta-analysis.

PURPOSE: Esophagectomy is the primary surgical treatment for esophageal cancer, although other treatment approaches are often incorporated, including preoperative chemotherapy and chemoradiotherapy. The two major routes of esophageal reconstruction after esophagectomy are the anterior mediastinal (retrosternal, heterotopic) and posterior mediastinal (prevertebral, orthotopic) routes. However, which of these two routes of reconstruction is the most appropriate remains controversial. This systematic review aimed to compare the efficacy and safety of anterior mediastinal reconstruction with those of posterior mediastinal reconstruction after esophagectomy in esophageal cancer. METHODS: In January 2022, a literature search of the CENTRAL, MEDLINE, and EMBASE databases was conducted to identify all published and unpublished randomized controlled trials, regardless of language. Eight studies were included for quantitative synthesis. RESULTS: Postoperative death (9/129 and 4/125, risk ratio [RR]: 2.07, 95% confidence interval [CI]: 0.65-6.64) and incidence of anastomotic leak (24/208 and 26/208, RR: 0.95, 95% CI: 0.56-1.62) were not significantly different between the two mediastinal reconstructions. We could not perform a meta-analysis for quality of life, loss of body weight, or postoperative hospital stay due to data limitations. CONCLUSION: Overall, there was low-quality evidence to suggest that the outcomes of the anterior and posterior mediastinal routes of reconstruction are not significantly different in patients with esophageal cancer.

Persistent Left Superior Vena cava with the Absence of the Right Superior Vena Cava and Atrial Appendage: Complex Pacemaker Implantation in a Patient Presenting with a Rare Vascular Anomaly.

A persistent left superior vena cava (PLSVC) is a commonly observed anatomical anomaly that is frequently detected incidentally via computed tomography (CT) imaging. However, the occurrence of a PLSVC with a right superior vena cava (RSVC) defect, also known as "isolated PLSVC," is a much rarer anomaly. This peculiar malformation can lead to sinoatrial dysfunction, thus necessitating pacemaker implantation, which requires delicate manipulation due to various anatomical complexities. We herein present a case of a sick sinus syndrome with this rare anomaly, which required special consideration when performing pacemaker lead placement.

Association with the nonparoxysmal atrial fibrillation duration and outcome of ExTRa Mapping-guided rotor ablation.

Background: Additional ablation strategies after pulmonary vein isolation (PVI) for patients with nonparoxysmal atrial fibrillation (non-PAF) lasting ≥2 years have not been fully effective. This is presumably because of insufficient identification of non-PAF maintenance mechanisms. In this study, we employed a novel online and real-time phase mapping system, ExTRa Mapping, to identify and modulate rotors as one of the non-PAF maintenance mechanisms in patients with non-PAF sustained after PVI. We investigated the relationship between outcomes of ExTRa Mapping-guided rotor ablation (ExTRa-ABL) and non-PAF duration prior to this procedure. Methods: This study consisted of 73 non-PAF patients (63 ± 8 years, non-PAF duration 31 ± 37 months) who underwent the first ExTRa-ABL in patients with non-PAF sustained after completion of PVI. Results: Freedom from non-PAF/atrial tachycardia (AT) recurrence at 12 months after ExTRa-ABL was achieved in 50 (69%) of patients. The non-PAF duration prior to ExTRa-ABL was significantly longer in patients with non-PAF/AT recurrence after ExTRa-ABL compared with those without (56 ± 50 vs. 19 ± 22 months, p = .001). In patients with non-PAF duration of ≤60 months prior to ExTRa-ABL, compared with >60 months, non-PAF/AT-free rate was significantly higher (68.9% vs. 23.1%, p < .001), during the follow-up of 36 ± 18 months. Conclusions: A non-PAF duration of ≤60 months prior to ExTRa-ABL was associated with a better outcome. The effect of ExTRa-ABL was considered to be limited in patients with >60 months of non-PAF duration.

Non-curative resection for surgical T4b esophageal cancer: esophagectomy or non-esophagectomy?

BACKGROUND: Recently, with the development of multidisciplinary treatment, the treatment outcomes of esophageal cancer (EC) have improved. However, despite advances in diagnostic imaging modalities, preoperative diagnosis of T4 EC is still difficult, and the prognosis of T4 EC remains very poor. In addition, the prognosis of surgical T4b EC (sT4b EC) after surgery remains unclear. In this study, we retrospectively reviewed sT4b EC. METHODS: We evaluated the clinical course of sT4b EC and compared palliative esophagectomy with R2 resection (PE group) with other procedures without esophagectomy (NE group) (e.g., only esophagostomy) for sT4b EC. RESULTS: Forty-seven patients with thoracic EC underwent R2 resection at our institution between January 2009 and December 2020. Thirty-four patients were in the PE group, and 13 patients were in the NE group. The 2-year overall survival rate was 0% in the PE group and 20.2% in the NE group (p = 0.882). There was one case of long-term survival in the NE group that underwent surgery followed by definitive chemoradiation. Postoperative complications (Clavien-Dindo grade ≥ 3) were observed in 25 patients (73.5%) in the PE group and in three patients (23.1%) in the NE group (p = 0.031). The median time to the initiation of postoperative treatment was 68.1 days in the PE group and 18.6 days in the NE group (p = 0191). CONCLUSIONS: If EC is diagnosed as sT4b, palliative esophagectomy should be avoided because of the high complication rate and the lack of long-term survival.

Deformed dose restoration to account for tumor deformation and position changes for adaptive proton therapy.

BACKGROUND: Online adaptation during intensity-modulated proton therapy (IMPT) can minimize the effect of inter-fractional anatomical changes, but remains challenging because of the complex workflow. One approach for fast and automated online IMPT adaptation is dose restoration, which restores the initial dose distribution on the updated anatomy. However, this method may fail in cases where tumor deformation or position changes occur. PURPOSE: To develop a fast and robust IMPT online adaptation method named "deformed dose restoration (DDR)" that can adjust for inter-fractional tumor deformation and position changes. METHODS: The DDR method comprises two steps: (1) calculation of the deformed dose distribution, and (2) restoration of the deformed dose distribution. First, the deformable image registration (DIR) between the initial clinical target volume (CTV) and the new CTV were performed to calculate the vector field. To ensure robustness for setup and range uncertainty and the ability to restore the deformed dose distribution, an expanded CTV-based registration to maintain the dose gradient outside the CTV was developed. The deformed dose distribution was obtained by applying the vector field to the initial dose distribution. Then, the voxel-by-voxel dose difference optimization was performed to calculate beam parameters that restore the deformed dose distribution on the updated anatomy. The optimization function was the sum of total dose differences and dose differences of each field to restore the initial dose overlap of each field. This method only requires target contouring, which eliminates the need for organs at risk (OARs) contouring. Six clinical cases wherein the tumor deformation and/or position changed on repeated CTs were selected. DDR feasibility was evaluated by comparing the results with those from three other strategies, namely, not adapted (continuing the initial plan), adapted by previous dose restoration, and fully optimized. RESULTS: In all cases, continuing the initial plan was largely distorted on the repeated CTs and the dose-volume histogram (DVH) metrics for the target were reduced due to the tumor deformation or position changes. On the other hand, DDR improved DVH metrics for the target to the same level as the initial dose distribution. Dose increase was seen for some OARs because tumor growth had reduced the relative distance between CTVs and OARs. Robustness evaluation for setup and range uncertainty (3 mm/3.5%) showed that deviation in DVH-bandwidth for CTV D95% from the initial plan was 0.4% ± 0.5% (Mean ± S.D.) for DDR. The calculation time was 8.1 ± 6.4 min. CONCLUSIONS: An online adaptation algorithm was developed that improved the treatment quality for inter-fractional anatomical changes and retained robustness for intra-fractional setup and range uncertainty. The main advantage of this method is that it only requires target contouring alone and saves the time for OARs contouring. The fast and robust adaptation method for tumor deformation and position changes described here can reduce the need for offline adaptation and improve treatment efficiency.

Surveillance Strategy after Curative Resection for Oesophageal Squamous Cell Cancer Using the Hazard Function.

BACKGROUND: The optimal surveillance period and frequency after curative resection for oesophageal squamous cell carcinoma (OSCC) remain unclear, and current guidelines are mainly based on traditional Kaplan-Meier analyses of cumulative incidence rather than risk analysis. The aim of this study was to determine a suitable follow-up surveillance program following oesophagectomy for OSCC using the hazard function. METHODS: A total of 1187 patients who underwent curative resection for OSCC between 2000 and 2014 were retrospectively analyzed. The changes in the estimated hazard rates (HRs) of recurrence over time were analyzed according to tumour-node-metastasis stage. RESULTS: Four hundred seventy-eight (40.2%) patients experienced recurrence during the follow-up period (median, 116.5 months). The risk of recurrence peaked at 9.2 months after treatment (HR = 0.0219) and then decreased to half the peak value at 24 months post-surgery. The HRs for Stage I and II patients were low (< 0.007) post-treatment. The HR for Stage III patients peaked at 9.9 months (HR = 0.031) and the hazard curve declined to a plateau at 30 months. Furthermore, the HR peaked at 10.8 months (HR = 0.052) in Stage IV patients and then gradually declined from 50 months. CONCLUSIONS: According to tumour-node-metastasis stage, changes in the HRs of postoperative recurrence in OSCC varied significantly. Intensive surveillance should be undertaken for 3 years in Stage III patients and for 4 years in Stage IV patients, followed by annual screening. For Stage I OSCC patients, a reduction in the surveillance intensity could be taken into consideration.

Clinicopathological Features of Early-Stage Esophageal Carcinosarcoma.

Esophageal carcinosarcoma (EC) is a rare malignant tumor, accounting for 0.5-2.8% of esophageal cancers. Most are advanced cancers that are detected as polypoid lesions and are treated with multidisciplinary therapy with a focus on surgery. However, endoscopic findings, pathological findings, and long-term outcomes of early-stage EC are often unclear because there are very few reported cases. This paper reports three cases of EC confined to the mucosal layer. The macroscopic type of all tumors was polypoid lesion with a slightly depressed lesion. All cases were clinically diagnosed as invasive cancer before treatment. Pathological diagnosis of tumor depth showed that one case had invaded the lamina propria mucosae, and two cases had invaded the muscularis mucosae (MM). One case of diagnosed MM had lymphoid invasion and lymph node metastasis to the upper mediastinum. After 1 year, although adjuvant treatment had been administered, there was lymph node recurrence in the left upper clavicle, and thus chemoradiation therapy was performed. Two other cases survived without recurrence. Early-stage EC is characterized by polypoid lesions with a slightly depressed lesion, and it is challenging to predict the histology on biopsy. Furthermore, it is difficult to determine the depth of invasion in the MM and submucosal layer in squamous cell carcinoma by endoscopy alone, and hence depth diagnosis by multiple modalities should be considered.

Predictive Ability of the Five-time Chair Stand Test for Postoperative Pneumonia after Minimally Invasive Esophagectomy for Esophageal Cancer.

BACKGROUND: The revised sarcopenia guidelines proposed handgrip strength (HGS) and five-time chair stand test (5-CST) as the primary parameters of muscle function. HGS and 5-CST are associated with pulmonary function among community-dwelling people, although few reports have described an association between these parameters and surgical outcomes in carcinomas. We examined the predictive ability of 5-CST for postoperative pneumonia after minimally invasive esophagectomy (MIE) compared with that of HGS. METHODS: This retrospective, single-center, observational study evaluated 222 male patients who underwent MIE for esophageal cancer between February 2018 and October 2020. Sarcopenia parameters included 5-CST, HGS, and skeletal muscle index. Postoperative pneumonia predictors were determined by using multivariate logistic regression analysis. We assessed the net reclassification improvement (NRI) and integrated discrimination improvement (IDI) to analyze the predictive ability of 5-CST and HGS. RESULTS: MIE was performed for squamous cell carcinoma (n = 179), adenocarcinoma (n = 38), and other cancers (n = 5). Forty-nine (22.1%) patients developed postoperative pneumonia. Multivariate logistic regression showed that age (odds ratio [OR] 1.05; 95% confidence interval [CI] 1.01-1.10; p = 0.027), 5-CST (OR, 1.19; 95% CI 1.00-1.40; p = 0.046), and recurrent laryngeal nerve palsy (RLNP) (OR, 3.37; 95% CI 1.60-7.10; p = 0.001) significantly predicted postoperative pneumonia. Category-free NRI and IDI showed that adding 5-CST in the prediction model with age and RLNP resulted in significantly greater reclassification and discrimination abilities than did HGS. CONCLUSIONS: The 5-CST significantly predicted postoperative pneumonia after MIE. NRI and IDI analyses suggested that 5-CST had significantly better predictive ability for postoperative pneumonia than did HGS.

Laparoscopic Esophagogastric Anastomosis With Stapled Pseudo-Fornix for Reflux Esophagitis Prevention After Proximal Gastrectomy.

Laparoscopic esophagogastric anastomosis is not commonly performed after proximal gastrectomy (PG) because of its technical complexity and the lack of a gold standard for reconstruction. We describe a simple and convenient technique of laparoscopic esophagogastrostomy with stapled pseudo-fornix for reflux esophagitis (RE) prevention after PG. Laparoscopic PG (LPG) was performed in four patients with gastric cancer in the upper third of the stomach, and the remnant stomach was prepared for reconstruction. After making a small hole on the anterior wall of the remnant stomach 45 mm distal to the proximal stump and on the dorsal side of the esophageal stump, a 45 mm no-knife linear stapler was applied. To create a "pseudo-fornix," a common lumen was made by cutting the center of the four staple rows at a length of 15 mm. The entry hole was closed using the laparoscopic hand-sewn suturing technique. The mean operation time was 240 min, with an estimated blood loss of <10 ml. No intraoperative complications or conversion to open surgery were observed. One patient developed stenosis of the esophagogastrostomy successfully treated by endoscopic balloon dilatation. Endoscopic surveillance three months after surgery revealed no incidence of RE in any of the patients. Laparoscopic esophagogastric anastomosis with stapled pseudo-fornix is convenient and beneficial in preventing RE after PG and should be considered the treatment of choice for reconstruction after LPG in selected patients with proximal gastric cancer.

Does Preoperative Corticosteroid Administration Improve the Short-Term Outcome of Minimally Invasive Esophagectomy for Esophageal Cancer? A Propensity Score-Matched Analysis.

BACKGROUND: In open esophagectomy for esophageal cancer, steroid administration is associated with attenuated postoperative inflammation and reduced complications. However, the efficacy of steroids in minimally invasive esophagectomy (MIE) is uncertain. This study aimed to investigate the impact of steroid administration on short-term postoperative outcomes in MIE. METHODS: The study compared 458 patients who underwent MIE between April 2017 and December 2021. The patients were divided into steroid (n = 206) and non-steroid (n = 252) groups, and 160 paired cases were compared by 1:1 propensity score-matching. RESULTS: In the steroid group versus the non-steroid group, the intensive care unit stay was significantly shorter (2.6 vs 3.3 days; P = 0.001), and the incidence of surgical-site infection (SSI) was significantly lower (1.2 % vs 13.1 %; P < 0.001). The incidence of pneumonia tended to be lower in the steroid group, but not significantly lower (19.3 % vs 29.3 %; P = 0.065). Multivariate analysis showed that steroid administration independently affected SSI (odds ratio, 11.6; 95 % confidence interval, 3.3-73.6; P < 0.001). Compared with the non-steroid group, the steroid group had more favorable arterial partial pressure of oxygen/fraction of inspired oxygen ratio (503 ± 178 vs 380 ± 104; P < 0.001) and body temperature (37.2 ± 0.54 °C vs 38.3 ± 0.66 °C; P < 0.001) on postoperative day (POD) 0, heart rate (beats per minute) (74.6 ± 8.9 vs 84 ± 11.4; P < 0.001) on POD 1, and C-reactive protein concentration (7.07 ± 3.4 vs 13.7 ± 6.4 mg/dL; P < 0.001) on POD 3. CONCLUSIONS: In MIE, steroid administration was associated with reduced SSI, suggesting an attenuated inflammatory response to surgical stress.

Handgrip strength predicts early postoperative dysphagia after thoracoscopic-laparoscopic esophagectomy in male patients with esophageal cancer.

BACKGROUND: Dysphagia after esophagectomy, especially in the early postoperative period, remains a severe complication. The association between sarcopenia and dysphagia has received attention in geriatric non-cancer populations. This study aimed to determine the associations between sarcopenia parameters and early postoperative dysphagia after esophagectomy. METHODS: This retrospective observational study included 201 consecutive male patients undergoing thoracoscopic-laparoscopic esophagectomy (TLE) for esophageal cancer between October 2018 and December 2020. We used three sarcopenia parameters: handgrip strength (HGS), skeletal muscle index, and gait speed. Postoperative swallowing function was assessed by videofluoroscopy using the penetration-aspiration scale (PAS; range 1-8). Logistic regression analyses were used to predict factors associated with postoperative aspiration (PAS 6-8). Furthermore, we compared values in patients with symptomatic aspiration (PAS 6-7) and with silent aspiration (PAS 8). RESULTS: Aspiration occurred in 38 of 201 patients (18.9%). On multivariate analysis, significant predictors of aspiration included age [odds ratio (OR) 1.11; 95% confidence interval (CI) 1.05-1.17; p < 0.001], low HGS (OR 3.05; 95% CI 1.06-8.78; p = 0.039), upper third esophageal cancer (OR 2.79; 95% CI 1.03-7.54; p = 0.044) and recurrent laryngeal nerve palsy (OR 2.98; 95% CI 1.26-7.06; p = 0.013). Furthermore, among patients with aspiration (PAS 6-8), low HGS was significantly associated with silent aspiration (OR 6.43; 95% CI 1.06-39.00; p = 0.043). CONCLUSIONS: Low HGS was significantly associated with early postoperative aspiration and impairment of airway protective reflexes after TLE.

Toe grip force of the dominant foot is associated with fall risk in community-dwelling older adults: a cross-sectional study.

BACKGROUND: It is unclear whether the toe grip force (TGF) of the dominant foot (DF) and the lower limb function asymmetry (LLFA) in older adults are associated with fall risk. Therefore, this study aimed to investigate the effect of lower limb properties (such as TGF, muscle strength, and plantar sensation) on the risk of falls in older adults, while considering the foot dominance and asymmetry of lower limb function. METHODS: This study was a cross-sectional study. We determined whether the lower limb function of the DF and non-dominant foot (non-DF) and LLFA had any effect on the fall risk in 54 older adults (mean ± standard deviation: 72.2 ± 6.0, range: 60-87 years). We examined the participants' fall history, Mini-Mental State Examination (MMSE) score, lower limb function, and LLFA. To determine fall risk factors, we performed logistic regression analysis, with presence or absence of falls as the dependent variable. RESULTS: The independent variables were age, sex, MMSE score, two-point discrimination of the heel (non-DF) as plantar sensation index, and the TGF of both feet. Only the TGF of the DF was identified as a risk factor for falls (p < 0.05). CONCLUSIONS: In older adults, clinicians should focus on the TGF of the DF as a risk factor for falls. TRIAL REGISTRATION: This study was retrospectively registered. https://center6.umin.ac.jp/cgi-bin/ctr/ctr_up_rec_f1.cgi .

Simple and simultaneous quantification of cyanide, ethanol, and 1-propanol in blood by headspace GC-MS/NPD with Deans switch dual detector system.

Cyanide is a powerful and rapidly acting poison. In Japan, cyanide poisoning is rare, and regular cyanide testing can be costly and time consuming. In contrast, alcohol analysis is routinely performed in most forensic laboratories. In this study, we attempted to develop a method for the simultaneous quantification of cyanide and alcohols in blood using headspace gas chromatography (HS-GC). As nitrogen-phosphorus detection (NPD) is more sensitive to hydrogen cyanide than mass spectrometry (MS), a Deans switch was used to switch the detectors during a single run. The separation provided by three analytical columns, PoraBOND Q, CP-Sil 5 CB, and HP-INNOWax, was investigated, and PoraBOND Q was selected. The use of HS-GC-MS/NPD with a Deans switch enabled the simple and simultaneous quantification of cyanide, ethanol, and 1-propanol. Eighteen other volatile compounds were detected in the SIM/scan mode of the MS.

Successful Management of a Young Athlete with Type 2 Long QT Syndrome by Genotype-specific Risk Stratification and Bridging Therapy with a Wearable Cardioverter Defibrillator.

We herein report a 14-year-old boy with repetitive nocturnal syncope related to medication-refractory long QT syndrome (LQTS). Although the use of an implantable cardioverter-defibrillator (ICD) was inevitable to prevent sudden cardiac death, he refused immediate implantation in order to play in a baseball competition six weeks away. Given his genetic diagnosis of type 2 LQTS, which is associated with cardiac events unrelated to exercise, we prescribed a wearable cardioverter defibrillator (WCD) to be donned at night, without limiting his exercise participation. An ICD was implanted after the competition. We successfully performed the preplanned treatment while maximizing the patient's quality-of-life with a WCD and genotype-specific risk stratification.

An initial systematic study of the linear energy transfer distributions of a proton beam under a transverse magnetic field.

PURPOSE: To evaluate the biological effectiveness of magnetic resonance (MR)-guided proton beam therapy, comprehensively characterizing the dose and dose-averaged linear energy transfer (LETd ) distributions under a magnetic field is necessary. Although detailed analysis has characterized curved beam paths and distorted dose distributions, the impact of a magnetic field on LETd should also be explored to determine the proton relative biological effectiveness (RBE). Hence, this initial study aims to present a basic analysis of LETd distributions in the presence of a magnetic field using Monte Carlo simulation (MCS). METHODS: Geant4 MCS (version 10.1.p01) was performed to calculate the LETd distribution of proton beams. The incident beam energies were set to 70.2, 140.8, and 220 MeV, and both zero- and finite-emittance pencil beams as well as scanned field were simulated. A transverse magnetic field of 0-3 T was applied within a water phantom placed at the isocenter, and the three-dimensional dose and LETd distributions in the phantom were calculated. Then, the depth profiles of LETd along the curved trajectory and the lateral LETd profile at the Bragg peak (BP) depth were analyzed under changing energies and magnetic fields. In addition, for zero- and finite-emittance beams, the correlation of the lateral asymmetries between the dose and LETd distributions were analyzed. Finally, spread-out Bragg peak (SOBP) fields were simulated to assess the depth-dependent asymmetry of the LETd distributions. RESULTS: A transverse magnetic field distorted the lateral LETd distribution of a pencil beam at close to the BP, and the magnitude of the distortion at the BP increased for higher energy beams and larger magnetic fields. For a zero-emittance beam, the differences in LETd between the left and right D20 positions were relatively large; the difference in LETd was 1.5 and 2.3 keV/µm at 140.8 and 220 MeV, respectively, at a magnetic field of 1.5 T. These asymmetries were pronounced at positions where the dose asymmetries were large. The size of the asymmetry was less substantial for a finite-emittance beam and even less for a scanned field. However, a 1.5-keV/µm difference still remained between the left and right D20 positions of a scanned field penumbra for a 220 MeV beam under the same magnetic field. For the SOBP field, it was found that the distal region of SOBP had the highest LETd distortions, followed by the central and proximal regions for the middle-sized SOBP (5 × 5 × 5 cm3 ), whereas the degree of LETd distortion did not vary much with depth for the 10 × 10 × 10-cm3 SOBP field. CONCLUSION: Our results indicate that not only the dose but also LETd distortions should be considered to accurately evaluate the biological effectiveness of MR-guided proton beam therapy.