Computational dielectric spectroscopy on solid-solution interface by time-dependent voltage applied molecular dynamics simulation.

A frequency-dependent dielectric constant characterizes the dielectric response of a medium and also represents the time scale of system's collective dynamics. Although it is valuable not only academically but also practically for developing advanced devices, getting the value of a solution at the interface with a solid or electrode surface is challenging both experimentally and computationally. Here, we propose a computational method that imitates the dielectric spectroscopy and AC impedance measurement. It combines a time-dependent voltage applied molecular dynamics simulation with an equivalent circuit representation of a system composed of a solution confined between two identical electrodes. It gives the frequency-dependent dielectric constants of the bulk solution and the interface simultaneously. Unlike the conventional method, it does not require computation of a dipole autocorrelation function and its Fourier transformation. Application of the method on a system of water confined between polarizable Pt electrodes gives the static dielectric constant and the relaxation time of the bulk water in good agreement with previous simulation results and experimental values. In addition, it gives a much smaller static dielectric constant at the interface, consistent with previous observations. The outline of the dielectric dispersion curve of the interface seems similar to that of the bulk, but the relaxation time is several times faster.

Anaesthetic management of an abdominal aortic aneurysmorrhaphy in Klippel-Trenaunay-Weber syndrome: a case report.

BACKGROUND: Klippel-Trenaunay-Weber syndrome (KTWS) is a rare congenital malformation. Although there have been few reports on anaesthetic management of patients with KTWS, there is a lack of data on anaesthetic management for abdominal aortic aneurysm (AAA) surgeries in these patients. CASE PRESENTATION: A 74-year-old man (height, 160 cm and body weight, 51.5 kg) with KTWS was scheduled for AAA replacement. Abdominal computed tomography (CT) showed prominent tortuosity below the abdominal aorta with an infrarenal abdominal aortic aneurysm, right common iliac artery aneurysm, and right external iliac artery aneurysm. Moreover, a remarkably noted arteriovenous fistula had developed between the aneurysm and peripheral artery. General anaesthesia was induced. Furthermore, a central venous catheter and an 8.5 French sheath in the left internal jugular vein were inserted. During the operation, bleeding from a collateral vessel in the cross-clamped aorta led the surgeon to decide to perform aneurysmorrhaphy. Intraoperatively, blood loss was 1500 ml, and 20 units of red blood cell concentrate were used. CONCLUSIONS: Regarding AAA procedures in patients with KTWS, aortic cross-clamping may not sufficiently intercept blood flow due to collateral vessels. In these patients, the anaesthesiologist must be prepared to transfuse blood more rapidly and frequently than during normal AAA procedures.

[Successful R0 Resection of Hilar Cholangiocarcinoma Invading the Inferior Vena Cava through Left Trisegmentectomy with Combined Resection of the Portal Vein and Inferior Vena Cava after Gemcitabine/Cisplatin Combination Chemotherapy-A Case Report].

A 65-year-old woman was admitted to our institution with sonography results indicating a caudate lobe mass. CT showed a large low-density mass in the caudate lobe, extensively involving the inferior vena cava and main portal vein. Moderately differentiated adenocarcinoma was found on transcutaneous biopsy. We therefore regarded this tumor as a severe locally advanced hilar cholangiocarcinoma and initiated gemcitabine/cisplatin combined chemotherapy. The tumor gradually reduced in size. However, after 28 courses of treatment, CT showed persistent tumor invasion in the left trunk of the portal vein and inferior vena cava invasion in succession in the middle; the tumor had not yet invaded the left hepatic vein. Owing to myelosuppression and general malaise, it was difficult to continue chemotherapy. After 32 courses of treatment, the patient underwent a left trisegmentectomy with combined resection of the portal vein and inferior vena cava. Postoperative microscopic findings revealed no apparent invasion of the tumor in the inferior vena cava, thus suggesting successful R0 resection. The patient is alive without recurrence 18 months postoperatively.

Phase II Study of the Reuse of Trastuzumab with Docetaxel beyond Progression after First-Line Treatment in Second-Line Treatment for Unresectable, Metastatic Gastric Cancer (T-CORE1203).

Whether trastuzumab use beyond disease progression is beneficial in second-line treatment for patients with unresectable human epidermal growth factor receptor 2 (HER2)-positive gastric cancer remains to be elucidated. We conducted this phase II study to assess whether trastuzumab plus docetaxel was effective for patients with previously treated advanced HER2-positive gastric cancer. This trial was a single-arm, open-label, multicenter, phase II study, conducted by Tohoku Clinical Oncology Research and Education Society (T-CORE). Patients aged 20 years or older who had advanced HER2-positive gastric cancer and were refractory to trastuzumab, fluoropyrimidine, and cisplatin were enrolled. Patients were treated with 6 mg/kg trastuzumab and 60 mg/m2 docetaxel every 3 weeks. The primary endpoint was the overall response rate. The threshold overall response rate was estimated to be at 15%. Secondary endpoints were progression-free survival, 6-month survival rate, overall survival, and toxicities. A total of 27 patients were enrolled from 7 hospitals. The median age was 67 years. Partial response was seen in 3 patients among the 26 evaluated patients. The overall response rate was at 11.5% (90% confidence interval 1.2%-21.8%). The median progression-free survival was 3.2 months, the 6-month survival rate was 85%, and the median overall survival was 11.6 months. Febrile neutropenia was observed in 14.8%. The most frequently observed grade 3 non-hematologic toxicity was anorexia (14.8%). The primary endpoint was not achieved. The results support a current consensus that the continuation of trastuzumab in second-line therapy for gastric cancer is not a recommended option.

Anatomical and physiological variables influencing measurement of regional cerebral oxygen saturation by near infrared spectroscopy using the Sensmart Model X-100TM.

The Sensmart Model X-100 (Nonin Medical Inc, Plymouth, MN, USA) is a relatively new device that possesses two sets of emitters and detectors and uses near infrared spectroscopy (NIRS) to measure regional cerebral oxygen saturation (rSO2). The value of rSO2 obtained by other NIRS devices is affected by physiological and anatomical variables such as hemoglobin concentration, area of cerebrospinal fluid (CSF) layer and skull thickness. The effects of these variables have not yet been determined in measurement of rSO2 by Sensmart Model X-100. We examined the effects of area of CSF, hemoglobin concentration, and skull thickness on the values of rSO2 measured by Sensmart Model X-100 and tissue oxygen index (TOI) measured by NIRO-200NX (Hamamatsu Photonix, Hamamatsu, Japan). Forty neurosurgical, cardiac and vascular surgical patients who underwent preoperative computed tomographic (CT) scan of the brain were enrolled in this study. Regional cerebral oxygen saturation (rSO2) at the forehead was measured sequentially by NIRO-200NX and by Sensmart Model X-100. Simultaneously, mean arterial pressure, hemoglobin concentration, and partial pressure of carbon dioxide in arterial blood (PaCO2) were measured. To evaluate the effects of anatomical factors on rSO2, we measured skull thickness and area of CSF layer using CT images of the brain. Multiple regression analysis was used to examine the relationships between the rSO2 values and anatomical and physiological factors. The area of the CSF layer and hemoglobin concentration had significant associations with rSO2 measured by the Sensmart Model X-100, whereas none of the studied variables was significantly associated with TOI. The measurement of rSO2 by Sensmart Model X-100 is not affected by the skull thickness of patients. Area of the CSF layer and hemoglobin concentration may be the main biases in measurement of rSO2 by Sensmart Model X-100.

The Fate of Transplanted Periodontal Ligament Stem Cells in Surgically Created Periodontal Defects in Rats.

Periodontal disease is chronic inflammation that leads to the destruction of tooth-supporting periodontal tissues. We devised a novel method ("cell transfer technology") to transfer cells onto a scaffold surface and reported the potential of the technique for regenerative medicine. The aim of this study is to examine the efficacy of this technique in periodontal regeneration and the fate of transplanted cells. Human periodontal ligament stem cells (PDLSCs) were transferred to decellularized amniotic membrane and transplanted into periodontal defects in rats. Regeneration of tissues was examined by microcomputed tomography and histological observation. The fate of transplanted PDLSCs was traced using PKH26 and human Alu sequence detection by PCR. Imaging showed more bone in PDLSC-transplanted defects than those in control (amnion only). Histological examination confirmed the enhanced periodontal tissue formation in PDLSC defects. New formation of cementum, periodontal ligament, and bone were prominently observed in PDLSC defects. PKH26-labeled PDLSCs were found at limited areas in regenerated periodontal tissues. Human Alu sequence detection revealed that the level of Alu sequence was not increased, but rather decreased. This study describes a novel stem cell transplantation strategy for periodontal disease using the cell transfer technology and offers new insight for cell-based periodontal regeneration.

Probing the Most Stable Isomer of Zirconium Bis(phenoxy-imine) Cation: A Computational Investigation.

The possibility of coexistence of multiple isomers for zirconium bis(phenoxy-imine) catalyst has been systematically studied by computational approaches. The energetics among the five different isomers of neutral Zr-catalyst have been assessed quantum mechanically. The results suggest that isomer cis-N/trans-O/cis-Me is the most stable among the five isomers in accordance with the general observations of these kinds of phenoxy-imine catalyst. However, for the polymerization reaction, the active species is known to be the cationic form of the Zr-catalyst. The Zr-cation can exist in three different isomers, viz., cis-N/trans-O (A), cis-N/cis-O (B), and trans-N/cis-O (C), and the presence of flexible ligands makes the modeling considerably challenging to determine the most preferable isomers. For the efficient modeling, altogether 80 different structures for each of the three cationic isomers have been generated by using molecular dynamics simulations, and subsequently, the quantum mechanical optimization of these structures has been performed to obtain the most preferable conformation for each isomer. The existing probability derived from the obtained free energy values suggests that isomer C is comparable with isomer A. Even more, isomer A of the cation can be present in two different conformations, where the orientation of side groups is altered at the imine nitrogen atoms. The transition state calculations also confirm that the Zr-cation can exist as a mixture of three structures, "up-down" and "down-down" orientations of the isomers A along with isomer C's "up-up" orientation. However, by varying the substituents at imine nitrogen atoms, one could modulate multimodal to unimodal polymerization behavior of the Zr-catalysts. We believe that this study should provide a starting point for theoretically exploring the mechanistic pathway of the complicated polymerization reactions.

Reappearance of Motor-Evoked Potentials During the Rewarming Phase After Deep Hypothermic Circulatory Arrest.

OBJECTIVE: Although motor-evoked potentials (MEPs) disappear in deep hypothermic circulatory arrest (DHCA), MEPs have been used to confirm whether motor function is intact after DHCA. It is crucial to know the timing, body temperature, and MEP amplitude at MEP reappearance to detect spinal cord ischemia after DHCA. However, data on these parameters are sparse. The authors investigated the characteristics of MEPs at reappearance after DHCA. DESIGN: A retrospective observational study. SETTING: Single national center. PARTICIPANTS: Sixty-one patients who underwent descending aortic replacement and thoracoabdominal aortic replacement with DHCA between January 2013 and December 2015. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The authors extracted the following data: time to MEP reappearance after the end of lower extremity circulatory arrest, bladder temperature (BT) and nasopharyngeal temperature (NPT) when MEPs recovered, and %amplitude of MEPs relative to control values at MEP reappearance. The median time to MEP reappearance was approximately 70 minutes. BT at MEP reappearance ranged from 34.3°C to 34.6°C and NPT ranged from 36.2°C to 36.4°C. At MEP reappearance, %amplitude less than 50% of the control value was observed in more than 50% of patients. Time to MEP reappearance had a significant positive association with rewarming time (p < 0.01) and BT (p = 0.03). CONCLUSIONS: There was a wide variation in MEP amplitude at reappearance during the rewarming phase. BT was approximately 34°C when MEPs in the leg recovered. The time to MEP reappearance is influenced significantly by rewarming time and BT.

Solvatochromism and preferential solvation of Brooker's merocyanine in water-methanol mixtures.

The excitation energy of Brooker's merocyanine in water-methanol mixtures shows nonlinear behavior with respect to the mole fraction of methanol, and it was suggested that this behavior is related to preferential solvation by methanol. We investigated the origin of this behavior and its relation to preferential solvation using the three-dimensional reference interaction site model self-consistent field method and time-dependent density functional theory. The calculated excitation energies were in good agreement with the experimental behavior. Analysis of the coordination numbers revealed preferential solvation by methanol. The free energy component analysis implied that solvent reorganization and solvation entropy drive the preferential solvation by methanol, while the direct solute-solvent interaction promotes solvation by water. The difference in the preferential solvation effect on the ground and excited states causes the nonlinear excitation energy shift. © 2017 Wiley Periodicals, Inc.

Collateral Flow and White Matter Disease in Patients with Internal Carotid Artery Occlusion.

BACKGROUND: When an internal carotid artery (ICA) occludes, a patient may develop cerebral infarction (CI). We investigated whether CI caused by ICA occlusion (ICAO) is associated with collateral flow through the anterior and posterior communicating arteries (ACoA and PCoA). METHODS: In 100 patients with ICAO, we investigated CI and white matter disease by performing an MRI and the anatomy of the ACoA and PCoA were investigated by performing magnetic resonance angiography. All patients were divided into the symptomatic CI group or the no-CI group. The collateral flow pathway was estimated by the anterior cerebral artery (ACA)-PCoA score and the collateral flow volume after ICAO was estimated by the middle cerebral artery (MCA) flow score, based on how well the MCA was visualized. RESULTS: Of 100 patients with ICAO, the symptomatic CI group included 36 patients. ACA-PCoA score and white matter disease grades were significantly higher in the CI group (indicating poor collateral flow). More than 80% of patients with an ACA-PCoA score of 4 (poor collateral) experienced symptomatic CI. Thirty-one symptomatic CI patients (86%) had an MCA flow score of 1 or 2 (decreased MCA flow). CONCLUSION: The ACA-PCoA score and white matter disease grade may suggest an increased risk of CI following ICAO.

Leukocyte plugging and cortical capillary flow after subarachnoid hemorrhage.

BACKGROUND: It is believed that increased intracranial pressure immediately after subarachnoid hemorrhage (SAH) causes extensive brain ischemia and results in worsening clinical status. Arterial flow to the cerebral surfaces is clinically well maintained during clipping surgery regardless of the severity of the World Federation of Neurological Societies grade after SAH. To explore what kinds of changes occur in the cortical microcirculation, not at the cerebral surface, we examined cortical microcirculation after SAH using two-photon laser scanning microscopy (TPLSM). METHODS: SAH was induced in mice with an endovascular perforation model. Following continuous injection of rhodamine 6G, velocities of labeled platelets and leukocytes and unlabeled red blood cells (RBCs) were measured in the cortical capillaries 60 min after SAH with a line-scan method using TPLSM, and the data were compared to a sham group and P-selectin monoclonal antibody-treated group. RESULTS: Velocities of leukocytes, platelets, and RBCs in capillaries decreased significantly 60 min after SAH. Rolling and adherent leukocytes suddenly prevented other blood cells from flowing in the capillaries. Flowing blood cells also decreased significantly in each capillary after SAH. This no-reflow phenomenon induced by plugging leukocytes was often observed in the SAH group but not in the sham group. The decreased velocities of blood cells were reversed by pretreatment with the monoclonal antibody of P-selection, an adhesion molecule expressed on the surfaces of both endothelial cells and platelets. CONCLUSIONS: SAH caused sudden worsening of cortical microcirculation at the onset. Leukocyte plugging in capillaries is one of the reasons why cortical microcirculation is aggravated after SAH.

Three-dimensional reference interaction site model self-consistent field analysis of solvent and substituent effects on the absorption spectra of Brooker's merocyanine.

Solvent and substituent effects on the absorption spectra of Brooker's merocyanine (BM) are investigated using the three-dimensional reference interaction site model self-consistent field method and time-dependent density functional theory. The π-π* excitation energies are computed for BM and its derivative 2,6-di-tert-butyl (di-t-Bu) BM. The behaviors of the computed excitation energies with increasing solvent polarity are in good agreement with those of the corresponding experimental measurements. In addition, analysis of the solute-solvent interaction energies and spatial distribution functions reveals that the effects of the solvent on the absorption spectra are reduced by the steric hindrance of the t-Bu groups. Furthermore, from the difference in the solute-solvent interaction energies of BM and di-t-Bu BM, it is shown that the effect of the t-Bu substituents on the absorption spectrum is greater in high-polarity solvents.

Early diagnosis of cerebral ischemia in cerebral vasospasm by oxygen-pulse near-infrared optical topography.

PURPOSE: Early diagnosis of vasospasm is a key factor in the choice of treatment after subarachnoid hemorrhage (SAH). However, a noninvasive method of diagnosing delayed ischemic neurological deficit (DIND) has not been established. We therefore propose a new method of diagnosing cerebral ischemia using near-infrared optical topography (OT) with oxygen inhalation. MATERIALS AND METHODS: We used a 44-channel OT system that covers the bilateral front otemporoparietal areas to assess 29 patients who underwent surgery within 72 h of the onset of SAH. The patients inhaled room air followed by oxygen for 2 min, and then peripheral oxygen saturation (SpO2) was continuously monitored at the index fingertip. The patients were assessed by N-isopropyl-p-[¹²³I]iodoamphetamine (IMP)-SPECT and OT on the same day. Ischemic findings were confirmed using principal component analysis with reference to the systemic SpO2value. RESULTS: Seven of 29 patients developed DIND. Evidence of ischemia was identified by OT in all seven of these patients before the onset of DIND. The OT and SPECT findings agreed in 27 (93 %) of the 29 patients. DISCUSSION AND CONCLUSIONS: Our method might detect cerebral ischemia before the onset of DIND and thus be clinically useful for assessing cerebral ischemia with vasospasm.

Microvascular decompression under neuroendoscopic view in hemifacial spasm: rostral-type compression and perforator-type compression.

We report microvascular decompression (MVD) under neuroendoscopic view in hemifacial spasm (HFS) patients with rostral- and perforator-type compression of the root exit zone (REZ) of the facial nerve. Using either a wireless iPad Mini as a monitor on the microscope or a high-resolution monitor, microscopic and endoscopic views enabled MVD for complete cure of HFS with rostral-type compression (the offender compressing the REZ on the opposite rostral side to the operative approach) or perforator-type compression (the offender tethered to the REZ by the perforator). MVD under neuroendoscopic view may offer more accurate MVD and complete resolution of HFS.

Endonasal ultrasonography-assisted neuroendoscopic transsphenoidal surgery.

We report endonasal ultrasonography (US)-assisted neuroendoscopic transsphenoidal surgery (TSS) in seven patients. With sagittal and coronal US images, internal carotid arteries, anterior cerebral arteries, residual tumor, and lateral ventricles were recognized, and the tumors were removed without leakage of cerebrospinal fluid in patients with pituitary adenoma. US images clearly depicted the carotid arteries, anterior cerebral arteries, middle cerebral arteries, chiasmatic cistern, and residual tumor. Endonasal US images can provide real-time animated information and may help neuroendoscopic TSS, whenever needed during TSS.

[Two cases of intravascular lymphoma diagnosed by random liver biopsy].

The pathogenesis of intravascular lymphoma (IVL) remains inadequately understood. Furthermore, its prognosis remains extremely poor despite combination chemotherapy. Lymphoma cells and hemophagocytosing cells are commonly observed in the livers of IVL patients and less frequently in the bone marrow. We recently encountered an 83-year-old female and a 78-year-old female with IVL, both of whom presented with fever of unknown origin. Following examination, we decided to perform random liver biopsy for diagnostic purposes. The former patient died because of rapid tumor growth, while the latter achieved remission following treatment with a modified R-VNCOP-B (etoposide, mitoxantrone, cyclophosphamide, vincristine, prednisolone, and bleomycin plus rituximab) regimen. Considering the possibility of IVL is important when examining a patient presenting with fever of unknown origin. This report demonstrates that random liver biopsy represents a useful diagnostic strategy, particularly in patients with elevated liver enzyme levels.

Modeling Complex EEG Data Distribution on the Riemannian Manifold Toward Outlier Detection and Multimodal Classification.

OBJECTIVE: The usage of Riemannian geometry for Brain-computer interfaces (BCIs) has gained momentum in recent years. Most of the machine learning techniques proposed for Riemannian BCIs consider the data distribution on a manifold to be unimodal. However, the distribution is likely to be multimodal rather than unimodal since high-data variability is a crucial limitation of electroencephalography (EEG). In this paper, we propose a novel data modeling method for considering complex data distributions on a Riemannian manifold of EEG covariance matrices, aiming to improve BCI reliability. METHODS: Our method, Riemannian spectral clustering (RiSC), represents EEG covariance matrix distribution on a manifold using a graph with proposed similarity measurement based on geodesic distances, then clusters the graph nodes through spectral clustering. This allows flexibility to model both a unimodal and a multimodal distribution on a manifold. RiSC can be used as a basis to design an outlier detector named outlier detection Riemannian spectral clustering (odenRiSC) and a multimodal classifier named multimodal classifier Riemannian spectral clustering (mcRiSC). All required parameters of odenRiSC/mcRiSC are selected in data-driven manner. Moreover, there is no need to pre-set a threshold for outlier detection and the number of modes for multimodal classification. RESULTS: The experimental evaluation revealed odenRiSC can detect EEG outliers more accurately than existing methods and mcRiSC outperformed the standard unimodal classifier, especially on high-variability datasets. CONCLUSION: odenRiSC/mcRiSC are anticipated to contribute to making real-life BCIs outside labs and neuroergonomics applications more robust. SIGNIFICANCE: RiSC can work as a robust EEG outlier detector and multimodal classifier.

Determination of severity of murine IgA nephropathy by glomerular complement activation by aberrantly glycosylated IgA and immune complexes.

The pathogenic roles of glomerular deposition of components of the complement cascade in IgA nephropathy (IgAN) are not completely clarified. To investigate the pathologic role of complement pathways in IgAN, two IgAN-prone mouse models were examined. Grouped ddY (gddY) mice showed significant high proteinuria, severe glomerular lesions, and extracellular matrix expansion compared with high serum IgA (HIGA) mice but with similar intensity of glomerular IgA deposition. Glomerular activation of the classical, lectin, and alternative pathways was demonstrated by significantly stronger staining for complement (C)3, C5b-9, C1q, C4, mannose-binding lectin (MBL)-A/C, MBL-associated serine protease-2, and factor B and properdin in gddY mice than in HIGA mice. Similarly, the serum levels of IgA-IgG2a/IgM and IgA-MBL-A/C immune complexes and polymeric IgA were significantly higher in gddY mice than in HIGA mice. Moreover, the serum levels of aberrantly glycosylated IgA characterized by the binding of Sambucus nigra bark lectin and Ricinus communis agglutinin I were significantly higher in gddY mice than in HIGA mice. This aberrancy in glycosylation was confirmed by monosaccharide compositional analysis of purified IgA using gas-liquid chromatography. This study is the first to demonstrate that aberrantly glycosylated IgA may influence the formation of macromolecular IgA including IgA-IgG immune complexes and subsequent complement activation, leading to full progression of IgAN.

Development of a novel delivery quality assurance system based on simultaneous verification of dose distribution and binary multi-leaf collimator opening in helical tomotherapy.

BACKGROUND: Intensity-modulated radiation therapy (IMRT) requires delivery quality assurance (DQA) to ensure treatment accuracy and safety. Irradiation techniques such as helical tomotherapy (HT) have become increasingly complex, rendering conventional verification methods insufficient. This study aims to develop a novel DQA system to simultaneously verify dose distribution and multi-leaf collimator (MLC) opening during HT. METHODS: We developed a prototype detector consisting of a cylindrical plastic scintillator (PS) and a cooled charge-coupled device (CCD) camera. Scintillation light was recorded using a CCD camera. A TomoHDA (Accuray Inc.) was used as the irradiation device. The characteristics of the developed system were evaluated based on the light intensity. The IMRT plan was irradiated onto the PS to record a moving image of the scintillation light. MLC opening and light distribution were obtained from the recorded images. To detect MLC opening, we placed a region of interest (ROI) on the image, corresponding to the leaf position, and analyzed the temporal change in the light intensity within each ROI. Corrections were made for light changes due to differences in the PS shape and irradiation position. The corrected light intensity was converted into the leaf opening time (LOT), and an MLC sinogram was constructed. The reconstructed MLC sinogram was compared with that calculated using the treatment planning system (TPS). Light distribution was obtained by integrating all frames obtained during IMRT irradiation. The light distribution was compared with the dose distribution calculated using the TPS. RESULTS: The LOT and the light intensity followed a linear relationship. Owing to MLC movements, the sensitivity and specificity of the reconstructed sinogram exceeded 97%, with an LOT error of - 3.9 ± 7.8%. The light distribution pattern closely resembled that of the dose distribution. The average dose difference and the pass rate of gamma analysis with 3%/3 mm were 1.4 ± 0.2% and 99%, respectively. CONCLUSION: We developed a DQA system for simultaneous and accurate verification of both dose distribution and MLC opening during HT.

Dosimetric Predictors of Toxicity after Prostate Stereotactic Body Radiotherapy: A Single-Institutional Experience of 145 Patients.

The indications for stereotactic body radiotherapy (SBRT) for prostate cancer have increased. However, the relationships between adverse events and risk factors remain unclear. This study aimed to clarify associations between adverse events and dose index for prostate SBRT. Participants comprised 145 patients irradiated with 32-36 Gy in 4 fractions. Radiotherapy-related risk factors such as dose-volume histogram parameters and patient-related risk factors such as T stage and Gleason score were evaluated in a competing risk analysis. Median follow-up duration was 42.9 months. A total of 9.7% had acute Grade ≥ 2 GU toxicities and 4.8% had acute Grade ≥ 2 GI toxicities. A total of 11.1% had late Grade ≥ 2 GU toxicities and 7.6% had late Grade ≥ 2 GI toxicities. Two (1.4%) patients suffered from late Grade 3 GU toxicities. Similarly, two (1.4%) patients suffered from late Grade 3 GI toxicities. Acute GU and GI events correlated with prostate volume and dose to the hottest 10 cc volume (D10cc)/volumes receiving a minimum of 30 Gy (V30 Gy) of rectum, respectively. Late GI toxicity, frequency, and rectal hemorrhage correlated with rectal D0.1 cc/D1 cc, maximum dose to the bladder, and rectal D0.1 cc, respectively. Toxicities after prostate SBRT using 32-36 Gy/4 fractions were acceptable. Our analysis showed that acute toxicities correlated with volume receiving a medium dose level, and late toxicities correlated with highest point dose of organs at risk.