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.

Risk factors for catheter-related bloodstream infections in patients with intestinal failure undergoing home parenteral nutrition: a single-center study.

PURPOSE: The incidence and risk factors of catheter-related bloodstream infections (CRBSI) in patients with intestinal failure (IF) have not been established, partly because catheter management methods vary from different facilities. This study aimed to identify the risk factors and incidence rate of CRBSIs in patients with IF who were given prophylactic treatment. METHODS: Sixteen patients with IF who required home parenteral nutrition were enrolled in this study. Prophylactic management of CRBSI included monthly ethanol lock therapy and standardized infection prevention education. The outcomes included the incidence and risk factors of CRBSI. RESULTS: The median incidence rate of CRBSI was 1.2 per 1000 catheter days. Univariate analysis showed that the risk of developing CRBSI was significantly associated with short bowel syndrome (< 30 cm) (p = 0.016). Other relevant findings included a significant negative correlation between serum albumin and CRBSI rate (r = - 0.505, p = 0.046), and past history of mixed bacterial infections was significantly associated with increased CRBSI rate (p = 0.013). CONCLUSION: CRBSIs can still develop despite undergoing prophylactic management. Risk factors for CRBSI include the residual intestinal length, nutritional status, and susceptibility to certain microorganisms.

Dedicated phantom tools using traceable 68Ge/68Ga point-like sources for dedicated-breast PET and positron emission mammography scanners.

Since the early 2000s, many types of positron emission tomography (PET) scanners dedicated to breast imaging for the diagnosis of breast cancer have been introduced. However, conventional performance evaluation methods developed for whole-body PET scanners cannot be used for such devices. In this study, we developed phantom tools for evaluating the quantitative accuracy of positron emission mammography (PEM) and dedicated-breast PET (dbPET) scanners using novel traceable point-like 68Ge/68 Ga sources. The PEM phantom consisted of an acrylic cube (100 × 100 × 40 mm) and three point-like sources. The dbPET phantom comprised an acrylic cylinder (ø100 × 100 mm) and five point-like sources. These phantoms were used for evaluating the fundamental responses of clinical PEM and dbPET scanners to point-like inputs in a medium. The results showed that reasonable recovery values were obtained based on region-of-interest analyses of the reconstructed images. The developed phantoms using traceable 68Ge/68 Ga point-like sources were useful for evaluating the physical characteristics of PEM and dbPET scanners. Thus, they offer a practical, reliable, and universal measurement scheme for evaluating various types of PET scanners using common sets of sealed sources.

Intraoperative Placement of an Absorbable Spacer Prior to Radiation Therapy for a Malignant Peripheral Nerve Sheath Tumor.

A 7-year-6-month-old female was diagnosed with a pelvic malignant peripheral nerve sheath tumor and lymph node metastases. Tumorectomy was performed after four cycles of chemotherapy. A 33-mm cystic lesion was observed around the left iliac muscle after three cycles of postoperative chemotherapy, and proton beam therapy (PBT) was recommended. She was referred for absorbable spacer (AS) placement. The left ovarian appendage (OA) was resected due to the direct tumor infiltration. The right OA was fixed to the uterosacral ligament. The AS was fixed to the lateral pelvis. The PBT (70.3 Gy relative biological effectiveness) was performed successfully with the AS, and she also had the reproducing possibility due to prevention of severe irradiation damage of the right OA. AS eliminated the surgical removal of spacers and enabled us high-dose PBT for residual tumor without severe irradiation damage including infertility.

Association between mitochondrial and nuclear DNA damages and cellular senescence in the patients with biliary atresia undergoing Kasai portoenterostomy and liver transplantation.

Biliary atresia (BA) is a cholestatic disease with extrahepatic bile duct obstruction that requires early surgical intervention and occasionally liver transplantation (LT). Accumulation of toxic bile acids induces oxidative stress that results in cell damage, such as cell senescence, mitochondrial dysfunction and others. However, details of their reciprocal association and clinical significance are unexplored. Therefore, we used immuno-localization of markers for cell senescence (p16 and p21), nuclear double-strand DNA damage (γH2AX), autophagy (p62), and mtDNA damage (mtDNA copy number) in patients with BA who underwent Kasai portoenterostomy (KP) and LT. We studied liver biopsy specimens from 54 patients with BA, 14 who underwent LT and 11 from the livers of neonates and infants obtained at autopsy. In hepatocytes, p21 expression was significantly increased in KP. In cholangiocytes, p16 expression was significantly increased in LT, and p21 expression was significantly increased in KP. p62 expression was significantly increased in the KP hepatocytes and LT cholangiocytes. Furthermore, mtDNA copy number significantly decreased in KP and LT compared with the control. Cell senescence and mitochondrial DNA damage progression were dependent on the BA clinical stages and could possibly serve as the markers of indication of LT.

Necroptosis in Esophageal Squamous Cell Carcinoma: An Independent Prognostic Factor and Its Correlation with Tumor-Infiltrating Lymphocytes.

Necroptosis is a pivotal process in cancer biology; however, the clinical significance of necroptosis in esophageal squamous cell carcinoma (ESCC) has remained unknown. Therefore, in this study, we aimed to verify the potential involvement of necroptosis in the clinical outcome, chemotherapeutic resistance, and tumor microenvironment of ESCC. Mixed lineage kinase domain-like protein (MLKL) and phosphorylated MLKL (pMLKL) were immunohistochemically examined in 88 surgically resected specimens following neoadjuvant chemotherapy (NAC) and 53 pre-therapeutic biopsy specimens, respectively. Tumor-infiltrating lymphocytes (TILs) were also evaluated by immunolocalizing CD3, CD8, and forkhead box protein 3 (FOXP3) in the residual tumors after NAC. High pMLKL status in the post-NAC resected specimens was significantly correlated with worse prognosis in ESCC patients. Multivariate analysis demonstrated that a high pMLKL status was an independent prognostic factor. In pre-NAC biopsy specimens, a high pMLKL status was significantly associated with a lower therapeutic efficacy. CD8+ TILs were significantly lower in the high-pMLKL group. FOXP3+ TILs were significantly higher in both high-MLKL and high-pMLKL groups. We first demonstrated pMLKL status as an independent prognostic factor in ESCC patients. Our study revealed the possible involvement of necroptosis in the immunosuppressive microenvironment, resulting in the attenuated therapeutic efficacy of NAC and eventual adverse clinical outcomes in ESCC.

Intestinal Transplantation at a Single Institution in Japan.

BACKGROUND: This study aimed to compare the clinical outcomes of intestinal transplantation (ITX) between 2 groups by using medications for induction treatment and assess the utility of the current protocol. METHODS: From 2003 to 2020, 11 patients underwent ITX. Recipients were classified into 2 groups: group IL-2Ra (interleukin-2 receptor antagonist therapy, n = 6) and ATG (rabbit antithymocyte globulin therapy, n = 5). We conducted a retrospective review of patient and graft survival rates and the postoperative course. RESULTS: The 1-, 5-, and 10-year patient and graft survival rates of the 11 primary grafts in the 11 recipients were 100%, 88.9%, 62.2% and 90.0%, 78.8%, 56.3%, respectively. The median duration of follow-up for the IL-2Ra and ATG groups was 197.3 and 87.3 months, respectively. The 1-, 5-, and 10-year patient survival rates were 100%, 83.3%, 50% and 100%, 100%, 100% for the IL-2Ra and ATG groups, respectively (P = .25) and 83.3%, 66.7%, 33.3% and 100%, 100%, 100% for graft survival in the IL-2Ra and ATG groups, respectively (P = .08). The incidence of moderate and severe acute rejection was 100% and 20% in the IL-2Ra and ATG groups, respectively (P = .02). The 1- and 5-year moderate and severe rejection-free survival rates were 33.3%, 0% and 80%, 80% in the IL-2Ra and ATG groups, respectively (P = .04). CONCLUSIONS: ATG significantly suppressed moderate and severe acute rejection compared with IL-2Ra, thereby showing better short- and mid-term rejection-free survival rates. Additional clinical experience is needed to determine the optimal regimen for the management of ITX recipients.

Necroptosis in biliary atresia of the liver.

Biliary atresia (BA) is characterized by the occlusion of extrahepatic bile ducts due to sclerosing inflammation. Necroptosis is a recently characterized form of programmed cell death but has not been examined in BA. We, therefore, explored the potential involvement of necroptosis in the pathogenesis of BA by evaluating the correlation between necroptosis-related factors and clinicopathological features of BA patients. We studied liver biopsy specimens of 59 patients with BA and 30 with congenital biliary dilatation (CBD). We also evaluated 14 surgical BA cases, who eventually underwent liver transplantation and 9 normal liver from neonates and infants obtained at autopsy. Necroptosis-related factors including toll-like receptor 3 (TLR3), receptor-interacting protein kinase1 (RIP1), receptor-interacting protein kinase3 (RIP3), mixed lineage kinase domain-like (MLKL), and phosphorylated mixed lineage kinase domain-like (pMLKL) in these liver specimens were immunolocalized. TLR3, RIP1, MLKL in the intrahepatic cholangiocytes was significantly higher in BA than CBD. pMLKL immunoreactivity was significantly greater at an earlier age of BA patients. The native liver survival period was significantly prolonged in the high RIP3 group. The low RIP3 status could serve as an adverse clinical prognostic factor for the native liver survival among the necroptosis-related factors examined in this study.

Tumor necroptosis is correlated with a favorable immune cell signature and programmed death-ligand 1 expression in cholangiocarcinoma.

Necroptosis, a regulated form of necrosis, has emerged as a novel therapeutic strategy that could enhance cancer immunotherapy. However, its role in tumorigenesis is still debated because recent studies have reported both anti- and pro-tumoral effects. Here, we aimed to systematically evaluate the associations between tumor necroptosis (mixed lineage kinase domain-like protein, MLKL; phosphorylated MLKL, pMLKL; and receptor-interacting protein kinase 1-receptor-interacting protein kinase 3, RIPK1-RIPK3 interaction) and tumor-infiltrating immune cells (CD8+ and FOXp3+ T cells and CD163+ M2 macrophages) and tumor PD-L1 by immunohistochemistry in 88 cholangiocarcinoma (CCA) patients who had undergone surgical resection. Their associations with clinicopathological characteristics, survival data, and prognosis were evaluated. MLKL was found to be an unfavorable prognostic factor (p-value = 0.023, HR = 2.070) and was inversely correlated with a clinically favorable immune cell signature (high CD8+/high FOXp3+/low CD163+). Both pMLKL and RIPK1-RIPK3 interaction were detected in CCA primary tissues. In contrast to MLKL, pMLKL status was significantly positively correlated with a favorable immune signature (high CD8+/high FOXp3+/low CD163+) and PD-L1 expression. Patients with high pMLKL-positive staining were significantly associated with an increased abundance of CD8+ T cell intratumoral infiltration (p-value = 0.006). Patients with high pMLKL and PD-L1 expressions had a longer overall survival (OS). The results from in vitro experiments showed that necroptosis activation in an RMCCA-1 human CCA cell line selectively promoted proinflammatory cytokine and chemokine expression. Jurkat T cells stimulated with necroptotic RMCCA-1-derived conditioned medium promoted PD-L1 expression in RMCCA-1. Our findings demonstrated the differential associations of necroptosis activation (pMLKL) and MLKL with a clinically favorable immune signature and survival rates and highlighted a novel therapeutic possibility for combining a necroptosis-based therapeutic approach with immune checkpoint inhibitors for more efficient treatment of CCA patients.

Wearable Artificial Fingers With Skin Vibration and Multi-Axis Force Sensors.

Tactile sensations are based on stimulation elicited on the skin through mechanical interactions between the skin and an object. Hence, it is important to consider skin properties as well as objects. In this article, we aim to develop wearable artificial fingers for quantitative evaluations reflecting individual differences in human fingers. In a previous study, a wearable skin vibration sensor was attached to artificial fingers and it was demonstrated that the skin vibrations differed according to the dimension of surface ridge and the artificial finger is useful for roughness evaluation. This article improved the artificial finger to measure the contact force and friction in addition to the skin vibration. A small three-axis force sensor was embedded into the base of the finger, and normal and friction forces were estimated via a multi-regression method. Furthermore, artificial fingers with different hardness were prepared and six different textures were used to investigate tactile evaluation. Experimental results showed that the artificial fingers could measure normal and friction forces along with the skin vibration and were useful to evaluate textures. Resulting distributions of the vibration intensity and friction coefficient were different for the soft and hard artificial fingers, indicating the complex influence of skin properties on tactile sensations.

Size of pelvic bone metastasis as a significant prognostic factor for metastatic prostate cancer patients.

INTRODUCTION: To investigate the potential prognostic value of image analysis of pelvic bone metastasis in newly diagnosed prostate cancer patients. METHODS: Data from 69 patients with both bone scintigraphy and pelvic CT images were selected for this analysis. Open source software (3D Slicer version 4.8.1.) was used for image analysis. Metastatic pelvic bone lesions were manually contoured, and radiomic features were extracted. As risk factors for overall survival (OS) and cause-specific survival (CSS), 105 radiomic features and clinical risk factors including age, initial prostate-specific antigen, Gleason score, TNM stage, lactate dehydrogenase (LDH), hemoglobin (Hb), alkaline phosphatase, extent of disease, visceral metastases, and radiotherapy were assessed by uni- and multivariate analyses. RESULTS: Median follow-up was 41 months (range 0-157 months). Five-year overall survival and cause-specific survival rate were 37.9% and 43.5%, respectively. After multivariate analysis, LDH, Hb, and "maximum 2D diameter" defined as maximum tumor size in the axial plane were detected as risk factors for OS. Gleason sum, LDH, and maximum 2D diameter were detected as risk factors for CSS. CONCLUSION: Maximum 2D diameter was detected as a significant prognostic factor for metastatic prostate cancer patients.

Correctable biliary atresia and cholangiocarcinoma: a case report of a 63-year-old patient.

BACKGROUND: Although cancer occurrence following surgery for biliary atresia has gradually increased, the development of cholangiocarcinoma in a native liver survivor of biliary atresia is extremely rare. CASE PRESENTATION: A 3-month-old female patient with the correctable type of biliary atresia underwent a cystoduodenostomy. At 16 years of age, she underwent multiple surgeries including lysis of intestinal adhesions, ileostomy, and gastrojejunostomy at another hospital. At 54 years of age, she underwent lithotomy at the porta hepatis, resection of the residual cystic bile duct with gallbladder, and hepaticojejunostomy in Roux-en-Y fashion. As she approached the age of 63, her computed tomography scan showed no liver tumors. In the following year, she developed cholangiocarcinoma at the porta hepatis and underwent chemotherapy. However, the cancer progressed, and she died before she reached the age of 64 years. CONCLUSIONS: Cholangiocarcinoma is extremely rare in patients with biliary atresia. However, physicians should follow up patients with biliary atresia as closely as possible, as malignant tumors secondary to biliary atresia may increase in number in the near future because of the growing number of long-term survivors with biliary atresia.

Does antithrombotic therapy improve survival with colorectal cancer?

BACKGROUND: The study aimed to evaluate the prognosis for patients with colorectal cancer who underwent surgery while receiving antithrombotic therapy (ATT) across all disease stages and for patients at disease stages 0-III. METHODS: This retrospective cohort study included 710 Japanese patients who underwent surgery for colorectal cancer between January 2009 and November 2015 at our institution. Approximately 35% of these patients received ATT. Of these, 199 (28.0%) received antiplatelet therapy, and 76 (10.7%) received anticoagulant therapy. We investigated the prognosis among patients with colorectal cancer receiving ATT, antiplatelet therapy, or anticoagulant therapy in all-stage and stage 0-III cancers. RESULTS: For all disease stages combined, no benefit was observed for ATT, antiplatelet therapy, and anticoagulant therapy groups in the overall survival rates (ATT: 87.8 vs. 78.4%, P = 0.23; antiplatelet therapy: 87.8 vs. 78.6%, P = 0.25; and anticoagulant therapy: 92.2 vs. 80.2%, P = 0.26). However, overall survival rates of patients with stage 0-III colorectal cancer undergoing ATT, antiplatelet therapy, and anticoagulant therapy significantly improved. (ATT: 98.5 vs. 92.7%, P = 0.01; antiplatelet therapy: 98.3 vs. 91.1%, P = 0.02; and anticoagulant therapy: 100 vs. 92.1%, P = 0.00). CONCLUSION: Receiving ATT significantly improves overall survival rates in patients with stage 0-III colorectal cancer.

Association between antithrombotic therapy and risk of postoperative complications among patients undergoing endovenous laser ablation.

BACKGROUND: The aim of the study was to evaluate the clinical results and postoperative complications, especially recanalization or bleeding complications, in patients with saphenous varicose veins undergoing endovenous laser ablation (EVLA) while receiving antithrombotic therapy (ATT). METHODS: This retrospective cohort study included 1136 Japanese patients undergoing EVLA with a 980-nm diode laser between January 2012 and November 2015 at our institution. The patients were divided into two groups: ATT users (ATT group) and nonusers (control group). The ATT group was further divided into two subgroups according to whether the patients received antiplatelet or anticoagulant therapy. Clinical outcomes and postoperative complications among these patients were assessed. RESULTS: Approximately 20% of the patients undergoing surgery for saphenous varicose veins at our institution received ATT. Of these, 141 (12.4%) received antiplatelet therapy and 95 (8.4%) received anticoagulant therapy. Successful occlusion of the full length of the treated vein was achieved in 99.9% of the patients; there were no severe perioperative complications. Endovenous heat-induced thrombosis occurred in 2.4% of patients, whereas postoperative complications developed in 1.2% of patients. One patient experienced recanalization (0.08%). There were no significant between-group differences in the incidence of recanalization and postoperative complications on univariate analysis. CONCLUSIONS: The clinical outcomes and postoperative complications of EVLA in the ATT group were equivalent to those in the control group, indicating that EVLA can be safely performed in patients receiving ATT.

Acute and late complications after hypofractionated intensity modulated radiotherapy in prostate cancer.

PURPOSE: The present study compared the complications associated with hypofractionated intensity-modulated radiation therapy (Hypo-IMRT) of prostate cancer to conventionally fractionated IMRT (Conv-IMRT). MATERIALS AND METHODS: Hypo-IMRT delivered 70 Gy in 28 fractions, whereas Conv-IMRT delivered 78 Gy in 39 fractions. Toxicity was graded with the Common Terminology Criteria for Adverse Events, version 4.0, weekly during radiotherapy, 1 month after radiotherapy, and annually in both patient groups. RESULTS: The median follow-ups were 39.1 and 38.7 months for patients in the Hypo- and Conv-IMRT groups, respectively. There was no significant difference in rates of acute and late adverse events. The proportions of grade 2 acute genitourinary complications were 48.4 and 51.2% in the Hypo- and Conv-IMRT groups, respectively. The presence of a baseline International Prostate Symptom Score (IPSS) of ten or more was the only significant prognostic factor for grade 2 acute genitourinary toxicity. The incidence of grade 2 late rectal hemorrhage at 3 years was 3.2 and 3.5% in the Hypo- and Conv-IMRT groups, respectively. Small rectal volume was significantly associated with grade 2 late rectal hemorrhage. CONCLUSION: Regarding acute and late adverse events, hypofractionated IMRT for prostate cancer was well tolerated and comparable with conventionally fractionated IMRT. Clinical trial registration no. UMIN000003218.

Adjuvant Chemotherapy with S-1 plus Cisplatin for Patients with Stage III Gastric Cancer After Curative Resection.

BACKGROUND/AIM: The aim of this study was to investigate the efficacy and safety of S-1 plus low-dose cisplatin for stage IIIB and stage IIIC gastric cancer patients after D2 gastrectomy. PATIENTS AND METHODS: The study group comprised of 52 patients. In the first cycle, S-1 (80 mg/m2) was administered daily for 3 weeks, followed by 2 weeks of rest; low-dose cisplatin (10 mg) was administered on days 1-5 and 8-12. In the second and third cycles, S-1 was administered alone. RESULTS: Overall survival was 47.0 months for stage IIIB patients and 24.0 months for stage IIIC (p=0.038). Disease-free survival was 17.0 and 16.0 months respectively (p=0.739). Grade 3 or 4 adverse events occurred in 20 patients (38.5%). Multivariate analysis identified stage IIIC as independent prognostic factor for survival. CONCLUSION: Our treatment was manageable and safe for stage IIIB or stage IIIC patients. Stage IIIC gastric cancer portends an especially poor prognosis following D2 gastrectomy.

Associations between antithrombotic therapy and the risk of perioperative complications among patients undergoing laparoscopic gastrectomy.

BACKGROUND: The aim of this study was to identify factors associated with perioperative morbidity among patients who underwent laparoscopic gastrectomy while receiving antithrombotic therapy (ATT). PATIENTS AND METHOD: This retrospective cohort study included 46 patients (14 females and 32 males) who underwent laparoscopic gastrectomy, including 12 (26.1 %) who received perioperative ATT, between January 2012 and November 2015 in our institution. Among patients receiving only aspirin as antiplatelet therapy, none were on anticoagulation therapy. All patients took aspirin as antiplatelet therapy for cardiac indications. The clinical findings and surgical outcomes of patients who did (ATT group) and did not (control group) receive ATT were compared. RESULTS: The intraoperative mortality was 0 % for both groups. There was no significant difference in the incidence of postoperative morbidity by univariate analysis between the control and ATT groups (8.8 vs. 8.3 %, p = 0.39). CONCLUSION: The risk of postoperative morbidity of laparoscopic gastrectomy can be equivalent between the ATT and non-ATT (control) groups.

Treatment of Chilaiditi syndrome using laparoscopic surgery.

Chilaiditi syndrome is defined as the interposition of the bowel between the liver and right diaphragm. It is a rare disease and may be difficult to diagnose and manage. Treatment for asymptomatic patients with Chilaiditi is usually conservative and does not require surgical intervention, but surgery may be necessary if conservative treatment fails. This report describes a rare case of Chilaiditi syndrome causing small bowel obstruction and corrected using laparoscopic surgery.

Postpancreatectomy Hemorrhage After Pancreatic Surgery in Patients Receiving Anticoagulation or Antiplatelet Agents.

Background Postpancreatectomy hemorrhage (PPH) is a serious complication after pancreatic surgery. In this study, we evaluated PPH and thromboembolic complications after pancreatic surgery in patients with perioperative antithrombotic treatment. Methods Medical records of patients undergoing pancreatic surgery were reviewed retrospectively. Patients receiving thromboprophylaxis were given either bridging therapy with unfractionated heparin or continued on aspirin as perioperative antithrombotic treatment according to clinical indications and published recommendations. The International Study Group of Pancreatic Surgery definition of PPH was used. Risk factors associated with PPH were assessed by multivariate analysis. Results Thirty-four of 158 patients received perioperative antithrombotic treatment; this group had a significantly higher PPH rate (29.4% vs 6.5%, P = .001) and mortality (11.8% vs 2.4%, P = .039) than patients not receiving thromboprophylaxis. Multivariate analysis revealed that perioperative antithrombotic treatment was the only independent risk factor for PPH after pancreatic surgery (odds ratio 4.77; 95% CI 1.61-14.15; P = .005). Conclusions Perioperative antithrombotic treatment is an independent risk factor for PPH in patients undergoing pancreatic surgery, although this treatment effectively prevents postoperative thromboembolic events.

[Optimal parameter decision method in VMAT for lung tumors with respiratory motions].

When performing lung cancer treatments using volumetric modulated arc therapy (VMAT) technique, dose error related to respiratory motion of tumors and multi leaf collimator (MLC) movement may occur. The dose error causes daily dose variation in multiple fractionations irradiation. The purpose of this study is to verify the influence of the respiratory motion and the MLC movement on the daily dose variation, and to confirm the feasibility of deciding robust planning parameter against the dose variation. We prepared 5 VMAT plans for imitating lung tumor in thorax dynamic phantom. Dose calculations of these plans were done taking into account the respiratory motions. We examined the relation between dose variation and two parameters that were number of respiration in an arc and MLC gap width. We presented the relationship between the dose variation and each parameters using regression analysis, and we could derive the approximation formula for estimating the dose variation using these parameters. We could estimate dose variation in another VMAT plans using the approximation formula and another plans parameters. By confirming dose variation in planning procedure using this estimation method, we may decide planning parameter taking the dose variation into account. So, we could establish the estimation method to decide adequate planning parameters in VMAT.