Determining a methodology of dosimetric quality assurance for commercially available accelerator-based boron neutron capture therapy system

The irradiation field of boron neutron capture therapy (BNCT) consists of multiple dose components including thermal, epithermal and fast neutron, and gamma. The objective of this work was to establish a methodology of dosimetric quality assurance (QA), using the most standard and reliable measurement methods, and to determine tolerance level for each QA measurement for a commercially available accelerator-based BNCT system. In order to establish a system of dosimetric QA suitable for BNCT, the following steps were taken. First, standard measurement points based on tissue-administered doses in BNCT for brain tumors were defined, and clinical tolerances of dosimetric QA measurements were derived from the contribution to total tissue relative biological effectiveness factor-weighted dose for each dose component. Next, a QA program was proposed based on TG-142 and TG-198, and confirmed that it could be assessed whether constancy of each dose component was assured within the limits of tolerances or not by measurements of the proposed QA program. Finally, the validity of the BNCT QA program as an evaluation system was confirmed in a demonstration experiment for long-term measurement over 1 year. These results offer an easy, reliable QA method that is clinically applicable with dosimetric validity for the mixed irradiation field of accelerator-based BNCT.     

Herbimycin A Suppresses the Reduction of Gap-junctional Intercellular Communication Induced by Tumor-promoting Phorbol Ester in 3T3-L1 Cells

We have examined the suppressive effect of herbimycin A on the reduction of gap-junctional Intercellular communication that is induced by a tumor-promoting phorbol ester in 3T3-L1 cells. Most cells in growth arrest participated in dye-coupling, as evaluated by the transfer between cells of a fluorescent dye (Lucifer Yellow CH). Treatment of cells with 0.25 μg/ml herbimycin A slightly enhanced the dye-coupling. This enhancement required treatment for periods as long as 24 h. Addition of 100 ng/ml 12-O-tetradecanoylphorbol-13-acetate (TPA) caused a rapid reduction of dye-coupling. However, addition of TPA did not suppress dye-coupling in cells pretreated for more than 24 h with herbimycin A. Pretreatment of cells for less than 6 h with herbimycin A did not suppress the TPA-induced reduction of dye-coupling. These results suggest that herbimycin A suppresses the reduction of gap-junctional intercellular communication that is induced by TPA through enhancement of the ability of the cells to participate in gap-junctional intercellular communication     

Predictive factors for surgical complications of laparoscopy-assisted distal gastrectomy for gastric cancer

Background  Some studies have found high incidences of intraoperative and postoperative complications for patients with gastric cancer. To determine the predictive factors for the surgical complications of laparoscopic gastric surgery, surgical outcomes were evaluated. Methods  Between April 2002 and December 2007, 152 patients with preoperatively diagnosed early gastric cancer who underwent laparoscopy-assisted distal gastrectomy (LADG) were enrolled. Visceral (VFA) and subcutaneous fat areas (SFA) were assessed by Fat Scan software. The predictive factors for surgical complications of LADG were evaluated by univariate and logistic regression analyses. Results  Of 152 patients, conversion to open surgery due to uncontrollable bleeding was observed in nine male patients, and postoperative complications were detected in seven male and one female patient (four anastomotic leakage, two intraabdominal abscess, one pancreatic fistula, and one lymphorrhea). High body mass index (BMI) and high VFA independently predicted conversion to open surgery and postoperative complications. VFA was significantly higher, operation time was longer, blood loss was greater, and SFA was lower in male than in female patients, whereas no significant difference was observed in BMI between male and female patients. Conclusions  High BMI and high VFA can predict technical difficulties during laparoscopic gastric surgery and postoperative complications. Particularly, LADG should be performed cautiously to prevent surgical complications for male patients with high VFA. Predictive impact of VFA should be further determined in a larger set of patients.     

An Anatomical Study of a Muscle Bundle Separated from the Medial Pterygoid Muscle

When mandibular dentures are fabricated, marginal sealing should be taken into consideration for the stability of the denture. We selected specimens of the medial pterygoid muscle showing insertion of an independent small muscle bundle at its insertion site, and evaluated the anatomical relationship between the morphology of the insertion site and the denture. The insertion of the pterygoid muscle was classified according to the insertion morphology of the independent small muscle bundle into three types using the retromolar pad as a reference: Type I, insertion of the independent muscle bundle posterior to the retromolar pad; Type II, insertion immediately below the retromolar pad; and Type III, insertion into the fascia of the mylohyoid muscle. Types II and III muscles seem to affect the denture because of their closeness to the mandibular denture. In the oral cavity, the independent small muscle bundle studied appeared as a streak-like structure. When such a structure is detected during examination for denture fabrication, the following consideration is necessary. Since the medial pterygoid muscle is a mouth-closing muscle, this independent small muscle bundle may contract during mouth closing, appearing more markedly in the oral cavity. Therefore, examination should be performed not only with the mouth closed but also with assumed centric occlusion.     

Comparison of Pentax-AWS Airwayscope, Airtraq and Miller laryngoscope for tracheal intubation by novice doctors during infant cardiopulmonary resuscitation simulation: a randomized crossover trial

Recent guidelines for infant cardiopulmonary resuscitation emphasize that all rescuers should minimize interruption of chest compressions, even for endotracheal intubation. We compared the utility of the Pentax-AWS Airway Scope (AWS) with an infant-sized Intlock (AWS-I), Airtraq laryngoscope (ATQ) and Miller laryngoscope during chest compressions on an infant manikin. Twenty-three novice doctors performed tracheal intubation on an infant manikin using the AWS-I, ATQ and Miller laryngoscope, with or without chest compressions. In Miller laryngoscope trials, one participant failed to secure the airway without chest compressions, while nine failed with compressions (P < 0.05). In ATQ trials, none of the participants failed without compressions, while six failed with compressions (P < 0.05). In AWS-I trials, all participants succeeded regardless of chest compressions. Intubation time was significantly longer with chest compressions with the Miller laryngoscope and ATQ, but not with the AWS-I. The AWS-I is an effective device for endotracheal intubation during chest compressions in infant simulations managed by novice doctors.