Contrasting seasonality of the incidence of incisional surgical site infection after general and gastroenterological surgery: an analysis of 8436 patients in a single institute.

BACKGROUND: While seasonality of hospital-acquired infections, including incisional SSI after orthopaedic surgery, is recognized, the seasonality of incisional SSI after general and gastroenterological surgeries remains unclear. AIM: To analyse the seasonality and risk factors of incisional SSI after general and gastroenterological surgeries. METHODS: This was a retrospective, single-institute, observational study using univariate and multivariate analyses. The evaluated variables included age, sex, surgical approach, surgical urgency, operation time, wound classification, and the American Society of Anesthesiologists physical status (ASA-PS). FINDINGS: A total of 8436 patients were enrolled. General surgeries (N = 2241) showed a pronounced SSI incidence in summer (3.9%; odds ratio (OR): 1.87; 95% confidence interval (CI): 1.05-3.27; P = 0.025) compared to other seasons (2.1%). Conversely, gastroenterological surgeries (N = 6195) showed a higher incidence in winter (8.3%; OR: 1.38; 95% CI: 1.10-1.73; P = 0.005) than in other seasons (6.1%). Summer for general surgery (OR: 1.90; 95% CI: 1.12-3.24; P = 0.018) and winter for gastroenterological surgery (1.46; 1.17-1.82; P = 0.001) emerged as independent risk factors for incisional SSI. Open surgery (OR: 2.72; 95% CI: 1.73-4.29; P < 0.001) and an ASA-PS score ≥3 (1.64; 1.08-2.50; P = 0.021) were independent risk factors for incisional SSI in patients undergoing gastroenterological surgery during winter. CONCLUSION: Seasonality exists in the incisional SSI incidence following general and gastroenterological surgeries. Recognizing these trends may help enhance preventive strategies, highlighting the elevated risk in summer for general surgery and in winter for gastroenterological surgery.

Accurate gamma-ray dose measurement up to 10 MeV by glass dosimeter with a sensitivity control filter for BNCT.

Glass dosimeters are very useful and convenient detection elements in radiation dosimetry. In this study, this glass dosimeter was applied to a BNCT treatment field. Boron Neutron Capture Therapy (BNCT) is a next-generation radiation therapy that can selectively kill only cancer cells. In the BNCT treatment field, both neutrons and secondary gamma-rays are generated. In other words, it is a mixed radiation field of neutrons and gamma-rays. We thus proposed a novel method to measure only gamma-ray dose in the mixed field using two RPLGD (Radiophoto-luminescence Glass Dosimeter) and two sensitivity control filters in order to control the dose response of the filtered RPLGD to be proportional to the air kerma coefficients, even if the gamma-ray energy spectrum is unknown. As the filter material iron was selected, and it was finally confirmed that reproduction of the air kerma coefficients was excellent within an error of 5.3% in the entire energy range up to 10 MeV. In order to validate this method, irradiation experiments were carried out using standard gamma-ray sources. As the result, the measured doses were in acceptably good agreement with the theoretical calculation results by PHITS. In the irradiation experiment with a volume source in a nuclear fuel storage room, the measured dose rates showed larger compared with survey meter values. In conclusion, the results of the standard sources showed the feasibility of this method, however for the volume source the dependence of the gamma-ray incident angle on the dosimeter was found to be not neglected. In the next step, it will be necessary to design a thinner filter in order to suppress the effect of the incident angle.

Experimental study on Compton camera for boron neutron capture therapy applications.

Boron neutron capture therapy (BNCT) is a high-dose-intensive radiation therapy that has gained popularity due to advancements in accelerator neutron sources. To determine the dose for BNCT, it is necessary to know the difficult-to-determine boron concentration and neutron fluence. To estimate this dose, we propose a method of measuring the prompt γ-rays (PGs) from the boron neutron capture reaction (BNCR) using a Compton camera. We performed a fundamental experiment to verify basic imaging performance and the ability to discern the PGs from 511 keV annihilation γ-rays. A Si/CdTe Compton camera was used to image the BNCR and showed an energy peak of 478 keV PGs, separate from the annihilation γ-ray peak. The Compton camera could visualize the boron target with low neutron intensity and high boron concentration. This study experimentally confirms the ability of Si/CdTe Compton cameras to image BNCRs.