This retrospective study investigates dose estimation in computed tomography pulmonary angiography (CTPA) by analyzing 200 examinations from 96 male and 104 female patients. Two size-specific dose estimation (SSDE) methods were evaluated: one based on effective diameter (SSDEDeff) and the other on water-equivalent diameter (SSDEDw). The effective diameter (Deff) was manually measured using the lateral (LAT) and anteroposterior (AP) dimensions, while the water-equivalent diameter (Dw) was calculated from the region of interest (ROI) using mean Hounsfield Unit (HU) values and cross-sectional area. SSDE calculations were compared to the conventional CT dose metric, CTDIvol, to assess its underestimation relative to SSDEDw. The findings revealed a dose underestimation of up to 18% for CTDIvol compared to SSDEDw, particularly for patients with larger body habitus. SSDEDeff consistently overestimated the dose by 7.73% compared to SSDEDw, as Deff relied only on external dimensions while Dw considered tissue attenuation for a more individualized dose assessment. High correlations were observed between lateral diameter (dLAT) and both Deff (R2 = 0.9175) and Dw (R2 = 0.7578). However, the systematic overestimation by SSDEDeff emphasizes the importance of clearly specifying the metric used for SSDE, as differences can influence reported doses by 5-10%, affecting clinical dose monitoring and adherence to diagnostic reference levels. This study highlights the limitations of CTDIvol and SSDEDeff compared to SSDEDw, especially in regions with heterogeneous tissue. The results support the use of individualized radiation dose assessments to improve radiation safety, particularly in CTPA, which has seen increased application during the COVID-19 pandemic.

The aim of the current study is to propose an algorithm for the automated calculation of water-equivalent diameter (Dw) and size-specific dose estimate (SSDE) from clinical computed tomography (CT) images in head protocol context, a python-based algorithm was developed in order to execute an interface to read DICOM images and compute the mentioned metrics. All CT datasets were retrospectively acquired by the Siemens emotion 16 CT scanner. The algorithm developed in this study presents a novel approach for preprocessing and analyzing DICOM images obtained from head CT scans. Exploiting a custom Python script, the preprocessing pipeline begins with the conversion of pixel values to Hounsfield Units (HU) to ensure quantitative analysis accuracy. Subsequently, Gaussian filtering reduced noise while preserving essential features, followed by thresholding using Otsu's method for head region segmentation. Morphological operations refined the binary mask, which enhanced the method for contour detection via active contours. The outcome of this procedure is an accurate measurement of the head size metrics, including lateral (LAT) and anteroposterior (AP) dimensions, effective diameter (Deff), and water equivalent diameter (Dw). Statistical analyses are performed to derive mean statistics and compute SSDE using a conversion factor derived from Dw. Validation of the proposed algorithm used images of patients who had undergone head examination in a major pediatric university hospital. The proposed algorithm was compared to IndoseCT v20b for Dw and SSDE calculations. The Dw values from HeadCTDosi were strongly correlated to those of IndoseCT by R2=0.97 and the SSDE values also presented high correlation of R2=0.93. This study presents an improved algorithm for calculating Dw and SSDE in the context of head CT, which notably can outperform the manual, subjective, and time-consuming process of contouring the head region, positioning it as a potentially essential tool for routine clinical dose monitoring.

This study develops novel brain-equivalent materials for radiation dosimetry using epoxy resin combined with sodium bicarbonate or acetone as fillers. The composites, cured for homogeneous filler distribution, were analyzed for attenuation properties and evaluated via Monte Carlo simulations using the GATE toolkit. At 10 keV, mass attenuation coefficients were 2.82 +/- 0.03 cm(2)/g (resin-acetone) and 3.16 +/- 0.01 cm(2)/g (resin-sodium bicarbonate), closely matching brain tissue. At 150 keV, all values converged to similar to 0.15 +/- 0.01 cm(2)/g. CT numbers ranged from 39.3 +/- 1.7 HU to 59.5 +/- 1.8 HU (80-120 kVp), aligning with brain tissue properties. These materials enhance dosimetry and imaging in diagnostic radiology where human tissue substitutes are impractical.

This study investigates the photon-shielding properties of novel tellurite-based glass compositions over a broad energy spectrum (0.015-15 MeV). Three glass samples (S1, S2 and S3) with varying concentrations of TeO2, Bi2O3, WO3, La2O3 and Gd2O3 were analyzed using Phy-X/PSD software and Gate/Geant4 simulations. Key radiation attenuation parameters, including mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), transmission factor (TF), effective atomic number (Zeff), effective electron density (Neff), and buildup factors, were evaluated. The comprehensive analysis reveals a critical interplay between compositional design and radiation attenuation mechanisms. Sample S3 emerges as a standout composition, demonstrating superior photon shielding capabilities through a synergistic combination of high-Z elements. The sample's exceptional performance is evidenced by its highest Zeff, ranging from 65 to 73 across the energy spectrum, directly correlating with enhanced photoelectric absorption and Compton scattering efficiency. The elemental configuration of S3 orchestrates its remarkable radiation attenuation capabilities. At lower energies (0.015-1 MeV), the sample exhibits peak MAC values, primarily attributed to the high photoelectric absorption of Bi2O3 and WO3. As energy increases, the composition maintains impressive attenuation through a balanced mechanism of Compton scattering and pair production, facilitated by incorporating La2O3 and Gd2O3. Buildup factor analysis provides critical insights into the material's radiation absorption capacity. S3 demonstrates the lowest buildup factor across the analyzed MFPs, indicating superior photon absorption capacity. The TF calculations further validate the material's shielding effectiveness, showing minimal photon transmission across various thicknesses and energies. The study provides comprehensive insights into the radiation attenuation capabilities of doped tellurite glasses, positioning them as promising candidates for radiation shielding in nuclear facilities, medical centers, and research institutions.

Pediatric head computed tomography (CT) scans necessitate precise determination of radiation dose to optimize image quality while minimizing patient exposure. This study explores the influence of head size variation on radiation dose and image quality using phantom and patients set, aiming to investigate the efficacy of Automatic Exposure Control (AEC) in dose modulation. Image noise and radiation dose were assessed using with and without AEC, maintaining a constant tube current of 180 mA. The correlation between CT dose index volume (CTDIvol) and water-equivalent diameter (Dw) was examined across 134 image sets, revealing an exponential relationship indicative of AEC's contribution to elevated radiation exposure in larger heads. Furthermore, a slice-based analysis demonstrated a consistent variation in tube current along the slice location, effectively modulated by Dw. However, discrepancies in tube current were observed in the caudal region, suggesting the influence of factors beyond section size. Refinement of analysis improved curve fitting, highlighting the importance of section size in dose modulation. AEC proved essential in maintaining image quality consistency across slices, with inactive AEC resulting in lower image noise in cranial slices. These findings highlight the significance of AEC-based dose modulation in pediatric head CT to ensure optimal image quality while minimizing radiation exposure, emphasizing the need for comprehensive understanding and implementation of AEC systems from different manufacturers.

This study investigates the applicability of cost-effective and commercially available polyester and epoxy resins as alternative materials for polymethyl methacrylate (PMMA) in computed tomography (CT) dosimetry phantoms. The mass attenuation coefficients (mu/rho) of the resin samples were determined using the GEANT4/GATE simulation framework and compared with those of PMMA material over a spectrum of diagnostic photon energies from 10 to 150 keV. A CT scanner was used to acquire the mean attenuation values (CT number) of the fabricated samples at 80,100,120 and 140 kVp CT tube energy. The study found that the resins have similar physical properties and dosimetry behavior to PMMA at all energies. Polyester has a negligible 1% deviational variance in mass attenuation from PMMA. Epoxy demonstrates substantially elevated mass attenuation coefficients compared to PMMA at inferior photon energies between 10 and 40 Kvp. However, with ascending photon energy, the mass attenuation coefficients of epoxy resin and PMMA become more homologous, ultimately converging indistinguishably at 100 Kvp. The CT number results showed that polyester has a 3% difference from PMMA. Moreover, the epoxy resin's CT numbers were within 18HU of PMMA material. These findings demonstrate the feasibility of using low-cost, readily available resin composites such as polyester and epoxy resins as a substitute material for CT dosimetry phantom in computed tomography.

This study aims to establish comprehensive relationships between patient size, focusing on effective diameter (Deff) and water-equivalent diameter (Dw), in conjunction with anterior-posterior (AP) and lateral (LAT) dimensions. The primary goal is to refine precise patient dose estimations in pediatric head computed tomography (CT) examinations. Our examination involved a dataset of 105 pediatric head CT images sourced from a Moroccan pediatric university hospital. These images, selected from the central scanning range, underwent quantification for LAT, AP, Deff, and Dw, with measurements carried out using RadiAnt Dicom Viewer for lateral and anteroposterior dimensions. Our analytical approach encompassed modeling Deff and Dw as functions of LAT, AP, and combined AP + LAT dimensions. Additionally, Dw was modeled as a function of Deff and calculated Size Specific Dose Estimates (SSDE) based on Dw was compared to SSDE computed from one single dimension. The outcomes revealed strong correlations among Deff, Dw, and fundamental geometric dimensions (LAT, AP, and AP + LAT), as indicated by consistently high coefficients of determination ( R superset of 2 > 0.8). SSDE calculated from Dw shows impressive correlation with SSDE computed from a single dimension ( R superset of 2 > 0.9). This study offers insights into the relationships between patient size and critical dimensions, identifying high correlations that can represent a significant advancement in predicting doses for pediatric head CT examinations. This introduces the potential for streamlining the determination of head diameter and dose by relying on a single dimension, thereby enhancing the efficiency of dose predictions by facilitating the monitoring of radiation exposure of this population in clinical routine.

This study examined radiation exposure from CT scans performed on 500 adult COVID-19 patients at two major university hospitals in Morocco. A robust correlation (r = 0.82) was found between patient size and Size-Specific Dose Estimate (SSDE), which ranged from 10.11 to 17.87 mGy. The mean CTDIvol was 6.7 mGy, contrasting markedly with the mean SSDE of 12.81 mGy. This highlights a substantial difference, with the SSDE-to-CTDIvol ratio being approximately 1.91. Notably, the SSDE was nearly twice as high as the CTDIvol, underscoring the vulnerability of obese COVID-19 patients. Evaluation of different CT scanner models showed higher radiation doses associated with the Siemens Somaton Emotion 16 compared to the GE Optima CT520 Series, emphasizing the need to account for scanner-specific factors in dose optimization protocols. A comparison of chest CT reference doses (DRL) from this study with international data showed a lower mean CTDIvol here (6.7 mGy) than reported in other countries. However, the DRL in terms of DLP is in the same range or lower as compared to others. Using the BEIR VII model, the lifetime attributable risk (LAR) of cancer from COVID-19 chest CTs was estimated. Elevated risks of lung cancer in both genders and increased breast cancer risk in females were projected, albeit with limitations regarding overestimated cancer incidence. The high effective dose values, approaching 15.3 mSv, underscore the need for dose optimization, especially in obese COVID-19 patients receiving chest CTs.

This review systematically examines the optimization of radiological imaging protocols and practices from December 2023 to April 2024. Through a rigorous selection process, 97 relevant articles and reports were identified from databases like PubMed, Scopus, and Web of Science. Screening of titles and abstracts, followed by a thorough evaluation of full-text articles meeting inclusion criteria, yielded 63 studies for qualitative analysis. Advancements in digital radiography, mammography, fluoroscopy, and interventional radiology have reshaped imaging techniques. Traditional methods, augmented by digital tools and algorithms, optimize imaging while minimizing radiation exposure. Innovations such as ultra-low-dose imaging in mammography aim to enhance cancer detection with reduced radiation. Optimization in fluoroscopy and interventional radiology involves a nuanced approach, considering both equipment protocols and operator behavior. Collaboration between medical physicists and optimization teams aligns protocols with equipment functionality. ISO-defined quality management principles guide the establishment of quality in radiology departments through components like quality control and assurance. Dosimetry monitors equipment performance and estimates individualized radiation risks, ensuring patient safety. Performance indicators help in assessing departmental performance, with medical physicists driving their development and monitoring. Collaborative initiatives and emerging technologies, including artificial intelligence and theranostics, underscore the ongoing journey of dose optimization in radiology. These strategies will shape the future of radiological imaging, enabling personalized patient care and advancing our understanding of health and disease.

Background : Computed tomography (CT) scans have become an essential diagnostic tool, but they carry significant risks due to the exposure of patients to ionizing radiation. Therefore, healthcare professionals have a responsibility to optimize radiation dose and image quality simultaneously. One factor that significantly affects the quality of images and radiation dose is the bowtie filter used in CT systems, which homogenizes and shapes the X-ray spectrum. However, its characteristic shape, specific to each manufacturer makes it impossible to model it from only the information in the technical note alone. Materials and Methods: This study presents a novel methodology using optically stimulated luminescence (OSLD) nanodots to determine the body bowtie filter shape in a Siemens SOMATOM EMOTION 16 -slice CT. The accuracy of the body bowtie filter shape generated by OSLD was validated by performing Monte Carlo simulations of CT scans. Results: The difference between simulated and measured CTDIw values for the PET/CT Siemens at 80, 110 and 130 kVp were 4.02%, 7.74%, and 4.81%, respectively. Conclusion: In this work, it has been demonstrated that the use of OSLD nanodots allows for the determination of the shape of bowtie filters in CT scans with acceptable accuracy. This work has the potential to address a significant gap in the modeling of bowtie filters, which could significantly improve the optimization of radiation dose and image quality in CT scans.

Accurate dose estimation in computed tomography (CT) scans is crucial and relies on precise normalization of output dose, typically measured by the volume CT dose index (CTDIvol). Key metrics, including effective diameter (Deff) and water-equivalent diameter (Dw), play pivotal roles in characterizing patient size. However, a notable gap exists in delineating the specific relationships between age and head patient size (Deff and Dw) for pediatric patients in Morocco. The primary objective of this study was to establish these critical associations between patient age and head patient size (Deff and Dw), providing a foundation for calculating size-specific dose estimates (SSDE) in pediatric head CT examinations. A retrospective analysis of data from 134 pediatric patients, aged 0-13 yr, comprising 71 males and 63 females who underwent head CT scans, was conducted. Utilizing the Radiant DICOM Viewer, patient sizes were measured in terms of both lateral and anterior-posterior dimensions for Deff and Dw calculations based on CT images in DICOM format. Our analysis revealed robust correlations between patient size (Deff and Dw) and the patient's age, with R2 values ranging from 0.65 to 0.86. Notably, larger Dw values were consistently observed compared to Deff. For male patients, Deff measurements ranged from 9.02 to 18.77 cm, with Dw values spanning 9.83 to 20.16 cm. Female patients exhibited Deff values ranging from 8.77 to 17.41 cm and Dw values ranging from 8.92 to 18.37 cm. These findings shed light on the crucial relationship between age and patient size, facilitating more precise dose calculations.

The objective of this investigation was to assess the computed tomography dose index (CTDI) for various tube potentials utilizing epoxy and polyester-resin phantoms, and compare the results to those obtained from a standard polymethyl methacrylate (PMMA) phantom, employing the GEANT4/GATE simulation framework. Three cylindrical phantoms with a diameter of 32 cm were simulated from epoxy resin, polyester resin and PMMA. The phantoms were analyzed for their atomic composition, effective atomic number, electron density, and mass density. The weighted CTDI (CTDIw) was calculated for each phantom at 80, 110 and 130 kV tube potentials based on measurements of the CTDI100, c and CTDI100, p. The results demonstrated that the CTDIw values of the epoxy and polyester phantoms were dependent on the tube potential and exhibited similar trends to the PMMA phantom. The maximum discrepancy in CTDIw between the epoxy and PMMA phantoms was 3%, while the maximum difference in CTDIw between the polyester and PMMA phantoms was 2%. Therefore, the researchers concluded that the physical properties of the resin materials were comparable to PMMA, and the phantoms displayed equivalent dosimetry behavior to the PMMA phantom at all tube potentials. This study determined that epoxy and polyester resin phantoms exhibited commensurate radiation dosimetry to a standard PMMA phantom for assessing CT dose. As such, the epoxy and polyester resin phantoms may be considered as a suitable substitute for the PMMA phantom when it is not readily available.

A pediatric head phantom was created using epoxy resin to evaluate the amount of radiation exposure in computed tomography (CT) scans. The phantom's size resembled that of a child's head, with a diameter of 10 cm and a length of 15 cm. A comparative analysis was conducted to examine and compare the atomic composition, effective atomic number, electron density, and mass density of the epoxy resin material with those of polymethyl methacrylate (PMMA). To measure the radiation dose received by the phantom, a 100 mm pencil ion chamber was used at both the center and periphery. The weighted CT dose index (CTDIw) and volumetric CT dose index (CTDIvol) were determined for various tube potentials, keeping the current-time product constant. A standard calibrated phantom was also used for a comparable analysis. The results indicated that the physical properties of the epoxy resin material were similar to PMMA, and the phantom demonstrated equivalent dosimetric performance to the PMMA phantom across all tube voltages. Lastly, the CTDIvol values obtained from the fabricated and standard phantoms were compared with the corresponding values displayed on the CT console. The differences fell within the limits set by the American Association of Physicists in Medicine (AAPM). These findings demonstrate that the cost-effective pediatric phantom offers a practical and economical approach to assessing the radiation dose in CT scans for children, while exhibiting dosimetric properties comparable to those of commercially available phantoms.

The current study aimed to evaluate the suitability of polyester resin as an alternative material to polymethyl methacrylate (PMMA) for computed tomography (CT) dosimetry phantoms using the GEANT4/GATE Monte Carlo simulation platform. Cylindrical phantoms (32 cm diameter) constructed of polyester resin and PMMA were simulated and compared in terms of atomic composition, effective atomic number, electron density, mass density, and photon interaction mechanisms. Weighted CT dose index (CTDIw) values were calculated for each phantom at 80, 110, and 130 kVp tube voltages based on measurements of CTDI100,c and CTDI100,p. Results demonstrated that the physical properties of polyester closely matched those of PMMA, and the polyester phantom displayed equivalent dosimetric behavior to the PMMA phantom at all tube voltages tested. CTDIw values from the polyester phantom were within 1.4 % of the PMMA phantom across all tube voltages. Conversion coefficients were derived to equate polyester CTDIw values to PMMA dose equivalents. This study found that a polyester resin phantom exhibited radiation dosimetry commensurate with the standard PMMA phantom for CT dose assessment. Consequently, polyester resin represents a viable substitute material when PMMA is unavailable for construction of CT dosimetry phantoms.

Introduction: Upfront surgery is standard treatment for resectable pancreatic cancer according to National Comprehensive Cancer Network guidelines. In contrast, neoadjuvant treatment is recommended for borderline resectable disease due to positive associations with microscopic radicality and survival. A dividing line between resectable and borderline resectable criteria is portal/superior mesenteric vein contact below or above 180°. This dividing line is based on technical rather than biological factors and has an unknown impact on survival. Purpose: We aimed to determine if resectable pancreatic cancer patients with radiological venous engagement ≤180° have worse outcomes compared to no venous engagement, after upfront surgery. Method: We conducted a retrospective case-control study including patients with resectable pancreatic adenocarcinoma planned for upfront surgery between the years 2010–2020 at Umeå University Hospital, Sweden. Patients were categorized into two groups: (1) no venous engagement vs. (2) venous engagement ≤180°, based on preoperative radiological assessment. Survival (intention-to-treat) was analyzed with Kaplan-Meier curves, log-rank test, and Cox proportional hazards model. Results: Two-hundred-nine patients with NCCN resectable pancreatic adenocarcinoma were included: 39 cases with radiological venous engagement ≤180° and 170 controls with no venous engagement on preoperative imaging. Radiological venous engagement ≤180° was associated with shorter median survival compared to no radiological venous engagement (15.3 vs. 23.0 months, P=0.047) and was an independent negative prognostic factor for survival in multivariable models (HR 1.59 95% CI 1.06-2.40, P=0.026). There was no difference in the rate of open-close procedures between the groups (9/39 vs. 36/170). The rate of microscopically non-radical resections (R1) was higher among cases with venous engagement ≤180°, P< 0.001. There were no differences in the rates of adjuvant chemotherapy, postoperative complications, and 90-day mortality between the groups. Conclusion: Radiological venous engagement ≤180° is a negative prognostic factor for survival, associated with higher rates of R1 resections, and worse overall survival compared to patients without venous engagement, when planned for upfront surgery. These findings suggest that neoadjuvant chemotherapy should be considered with any degree of tumor contact with the portal/superior mesenteric vein.

During the COVID pandemic, elective global surgical missions were temporarily halted for the safety of patients and travelling healthcare providers. We discuss our experience during our first surgical mission amidst the pandemic. We report a safe and successful treatment of the patients, detailing our precautionary steps and outcomes.Retrospective manual chart review and data collection of patients’ charts was conducted after IRB approval. We entail our experience and safety steps followed during screening, operating and postoperative care to minimize exposure and improve outcomes during a surgical mission in an outpatient setting during the pandemic. The surgical mission was from February 8 to February 12, 2022.A total of 60 patients who were screened. 33 patients underwent surgical intervention. One patient required postoperative hospitalization for a biliary duct leak. No patient or healthcare provider tested positive for COVID at the end of the mission. The average age of patients was 46.9 years. The average operative time was 116 min, and all patients had local nerve blocks. It included 45 health work providers.It is safe to perform outpatient international surgery during the pandemic while following pre-selected precautions.Durante la pandemia de COVID, las misiones quirúrgicas globales electivas se detuvieron temporalmente por la seguridad de los pacientes y los proveedores de atención médica que viajaban. En el presente trabajo presentamos nuestra experiencia durante la primera misión quirúrgica en medio de la pandemia. Reportamos el tratamiento seguro y exitoso de los pacientes, detallando nuestros pasos de precaución y resultados.Luego de obtener la aprobación del IRB, se realizó la revisión manual retrospectiva de las historias clínicas y la recopilación de datos de las historias clínicas de los pacientes. Exponemos nuestra experiencia y los pasos de seguridad seguidos durante la detección, la operación y la atención posoperatoria para minimizar la exposición y mejorar los resultados durante una misión quirúrgica en un entorno ambulatorio durante la pandemia. La misión quirúrgica fue del 8 al 12 de febrero de 2022.Un total de 60 pacientes fueron tamizados. De ellos, 33 pacientes fueron intervenidos quirúrgicamente. Un paciente requirió hospitalización postoperatoria por una fuga del conducto biliar. Ningún paciente o proveedor de atención médica dio positivo por COVID al final de la misión. La edad media de los pacientes fue de 46,9 años. El tiempo operatorio promedio fue de 116 min, y todos los pacientes tuvieron bloqueos nerviosos locales. Participaron 45 proveedores de trabajo de salud.Es seguro realizar una cirugía internacional ambulatoria durante la pandemia siguiendo las precauciones preseleccionadas.

Distal pancreatectomy with celiac axis resection (DP-CAR) is a surgical procedure with high morbidity and mortality performed in patients with locally advanced pancreatic cancer. Preoperative embolization of hepatic artery (PHAE) has been postulated as a technical option to increase resection rate.comparison of morbidity and mortality at 90 days, operative time, hospital stay and survival between patients that performed DP-CAR with and without PHAE.Observational retrospective multicentre study. Inclusion criteria: patient operated in Spanish centers with DP-CAR for pancreatic cancer from April 2004 until 23 June 2018. Preoperative (PHAE, neodjuvant treatment), intraoperative (operative time and blood loss) and postoperative data (morbidity, hospital stay, R0 and survival) were studied. Complications were measured with Clavien classification at 90 days. Specific pancreatic complications were measured using ISGPS classifications. Data were analyzed using R version 3.1.3 (http://www.r-project.org). Level of significance was set at 0.05.41 patients were studied. 26 patients were not embolized (NO-PHAE group) and 15 patients received PHAE. Preoperative BMI and percentage of neoadjuvant chemotherapy were the only preoperative variables different between both groups. The operative time in the PHAE group was shorter (343 min) than in the non-PHAE group (411 min) (p < 0.06). Major morbidity (Clavien > IIIa) and mortality at 90 days were higher in the PHAE group than in the non-PHAE group (60% vs 23% and 26.6% vs 11.6% respectively) (p < 0.004). No statistical difference in overall survival was observed between both groups (p = 0.14).In our study PHAE is not related with less postoperative morbidity. Even more, major morbidity (Clavien III-IV) and mortality was higher in PHAE group.

Purpose: Ampullary adenocarcinoma (AAC) is a rare malignancy with extensive morphological heterogeneity. Variable results have been reported regarding the predictive value of lymph node ratio (LNR) on survival in patients with resected AAC. The aim of this study was to investigate the prognostic predictive value of LNR adjusted for factors influencing survival in patients with resected AAC. Methods: This retrospective international multicenter cohort study included all patients who underwent pancreatoduodenectomy for AAC (2006-2020). Patients who underwent palliative procedures or local excision of AAC were excluded, as were patients with an R2 resection, distant metastasis, or 30-day postoperative mortality. Overall survival(OS) was assessed using the Kaplan-Meier method and log-rank tests. Cox proportional hazard models were performed to identify independent predictors of OS. Optimal cut-off for LNR was determined calculating the Youden's index and logrank test. Results: Overall, 1230 patients after pancreatoduodenectomy for AAC were included. Histopathologic subtype was documented in 907 patients (73.7%), of whom 369 had intestinal subtype (40.7%), 477 pancreaticobiliary subtype (52.6%), and 61 a mixed subtype (6.7%). Median survival was not reached for the intestinal subtype. For the pancreatobiliary subtype and mixed subtype, median survival was 60 (42-77), and 76 (35-116) months, respectively(Figure1). The optimal cut-off for the LNR was 0.10. Age, tumor size, resection margin, T3/4 stage, poor tumor differentiation, and LNR were independent predictors of survival (Table 1). Conclusion: This study shows the importance of LNR for prognosis in patients with all histopathological subtypes of resected AAC and an optimal cut-off point for the LNR of 0.10.Table 1Multivariable Analysis identifying Risk Factors Associated With Overall Survival According to the Cox Proportional Hazard ModelHazard Ratio[95% CI]P ValueAge1.028(1.017-1.040)<0.001Tumor Size1.011(1.003-1.019)0.006Resection margin1.295(1.012-1.655)0.040Perineural invasion1.036(0.820-1.310)0.765Lymphovascular invasion1.193(0.972-1.536)1.171T stage 3/41.614(1.241-2.097)<0.001Tumor differentiation1.297(1.058-1.589)0.012LNR LNR 0-0.1 LNR > 0.11.4333.289(1.020-2.012)(2.485-4.401)0.038<0.001 Open table in a new tab