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Purpose: To evaluate customizing a knowledge-based planning (KBP) model using dosimetric analysis for volumetric modulated arc therapy for pancreatic cancer. Materials and Methods: The first model (M1) using 56 plans and the second model (M2) using 31 plans were created in the first 7 months of the study. The ratios of volume of both kidneys overlapping the expanded planning target volume to the total volume of both kidneys (Voverlap/Vwhole) were calculated in all cases to customize M1. Regression lines were derived from Voverlap/Vwhole and mean dose to both kidneys. The third model (M3) was created using 30 plans which data put them below the regression line. For validation, KBP was performed with the three models on 21 patients. Results: V18 of the left kidney for M1 plans was 7.3% greater than for clinical plans. Dmean of the left kidney for M2 plans was 2.2% greater than for clinical plans. There was no significant difference between all kidney doses in M3 and clinical plans. Dmean of the left kidney for M2 plans was 2.2% greater than for clinical plans. Dmean to both kidneys did not differ significantly between the three models in validation plans with Voverlap/Vwhole lower than average. In plans with larger than average volumes, the Dmean of validation plans created by M3 was significantly lower for both kidneys by 1.7 and 0.9 Gy than with M1 and M2, respectively. Conclusions: Selecting plans to register in a model by analyzing dosimetry and geometry is an effective means of improving the KBP model. [ABSTRACT FROM AUTHOR]

Introduction: Early and accurate diagnosis is paramount for improving the therapeutic efficacy of pancreatic cancers. Endoscopic ultrasonography-- fine needle aspiration (EUS-FNA) cytology has come up with the advantage of an early and accurate diagnosis of pancreatic cancers. This study was conducted to analyze the spectrum of pancreatic lesions cytology, and appraise the diagnostic accuracy of EUS-FNA cytology for pancreatic solid and cystic lesions. Materials and Methods: This retrospective study includes 288 EUS-guided pancreatic FNA cases. Clinical data, laboratory tests, cytopathology, histopathology, and imaging reports were retrieved. The final diagnosis was based on EUS-FNA cell block and/or pathology in surgical specimens, with immunohistochemistry support. The results of EUS-guided FNA were compared with the final diagnoses to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Among 288 EUS-guided pancreatic FNA cases, 175 (62.0%) were malignant. The mean age was 57.8 ± 13.5 years and 50.1 ± 13.7 years, and the mean size of the lesion was 4.1 ± 1.8 cm and 2.2 ± 1.1 cm in malignant and benign groups, respectively. Sensitivity, specificity, PPV, and NPV of EUS-FNA cytology for solid malignant lesions were 98.3%, 95.1%, 98.3%, and 95.1%, and those for cystic lesions were 88%, 92.3%, 100%, and 100%. Diagnostic accuracy of EUS-FNA cytology for solid and cystic pancreatic lesions is 97.4% and 95.0%, respectively. In conclusion of the above; diagnosis of pancreatic solid and cystic malignancy can be assigned from a composite of the EUS-FNA cytology, cell block preparation and immunohistochemistry Diagnosis of pancreatic solid and cystic malignancy can be assigned from a composite of the EUS-FNA cytology, cell block preparation, and immunohistochemistry. [ABSTRACT FROM AUTHOR]