Automatic Scanning by Scanning Electron Microscopy: The First Step towards Automation of Forensic Diatom Test

The diatom test is considered as the most reliable scientific method in solving the drowning cases. However, the detection and identification of diatoms have to be accomplished manually with the techniques of nowadays, which makes this test a time consuming work and therefore a bottleneck in its application in forensic casework. In the presented paper, we describe a new method for qualitative and quantitative analysis of diatoms in water and organ samples using the function of automatic scanning of scanning electron microscopy (SEM). Samples are divided into certain amount of fields at a preset magnification under SEM, each field is scanned automatically and the image of each field is captured and stored in the computer accordingly, and the diatom analysis is performed manually based on the images of all field. By automatic scanning with SEM, the labor for diatom analysis is able to be saved to a great extent and the accuracy of the results of qualitative and quantitative diatom analysis is improved compared to the methods with light microscopy. Automatic scanning by scanning electron microscopy is just the first step towards automation of forensic diatom test while further scientific research in the field of automatic diatom identification using SEM images has to be done in the future.

I. Introduction

The diagnosis of drowning is one of the most difficult tasks in forensic pathology. At present, the diatom test is considered as the most reliable scientific method or “the golden standard” in solving the drowning cases [1]. When the qualitative and quantitative diatom analysis is introduced with the prerequisite of avoiding contamination, the test provides supportive evidence of drowning and also gives evidence of the probable site of drowning [2] [3] [4] [5] [6].