Keywords:
Forensic / Necropsy studies, Cone beam CT, Experimental investigations, Forensics
Authors:
M. Bisceglia1, M. Weber2, G. Pelletti1, G. Viel1, D. Miotto1, M. Montisci1, G. Cecchetto1, C. Giraudo1; 1Padova/IT, 2Vienna/AT
DOI:
10.1594/ecr2018/C-0731
Methods and materials
Three types of saws (saw1,
saw2,
saw3),
differing for set (saw1 and saw2=alternating; saw3=wavy) and shape (saw1=crosscut; saw2 and saw3=ripcut) were selected.
For each type,
two saws differing only for TPI (saw1_8TPI; saw1_11TPI; saw2_8TPI; saw2_10TPI ; saw3_18TPI; saw3_24TPI) (Fig 1) were used to perform 84 SMs (i.e.,
14 with each saw) on as many human bone samples (e.g.,
phalanx).
Each sample was scanned by MicroCT applying the following parameters: 14 μm isotropic voxel size,
51 Kv,
194 uA,
exposition time 6050 ms,
rotation step 0.7,
frame averaging 2,
1280 x 1024 pixel Field of View.
A radiologist,
blind to the experimental tests,
used Micro-CT multiplanar images to classify the SMs according to set and shape (morphologic assessment) and referring to a previously published classification (saw1=two triangular marks; saw2=two quadrangular marks; saw3=one quadrangular mark) [1] (Figure 2).
A quantitative assessment was then also performed,
indeed,
for SMs attributed to saw1 and saw3,
depth,
kerf width (KW),
two angles,
and their distance were assessed; for saw1 and saw2 also the mean of the distance between the two angles was assessed; only for SMs attributed to saw2 two additional angles,
the width of the two floors,
and their mean were measured.
Student’s t-test (p<0.001) was used to compare SMs differing only for TPI; if significant differences occurred,
the ROC curves were then computed (Fig 2).