Peak skin and eye lens radiation dose from brain perfusion CT: CTDIvol and Monte Carlo based estimations.

PURPOSE: To quantify the eye lens, peak skin and brain doses associated with head CT perfusion exam by means of thermoluminescent dosimeters (TLDs) measurements in a cadaver and compare them to Monte Carlo (MC) dose estimations as well as to the CTDIvol. METHOD: 18 TLDs were inserted in the brain, skin, and eye lenses of a female cadaver head, who underwent a CT brain perfusion scan using a Siemens Definition Flash. The table-toggling protocol used 80 kVp, 200 mAs, 32 × 1.2 mm collimation and 30 sequences. From the CT images, a voxel model was created. Doses were calculated with a MC framework (EGSnrc) and compared to TLD measurements. TLD measurements were also compared to the displayed CTDIvol. RESULTS: The average measured doses were: 185 mGy for the eyes lenses, 107 mGy for the skin, 172 mGy for the brain and 273 mGy for the peak skin. The reported CTDIvol of 259 mGy overestimated the averaged organ doses but not the peak skin dose. MC estimated organ doses were 147 mGy for the eyes (average), 104 mGy for the skin and 178 mGy for the brain (-20 %, -3% and 4% difference respect to the TLDs measurements, respectively). CONCLUSIONS: CTDIvol remains a conservative metric for average brain, skin and eyes lenses doses. For accurate eye lens and skin dose estimates MC simulations can be used. CTDIvol should be used with caution as it was of the same order of magnitude as the peak skin dose for this protocol and this particular CT scanner.

Differentiation between decomposed remains of human origin and bigger mammals.

This study is a follow-up study in the search for a human specific marker in the decomposition where the VOC-profile of decomposing human, pig, lamb and roe remains were analyzed using a thermal desorber combined with a gas chromatograph coupled to a mass spectrometer in a laboratory environment during 6 months. The combination of 8 previously identified human and pig specific compounds (ethyl propionate, propyl propionate, propyl butyrate, ethyl pentanoate, 3-methylthio-1-propanol, methyl(methylthio)ethyl disulfide, diethyl disulfide and pyridine) was also seen in these analyzed mammals. However, combined with 5 additional compounds (hexane, heptane, octane, N-(3-methylbutyl)- and N-(2-methylpropyl)acetamide) human remains could be separated from pig, lamb and roe remains. Based on a higher number of remains analyzed, as compared with the pilot study, it was no longer possible to rely on the 5 previously proposed esters to separate pig from human remains. From this follow-up study reported, it was found that pyridine is an interesting compound specific to human remains. Such a human specific marker can help in the training of cadaver dogs or in the development of devices to search for human remains. However, further investigations have to verify these results.

Time-dependent VOC-profile of decomposed human and animal remains in laboratory environment.

A validated method using a thermal desorber combined with a gas chromatograph coupled to a mass spectrometer was used to identify the volatile organic compounds released in decomposed human and animal remains after 9 and 12 months in glass jars in a laboratory environment. This is a follow-up study on a previous report where the first 6 months of decomposition of 6 human and 26 animal remains was investigated. In the first report, out of 452 identified compounds, a combination of 8 compounds was proposed as human and pig specific. The goal of the current study was to investigate if these 8 compounds were still released after 9 and 12 months. The next results were noticed: 287 compounds were identified; only 9 new compounds were detected and 173 were no longer seen. Sulfur-containing compounds were less prevalent as compared to the first month of decomposition. The appearance of nitrogen-containing compounds and alcohols was increasingly evident during the first 6 months, and the same trend was seen in the following 6 months. Esters became less important after 6 months. From the proposed human and pig specific compounds, diethyl disulfide was only detected during the first months of decomposition. Interestingly, the 4 proposed human and pig specific esters, as well as pyridine, 3-methylthio-1-propanol and methyl(methylthio)ethyl disulfide were still present after 9 and 12 months of decomposition. This means that these 7 human and pig specific markers can be used in the development of training aids for cadaver dogs during the whole decomposition process. Diethyl disulfide can be used in training aids for the first month of decomposition.

The Search for a Volatile Human Specific Marker in the Decomposition Process.

In this study, a validated method using a thermal desorber combined with a gas chromatograph coupled to mass spectrometry was used to identify the volatile organic compounds released during decomposition of 6 human and 26 animal remains in a laboratory environment during a period of 6 months. 452 compounds were identified. Among them a human specific marker was sought using principle component analysis. We found a combination of 8 compounds (ethyl propionate, propyl propionate, propyl butyrate, ethyl pentanoate, pyridine, diethyl disulfide, methyl(methylthio)ethyl disulfide and 3-methylthio-1-propanol) that led to the distinction of human and pig remains from other animal remains. Furthermore, it was possible to separate the pig remains from human remains based on 5 esters (3-methylbutyl pentanoate, 3-methylbutyl 3-methylbutyrate, 3-methylbutyl 2-methylbutyrate, butyl pentanoate and propyl hexanoate). Further research in the field with full bodies has to corroborate these results and search for one or more human specific markers. These markers would allow a more efficiently training of cadaver dogs or portable detection devices could be developed.

Development and validation of a new TD-GC/MS method and its applicability in the search for human and animal decomposition products.

Differentiation between human and animal remains by means of analysis of volatile compounds released during decomposition is impossible since no volatile marker(s) specific for human decomposition has been established today. Hence, the identification of such a marker for human decomposition would represent great progression for the discovery of buried cadavers by analytical techniques. Cadaver dogs can be trained more efficiently, the understanding of forensic entomology can be enhanced, and the development of a portable detection device may be within reach. This study describes the development and validation of a new analytical method that can be applied in the search of such (a) specific marker(s). Sampling of the volatile compounds released by decomposing animal and human remains was performed both in a laboratory environment and outdoors by adsorption on sorbent tubes. Different coatings and several sampling parameters were investigated. Next, the volatile compounds were analyzed and identified by a thermal desorber combined with gas chromatography coupled to mass spectrometry (TD-GC/MS). Different GC columns were tested. Finally, the analytical method was validated using a standard mixture of nine representative compounds.

Abdominal wall phlebitis due to Prevotella bivia following renal transplantation in a patient with an occluded inferior vena cava.

Pre-existing occlusion of the inferior vena cava may complicate renal transplantation. Suppurative abdominal wall phlebitis following renal transplantation was diagnosed in a patient with pre-existing thrombosis of the inferior vena cava of unknown cause. The phlebitis developed in the subcutaneous collateral veins of the abdominal wall contra-laterally to the renal transplant. Cultures from abdominal wall micro-abscesses yielded Prevotella bivia as the causative agent. This complication has not been described before in the context of renal transplantation. The pathogenesis and management of this serious complication are discussed in this paper.