RU2613783C1 - Method for targeted body-lower limbs complex research for a dead body by x-ray computer tomography - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: dead body is scanned while it is in a sealed bag in the lying position, scanning mode is continuous spiral. The following zones are examined sequentially: body - from C7 vertebra to the lower edge of the pubic bone; lower limbs - from the upper edge of the acetabulum to the tips of the big toes. To scan the "body" (B) zones, the following parameters are used: scan slice thickness - 0.9 mm, image viewer reconstruction slice thickness - 2-3 mm, kV - 120, mAs - 250, increment - 0.45×, collimation - 1280.625, pitch - 0.993, tube rotation speed - 0.5, matrix - 512512×, image field - 350. To scan the "lower limbs" (LL) zone: scan slice thickness - 0.9 mm, image viewer reconstruction slice thickness - 2mm, kV - 120, mAs - 175, increment - 0.45, collimation -× 640.625, pitch - 0.297, tube rotation speed - 0.4, matrix - 768768×, image field - 150. To view zone B images, the following modes are used: bone with C1500-W3000 window width, soft-tissue with C60-W350 window width, pulmonary with C500-W1500 window width; to view zone LL images, the following modes are used: bone with C1500-W3000 window width, soft-tissue with C60-W350 window width. For zone B multiplanar reconstructions are plotted in sagittal and coronal planes and three-dimensional reconstructions, with colored metal mapping, maximum and minimum intensity reconstructions. For zone LL multiplanar reconstructions are plotted in sagittal and coronal planes and three-dimensional reconstructions, with colored metal mapping, maximum intensity reconstructions. All the results are used for personality identification, cause of death determination.

EFFECT: method provides comprehensive precision with optimal informative research parameters, research and findings acceleration, including urgent results without a classical autopsy, with the exception of personnel infection risk.

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Description

The invention relates to the field of high-tech methods of radiation diagnostics and can be used in forensics and forensic science to establish a diagnosis, cause and mechanism of death, identification of the victims and a number of other issues. The invention can be used at the stage of urgent investigative actions after examining the corpse at the place of its discovery.

Computed tomography (CT) scan of a corpse can help answer questions posed by inquiry bodies when dying from mechanical injuries caused by blunt and sharp objects, as well as gunshot injuries. A CT scan of a corpse can help determine the mechanism of damage, the characteristics of the traumatic object, the direction of movement of the traumatic object and the position of the body during the damage, the lifetime, the duration and sequence of the damage, and the cause of death. A CT scan of a corpse can also assist investigators and forensic experts in cases of investigation of a corpse and parts of a corpse during death as a result of mechanical asphyxiation, exposure to flames and a number of other physical factors.

The CT corpse method was first described by a team of researchers led by prof. M.J. Thali (Institute of Forensic Medicine, University of Zurich, Switzerland). The method consists in a full detailed CT scan of the entire corpse. Examination of a corpse is carried out according to a standard protocol, regardless of the cause of death. At the first stage, a CT of the whole body with a large image field (FOV) is performed. At the second stage - the study of the head and neck of a corpse with a small image field and thin sections. In the third stage, the chest, abdominal cavity and pelvis with arms raised up are examined. Separately, according to indications, the dental protocol and larynx examination are used. All these stages are accompanied by the construction of multiple reconstructions, both axial thinner sections, and multi-planar and three-dimensional (aiming for each area). The specified protocol is described in detail in the work: P.M. Flach, D. Gascho, W. Schweitzer, Th.D. Ruder, N. Berger, S.G. Ross, M. J. Thali, G. Ampanozi. Imaging in forensic radiology: an illustrated guide for postmortem computed tomography technique and protocols. Forensic Sci Med Pathol, March 2014. DOI 10.1007 / s12024-014-9555-6 (prototype).

The disadvantage of this technique is the duration of the study itself and the large amount of post-processing processing, which takes about 1.5-2 hours. In addition, the duration of the study inevitably leads to overheating of the tomograph tube, thereby prolonging the time of the study itself and the sequence subsequent studies, if required, which is especially true in cases of mass deaths and crimes with more than one corpse.

The technique developed by the authors allows us to accelerate both the CT scan of the corpse itself and obtain results in a shorter time. This is especially true at the stage of urgent investigative actions.

Effect: the possibility of establishing the cause of death without classical autopsy with the exception of the possibility of infection of personnel due to the lack of direct contact with cadaveric tissues, reducing the time of the examination procedure, as well as identifying the person by the characteristics of the body and limbs of the corpse. Exact accuracy and speed of research is provided precisely by the indicated sequence of our research protocol.

The authors developed a CT scan technique for the torso complex — the lower limbs of the corpse with a lower load with an optimally informative slice thickness of 2 mm to prevent tube overheating. Our technique combines such difficultly compatible parameters in CT as a high research speed without loss of information content. By optimizing the parameters of the study, the duration of the study, the amount of post-processing processing, and the likelihood of overheating of the tomograph tube are reduced.

In contrast to the methodology of foreign authors, which involves a standard undifferentiated study of corpses, both forensic and pathological, which greatly complicates the study and delays obtaining results for a long time, targeted research, a detailed study of all areas of interest of corpses with signs of violent death allows for detailed and high-quality identify damage and give them a forensic assessment.

A targeted study of individual parts of the body can be used in cases: traumatic injuries of the limbs and body to clarify the direction of the acting force in blunt trauma, assess the wound channel in trauma caused by a sharp object; identify the exact localization of foreign bodies (bullets, metal fragments); confirmation of the iatrogenic cause of death with known medical interventions (installation of a pacemaker, prosthesis); for personal identification, in the presence of prostheses and intravital radiological data.

A targeted study of certain areas of interest, in this case the torso-limb complex, is carried out with a slice thickness of 0.6 mm to 5 mm and a smaller image field for the purpose of a detailed analysis of damage with the possibility of establishing: the mechanism for causing damage, the characteristics of the injuring object, the direction of movement of the injuring subject, intravital and prescription damage. It is also possible to establish the most common causes of death with mechanical and other injuries: acute blood loss, hemopneumothorax, gas embolism, etc.

When analyzing the literature data on CT examination of the trunk and extremities of both living patients with multiple injuries and corpses, the authors found that when examining a corpse with suspected violent death, in particular, of a mechanical nature, the optimal informative scan thickness is 2 mm with subsequent reconstruction of the image by 1 mm; reduction of mAs to 85. These parameters with a sufficient degree of accuracy and reliability allow you to analyze all the necessary details to establish the cause of death and personal identification. The above parameters are averaged. More detailed scanning parameters developed by the authors are given in table 1.

The parameters indicated in the table, such as: thickness of the scan slice and reconstruction of image viewing, kV, mAs, increment, collimation, pitch, tube rotation speed, matrix, FOV, mode and window width, are selected by the authors depending on the area of interest (chest, abdominal cavity, pelvis, upper and lower extremities), taking into account the main tasks that are posed during the forensic examination of a corpse, are optimal for obtaining a detailed picture of injuries and are necessary to assess the condition of the corpse, the mechanism of injury, the causes of death, etc. Some parameters indicated in the table (for example, matrix, image field) are scanning standards, constants embedded in the program. Some parameters (for example, scan cut thickness) are not “hard” and can be partially changed depending on the objectives of a particular study. Nevertheless, a fundamental departure from this protocol is impractical, since these parameters are selected on the basis of published data and our extensive experience in CT studies of patients, including those with various types of mechanical injuries.

The difference between the parameters developed by the authors, in particular, an increase in the thickness of the scan slice and a decrease in mAs, lies in the possibility of obtaining the optimal both visual and quantitative image, thus avoiding overheating of the tube (which allows delaying, if necessary, further targeted investigation of individual parts of the body), reduce the time the study itself, the subsequent construction of reconstructions and image evaluation.

The importance of a single study of the torso-limb complex lies in the need to answer the questions most often faced by forensic experts, in particular the direction of the acting force for blunt trauma, the assessment of wound canals in case of injuries caused by sharp guns and firearms. Based on these data, it is also possible to conduct criminalistic examinations to model events related to the position of the attackers and the victim, the direction of movement of the traumatic object and the position of the body during the damage, the position of the bodies in the car cabin during the accident, etc.

Our research protocol for MSCT complex of the body - lower limbs of the corpse (table) is suitable for use in the "field" conditions and at the stage of urgent investigative actions in case of detection of the corpse or its parts, including for mobile CT systems.

The results of the study are used to identify a person and / or to establish the causes of death.

Claims (11)

The method of targeted research of the complex of the body - lower limbs of a dead body using x-ray computed tomography, characterized in that: - performed in sealed bags in a supine position, - scanning continuous spiral mode, - in this case, the following zones are successively examined: trunk - from the C7 vertebra to the lower edge of the pubic bone; lower limbs - from the upper edge of the acetabulum to the tips of the big toes; - moreover, the following parameters are used for scanning the “torso” zone: scan cut-off thickness - 0.9 mm, cut-off thickness of image viewing reconstruction - 2-3 mm, kV - 120, mAs - 250, increment - 0.45, collimation - 128 × 0.625 , pitch - 0.993, tube rotation speed - 0.5, matrix - 512 × 512, image field - 350; - for scanning the “lower extremities” zone, the following parameters are used: scanning cutoff thickness - 0.9 mm, image viewing reconstruction cutoff thickness - 2 mm, kV - 120, mAs - 175, increment - 0.45, collimation - 64 × 0.625, pitch - 0.297, tube rotation speed - 0.4, matrix - 768 × 768, image field - 150; - to view images of the “torso” zone, the following modes are used: bone with a window width of C1500-W3000, soft-tissue with a window width of C60-W350; pulmonary - window width C500-W1500; - to view images of the “lower limbs” zone, the following modes are used: bone with a window width of C1500-W3000, soft-tissue with a window width of C60-W350; - carry out the construction for the “torso” zone of multiplanar reconstructions in the sagittal and coronal planes and three-dimensional reconstructions with color mapping of the metal, reconstructions of the maximum and minimum intensity; - carry out the construction for the zone of "lower limbs" of multiplanar reconstructions in the sagittal and coronal planes and three-dimensional reconstructions with color mapping of the metal, reconstructions of maximum intensity; - the results of the study are used to identify the person and / or to establish the causes of death.