In CAS literature, one finds numerous examples of the usage of directly measured surfaces. Those surfaces are usually
measured using so called "Surface Scanners" which employ structured light (pattern projection or laser) to measure the
surface. From an integration standpoint, it would be beneficial for many applications to have all patient data in a
common repository and since in many cases radiology images are involved as well, a PACS is a natural option for
storage of this data. DICOM - the major standard used for storage and transmission of data within a PACS - has recently
been extended by the option to store surface meshes using a newly introduced data structure. This new Surface Mesh
Module can serve as a basis for storage of data generated by an optical surface scanner. Nonetheless, a new Information
Object Definition for this kind of data has to be introduced to reflect the specific needs: Device specific parameters have
to be stored and, in addition to the Surface Mesh Module, there must be the possibility to store textures as well. This
paper gives an overview about the specific requirements and an outline of a Work Item leading to an Optical Surface
Scan Information Object Definition (IOD).
Stenosis of the aortic valve is a common cardiac disease. It is usually corrected surgically by replacing the valve
with a mechanical or biological prosthesis. Transapical aortic valve implantation is an experimental minimally
invasive surgical technique that is applied to patients with high operative risk to avoid pulmonary arrest. A
stented biological prosthesis is mounted on a catheter. Through small incisions in the fifth intercostal space and
the apex of the heart, the catheter is positioned under flouroscopy in the aortic root. The stent is expanded
and unfolds the valve which is thereby implanted into the aortic root. Exact targeting is crucial, since major
complications can arise from a misplaced valve. Planning software for the perioperative use is presented that
allows for selection of the best fitting implant and calculation of the safe target area for that implant. The
software uses contrast enhanced perioperative DynaCT images acquired under rapid pacing. In a semiautomatic
process, a surface segmentation of the aortic root is created. User selected anatomical landmarks are used to
calculate the geometric constraints for the size and position of the implant. The software is integrated into a
PACS network based on DICOM communication to query and receive the images and implants templates from
a PACS server. The planning results can be exported to the same server and from there can be rertieved by an
intraoperative catheter guidance device.
Proc. SPIE. 6919, Medical Imaging 2008: PACS and Imaging Informatics
KEYWORDS: Picture Archiving and Communication System, Data modeling, Systems modeling, Process modeling, Surgery, Telecommunications, Ear, Standards development, Imaging systems, Optical character recognition
The integration of imaging devices, diagnostic workstations, and image servers into Picture Archiving and Communication
Systems (PACS) has had an enormous effect on the efficiency of radiology workflows. The standardization
of the information exchange between the devices with the DICOM standard has been an essential
precondition for that development.
For surgical procedures, no such infrastructure exists. With the increasingly important role computerized planning
and assistance systems play in the surgical domain, an infrastructure that unifies the communication between
devices becomes necessary. In recent publications, the need for a modularized system design has been established.
A reference architecture for a <i>Therapy Imaging and Model Management System</i> (TIMMS) has been proposed.
It was accepted by the DICOM Working Group 6 as the reference architecture for DICOM developments for
In this paper we propose the inclusion of implant planning systems into the PACS infrastructure. We propose
a generic information model for the patient specific selection and positioning of implants from a repository according
to patient image data. The information models are based on clinical workflows from ENT, cardiac, and
orthopedic surgery as well as technical requirements derived from different use cases and systems.
We show an exemplary implementation of the model for application in ENT surgery: the selection and positioning
of an ossicular implant in the middle ear. An implant repository is stored in the PACS. It makes use of an
experimental implementation of the Surface Mesh Module that is currently being developed as extension to the
For the pre-operative definition of a surgical workspace for Navigated Control<sup>®</sup> Functional Endoscopic Sinus
Surgery (FESS), we developed a semi-automatic image processing system. Based on observations of surgeons
using a manual system, we implemented a workflow-based engineering process that led us to the development of
a system reducing time and workload spent during the workspace definition. The system uses a feature based on
local curvature to align vertices of a polygonal outline along the bone structures defining the cavities of the inner
nose. An anisotropic morphologic operator was developed solve problems arising from artifacts from noise and
partial volume effects. We used time measurements and NASA's TLX questionnaire to evaluate our system.
Neck dissection is a surgical intervention at which cervical lymph node metastases are removed. Accurate surgical planning is of high importance because wrong judgment of the situation causes severe harm for the patient. Diagnostic perception of radiological images by a surgeon is an acquired skill that can be enhanced by training and experience. To improve accuracy in detecting pathological lymph nodes by newcomers and less experienced professionals, it is essential to understand how surgical experts solve relevant visual and recognition tasks. By using eye tracking and especially the newly-developed attention landscapes visualizations, it could be determined whether visualization options, for example 3D models instead of CT data, help in increasing accuracy and speed of neck dissection planning. Thirteen ORL surgeons with different levels of expertise participated in this study. They inspected different visualizations of 3D models and original CT datasets of patients. Among others, we used scanpath analysis and attention landscapes to interpret the inspection strategies. It was possible to distinguish different patterns of visual exploratory activity. The experienced surgeons exhibited a higher concentration of attention on the limited number of areas of interest and demonstrated less saccadic eye movements indicating a better orientation.
The generation, storage, transfer, and representation of image data in radiology are standardized by DICOM. To cover the needs of image guided surgery or computer assisted surgery in general one needs to handle patient information besides image data. A large number of objects must be defined in DICOM to address the needs of surgery. We propose an analysis process based on Surgical Workflows that helps to identify these objects together with use cases and requirements motivating for their specification. As the first result we confirmed the need for the specification of representation and transfer of geometric models. The analysis of Surgical Workflows has shown that geometric models are widely used to represent planned procedure steps, surgical tools, anatomical structures, or prosthesis in the context of surgical planning, image guided surgery, augmented reality, and simulation. By now, the models are stored and transferred in several file formats bare of contextual information. The standardization of data types including contextual information and specifications for handling of geometric models allows a broader usage of such models. This paper explains the specification process leading to Geometry Mesh Service Object Pair classes. This process can be a template for the definition of further DICOM classes.