Biomedical subjects
Publications and source records attributed to A J Lomax.
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PURPOSE: A comparative treatment planning study has been undertaken between standard photon delivery techniques,b intensity modulated photon methods and spot scanned protons in order to investigate the merits and limitations of each of these treatment approaches. METHODS: Plans for each modality were performed using CT scans and planning information for nine patients with varying indications and lesion sites and the results have been analysed using a variety of dose and volume based parameters. RESULTS: Over all cases, it is predicted that the use of protons could lead to a reduction of the total integral dose by a factor three compared to standard photon techniques and a factor two compared to IM photon plans. In addition, in all but one Organ at Risk (OAR) for one case, protons are predicted to reduce both mean OAR dose and the irradiated volume at the 50% mean target dose level compared to both photon methods. However, when considering the volume of an OAR irradiated to 70% or more of the target dose, little difference could be shown between proton and intensity modulated photon plans. On comparing the magnitude of dose hot spots in OARs resulting from the proton and IM photon plans, more variation was observed, and the ranking of the plans was then found to be case and OAR dependent. CONCLUSIONS: The use of protons has been found to reduce the medium to low dose load (below about 70% of the target dose) to OARs and all non-target tissues compared to both standard and inversely planned photons, but that the use of intensity modulated photons can result in similar levels of high dose conformation to that afforded by protons. However, the introduction of inverse planning methods for protons is necessary before general conclusions on the relative efficacy of photons and protons can be drawn.
By understanding surgeons' patterns of gaze, and what visual information is being obtained during a procedure, one can improve the operation via new techniques or instrumentation. Part of a larger project on Remote Manipulation in Endoscopic Surgery, we analyzed eye patterns of surgeons from videotape annotation. Three categories of eye patterns were defined: 1) eyes on (gaze on monitor); 2) eyes down (gaze on external operative space); 3) eyes off (gaze away from monitor/hands). In the context of hierarchical decomposition of procedures we compared eye patterns and sequential dependencies (gaze as a function of previous gaze) by procedure, surgical steps and tasks. Timelines showed transitions in eye patterns during the procedure. We determined what visual information is available and what visual information is needed by the surgeons. By comparing these, we suggest technology that can provide these needs.
We describe two recent research projects: the Virtual Hand Laboratory, and Remote Manipulation in Endoscopic Surgery. The Virtual Hand Laboratory (VHL) is a prototype experimental tool for investigating human visuomotor coordination for object manipulation in augmented and virtual environments. The Remote Manipulation in Endoscopic Surgery (RMES) project examined surgeon's use of viewing and manipulating technologies in laparoscopic surgery, both in clinical and experimental settings. Current research brings together these two parallel research projects (VHL and RMES), for applications in planning and real-time execution of surgical procedures as well as for surgical training. We outline our research directions and detail current activities on superposition of display space on the workspace for the surgeon's hands.
In Aberdeen, a single-section transverse emission scanner has been adapted to trigger off patient ECG signals, allowing for the acquisition of gated blood pool tomograms at a number of slice levels through the patient's heart. This paper describes a system for the routine generation and display of surface rendered images derived from this data using a transputer based hardware system. Surface rendering algorithms have been implemented to provide an indication of the distribution of the cardiac blood pool in three dimensions, whilst the additional use of colour and/or cine sequences provide a succinct method of representing the extra information provided by gated acquisition. The transputer provides sufficient computing power to produce rendered views at a rate of about 1 frame per second, thus putting view selection fully under operator control. The success of the system described is reflected in its routine use in a busy clinical department.
The ageing process has changed little since the days of the psalmist. The number of elderly patients, however, is increasing. Old people seem more reluctant to undergo surgery than younger patients and more concerned with quality of life. The authors conducted a survey in a small community in British Columbia to determine the attitudes of old people towards surgery. The survey confirmed that they are reluctant to undergo surgery if there is an appreciable risk that they will be physically or mentally impaired afterwards. A substantial number also do not wish to undergo complicated procedures to prolong their lives. Quality of life and conservatism should be important considerations in the surgical management of elderly patients.
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Explore the source record for details and available documents.