Magnetic Resonance Imaging (MRI) And Functional Computerized Tomography (4DCT) In Radiotherapy

Magnetic resonance imaging (MRI) is traditionally used in the diagnostic and staging parts of a patient’s treatment pathway. More recently however, it has also been used to help determine the planning target volume (PTV). In many CNS patients their diagnostic MRI scan is fused with their radiotherapy planning CT scan. (REF) The oncologist is then able to outline the Tumour mass on the MRI as a GTV, which can then be superimposed on the planning CT scan, to check the area for treatment and the margins to be used. This fusion of images, is advantages for two reasons. Firstly the MRI image shows far greater resolution in soft tissue, than the CT, and secondly because the CT scan is carried out post surgery following de-bulking, whilst the MRI is carried out prior to any clinical intervention. Therefore the oncologist is in effect, able to treat where the gross tumour was actually initially located.

Functional MRI (fMRI) is a relatively new technology, which is used with the aim to try to determine precisely which part of the brain is handling which critical functions. This is called brain mapping and is used primarily during surgery before the patient comes for any radiotherapy. The use of fMRI has been extended more recently, as it has now also been used as tool, in order to monitor the growth and function of any remaining brain tumour following treatment.

Functional computerised tomography (4DCT) is a normal CT scanner with software incorporated, or hardware adaptations, which allow it to look at organ motion in relation to bony anatomy. These fall into three main categories; 1 Breath Hold, 2 Gating and 3 Tracking the movements of the tumour.

Another method, which can also be used to monitor and control organ motion linked to breathing, is a type of active breathing control device. An active breathing device allows imaging in only one specific part of the patient’s breathing cycle. The benefit of this is that it allows for the scan to be constructed with the tumour in one position, and therefore hopefully not as effected by organ motion. The same active breathing device is then used each day while the patient is having their radiotherapy treatment, so the tumour is localised while the treatment machine is delivering dose. This technique does require much cooperation from the patient, and would only be suitable for patients whose thoracic tumours were not too severe to have caused severely laboured, or erratic breathing patterns.

Another type of tumour tracking device uses reference points that are actually attached to the patient’s skin surface. These reference points are then tracked while the patient is being CT scanned to determine at which point in their breathing cycle they were at any given point during the scan. When the data from the CT scan is then being consolidated, this additional motion information is added allowing the actual specific motion of any tumour to be linked to each patient’s own specific breathing cycle.

Engineering Technology – Better, Faster, Cheaper

I work in an industry that has seen huge changes in the past 25 years. The technology in engineering has grown and changed so much that we are executing project with half (sometimes less) the manpower we needed before. I work mainly in the oil and gas industry but I know that in other areas it is possibly even more dramatic. I have been in engineering industry for 25 years and when I started computers were in a main computer room and there were only a few and only few people who could run them. They slowly started moving on to the desktop about five years later. I was hired mainly because I had taken CAD courses to upgrade my skills during an economic downturn. I ended up developing and teaching courses in AutoCAD for the company. From those simple beginnings we have come a long way.

Let me give an example of that change. The company I work for had a project for a client 30 years ago and we managed to get the second phase of the project 12 years later while I was with the company. The technology of the process had not changed much so the plant was almost a twin of the first phase. The first phase was executed on the drafting board the second phase was done using brand new 3D design technology called Calma developed by GE (this software is gone now). During the execution of the engineering many of the engineers and design supervisors commented that they only had half the people for phase two compared to phase one. Another comparison on this project was in the construction. 30 years ago it was not uncommon in our industry to have 15% rework in the field due to clashes between piping, structural and electrical. With the new 3D technology we were able use clash reporting to fix most of these clashes on the computer before construction. The rework in field came down to 3% on this project and much of this was due to pipes that were field routed and were not in the model.

Leap forward now to 2005. Another example is from an article I read in Design News magazine it was about the development of Lance Armstrong’s time trial bike. Trek’s Advanced Concept Group was given only 28 days to redesign the bike to make it faster. A group of 14 engineers and designers went work using desktop workstations and eight different software programs. Even 2 years ago a redesign of this nature would have taken them 4 months. They did everything in 3D using Solidworks 3D CAD. This allowed them to do virtual tests on everything form the wind tunnel to reduce drag, to stress analysis to ensure the bike was safe. Using software called thinkid from think3 they were actually able to deform the solid shapes and the software was able to redo to geometric calculations to accommodate the shape change and still maintain the integrity of the design. With this technology they were able to go straight into production knowing what they had designed worked because the model simulations proved it. They ended up with a bike that was 2% lighter, 10% faster, and 15% stiffer then the model they produced in 2004. Lance Armstrong proved it was better by winning the time trials and ultimately winning the Tour de France for a record 7th time. I doubt that a bike of this nature could have been produced in under a year 30 years ago using the same amount of people.

One of the main reasons for these advances in that the amount of RAM and speed of processing has increased exponentially. These new programs require huge amounts of memory and processing power due to their graphic and interactive capabilities. The new systems of today deliver that power (my workstation is now over 3 years old). 15 years ago I would load one design area of a processing plant. One design area might have represented 10% to 15% of the whole plant. Once I called up the design area it was time to go get coffee because it could take about 10 to 15 minutes to load, and you would pray it didn’t crash. Today I am able to load an entire process plant in solid model image in about one minute using Intergraph’s Smart Plant Review technology. The ability this gives me as a supervisor to check designs and make comments is invaluable, this technology increases our quality.

For engineers and designers the changes have been staggering, even in my 25 years of design work I have gone from producing a limited plastic model of an oil and gas plant to giving the client a virtual walkthrough of every detail of an oil and gas plant. We must constantly keep ourselves up to date with the latest technologies to keep a competitive advantage. Those who don’t keep up will loose the race.