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BRITISH BROADCASTING CORPORATION
RADIO SCIENCE UNIT
CASE NOTES
Programme 1. - Radiology
RADIO 4
TUESDAY 08/05/07 2100-2130
PRESENTER:
MARK PORTER
CONTRIBUTORS:
NICOLA STRICKLAND
DAVID GRANT
VIKKI AYTON
CARRIE SHAW
GILL MARKHAM
RICK POPERT
PRODUCER:
HELENA SELBY
NOT CHECKED AS BROADCAST
PORTER
Welcome to one of the busiest radiology departments in the NHS. Nearly a quarter of a million investigations are done every year here at Hammersmith Hospital in London, and its sister unit, at the Charing Cross. It's not only busy - but as I'll be discovering - it's also one of the most advanced, being the first department in Europe to go film-less. No wayward packs of x-rays here - doctors can check them on computer.
I'll also be finding out about a new type of scanner that's proving popular with patients who find conventional machines too claustrophobic - and which can sometimes pick up problems older scanners miss.
And later on, away from the world of imaging and diagnosis, I'll be finding out how the destructive power of radiation is being harnessed using a novel technique to treat men with cancer of the prostate.
But first a tour of the some of the more complex equipment here at the Hammersmith. Although often referred to as an x-ray department, not all the tests involve x-rays - modern imaging using a range of alternatives including sound waves, magnets, dyes and radioactive isotopes. My guide is consultant radiologist Dr Nicola Strickland.
STRICKLAND
So this is our CT scanner. As you see we have three radiographers in here. This is Kate Pearson, our superintendent radiographer, who's in charge of CT and her two colleagues who are just scanning a patient on the table now. As you see we've got a ring shaped scanner - the patient lies on the table and that table moves through the centre of that ring where there are all the x-ray elements and the detectors. This is a spiral CT scanner, so-called, as most of them are nowadays, which means it's very fast and the patient is actually moving through the table on that moving bed whilst being scanned. So the trajectory of the x-ray passes rather like a spiral spring.
PORTER
And CT means what?
STRICKLAND
It means computer tomography and it's a way of getting cross sectional x-rays, if you like, of the patient. It's a bit like slicing a sausage into transverse sections so that you're looking at slices of the patient's body.
PORTER
Say I was to have a CT of my forearm, if I was to slice through my forearm, slice my hand off if you like, and then look at the stump, that's the sort image that you can get from the CT scan?
STRICKLAND
Yes in multiple slices...
PORTER
So you're taking one every centimetre or something?
STRICKLAND
We're actually taking one usually every one or two millimetres. And then we post process those, we put them on a special workstation, and we can reconstruct them in any plane, so I can look at them at any angle afterwards.
PORTER
There's a 3D image that you can get from those slices?
STRICKLAND
Yes you can form a 3D image, you can run through it in a quick stack, like flicking through a pack of cards, so that you get the impression that you're looking at a cine movie going through the body.
PORTER
Who decides whether a scan, an image, an x-ray, or whatever is appropriate or not because I mean if I was suspicious that a patient of mine had a problem with their lungs a sensible first step might be to organise a chest x-ray?
STRICKLAND
A chest x-ray and that would be the first step.
PORTER
But we know that CT is the better test for most things, why not just go straight to the CT?
STRICKLAND
Well mainly because there's a relatively high dose of radiation from a CT scanner, so you don't want to have too many CTs, you want to reserve CT for investigating an abnormality which is likely to be significant. In other words, a lesion that you've seen on a chest x-ray or a patient that has symptoms such as coughing up blood, which might suggest to you that they have lung cancer, those are the patients who need to be investigated in detail using a technique which is highly specific and sensitive with great resolution but nevertheless has a considerable x-ray dose.
PORTER
One way around the problem of exposing patients to radiation - albeit relatively small doses - is to use magnetic resonance imaging or MRI. MR scanners don't use x-rays to create an image, instead they use huge cylinder shaped magnets to create a magnetic field around the patient. This acts on atoms within the tissues temporarily altering their make-up causing them to emit a radio signal which the scanner picks up.
Different tissues respond in different ways depending on the type of atoms they contain and a powerful computer assimilates all the signals to produce an image of the part of the body being scanned. Tissues with few hydrogen atoms, like bone, show up dark - tissues with lots, like fat, show up white. The exact opposite of what you see on an x-ray.
STRICKLAND
Right this is the magnetic resonance scanner, the MR scanner. As you can see we've got a very thick door here to protect everybody from the strong magnetic fields that there are surrounding this scanner because unlike the CT scanner you just saw this doesn't use x-rays, it uses magnetic fields.
PORTER
To look at - to the uninitiated - it looks much the same as the machine that we were looking at before - the patient's lying on a flat bed going through a large tube, much larger tube in this case. The first thing that strikes is it's noisier isn't it, and that's something that my patients often tell me.
STRICKLAND
Yes it is noisy, they have to wear ear plugs and earphones generally to protect their ears from the noise.
PORTER
And slower as well, this takes a lot longer to collect an image than the CT.
STRICKLAND
Yes it's a completely different technique.
PORTER
And to look at, I mean the image to me looks very similar to the sort of image that you might get with a CT. As a radiologist what's the particular value of MRI over CT, I mean what do you use it for, do you use it for similar things?
STRICKLAND
In many respects we use it for similar things but you'll see that on that image you're looking at there you don't see any bones because there are very few hydrogen atoms that are mobile within bones and therefore they don't show up - they don't produce much of a signal. We use it whenever we want to obtain an image particularly of the soft tissues.
PORTER
So this is a heart and the main blood vessel - the aorta - coming out and going down the back divided into the arteries of the leg.
STRICKLAND
So this is an MR angiogram, as it's called, so it's the sort of study that we used in the old days to have to do by injecting contrast into a patient's arteries directly and then taking x-rays. Now we can do it completely non-invasively using the properties of flowing blood to construct an image of that nature.
PORTER
You talked about the safety issue of CT, there's a very small risk from exposure to radiation which we try and minimise by doing appropriate tests etc., but what MR - what do you know about the safety of strong magnetic fields?
STRICKLAND
Well they're thought to be very safe and of course there is a lot of evidence now that that is the case. The great thing about MR is that there is no ionising radiation whatsoever. As always in medicine it's a question of balancing the risks with the advantages and the diagnostic potential of both CT and MR is so great that it is almost always very well justified. So the majority of patients can go in an MR scanner without any problem because they don't have any contraindications. Interestingly one of the biggest problems that we have in the MR scanner is patients with claustrophobia and they don't like being shut in a tunnel, even though we give them ear plugs, we play them music so that they're distracted. It is nevertheless, for some people, an unpleasant experience going into a tunnel and feeling shut in. And interestingly more recently, because of the population becoming fatter, obese patients are often unable to get into this MR scanner, firstly because the actual weight of the patient is too great for the table and it won't support them, and secondly because if you look at that tube there the patient has to lie inside that tube and it's a relatively small diameter. So patients who are very obese literally can't fit and so funnily enough that is quite a problem.
PORTER
Open MRI scanners - where the patient isn't enclosed in such a small cylinder - are one way around the problem, but they are few and far between, with most being in the private sector. So how does the NHS cope with people who find conventional scanners claustrophobic?
David Grant is consultant radiologist at the Whittington Hospital in North London.
GRANT
I think there are several strategies. We try and spend time with the patients and explain what's going to happen and if need be actually give them a dummy run into the machine. But if you're truly claustrophobic it's considerate but it's not helpful. If you actually then go on to the next step of giving some form of oral sedation a small proportion of mild claustrophobics may be able to tolerate that. Having a general anaesthetic for a purely diagnostic test is actually quite a tall order and we would like really to avoid that if we could. So we would in the NHS outsource now to a open system.
PORTER
Dr Grant is also a medical director of the privately run London Upright MRI Centre which has England's first open scanner that also allows patients to be scanned in different positions - rather than just lying down.
GRANT
The Fonar upright MRI scanner, which we have at this centre, has nothing in front of the patient at all and they sit in a chair which can either be reclined into a lying position but effectively they can be scanned in any position, so we can immediately mimic the position that they get their symptoms in. And that has major advantages because we know that a number of patients that had multiple scans in conventional units have not reached a diagnosis and then when they have their scan in an upright position or a sitting position suddenly the abnormality becomes apparent.
PORTER
So what sort of patients do you see here?
GRANT
We see patients who have had problems with multiple scans in the past with no diagnosis, we see patients who've had previous surgery with no apparent clinical benefit and they still have their pain or disability and we see an increasing number of patients who opt to have this as a primary investigation simply because it's much more pleasant.
PORTER
You mentioned being able to change the patient's posture within the scanner, how might that be of an advantage?
GRANT
Well we know from research papers that the diameter of the holes that the nerves actually travel through changes in the horizontal position, supine, lying down as compared with standing up. And the change is quite significant.
PORTER
This is for back trouble so the nerves coming out the back.
GRANT
The nerves coming out of the back. And in general terms that can be around about 15%-20% in change in the size of the aperture. And there was a case that we've had here at this centre where somebody had intractable pain but only when they were sitting and they had no pain when they were lying down and they had multiple scans in previous conventional tunnel systems ...
PORTER
Always lying down of course.
GRANT
Always lying down and the scans were normal. When we sat them up here we did a conventional scan, just to see what it was like horizontal, and they were normal and when we sat them up they were very clearly not normal and you could see that part of the spine had actually moved relative to the bottom half and the cause of the problem was immediately there.
PORTER
Of course it's not only radiologists who often or normally examine their patients lying down, doctors, orthopaedic surgeons we're always looking at our patients lying on couches.
GRANT
It's the convention, it's the traditional way of doing it but it's not the way we actually spend most of our lives.
PORTER
So you would aim here using the alternate positions to replicate the position in which the patient gets the pain and then look to see whether there's any demonstrable abnormality?
GRANT
It's very much a problem solving technique.
PORTER
And in designing a scanner that allows you to move the position of the patient and there's nothing in front of them because it's open, are you compromising the quality of the pictures that you're getting at all?
GRANT
I think that the answer to your question is essentially yes but everything in radiology, in terms of the technology, is a design compromise. And if you're able to actually obtain meaningful information on patients who previously undergo this then clearly that is a greater strength than having something that may give anatomically sharper images but the patient can't undergo the study. And when I say anatomically sharper it's a very minor degree of difference.
PORTER
Next door a patient was having his head scanned. Vikki Ayton is the centre's radiology manager.
Okay so we're in the room where the scanner is now, I suppose the best way to describe it is it's a bit like a narrow passageway with no roof to the top of the passageway and the patient's sort of halfway down sitting on a chair. And I notice that his head's fixed there.
AYTON
His head is actually positioned within a head coil, the coil actually picks up the signal from the patient and gives us the information. This particular coil is quite open in front, as you can see, so the patient can see out and he's actually watching - he's actually transfixed - watching the television which is a 42 inch plasma screen.
PORTER
Whereas in a conventional scanner, I mean the manufacturers of conventional scanners have done things to make them better - they have lights in and a little mirror so that you can see your feet - but they don't have 42 inch plasma screens.
AYTON
Absolutely not.
PORTER
So we're sitting outside the scanning room here - outside a thick wall and thick doors to keep all the magnetic fields out - but I can still just about hear something, the patient's hearing that much louder presumably?
AYTON
Yes they can hear that, it's actually the magnetic field grading switching on and off very rapidly. But it's not as loud as in the conventional MRI scanner, this is quite a gentle one.
PORTER
So you've just finished your scan, now you've had a scan - this is your second scan isn't it, what happened the first time?
PATIENT
I couldn't stay in there, I was in there 14 minutes and I had a panic attack because they put the mask over me and it was like just going in a tumble dryer.
PORTER
This was in a conventional scanner.
PATIENT
Correct yes.
PORTER
And are you a claustrophobic chap, have you had problems with claustrophobia in the past?
PATIENT
Not before no, no.
PORTER
So you thought this won't be a problem?
PATIENT
This is it, no, it's true, yeah. Just went up there, they put me on the bed and then they put this mask on and then they tightened the screws up and I thought this is it, didn't like it, panic, panic. This I just settled down, I just relaxed, the TV was there.
PORTER
You're watching a great big plasma screen.
PATIENT
Yeah, which was good, you know it takes it off of you.
PORTER
I was watching you because I'd heard you'd had a little bit of a problem with your last one, so I was watching you through the screen here, I mean you looked very relaxed.
PATIENT
I couldn't wait to get back in, to be perfectly honest.
PORTER
To catch up with the television programme.
PATIENT
That's right. I'd been in there for an hour and a half before you got here and I was totally relaxed.
PORTER
Well that patient's scan was immediately available for viewing on the screen in front of Vikki - which is exactly what happens to all the images taken at the Hammersmith Hospital. Images go straight onto computer, where they are checked and reported on by radiologists before being made available to doctors at terminals throughout the hospital. No more lost x-rays or scans - the bane of many an outpatient appointment. Dr Nicola Strickland, and radiographer Carrie Shaw, showed me how the system works.
STRICKLAND
The patient lies on the table, has their x-ray, it goes through to a specially sensitised plate where the signal is picked up digitally and transmitted to this screen.
PORTER
So this is the sort of equivalent to a digital camera, there's absolutely no film involved at all, it literally goes straight through ...
STRICKLAND
No film, the radiographers don't have to put in any plates or anything, it's all done automatically and transmitted through to the monitors.
PORTER
Does the patient notice any difference?
STRICKLAND
I think the whole system's quicker - what do you think?
SHAW
Much quicker.
PORTER
No faffing around with films.
SHAW
You come round here, see the film on there and then send them.
PORTER
Presumably your job would have been to prepare the film, load the film, get the positioning right and then have to develop it afterwards?
SHAW
Yeah and then you've got - you obviously have to do any repeats, you got to go and check the film and then come back and get the patient back in. Throughout all this the patient's obviously got to wait.
STRICKLAND
And the patient used to have to wait until the film had been processed, so it could be checked. Now as soon as the film has been taken, just as you say like a digital camera, we see it on a monitor and the patient can go. And in fact to be honest by the time the patient has gone to their outpatient clinic that x-ray is already on our hospital wide computerised system, we - the radiologists - have reported it and it would be ready for their doctor to see down in the clinic.
PORTER
Well let's see how the system works.
SHAW
So basically when the reception book these in it comes straight to our computer and on to a work list, so all we have to do is just select the patient, which is ...
PORTER
So we've got a load of names up here and their name plus what needs to be. The one thing that always worries me about computers of course is if they crash, if the system goes down, the great thing about having a hard copy with all your films is that - particularly when you've got a new computer system - you're not going to be stuck in a clinic somewhere where all the doctors in the outpatients can't see the x-rays and the reports that they want. Has that - in the 11 years that you've been running - has that been a problem?
STRICKLAND
It has happened and anyone who has a computerised system of this complexity who says it hasn't happened isn't telling the truth. It does happen but that's why you need to have such a robust backup system, which we have here - we have a whole protocol for being able to deal with that. We can still produce film, we can produce CDs. It is very rare for the entire system to go down, one or two workstations may go down, the network may have a problem in going slowly but we've only once, that I can remember, had the entire system go down, and fortunately it was over Christmas and it was due to an upgrade which had a corrupt disk. But that is rare but you do have to have very good IT backup and support before you go anywhere near a system like this.
ACTUALITY
Okay breathe in for me there. Breathe right the way out. Okay stop there. Okay breathe normally there.
PORTER
And there it is, straight - just taken the x-ray, straight up on to the screen.
STRICKLAND
And that actually looks perfect but if we needed to my radiographer colleague here could just change the contrast, window, width and level to make it look more black or more grey, to make it look perfect, in other words.
PORTER
So you check the quality of that immediately to check that it's to the right standard and then that's it the patient can go.
So this is the reporting suite. Just describe where we are for us Nicola will you?
STRICKLAND
So we're in the main centralised reporting room of the imaging department in Hammersmith Hospital here. And as you can see it's divided into individual booths for each radiologist and in each booth we have a dual monitor, high quality diagnostic PACS workstation - for picture archiving and communications - and this is the list from which I would be doing my reporting work.
PORTER
And there's our lady at the top of that list. But there's quite a few names on there, I mean is this basically - do the radiologists come in here and just tuck into the work list?
STRICKLAND
Yes.
PORTER
So the x-rays come through here presumably and you're viewing them on this other monitor are you?
STRICKLAND
Yes, so I going to now display that study in order to dictate it. And you can see that it's come up at full size on my right hand monitor. Had there been any previous x-rays on this patient of the same body part then I would have seen them next door but in fact it's the first back x-ray that she's had. So here we can see the frontal view and if I click there we can see the lateral view. I've got the clinical details in front of me on this inset which are automatically displayed. So I'll dictate those onto my speech recognition system, which as you see looks like a normal microphone.
PORTER
So the clinical note says that this lady's had some lower back pain after lifting some of her shopping.
STRICKLAND
Yeah she's actually had a renal transplant in the past and that's actually very important information because that means that she will be on immunosuppressive treatment and she might be more susceptible to infection and we have to look out for that, in case she had a discitis or something of that sort. But she's particularly suffering from pain in the back after shopping and lifting heavy weights in other words. So I need to record that information onto this system here. Clinical details: [new line] - renal transplant. Pain after lifting heavy shopping. [New paragraph] Report: [new line] the alignment of the lumbosacral spine is normal. Vertebral body and in-vertebral disc heights are well preserved. The vertebral end plates are intact. The sacroiliac joints are also normal.
So in fact, as it turns out, the bony structures are all normal. She's most probably got a soft tissue, a muscle, sprain or something of that nature but it's not due to any fractures of the vertebral body, she hasn't got any vertebral body collapse and there's no evidence of any infection there.
PORTER
Dr Nicola Strickland.
One development in imaging that has not been welcomed by all is the use of total body CT scans as a form of screening. It started in the States, but a number of companies are now targeting the worried well here in the UK, particularly those who have good reason to be concerned - like smokers. Dr Gill Markham is Dean of the Royal College of Radiologists.
MARKHAM
We're very concerned about it actually. It's not just the radiation dosage, which of course if you are having what's sometimes called an MOT, how often do you do that? So a perfectly healthy person might feel that they have to have it done every three years or five years or whatever the recommendation is and it's all cumulative. But at least as worrying as that is because we have so much detail we can pick up now we pick up all sorts of little blobs and things that are there but are of no significance at all. But once you've seen something you then have to check whether or not it really is significant. So they are then referred on for either further x-rays, CTs, investigations, sometimes requiring a biopsy with a needle into the thing that you've seen to prove whether it is significant or not and this increases with age. So if you've got someone over 70 the chances are you will find something in 80% of patients, which is an awful lot of worry for the patient before it's confirmed to be nothing and anxiety and cost and everything else.
PORTER
I mean why not have a total body MRI then which gets around the radiation problem but still has this diagnosing problem where you're picking up bits that you wouldn't normally find?
MARKHAM
You still have that problem, yes, yes and that is a very significant problem.
PORTER
Leading to unnecessary anxiety and investigation.
MARKHAM
Anxiety in extra investigation, possibly irradiation, extra irradiation to prove what you've got and in the end something that wouldn't have been significant. So all in all it's fine for a patient who perhaps wants to go and is told yes that's fine but the downside of that is they might be, let's say, worried because they've been smoking or are not feeling well, there are many things that a scanner will not pick up and you need to very carefully explain that if you've got high blood pressure that won't be picked up, if you've got diabetes that won't be picked up. And you know they might think oh well fine, I'll carry on smoking because I'm alright, I've had this scan that's told me I'm fine.
PORTER
Radiation isn't only used to create diagnostic images, its destructive powers can also be put to use and form the basis of radiotherapy. The conventional approach is to use crossed beams of powerful x-rays to irradiate a cancerous growth to stop it growing, or to shrink it. The main risk being damage to nearby healthy structures.
Brachytherapy is a form of radiotherapy used to treat cancer of the prostate from the inside using multiple radioactive implants or seeds.
Consultant urologist Mr Rick Popert and his colleagues at Guy's Hospital have treated 170 patients over the last three years with brachytherapy. I joined them as they were about to treat this gentleman with early prostate cancer who was worried about side effects associated with other treatments.
PATIENT
Yeah well I was told that the other option I had was to have the prostate removed totally but because of the level of the cells etc., I was told that this one was relatively capable of killing the cells.
PORTER
But with fewer side effects though?
PATIENT
Yes.
PORTER
And what have you been told about the actual procedure, do you understand that there's going to be radio emitting implants put inside you?
PATIENT
Yes actually Mr Popert here explained fully to me that what would be happening is that they would inject some seeds into the area and try to place it as close as is possible to the cells with the hope that over a period of time they will kill off the cells that are near.
PORTER
And you're coming in as a day case today, you plan to go home later on?
PATIENT
Yes.
POPERT
What we have is a patient in the position where they are lying on the operating table, their legs are flexed backwards towards their chest and externally rotated - that means pushed outwards. And that allows us to have access to the back passage and access to the area called the perineum, which is the space between the back passage and the scrotum because that's where we're going to place the needle. So we're not going through the back passage, we're actually going through the skin. And it means that at the end the patient just has some puncture marks where the needles have been placed and they don't even see that or even really feel it. So from a patient perspective they often think what did I have done?
PORTER
So to give us some rough idea how big is this chap's prostate gland?
POPERT
So this gentleman's got a relatively small prostate, it only measures about 20 ccs, which is about the size of a small walnut or a Ferrero Roche. It has within the middle of it a deep vent which is the bit that we cored out. The cancer cells tend to be in the peripheral part of the prostate gland in the outer portion. And so what we have to do is place needles both within the outer portion and as close to the inner portion as we can to ensure that we can get full coverage of the prostate gland as a whole. So it's like producing a cloud of radiation which encompasses the whole of the prostate. And we're out to kill the prostate cancer cells but as a result of that the prostate itself is stopped from growing. So ultimately his prostate gland will probably shrink even more.
PORTER
But why brackytherapy using these implanted seeds rather than conventional radiotherapy where we'd be using external rays?
POPERT
Convenience is the main thing. There's probably no great difference in low risk patients as far as long term outcome is concerned. But the advantage of this is that it is a single visit day case procedure and once it's done that's it. If you have to have external beam radiotherapy then you have to go through a planning system, same as this, assess the patient, but then you have to attend on a daily basis for a period of about six weeks. So it's about 30 odd visits to get on to the table, get into the right position, then they give the external beam radiation. And although we can contour that radiation so that you can conform the radiation to the shape of the prostate it's an estimate and the potential for collateral damage is properly greater than with this, this is what we would call true conformal radiation, which is really conforming to the actual shape of the prostate.
PORTER
Mr Rick Popert. And I am pleased to say that the patient has since made an excellent recovery and is back at work.
If you want more information on brachytherapy, open MRI scanners, or any of the issues we have discussed today, then you can visit our website at www.bbc.co.uk/radio 4 or call our Action Line on 0800 044 044.
Next week I'll be looking at the latest developments in the diagnosis and treatment of MS - multiple sclerosis.
ENDS
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