July 2007 Archives

The AAPM annual meeting is over - the 100+ exhibitors have torn down their booths, the conference attendees have flown back around the world and the medicalphysicsweb team is back in the office. Asides coping with the shock of leaving hot and sticky Minneapolis for damp and drizzly Bristol, we're busy checking through our notebooks for any key news and events that we didn't have time to include in the blog. Look out for additional coverage on medicalphysicsweb over the next week or so.

The meeting attracted a record 2294 scientific registrants, up about 80 from last year, and a total of 3881 attendees, including exhibitors and companions - one of the highest attendance numbers to date. Personally, I thought it was a great success. If you'd like to share your own views on the conference or trade show - or your opinions on our blog coverage - please feel free to post your thoughts using the commenting tool at the end of each entry.

Finally, it's worth noting that 2008 is the 50th anniversary of the American Association of Physicists in Medicine. Next year's AAPM annual meeting (being held in Houston, TX, from July 27-31) will include a number of special sessions to celebrate this anniversary. According to Jean St. Germain, chair of the AAPM ad hoc committee for the 50th anniversary, the theme for 2008 will be: "Honouring the Past, Celebrating the Present and Preparing for the Future". See you there?

10:05 Wednesday CT: When I saw Radiological Imaging Technology's (RIT) latest advertising poster I had to go and find out more. It features leather clad men and a very hot custom motorcycle – not the usual marketing tactic of QA software vendors. Apparently, however, if you're a medical physicist then it's not only the motorcycle that's hot. RIT has just launched version 5 (V5) of its QA software package RIT113, and according to vice president of marketing Ellen Ritt, the new features are getting physicists at the show "very excited".

QA's darker side

Physicists aren't usually the most excitable of people, so what's all the fuss about? As well as many new time-saving features, V5 includes a "unique correction algorithm" that can be used to get more information from radiochromic film. Hospital physicists are under increasing pressure these days to find an alternative to the wet-film techniques traditionally used for many QA tasks. Wet film provides good-quality images, but processing it is costly and time-consuming. As a result, many hospitals are switching to radiochromic film.

Radiochromic film - much like Polaroid film - is very convenient because it doesn't need to be processed. The drawback is that you can't achieve the same level of image quality as you can with wet film. The new V5 software, however, has an image analysis tool that RIT claims can correct for this, allowing QA physicists to get as much information from radiochromic film images as they could get from wet film images. If it lives up to the marketing hype, then it sounds like this could make a lot of hospital physicists' jobs much easier.

RIT is inviting AAPM attendees to "test drive" V5 at its booth, so go along and see if it really is all it's cracked up to be. And if you're lucky staff will even give you some free (temporary) tattoos to complete the bad-boy image. Sadly, however, there is no sign of a prize draw or raffle to win the motorcycle.

06.57 Wednesday CT: It's not often that a clinical technology decision is made on the basis of who can make the most noise. Well, perhaps sometimes it is - but certainly never when that noise is being made by plastic clapping hands wielded by an audience of slightly overexcited medical physicists (see picture).

Vote now

The clinical decision in question was which of the numerous technologies employed for image-guided radiation therapy (IGRT) is most likely to succeed. In a session entitled "The Great Debate: The Future of IGRT Is...", five distinguished speakers presented opening arguments for megavoltage (MV) and kilovoltage (kV) CT, ultrasound-based hybrids, MRI guidance and 3D deformable image registration. As for the audience: well we got to decide the winner via a show of (clapping plastic) hands.

Timekeeper

In what was possibly the most entertaining - and certainly the most raucous - scientific conference session that I've ever attended, Marc Kessler (a professor of radiation oncology at University of Michigan Medical School, Ann Arbor, MI) demonstrated a novel, if somewhat unnerving, method of timekeeping. Any speaker running over their allocated time slot found themselves the target of Kessler's Nerf gun (which fires Styrofoam "bullets"). Kessler certainly seemed to be enjoying himself anyway.

Round one of the debate gave each speaker just six minutes to introduce their case. First up was Jean Pouliot of the University of California, San Francisco (San Francisco, CA) who described the advantages of cone-beam and fan-beam MV CT. "It's a long-term dream to turn the imaging machine into the treatment machine," he said. "[With MV CT], the treatment beam is the imaging beam - you treat what you see."

Pouliot rebuffed the claims from other panel members that the technique delivers too high a dose and doesn't give good enough image quality, pointing out that image quality has rapidly increased over the last five years, and continues to do so. "It provides equivalent alignment precision to kV cone-beam CT," he claimed, adding that the dose can be comparable too.

The second speaker to take the stand (and brave the Nerf gun) was Jan-Jakob Sonke of the Netherlands Cancer Institute in Amsterdam. Sonke presented the case for kV cone-beam CT and discussed the latest technology advances, such as 4D guidance to account for respiratory motion. Sonke told the audience how - following a quick vendor survey at the trade show - he concluded that kV CT represents the lowest cost option of all the proposed methods in the debate.

Next up, Wolfgang Tomé of the University of Wisconsin-Madison (Madison, WI) touted the idea of using optically guided 3D ultrasound for IGRT. He noted that ultrasound imaging can be used in combination with intermittent (say, weekly) cone-beam CT scans to minimize any uncertainties in the ultrasound-based alignment, while enabling accurate daily guidance with a large reduction in cumulative dose.

In a slight twist, Tomé actually suggested that none of the technologies in the debate are actually the future of IGRT. What's really needed, he explained, is a means by which to assess metabolic changes during the therapy itself - a scheme he dubbed image-guided treatment. "I can't say that ultrasound is the future of IGRT on its own, but it will play a key role, in conjunction with kV or MV CT," he concluded.

Jan Lagendijk, from the University Medical Center Utrecht in the Netherlands, proposed a novel scheme in which the treatment machine is fully integrated with an MR scanner, enabling precise soft-tissue visualization for treatment guidance and verification.

A key benefit of this technique is its ability to reduce the required margins and minimize normal tissue complications. "You need imaging during the treatment itself, and the only way to do this is with MRI," he declared somewhat controversially. Lagendijk brushed off the criticism from his fellow panellists that such a system doesn't actually exist yet, stating that it will be developed "quicker than expected".

Finally, Kristy Brock of the Princess Margaret Hospital in Canada (Toronto, ON) argued that the future of IGRT lies not in any one imaging modality, but in the use of deformable modelling to combine diagnostic-quality images with daily image guidance. "All these are great imaging technologies but we need to integrate them together," she explained.

Kristy Brock

And the winner? It was a resounding victory for Brock, proving perhaps that the debate is actually still to be resolved - or maybe never will be. It's likely that all of the above technologies will continue to be employed, and will be further developed and enhanced. As Brock said: "The future of IGRT lies not one of these modalities, but in all of them."

17.28 Tuesday CT: For many of the vendors exhibiting at the AAPM trade show, brachytherapy was the name of the game. For starters, medical device company Nucletron (Columbia, MD) was showcasing its latest brachytherapy offering - the microSelectron Digital afterloader.

microSelectron Digital

The afterloader offers a choice of six, 18 and 30 channels, as well as the ability to perform both high-dose-rate and pulsed-dose-rate brachytherapy. "It is new to have both treatment types in the same system," Nucletron's Tom Pollatz told me. The microSelectron Digital's big selling point, however, is the ease with which it can be upgraded.

A user looking to make a low capital investment could purchase a 6-channel system, for example, which is ideal for use in gynaecological procedures. Then, if at some stage in the future the clinic's resources increase, or the clinicians want to treat additional body parts, they can upgrade to an 18- or 30-channel system - enabling treatments such as prostate brachytherapy or interstitial breast brachytherapy.

The upgrade in itself is relatively straightforward, requiring only minimal downtime and staff training. Pollatz says that, unlike the case for some afterloaders, the main unit itself does not need to be changed, protecting the customer's initial investment. It's simply a case of uploading the software key required to use the higher-channel option.

"Our goal is to provide the lowest-cost entry level for a centre to start a brachytherapy programme," said Pollatz. "We're building a scalable brachytherapy treatment solution that our customers can tailor to whatever body site they want to treat."

The microSelectron Digital afterloader is compatible with a wide range of applicators - including those being newly showcased at this year's AAPM meeting, such as North American Scientific's ClearPath (see More from the exhibit hall) and the SAVI from BioLucent (Aliso Viejo, CA).

BioLucent's SAVI is a new breast brachytherapy device for accelerated partial-breast irradiation (APBI) following a lumpectomy. The applicator combines the tissue-sparing dosimetry of interstitial treatment with the single-entry ease of a balloon-based applicator.

SAVI

The SAVI applicator comprises a bundle of catheters surrounding a central lumen. It's placed into the lumpectomy cavity through a small incision, and the bundle is expanded to form an ellipsoid. The catheters can be individually imaged (some contain markers for easy identification) and then loaded as appropriate to comply with the medical physicist's treatment plan.

"SAVI combines the best of both worlds," Brian Driscoll, BioLucent's director of marketing explained to me. "It offers the benefits of needing just one incision, but with the dosimetry benefits of an interstitial device." The ability to contour the dose also enables the device to perform APBI in areas located close to the heart or skin, which are not suitable for treatment with a balloon-based applicator.

Driscoll explained that the SAVI received FDA approval last July, treated its first patient in November and is now being exhibited for the first time at a trade show. "It's still a controlled launch, but we're getting closer to a full national launch," he added.

17:19 Tuesday CT: At 5.45 this morning (thank goodness for jet lag!), early-rising locals were treated to the unusual sight of a large gathering of shorts-and-T-shirt clad medical physicists, exhibitors and one journalist in Minneapolis' Boom Island Park. Today was the annual AAPM/Gammex 5k run, which each year sees hundreds of delegates braving an early start and punishing heat in search of that elusive personal best.

Get set, go

Heat certainly was a feature of this year's run. The thermometer was showing 75°F as we pounded past, but the humidity made it feel considerably hotter. Our very own runner extraordinaire, Simon Harris, reckoned that this year's temperatures trumped even those suffered by last year's competitors in Orlando, FL. Perhaps this is why, out of approximately 230 people who registered for the run, only 155 actually turned up.

Tim wins

The conditions didn't seem to hamper race winner Tim Szczykutowicz too much. Making his debut at this event, the physics student from the University at Buffalo (New York, NY) completed the 5k in 18 minutes 43 seconds, well ahead of his quickest competition. What's more, rumour has it that this trifling distance didn't tire him out enough, so he planned to run the extra couple of kilometres back to his hotel. medicalphysicsweb's Tami Freeman asked him how it felt to win: "Very good," said Tim.

Simon

Michelle

All in all, the medicalphysicsweb contingent didn't do too badly. Physics in Medicine and Biology publisher Simon Harris came 15th, with a time of 23:30. "Never again," said AAPM meeting regular Simon while cooling down in the park afterwards. "Mind you, I said that after the race last year!" My effort of 27:50 yielded 40th place - making me not only the fifth woman across the line, but also faster than medicalphysicsweb editor Joe McEntee, who competed in the event last year. (That's enough self-congratulatory reporting - JM)

The full results are available at the Gammex booth, and will be put up on the Gammex website shortly.

17.47 Monday CT: Early this morning, a crowd was gathering at IBA's booth to find out exactly what the Belgian particle-therapy company has been keeping under wraps. So what was hiding under that cover? IBA's staff dramatically swept the cloth away to reveal...its Universal Nozzle.

Under the cover

It may not look particularly impressive, but the Universal Nozzle is a nifty piece of kit. In simple terms, the nozzle can be used to perform four different types of proton therapy: single scattering, double scattering, uniform scanning and pencil-beam scanning. What this means is that users wanting to perform these different techniques no longer have to build separate treatment rooms for each one.

"The Universal Nozzle is a way of delivering protons that allows you to do scanning and scattering techniques in one room," announced Stephen Sledge, IBA's marketing director.

By the way, if you were there, and you're still wondering what to do with the small green objects that IBA was handing out, just peer into the end - the effect is quite startling.

17.35 Monday CT: Using medical images to gauge a patient's response to treatment is nothing new. But with the emergence of advanced imaging methods, and applications like drug development becoming increasingly reliant on such techniques, the use of imaging as a biomarker for therapeutic response has become a prominent area of research. So much so that "Imaging as a Biomarker for Therapy Response" was chosen as the theme for this year's AAPM President's Symposium.

The symposium kicked off with Lawrence Schwartz of the Memorial Sloan Kettering Cancer Center (New York, NY) telling delegates about the intense interest in using imaging biomarkers for new drug development and drug discovery. Here, imaging is used to test the efficacy of potential drugs via direct visualization and quantification of changes in physiological processes following treatment. Imaging also offers a noninvasive means by which to assess the safety of a new drug.

The process of developing any new drug is a long and complex procedure. On average, a pharmaceutical company will shell out $802 million over 15 years to bring one new drug to market, with 99 other drugs typically discarded along the way. Anything that can speed this process is obviously of great interest.

"Imaging is more and more important in drug development," concurred Michael Vannier of the University of Chicago (Chicago, IL). "There is an opportunity here for imaging to remove materials that won't succeed in the long term at an earlier stage, thereby reducing the cost and saving time."

In particular, Schwartz believes that imaging biomarkers will play a key role in the development of targeted molecular therapies for cancer treatment. One technique that has proven invaluable is PET-CT, which can assess the impact of a treatment on tumour metabolism. Importantly, PET-CT can detect metabolic changes before any change in the tumour size is observed, providing an early predictor of therapeutic response. Schwartz also cited dynamic contrast-enhanced MRI, which can monitor changes in tumour vascularity.

There's still work to be done here, however. Vannier reckons that the full potential of imaging biomarkers cannot be realized without stringent quality control, the development of data repositories and a "community effort" to validate new techniques. "There's a critical and immediate need for the medical physics community to get involved in imaging biomarkers," he told delegates.

• In addition to the important application of drug development, imaging still has a big role to play in measuring treatment response and potentially providing a prediction of therapeutic outcome.

Daniel Hamstra

One such method was the subject of a presentation at Varian Medical Systems' Emerging Technologies Symposium held in the nearby Hyatt Regency hotel. Daniel Hamstra, a clinical lecturer in the University of Michigan's department of radiation oncology (Ann Arbor, MI), told Varian's guests about the potential of diffusion MRI for early response evaluation.

Diffusion MRI, he explained, measures the "thermally driven molecular motion of water" within tissue. Following treatment, the tumour's cellular membranes break down, which results in an increased mobility of water within the tissue. Diffusion MRI can pick up such histological changes, which occur much sooner than any changes in the tumour's overall volume. The diffusion MRI data also show potential as an early predictor of overall survival or time-to-progression.

"Ten years of preclinical data support the concept of changes in diffusion MRI data acting as an early indicator of tumour response," said Hamstra, adding that "diffusion is complementary to other measures of response, such as perfusion or PET," and concluding that a multimodality approach is likely to prove the most favourable way forward.

17:34 Monday CT:

"The g-force [felt by a CT source during a scan] is larger than that felt by the space shuttle during take off."

This interesting fact was produced by Otto Zhou, a professor at the University of North Carolina at Chapel Hill (Chapel Hill, NC), during the "Advances in X-ray imaging" symposium this afternoon. He was making the point that there is not much room for improving the temporal resolution of CT with current technology. This is because it relies on the mechanical rotation of large X-ray tubes, and Newtonian mechanics limits how fast that can practically be done.

Not surprisingly, he has a solution to offer. Perhaps slightly more surprising is the fact that it comes in the form of carbon nanotubes (CNTs). While these are being touted as a wonder material for their strength, toughness and electrical properties, it is hard to envisage them producing X-rays powerful enough for medical imaging.

Thanks to a phenomenon known as field emission, however, they can, and Zhou claimed that CNT-based X-ray sources would have several advantages over conventional technology. As well as being smaller and lighter, each nanotube would produce its own focal spot. This would allow for a source array that could surround the whole patient, meaning no mechanical motion would be needed and temporal resolution could be improved significantly.

As if that isn't enough, Zhou also thinks his nanotubes will one day form the basis of a novel radiation-therapy system. What's more, CNT-based microirradiation systems developed at the University of North Carolina are already contributing to radiobiological research, as medicalphysicsweb reported last year. Check out Nanotubes shed light on cancer therapies for the full story.

17:07 Monday CT: As I was continuing my quest for interesting exhibitor news this morning I was drawn to the large contraption on show at the Zeiss (Dublin, CA) booth. I wrote about the company's IntraBeam intraoperative radiotherapy (IORT) system earlier this year (see Where physics meets surgery on medicalphysicsweb), but this was the first time I had actually seen it in the flesh. To my journalist's eyes it certainly looked to be an impressive piece of kit.

Intrabeam

The stand was being manned by a fellow Brit - and a researcher at that. Marinos Metaxas of University College London Hospital (London, UK) - which played a large part in the development of IntraBeam and was the first institution to use it clinically - is so impressed by the results he has seen with the system that he's willing to stand at the Zeiss booth and extol its virtues to passing delegates (and the odd journalist) himself.

IORT describes a system of radiation therapy whereby immediately after a tumour is resected, a single dose of radiation is delivered directly to the tumour bed using a special applicator. This has several advantages for both patient and clinic because it is over in a single session, rather than requiring treatment over several weeks as is the case with conventional external-beam radiotherapy.

IntraBeam is currently being used in a multi-institution long-term clinical trial for breast-cancer patients. This is only half complete at the moment, but according to Metaxas the results are extremely encouraging. All patients are currently still disease-free, with the first being treated five years ago. We'll have to wait until 2009, however, to see if this is confirmed by the full statistical analysis.

Other exhibitor news:

• Standard Imaging (Middleton, WI) has added new features to its BeamChecker Plus QA system that enable the product to be used with TomoTherapy machines. The vendor is also showcasing two brand new phantoms: the QCkV-1, which is apparently the only system available that is capable of doing quantitative tests on kV imagers; and the stereotactic dose verification (SDV) phantom. The latter is a blue block that combines the necessary equipment for pretty much every test you could want to do on a stereotactic radiation-therapy system - or does it? Any QC physicists who have checked out the new SDV phantom, feel free to chime in using our commenting tool.

• North American Scientific (Chatsworth, CA) has just launched its breast brachytherapy system ClearPath, which is intended to be used after a lumpectomy. It features a unique system of expanding catheters that enables clinicians to produce a dose that conforms to the shape of the tumour bed without creating hotspots in surrounding healthy tissue. Exective vice president and CTO Michael Cutrer also told me that this is the only conformal breast brachytherapy system with the ability to do both high-dose-rate and low-dose-rate treatments.

17.35 Sunday CT: As the loudspeakers announced the opening of the AAPM Annual Meeting's trade exhibition, and the attendees flooded onto the show floor, the first booth to catch my eye was that of Varian Medical Systems (Palo Alto, CA), not least because all the Varian staff were adorned with rather large, brightly flashing badges.

Varian

Closer inspection revealed that the badges were promoting the company's new "Smart Segmentation" radiotherapy treatment planning tool. So I went along to find out what all the fuss (and the flashing lights) was about.

According to Robin Reddick, Varian's product manager for treatment planning systems, Smart Segmentation can significantly reduce the amount of time needed to create treatment plans for intensity-modulated radiation therapy (IMRT) and image-guided radiation therapy (IGRT). And it does this by taking a large chunk of the work out of the user's hands.

Smart Segmentation performs the contouring process (identifying the anatomy and any tumours) automatically. It detects the patient's orientation and gender, plus the region of anatomy being scanned, and then draws outlines on the CT images that define the body parts and target lesions.

Defining contours is one of the most time-consuming tasks in radiotherapy treatment planning. Reddick says that the software does 80% of this work, and then the clinician can review the contours and adjust them as they see fit. "It's about applying human input at the time when it's the most valuable," he explained to me.

"IMRT is critically dependent on defining everything that you want to hit and everything that you want to miss," Reddick added. "If you don't draw it on, then you can't control the dose to it."

Workflow efficiency is also a headline theme on the TomoTherapy booth. The Madison, WI company claims that StatRT, a new software package for its Hi•Art treatment system, enables the entire radiation-therapy process - from CT scanning to treatment delivery - to be completed in as little as 30 minutes.

"In one slot, we acquire a CT scan, use it for treatment planning and optimization, and do the treatment delivery, while the patient's still in the room," TomoTherapy's CEO Frederick Robertson explained to me, adding that this process usually takes over a day to complete.

The reason that StatRT can do all this lies in the unique design of TomoTherapy's Hi•Art product, which combines CT guidance and IMRT in one system. The entire process is also managed from a single computer. "An integrated system dramatically streamlines the workflow process, and therefore dramatically reduces the time requirement," Robertson explained.

What's inside?

• One final note. On passing by IBA's booth, I noticed that - despite the trade show starting today - the Belgian particle-therapy company is still keeping some things under wraps. According to IBA, a big news announcement (and what's under that cover) will be revealed first thing tomorrow morning.Watch this space...

17:30 Sunday CT. This year's exhibit features about 130 companies. As well as the usual suspects, such as Varian, Elekta and Siemens, this includes a host of smaller names. My mission for today was to chat to a few of these medium-sized companies. After an afternoon spent traipsing the aisles, partaking of the free food and drink, and grilling a selection of exhibitors, here's what I have to report:

Restitu 2.0

• Resonant Medical (Montreal, Canada) is previewing version 2.0 of its Restitu ultrasound-based IGRT system. Restitu enables clinicians to verify that a tumour is in the expected position before they commence treatment and, if necessary, to make adjustments to their set-up. The current version can only be used for prostate, bladder and gynaecological tumours.

Version 2.0 will also be suitable for breast cancers and, according to Mark Broeders, Resonant's director of marketing, it will be the only system suitable for verifying electron-boost treatments as well as conventional X-ray treatments. He also claims that Restitu 2.0 will be quicker than its predecessor, but that's all he'll say for now. The official launch is scheduled for the ASTRO annual meeting in LA in November.

Implantable dosimeter

• It's only been a year since Morrisville, NC-based company Sicel Technologies got FDA approval for its implantable dosimeter-based product DVS (Dose Verification System). Since then, things have been moving forward on several fronts. At the heart of DVS are tiny electronic gadgets that can be implanted into a patient's tumour. These devices can serve as fiducial markers for IGRT, and can also record the exact dose received by the tumour.

At the moment, the system is calibrated to work with 6-8 MeV photons, but in the next couple of months the company expects to bring out versions suitable for high-dose-rate (HDR) brachytherapy, hypofractionated radiation therapy and electron treatments. Sicel clinical specialist Connie Childress told me that the company is also developing a version of DVS that can measure the temperature of a tumour, and how much of a chemotherapy drug it has taken up.

Galaxy

• If lasers are your thing then LAP (Boca Raton, FL) has a couple of brand new products on show. Its Galaxy patient-alignment system, which was launched today, maps the entire body and checks patient position by comparing this map to the images used for treatment planning. Vice-president Trent van Arkel reckons that not only is Galaxy more accurate than previous systems (which only measure the position of three points on the body), it is also fast and user-friendly.

LAP has also redesigned its 3D simulation lasers. The new system won't be available to buy for another year, but there's one on show at the booth. New features include a new, lighter profile; wireless Bluetooth communication between the lasers; and a single tablet PC interface.

• The sponsor of the 5k "fun" run (check back on Tuesday to hear about how that goes) Gammex (Middleton, WI) has a new neonatal phantom on show, which is due to go on sale by the end of the year. Assessing and limiting the radiation dose to children from medical imaging and therapy is particularly important, as it could cause late effects long in the future. Gammex claims that this is the first product of its kind.

After a hard day's work at the AAPM meeting, delegates looking to relax a little will find plenty to do in and around Minneapolis. A quick search through the official visitors' web site revealed over 150 sports, theatre, musical and other events during the week of the AAPM meeting. I couldn't hope to even begin to summarize them all - but here are a few that caught my eye.

• Starting off with some theatrical highlights. Neil Simon's Fools is playing at Minneapolis' Theatre in the Round, tonight and tomorrow at 8.00, and on Sunday at 2.00. For fans of the musicals, the Tony Award-winning show 1776 is playing at the Guthrie Theatre every night except Monday. Further afield in the twin city of St Paul, Monty Python's Spamalot is running from Tuesday onwards at the Ordway Center for the Performing Arts.
• Minnesota Orchestra's Sommerfest series of concerts is in full swing now. Catch A Night in the Tropics on Saturday at 8.00; Neil Goldberg's Cirque Symphony and Cirque Populaire on Tuesday and Wednesday at 7.30; or The Steeles: How Sweet the Sound! on Thursday at 7.30. All at Orchestra Hall in downtown Minneapolis.
• Looking for something a bit different? Check out Midtown Global Market - a public market featuring fresh and prepared foods, restaurants, and a selection of arts and crafts from around the world. But there's more on offer than just shopping…Sunday is Salsa Sunday, an event featuring dance, recipes and more from 12.00 to 3.00. Monday features Chess Night (4.30-8.30), and on Wednesday and Thursday there's Irish dancing from 6.30-8.30.
• Minnesota Zoo is hosting Music in the Zoo throughout the summer. Sadly, Chris Isaak's performance tonight is already sold out, but you could check out Squirrel Nut Zippers with The Honeydogs tomorrow, Guster on Monday and Tuesday, or Subdudes and Marcia Ball on Friday. Or just get along to admire the animals - the zoo's open from 9.00 to 6.00 every day.
• Into baseball? Catch the Minnesota Twins' home games at the Metrodome tonight at 7.10, tomorrow at 6.10 or on Sunday at 1.10.
• Finally, a what's on guide for this particular week could not be complete without some mention of the release of the latest, and final, book in JK Rowling's Harry Potter series. Barnes & Noble Booksellers are celebrating the release of Harry Potter and the Deathly Hallows in style with a host of events at their stores this evening. Get yourself along to the downtown branch in the Midwest Plaza building for a "Midnight Magic" Harry Potter party, from 10pm onwards.

Wednesday morning's imaging symposium is entitled "Advances in CT hardware and algorithms". If that sounds somewhat dry, the abstracts suggest otherwise.

The programme kicks off with a talk from Toshiba Medical Systems extolling the promise of 256-slice CT. Whereas conventional multislice CT scanners can only cover a few centimetres of the body with each rotation, 256-slice CT can capture up to 13 cm at once. This means it can potentially provide artefact-free 3D images of entire organs. Toshiba researchers, for their part, reckon this capability will revolutionize several areas of diagnostic imaging.

That's a big claim, but just how much of this is marketing hype remains to be seen? The last talk in the session might help to put things in perspective, when radiology professor Michael Vannier (University of Chicago, IL) talks about the current status and future prospects of CT imaging. He'll argue that the larger-area detectors and higher frame acquisition rates associated with 64 to 256-slice CT scanners partly address the problems caused by organ motion, but don't provide a complete solution.

The other talks in this session cover the recent emergence of dedicated extremity scanners and the advantages and limitations of such devices. There's also a look at advances in CT imaging algorithms. If you're going along to this session on Wednesday, why not give us your take on things via the easy-to-use commenting tool at the end of this post.

Advances in CT hardware and algorithms symposium line-up:

• The promise of 256 Slice CT T Rifu and R Mather.

• Advances in CT: Dedicated extremity scanners E Bailey.

• CT algorithm development and applications X Pan.

• Clinical X-ray computed tomography in 2007: Status and future M Vannier.

There's just a few days to go now until we head out to Minneapolis. For those of you who haven't met us yet, here's the low down on the medicalphysicsweb team at the AAPM meeting.

Tami

Michelle

Rose

Zoe

Simon

First up, our journalists: Tami Freeman, medicalphysicsweb's industry editor, and Michelle Jeandron, medicalphysicsweb's science and technology reporter. Tami and Michelle will be pacing the corridors of the Minneapolis Convention Center on the lookout for hot stories and breaking news.

If you have any announcements, must-see products or new clinical results to tell us about - or you just want to find out more about getting editorial coverage on medicalphysicsweb - catch up with Tami and Michelle at the IOP Publishing booth (1241). If we're out and about when you call, just leave a note or drop us an email and we'll come and find you.

For sales and marketing enquiries, Rose Guardino, medicalphysicsweb's sales manager, and Zoe Anderson, medicalphysicsweb's marketing executive, will be on hand to answer any questions. Speak to Zoe and Rose for details of our fantastic prize draw, open to anyone signing up as a new medicalphysicsweb member. One lucky winner will get their hands on the brand new Apple iPhone.

If you have any questions about the journal Physics in Medicine & Biology, the publisher Simon Harris will be on site too. Come and see Simon at booth 1241 to find out more about: how to submit a research paper, the service offered to authors, subscribing to receive the journal, or how to access papers online.

Finally, don't forget, make sure that you visit booth 1241 to pick up your free copy of the medicalphysicsweb review, a special print supplement for conference delegates and exhibitors at the AAPM meeting.

As is the case at any major technical meeting, there's so much happening at the conference itself that delegates could easily spend all their time at the vast array of symposia, training courses, workshops and poster sessions on offer. But attendees at the AAPM meeting should ensure that they make some time in their packed schedules to check out the innovation being unveiled at the trade exhibition.

With over 130 companies highlighting their latest products and technologies, there's bound to be plenty to catch your eye down on the show floor. Here's just a small selection of products being showcased by the equipment manufacturers at this year's AAPM exhibition.

• Bard Urological Division (Covington, GA) claims that its QuickLink delivery system makes building custom seed trains simple, safe and fast enough to enable real-time linked brachytherapy. The cartridge-based QuickLink boasts an intuitive dial-and-dispense mechanism that makes linked seed trains fast and simple to create. The seeds, links and spacers are pre-loaded in cartridges, limiting handling exposure. Booth 144

• Best Medical International (Springfield, VA) is showcasing its range of gold fiducial markers for image-guided localization. The markers enable precise daily and real-time targeting, as well as tighter margins, resulting in a higher dose of radiation to the target site while sparing surrounding healthy tissue. Best Medical's gold markers/seeds are supplied in a variety of circumferences and lengths to meet localization needs within numerous soft-tissue sites, including the prostate, liver, pancreas, lung and breast. Booths 219, 319

• CDR Systems of Canada is highlighting its Prone Breast patient positioning system. Prone breast irradiation is growing in acceptance as an alternative to treating the breast in the supine position (CDR reckons that this was one of the hottest topics at last year's AAPM and ASTRO meetings). CDR's system uses a dual-density memory foam called PatientCare that enables clinicians to implement prone breast treatment that's comfortable for the patient, without compromising accuracy, reproducibility or treatment access. Booth 644

• Gammex (Middleton WI) is unveiling the newest addition to its range of phantoms for use in digital radiographic systems. Its Neonatal Chest Phantom was developed to simulate pneumothorax and hyaline membrane disease, while permitting system resolution and noise testing. The system addresses the quality-control needs of computed radiography and digital radiography, permitting simultaneous imaging of normal and disease states.

The company is also introducing its Gammex 1430GS LE Phantom - an ultrasound scanner testing tool that performs both Doppler and B-mode ultrasound system tests - and the Gammex Remote Control Laser Device - a hand-held transmitting device that enables manual adjustment of inaccessible ceiling lasers. Booth 729

• The QCkV-1 phantom from Standard Imaging (Middleton, WI) is designed to analyse the characteristics of the on-board imaging systems found on many new linear accelerators. When used with the company's PIPSpro software, the phantom provides quantitative measurement of the resolution, contrast-to-noise ratio and overall noise values of kilovoltage (kV) imaging systems. Standard Imaging claims that this is the first truly quantitative quality-control test object for on-board kV imaging systems. Booth 435

• TOPEX (Danbury, CT) is demonstrating the SRT 100, a superficial X-ray therapy system for treating skin cancer. Approved by the US Food and Drug Administration in January 2007, the SRT 100 offers a number of advantages over older X-ray systems, including: a mobile design with a compact 29x30 inch footprint; standard wall socket plug-in operation; automatic warm up; substantially reduced manual set-up procedures; direct system access for the medical physicist with set-up and calibration controls offering improved safety and quality control assurance. Booth 1046

One of the highlights of Sunday afternoon's programme will be the Young Investigators Symposium. Ten finalists - chosen from hundreds of hopeful graduate students, post doctoral fellows and medical physics residents - will each present a short talk about their research, and a panel of experts will then select the best three.

Variety is the order of the day for this year's symposium, with topics ranging from a technique for doing exit dosimetry on Tomotherapy systems to a theoretical analysis of the Swank Factors of segmented crystalline scintillating detectors. Look out in particular for an update on the development of the University of Wisconsin's (Madision, WI) brachytherapy robot, which medicalphysicsweb reported on last October (see Robotic brachytherapy: assuming control).

According to its developers, this device has the potential to revolutionize prostate brachytherapy, making it faster, more accurate and accessible to many more people. During the symposium graduate student Michael Meltsner will report how the addition of a magnetic tracking system has yielded improvements in both the robot's accuracy and its versatility.

There is also an interesting example of technology cross-over. In the seventh presentation, Youssef Charara will explain how researchers at the University of Tennessee (Knoxville, TN) have taken an instrument designed for characterizing the lunar radiation environment and used it as the basis for a proton-therapy calibration system.

The full line-up looks like this:

• Exit dosimetry treatment verification using auto-associative kernel regression R Seibert et al.
• Dose convolution filter: Incorporating spatial dose information into tissue response modeling Y Huang et al.
• The development and validation of an image-based dosimetry system for 90Y microspheres used to treat hepatic tumors R Selwyn et al.
• Localizing through optimization of image acquisition rate and tube current in X-ray fluoroscopy-guided therapy S Siddique and D Jaffray.
• Segmented crystalline scintillating detectors for radiotherapy imaging: A Monte Carlo investigation of Swank Factor Y Wang et al.
• Stray radiation exposure during proton radiotherapy of the prostate: The influence of the patient on scatter and production JD Fontenot et al.
• Development of a novel detector for measuring proton energy spectra Y Charara et al.
• Real-time three-dimensional position and orientation data of a brachytherapy robot using magnetic tracking M Meltsner et al.
• On the impact of functional imaging accuracy (sensitivity and specificity) on selective boosting IMRT Y Kim and W Tome.
• Quantitative assessment of the accuracy of proton beam range verification with PET/CT A Knopf et al.

With over 1100 abstracts submitted for presentation at this year's AAPM meeting, the reviewers had their work cut out picking the best of the bunch. Authors of the top ten abstracts, detailed below, were rewarded with extended time slots in which to present their findings. If you're heading to Minneapolis next week, be sure to check out some of the following:

• Plan space modelling and decision support system for multi-plan IMRT framework W. D'Souza et al. The authors present an IMRT treatment-planning framework in which multiple plans with differing input constraints are generated per patient. They also describe the decision support system used to help evaluate these sets of plans.
• Effect of a biologically-based prescription function in IMRT dose optimization S. Bowen et al. Delivering heterogeneous dose distributions based on biological image data is reliant upon the transformations used to map that data to the dose prescription values. This presentation discusses the feasibility of four possible image-to-dose-prescription transformations.
• Multiplexing radiography for ultra-fast computed tomography: a feasibility study J. Zhang et al. This work demonstrates the feasibility of multiplexing radiography, in which simultaneous collection of multiple X-ray projection images can significantly increase the speed of CT scanning.
• Development of a linac-MRI system for real-time ART B. Fallone et al. Coupling an MRI system to a linac enables real-time tracking of the tumour and surrounding healthy tissues during treatment. The authors of this paper show that such a design is practical, viable and realizable within a reasonable time frame.
• Assessment of the radiation shielding for a busy PET/CT facility S. Kappadath and R. E. Wendt III. This presentation describes a study to verify the adequacy of radiation shielding installed in a PET/CT facility. The authors also examine the validity of the computer program used to design the shielding.
• Cellular response to modulated radiation fields E. Claridge et al. The researchers reveal the results of in vitro experiments investigating cell survival following exposure to spatially-modulated beams, as created by intensity-modulated radiotherapy.
• Breast CT with energy resolved detection P. Shikhaliev. A breast CT system with energy-resolved X-ray detection and scanning multislit data acquisition shows potential to deliver improved sensitivity and specificity.
• A proposal for a novel compact intensity modulated proton therapy system using a dielectric wall accelerator T. Mackie et al. The authors present a compact, CT-guided intensity-modulated proton therapy system. The instrument, which is said to be ideal for large and complex target volumes in young patients, is designed to be housed in a conventional linac vault.
• Automated stereotactic radiosurgery quality assurance using a portal imager M. Mamalui-Hunter et al. This presentation details an automated portal-vision-based quality assurance scheme that could replace the labour-intensive manual processes currently used to ensure collimator alignment prior to stereotactic radiosurgery.
• Comparison of mammographic percent density and volumetric percent density determined from ultrasound tomography images C. Glide et al. The researchers describe the use of volumetric ultrasound percent density (USPD) for estimation of breast density. Their results show that USPD can provide a non-ionizing analysis of breast density, a known risk factor for breast cancer.

Welcome to The Main Event, medicalphysicsweb's news blog covering the 49th annual meeting of the American Association of Physicists in Medicine (AAPM) meeting in Minneapolis, MN (22-26 July). Whether you're attending the conference or not, The Main Event aims to keep you in touch with all the news, views and gossip from the Minneapolis Convention Center as it happens. Tami Freeman, medicalphysicsweb's industry editor, and Michelle Jeandron, medicalphysicsweb's science and technology reporter, will be filing daily reports on all the hot topics from the AAPM scientific sessions, as well as the pick of the latest technology innovations featuring over at the trade exhibition. Be sure to check out this blog for regularly updated previews of the show over the next week.