Roy and Niels

Roy and Niels

Thursday, June 21, 2012

libdEdx 1.2.0 released - stopping powers for the masses!

Our master's student Jakob Toftegaard has been very busy lately, and we're now ready to release a new version of the open-source stopping power library libdEdx - version 1.2.0.

Changes to the last version 1.0 are
  • first of all: a new, nice and clean API. This breaks compatibility with 1.0, but we will do our best to avoid this happening again in the future. (We now have extensive use of structs, which can be extended with new members.)
  • generic ICRU table included, which combines ICRU49 and the revised ICRU73.
  • all four calculation modes in MSTAR are now supported, the default is that recommended by Helmut Paul.
  • aggregate state can be specified, following ICRU recommendations
  • I-values can be overridden for analytical functions (BETHE_EXT)
  • provides a bunch of new functions
    • calculate CSDA range
    • inverse range lookup - a given range will return required particle energy in CSDA approximation. (Yes, this is the feature you have been waiting for all your life!)
    • inverse dEdx lookup - a given stopping power will yield an energy (either high or low value, depending on what the user requested)
  • version string of libdEdx can be accessed
  • memory leak fixes
  • typo fixes in material lists
  • code should now be thread-safe
And were just getting started!

A real gem is our new web based frontend at to libdEdx. Here you can lookup stopping power functions using various tables and energies, use it as a supplement to those from NIST. The website includes a nice plotting feature as well, where you can add multiple plots for comparison.

The web frontend is still in beta-testing phase and may reside in this state for a long time. Any feedback is appreciated.

We have a lot of plans regarding how to continue with this. In the next version of libdEdx we plan to include more features such as
  • more Bethe-based stopping power functions such as
  • Bethe-Bloch
  • Bethe-Bloch-Barkas
We also would like to include additional stopping power programs such as ESTAR, ATIMA and SRIM (just the stopping power part, of course), yet the outcome will depend on the willingness of the respective authors to contribute.
  • algorithms for nuclear stopping power
  • … and a surprise which we won’t reveal yet … :-)
Other contributors will be most welcome, the project is available on sourceforge for inspection.

We greatly acknowledge our hero Helmut Paul for contributing to the development with very fruitful discussions and suggestions. We also acknowledge the permission from the ICRU to use their stopping power tables in libdEdx.

Yet, we do not claim that the produced results are correct in any way, so any use of the data are on own risk. Nonetheless, if you DO find discrepancies, errors, misbehaviour of code, we would really appreciate if you tell us.


Friday, June 1, 2012

Don't Mention the War

Last year the Danish government announced that it will finance a national particle therapy facility together with some private funding agencies. Two applications were submitted for evaluation:

and of course there is a strong interest from each side to host this project. Naturally, since I am part of the Aarhus Particle Therapy Group, I will right out admit I am naturally in favour of our project in Aarhus.

The plan is now that an international expert commission is being setup by the ministry of health. That commission will then evaluate those two applications and give a suggestion where to place such a facility.

If you compare those two applications, you will see that they both apply for a 3-gantry treatment facility. Copenhagen lock themselves on a cyclotron solution, where we in Aarhus are also open to a synchrotron based solution.

Basically the differences can be summarized here:

Copenhagen Aarhus
3 treatment rooms with 2 gantries 3 treatment rooms with 2 gantries,
+1 research room
3rd gantry will be installed later 3rd gantry will be installed later,
a fourth treatment room with gantry can be added
CyclotronCyclotron or Synchrotron
1000 patients per year1000 patients per year

So basically what we apply for is rather similar.

What about the costs? If you compare those budgets, you will note that the prices of the equipment and the building are comparable too.

Copenhagen Aarhus
Equipment450 mio. DKK 475 mio. DKK
Building382 mio. DKK 295 mio. DKK
Supply systems and lines195 mio. DKK (incl. in building)
Purchase and demolition of Rockefeller Building147 mio. DKK (none)
Total1174 mio. DKK 770 mio. DKK
Optional 3rd gantry(not mentioned) 75 mio. DKK

Copenhagen need to build in the middle of the city, whereas we in Aarhus have a pristine green field adjacent to the New University Hospital. This means that the expenses for the Copenhagen proposal are significantly higher than the Aarhus solution, since a building has to be demolished first (they have simply a lack of space in Copenhagen). The "supply lines" cover, as far as I heard, establishing extra power for the facility, please correct me if I am wrong here. The annual operational costs are also similar.

There has been a few articles in the Danish press about the two applications. None of the Journalists managed to actually compare the two budgets, so basically the message was that Aarhus offeres particle therapy at dumping prices. Yeah right.

In addition, I hear a lot of weird arguments, e.g. such a facility MUST be build in Copenhagen, since it is the capital city, and it has a proximity to the airport.


How many of the existing facilities are located in capital cities? Lets pick some of the most famous ones: HIT is in Heidelberg (147.000 inhabitants, 1hours drive to next airport). PSI is in Villingen. The Swedish facility is built in Uppsala, and not Stockholm. Why is that so? These research institutions simply had the longest track record in terms of particle therapy! I don't get the point of the closeness of an airport either, since you can reach any point within a few hours in DK by car, and sorry guys... particle therapy is not that acute.

Now, today this conflict took a very curious turn, as Copenhagen announced in Dagens Medicin that they will cut the price 75 % (login required to view link). What is going on?
It seems that Copenhagen suddenly decided to go for a single gantry facility by Mevion, formerly known as StillRiver. To me this looks like a very poor decision. The Mevion facility has been controversial for a long list of reasons. In a scientific article by Schippers and Lomax they list some of the issues with this facility:

  • the very compact design of the cyclotron, may lead to large beam losses and resulting activation. 
  • repetition frequency of synchrocyclotrons are typically 1kHz which limits applicability of the different pencil beam scanning methods.
  • There is no beam analysis and no magnets in the beam path, in other words an energy selection system is missing. This means that the beam will have a poor distal edge, always looking as if it traversed 25-30 cm of material, e.g. when treating head an neck cancers. This limits possible treatment planning techniques, such as patch fields.
  • Neutron contamination may be an issue, due to the proximity of the degrader, modulator and collimator(s). 
To this, I might add that the construction of the prototype is still awaiting FDA approval, and we have not seen any data on how this machine operates. We are just in the middle of a never ending scandal about a couple of diesel IC4 trains ordered from AnsaldoBreda a decade ago, where the trains still are not functional and with a significant risk that they never will be. Billions of taxpayer money are lost here. Most Danes are therefore allergic to order unproven technology abroad.

Update: Mevion just got their FDA approval.

Another update: it's a "Premarket Notification" and not a "New Device Approval". Read it here. Thanks to Klaus Seiersen for pointing this out.

The recent article in Dagens Medicin does not even mention that cutting 75% of the price leads to a single-gantry facility, which means the patient numbers needs to be adjusted down, perhaps by 2/3rds.

Finally, if you need three treatment rooms, then measured in costs per treatment room, a conventional solution is cheaper than the Mevion solution, according to Schippers.

I am very astonished, it seems that Copenhagen just scored an own goal. However, I fear this may delay the decision process even more. In the end this is about patients, and if the money is there, we should not be satisfied with giving our patients the most inferior kind of proton therapy, and rely on unproven technology.