The "medical" version SHIELD-HIT (Heavy Ion Therapy)
The "medical" version SHIELD-HIT is being developed intensively since 2001 on the basis of the common version SHIELD in collaboration with colleagues from the Karolinska Institutet (KI, Stockholm) and the German Cancer Research Center (DKFZ, Heidelberg). The main stages of the development and of improvements of SHIELD-HIT are listed below.
In 2001 04, in collaboration with KI, version 1 (SHIELD-HIT, v.1) has been developed [1]:
- Implementation of the Gaussian and Vavilov's models of fluctuations of the ionization energy loss (the energy straggling) as well as of the Gaussian model of multiple Coulomb scattering (Fermi distribution).
- Track Length Estimation (TLE) of the differential in energy fluence of secondary particles and nuclear fragments in each geometric zone of the target.
- Scoring of contributions to the energy deposition from various types and from different generations of particles and nuclear fragments separately.
- Scoring of the double differential yield of particles and nuclear fragments from the target.
- Implementation of the stopping power for protons and α - particles in the tabular form according to ICRU 49 [2].
- The possibility to switch on/off various physics processes (energy straggling, multiple scattering, nuclear interactions) on the user request.
- Track Length Estimation (TLE) of the double differential fluence of secondary particles and nuclear fragments.
In 2005 on the basis of version 1, in collaboration with DKFZ, version 2 (SHIELD-HIT, v.2) has been developed [3]:
- All transport subroutines of the SHIELD-HIT code were ported to double precision.
- Variable dimensionality of energy grids in the transport part of SHIELD-HIT. Refinement of the energy grid for calculation of the stopping power, pass length and optical depth.
- Modification of the Bethe-Bloch equation for stopping powers and smooth sewing of it with the Lindhard Scharff equation at low energies. Reduction of the energy cutoff for a transport down to Ecut=25 keV/u.
- Implementation of the stopping power for the ions from Li up to Ar in the tabular form according to ICRU 73 [4].
- Improvement of the procedure of calculation of the total and inelastic cross section of hA and AA interaction.
- Improvement of the Fermi break-up model.
Further development of the SHIELD-HIT code was continuing in 2005-2008 on the basis of versions 1 and 2 in collaboration with both KI and DKFZ. The given version of the code has got the name SHIELD-HIT08 [5]. Additional capabilities of this version of the code are listed below:
- Variable dimensionality of the energy grid for scoring of TLE fluences.
- Improvement of the TLE procedure in the vicinity of the Bragg peak.
- Scoring of the production rate of the PET isotopes in each geometric zone of the target.
- Calculation of the absorbed dose by means of convolution of TLE fluences with stopping powers for various types of particles and nuclear fragments in each geometric zone of the target.
- Decomposition of the absorbed dose according to contributions of particles and fragments within given intervals of Linear Energy Transfer (LET). LET intervals are defined by the user.
- Implementation of the Moliere's model of the multiple Coulomb scattering. [6].
- Increasing of the number of chemical elements of biological tissues from 8 up to 13.
- Revision of the 28-group neutron data (En < 14.5 MeV) for several chemical elements (F, P, S, Cl, Ti, Zn, Au) which are relevant to the field of hadron therapy.
Since 2009, the development of the SHIELD-HIT code has continued in collaboration with the Aarhus University, Denmark [7-9]. The starting point was the SHIELD-HIT08 version. The main goal was to ensure the possibility of using the code in clinical practice. The final version of the code has got the name SHIELD-HIT12A. Detailed description of SHIELD-HIT12A can be found on the project website http://www.shieldhit.org. Neutron data for a number of elements of interest for hadron therapy have also been added or updated. The SHIELD-HIT12A code is distributed on the basis of commercial and non-commercial license.
- I.Gudowska, N.Sobolevsky, P.Andreo, Dz.Belkic, A.Brahme. Ion Beam Transport in Tissue-Like Media Using the Monte Carlo Code SHIELD-HIT. Phys.Med.Biol. 49 (2004) 1933-1958.
- ICRU Report 49. Stopping Powers and Ranges for Protons and Alpha Particles. The International Commission on Radiation Unit and Measurement, 1993.
- O.Geithner, P.Andreo, N.Sobolevsky, G.Hartmann, O.Jaekel. Calculation of Stopping Power Ratios for Carbon Ion Dosimetry. Phys.Med.Biol. 51 (2006) 2279-2292.
- ICRU Report 73. Stopping of Ions Heavier than Helium. The International Commission on Radiation Unit and Measurement, 2005.
- K.Henkner, N.Bassler, N.Sobolevsky, O.Jaekel. Monte Carlo Simulations on the water-to-air stopping power ratio for carbon ion dosimetry. Medical Physics 36 (2009) 1230-1235.
- CERN Program Library Long Writeup W5013. GEANT, Detector Description and Simulation Tool, 1994, section PHYS325: Moliere scattering.
- A.Luehr, D.C.Hansen, N.Sobolevsky, H.Palmans, S.Rossomme, N.Bassler. Fluence Correction Factors and Stopping Power Ratios for Clinical Ion Beams. Acta Oncologica 50 (2011) 797-805.
- D.C.Hansen, A.Luehr, N.Sobolevsky, N.Bassler. Optimizing SHIELD-HIT for carbon ion treatment.
Phys.Med.Biol. 57(2012)2393-2409.
- N.Bassler, D.C.Hansen, A.Luehr, B.Thomsen, J.B.Petersen, N.Sobolevsky. SHIELD-HIT12A - a Monte Carlo particle transport program for ion therapy research. Journal of Physics: Conference Series 489 (2014) 012004.
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