PMID- 23556894
OWN - NLM
STAT- MEDLINE
DCOM- 20130911
LR  - 20170214
IS  - 2473-4209 (Electronic)
IS  - 0094-2405 (Linking)
VI  - 40
IP  - 4
DP  - 2013 Apr
TI  - Evaluation of plastic materials for range shifting, range compensation, and 
      solid-phantom dosimetry in carbon-ion radiotherapy.
PG  - 041724
LID - 10.1118/1.4795338 [doi]
AB  - PURPOSE: Beam range control is the essence of radiotherapy with heavy charged 
      particles. In conventional broad-beam delivery, fine range adjustment is achieved 
      by insertion of range shifting and compensating materials. In dosimetry, solid 
      phantoms are often used for convenience. These materials should ideally be 
      equivalent to water. In this study, the authors evaluated dosimetric water 
      equivalence of four common plastics, high-density polyethylene (HDPE), polymethyl 
      methacrylate (PMMA), polyethylene terephthalate (PET), and polyoxymethylene 
      (POM). METHODS: Using the Bethe formula for energy loss, the Gottschalk formula 
      for multiple scattering, and the Sihver formula for nuclear interactions, the 
      authors calculated the effective densities of the plastics for these 
      interactions. The authors experimentally measured variation of the Bragg peak of 
      carbon-ion beams by insertion of HDPE, PMMA, and POM, which were compared with 
      analytical model calculations. RESULTS: The theoretical calculation resulted in 
      slightly reduced multiple scattering and severely increased nuclear interactions 
      for HDPE, compared to water and the other plastics. The increase in attenuation 
      of carbon ions for 20-cm range shift was experimentally measured to be 8.9% for 
      HDPE, 2.5% for PMMA, and 0.0% for POM while PET was theoretically estimated to be 
      in between PMMA and POM. The agreement between the measurements and the 
      calculations was about 1% or better. CONCLUSIONS: For carbon-ion beams, POM was 
      dosimetrically indistinguishable from water and the best of the plastics examined 
      in this study. The poorest was HDPE, which would reduce the Bragg peak by 0.45% 
      per cm range shift, although with marginal superiority for reduced multiple 
      scattering. Between the two clear plastics, PET would be superior to PMMA in 
      dosimetric water equivalence.
FAU - Kanematsu, Nobuyuki
AU  - Kanematsu N
AD  - Research Center for Charged Particle Therapy, National Institute of Radiological 
      Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan. nkanemat@nirs.go.jp
FAU - Koba, Yusuke
AU  - Koba Y
FAU - Ogata, Risa
AU  - Ogata R
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Med Phys
JT  - Medical physics
JID - 0425746
RN  - 0 (Plastics)
SB  - IM
MH  - Dose-Response Relationship, Radiation
MH  - Equipment Design
MH  - Equipment Failure Analysis
MH  - Heavy Ion Radiotherapy/*methods
MH  - Materials Testing
MH  - Plastics/*chemistry/*radiation effects
MH  - Radiation Dosage
MH  - Radiometry/*instrumentation/*methods
MH  - Reproducibility of Results
MH  - Sensitivity and Specificity
EDAT- 2013/04/06 06:00
MHDA- 2013/09/12 06:00
CRDT- 2013/04/06 06:00
PHST- 2013/04/06 06:00 [entrez]
PHST- 2013/04/06 06:00 [pubmed]
PHST- 2013/09/12 06:00 [medline]
AID - 10.1118/1.4795338 [doi]
PST - ppublish
SO  - Med Phys. 2013 Apr;40(4):041724. doi: 10.1118/1.4795338.