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Monte Carlo-based investigation of water-equivalence of solid phantoms at (137)Cs energy.

Vishwakarma RS, Selvam TP, Sahoo S, Mishra S, Chourasiya G - J Med Phys (2013)

Bottom Line: The investigation reveals that solid water, virtual water, and RW1 phantoms are water equivalent up to 15 cm from the source.Phantom materials such as plastic water, PMMA, and polystyrene phantom materials are water equivalent up to 10 cm.At 15 cm from the source, the phantom scatter corrections are 1.035, 1.050, and 0.949 for the phantoms PMMA, plastic water, and polystyrene, respectively.

View Article: PubMed Central - PubMed

Affiliation: Radiological Physics and Advisory Division, Health, Safety and Environment Group, Bhabha Atomic Research Centre, Anushaktinagar, Mumbai, Maharastra, India.

ABSTRACT
Investigation of solid phantom materials such as solid water, virtual water, plastic water, RW1, polystyrene, and polymethylmethacrylate (PMMA) for their equivalence to liquid water at (137)Cs energy (photon energy of 662 keV) under full scatter conditions is carried out using the EGSnrc Monte Carlo code system. Monte Carlo-based EGSnrc code system was used in the work to calculate distance-dependent phantom scatter corrections. The study also includes separation of primary and scattered dose components. Monte Carlo simulations are carried out using primary particle histories up to 5 × 10(9) to attain less than 0.3% statistical uncertainties in the estimation of dose. Water equivalence of various solid phantoms such as solid water, virtual water, RW1, PMMA, polystyrene, and plastic water materials are investigated at (137)Cs energy under full scatter conditions. The investigation reveals that solid water, virtual water, and RW1 phantoms are water equivalent up to 15 cm from the source. Phantom materials such as plastic water, PMMA, and polystyrene phantom materials are water equivalent up to 10 cm. At 15 cm from the source, the phantom scatter corrections are 1.035, 1.050, and 0.949 for the phantoms PMMA, plastic water, and polystyrene, respectively.

No MeSH data available.


Related in: MedlinePlus

Ratio of photoelectric cross-section to total cross-section presented for water and solid phantoms as a function of photon energy
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Figure 2: Ratio of photoelectric cross-section to total cross-section presented for water and solid phantoms as a function of photon energy

Mentions: Contribution of photoelectric effect and Compton scattering (CS) to total mass attenuation coefficient was studied by using the state-of-the art XCOM[18] photon interaction data set. The ratio of photoelectric cross-section to the total cross-section of the phantom material (σPE, Phant /σTot,Phant ) is presented in Figure 2. As seen from the figure, the ratio σPE,Phant /σTot,Phant for photons in the energy range 10-200 keV in solid water, virtual water, and RW1 is comparable to that of water. In phantom material having smaller Zeff such as polystyrene (Zeff = 5.70) and PMMA (Zeff = 6.47) as compared with water (Zeff = 7.42), the contribution of photoelectric effect to total interaction cross-section in material is less than that of water. Whereas, for the materials with Zeff values more than that of water, such as Plastic Water (Zeff = 9.37), larger contribution of photoelectric effect to the total cross-section of the phantom material is observed.


Monte Carlo-based investigation of water-equivalence of solid phantoms at (137)Cs energy.

Vishwakarma RS, Selvam TP, Sahoo S, Mishra S, Chourasiya G - J Med Phys (2013)

Ratio of photoelectric cross-section to total cross-section presented for water and solid phantoms as a function of photon energy
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3958994&req=5

Figure 2: Ratio of photoelectric cross-section to total cross-section presented for water and solid phantoms as a function of photon energy
Mentions: Contribution of photoelectric effect and Compton scattering (CS) to total mass attenuation coefficient was studied by using the state-of-the art XCOM[18] photon interaction data set. The ratio of photoelectric cross-section to the total cross-section of the phantom material (σPE, Phant /σTot,Phant ) is presented in Figure 2. As seen from the figure, the ratio σPE,Phant /σTot,Phant for photons in the energy range 10-200 keV in solid water, virtual water, and RW1 is comparable to that of water. In phantom material having smaller Zeff such as polystyrene (Zeff = 5.70) and PMMA (Zeff = 6.47) as compared with water (Zeff = 7.42), the contribution of photoelectric effect to total interaction cross-section in material is less than that of water. Whereas, for the materials with Zeff values more than that of water, such as Plastic Water (Zeff = 9.37), larger contribution of photoelectric effect to the total cross-section of the phantom material is observed.

Bottom Line: The investigation reveals that solid water, virtual water, and RW1 phantoms are water equivalent up to 15 cm from the source.Phantom materials such as plastic water, PMMA, and polystyrene phantom materials are water equivalent up to 10 cm.At 15 cm from the source, the phantom scatter corrections are 1.035, 1.050, and 0.949 for the phantoms PMMA, plastic water, and polystyrene, respectively.

View Article: PubMed Central - PubMed

Affiliation: Radiological Physics and Advisory Division, Health, Safety and Environment Group, Bhabha Atomic Research Centre, Anushaktinagar, Mumbai, Maharastra, India.

ABSTRACT
Investigation of solid phantom materials such as solid water, virtual water, plastic water, RW1, polystyrene, and polymethylmethacrylate (PMMA) for their equivalence to liquid water at (137)Cs energy (photon energy of 662 keV) under full scatter conditions is carried out using the EGSnrc Monte Carlo code system. Monte Carlo-based EGSnrc code system was used in the work to calculate distance-dependent phantom scatter corrections. The study also includes separation of primary and scattered dose components. Monte Carlo simulations are carried out using primary particle histories up to 5 × 10(9) to attain less than 0.3% statistical uncertainties in the estimation of dose. Water equivalence of various solid phantoms such as solid water, virtual water, RW1, PMMA, polystyrene, and plastic water materials are investigated at (137)Cs energy under full scatter conditions. The investigation reveals that solid water, virtual water, and RW1 phantoms are water equivalent up to 15 cm from the source. Phantom materials such as plastic water, PMMA, and polystyrene phantom materials are water equivalent up to 10 cm. At 15 cm from the source, the phantom scatter corrections are 1.035, 1.050, and 0.949 for the phantoms PMMA, plastic water, and polystyrene, respectively.

No MeSH data available.


Related in: MedlinePlus