The elemental composition of tumors: Kerma data for neutrons

Abstract

The elemental composition of a variety of tumor samples, including squamous cell lung carcinoma, sarcoma, adenoid cystic carcinoma, melanoma, and rectal carcinoma have been measured by combustion analysis. Hydrogen, carbon, nitrogen, and oxygen content have been determined. Using the elemental neutron kerma data published in ICRU Report #46 the neutron kerma factors for the various tumor samples have been calculated in the energy range 11 eV to 29 MeV. The average neutron kerma values for all tumor samples are approximately 6%-7% lower than those for average soft tissue in the energy range of interest in fast neutron therapy (energies > 1 MeV).

Neutrons absorbed dose rate calculations for interstitial brachytherapy with 252Cf sources

“…If muscle is taken as the reference medium, _ D N ðmuscleÞ= _ D N ðmediumÞ, the difference range is from À8.4% to 5.6%. Therefore, the muscle can be suggested as a reference medium for clinical calculations [3,4,[10][11][12][13][14]. The difference values between muscle and water are 5.6%.…”

“…These results demonstrate the influence of small differences in the elemental composition on the neutron dose rate. The elemental composition is of particular importance in neutron radiation therapy, where the kerma is mainly determined by the hydrogen and oxygen contents in tissue [1][2][3][4][10][11][12]. For example, the adipose tissue with 11.4% hydrogen and 27.8% oxygen contents, can receive approximately 9% more dose than soft tissue whose hydrogen and oxygen contents are 10.5% and 60.2%, respectively [3,4,[10][11][12]14].…”

Determination of mean ionization potential using magnetic resonance imaging for the reduction of proton beam range uncertainties: theory and application

“…In the case of neural tumors, concentrations of water may be higher with lower lipid content (~20% of dry weight for astrocytoma and glioblastoma multiforme) (Yates et al, 1979) than normal brain. In the work of Maughan et al (Maughan et al, 1997), they found significant differences in the hydrogen content of tumor samples (9.7% by mass) than the average for soft tissue (10.55%). Hydrogen, water, and lipid content variations can have a large impact on Im and SPR.…”

Preliminary investigation into sources of uncertainty in quantitative imaging features

“…Table 3 were determined through a process diagrammed in Figure 1. First, the published material composition of five common tumor types [18] were used as input to the online XCOM: Photon Cross Sections Database by NIST [19]. XCOM uses the atomic composition of a material and a selected monoenergetic beam energy to calculate the expected linear attenuation of the material.…”