Changes in RBE of 14-MeV (d+T) neutrons for V79 cells irradiated in air and in a phantom: Is RBE enhanced near the surface?

Abstract

The measured values of RBE as function of dose per fraction within the phantom is consistent with the energy of the neutron beam. The increased RBE free in air, however, is greater than expected from microdosimetric parameters of the beam and may be due to slow recoil protons produced by interaction of multiply scattered neutrons or to an increased contribution of alpha particles from C(n, alpha) reactions near the surface. An enhanced RBE in subcutaneous layers of skin combined with an increase in RBE at low doses per fraction outside the target volume could potentially have significant consequences for normal tissue reactions in radiotherapy patients treated with fast neutrons.

In vivo skin leptin modulation after 14 MeV neutron irradiation: a molecular and FT-IR spectroscopic study

“…The neutrons were generated by the linear electrostatic accelerator of the Frascati Neutron Generator (FNG, ENEA, Frascati, Italy) via the deuteriumtritium (D + T) reaction [27]. To minimize any differences due to treatment timing, and considering previous experimental evidence of negligible effects of dose rate compared to the effects of the total dose following in vivo neutron irradiation, the dose rates used were 25 cGy/min for the 1 Gy dose and 6 cGy/min for the 0.2 Gy dose [28,29]. At 6 h and 24 h after exposure, the mice were lethally anesthetized with Avertin-R, (1:1 w/v solution of 2,2,2-tribromoethanol and tert-amyl alcohol in 39 ml of H 2 O), administered intraperitoneally [30].…”

Dose-Dependent Onset of Regenerative Program in Neutron Irradiated Mouse Skin

“…These findings do not completely agree with experiments performed on phantom and survival curves of V79 cell line previously used as biological dosimeter to calculate the relative biological effectiveness (RBE) of 14 MeV neutrons. These data showed a higher RBE for the lower dose as compared with the higher dose [42]. However, what occur in vitro with a cell line may only approximate the whole tissue's response to radiation damage.…”

“…The mice, restrained in plastic boxes, received total body irradiation with 0, 0.2 and 1 Gy of 14 MeV neutron doses, generated by the linear electrostatic accelerator Frascati Neutron Generator (FNG, ENEA, Frascati, Italy) via the Deuterium-Tritium (D+T) reaction [40]. The dose rate was 25 cGy/min for the 1 Gy exposure, and 6 cGy/min for the 0.2 Gy exposure, to minimize any difference due to timing of treatments, and considering previous experimental evidences of negligible dose rate effects compared to total effects following in vivo neutron irradiation [41], [42]. At six and at twenty-four hours after exposure, the mice were lethally anesthetized with Avertin-R, (1∶1 w/v solution of 2,2,2-tribromoethanol, tert-amyl alcohol, in 39 ml of H 2 O), administered intra-peritoneally [43].…”

Der Fehler zweiter Art und seine Bedeutung bei der Beurteilung von Resultaten Qualitätsanalyse der Zeitschrift “Strahlentherapie und Onkologie”

“…Insgesamt waren dies 181 Publikationen. Da Überlegungen zum Fehler zweiter Art international nur bei klinischen Untersuchungen üblich sind, wurden 33 physikalisch-technische Arbeiten [8-10, 22, 28, 38, 49, 52, 58, 61, 66, 79, 80, 82, 89, 92, 102, 106, 110, 111, 116, 119, 121, 141, 143, 146, 147, 149, 156, 159, 163, 169, 183], 19 In-vitro-Untersuchungen [11,13,21,35,55,56,78,97,100,103,112,120,126,135,142,148,161,179,182], sieben tierexperimentelle Untersuchungen [7,54,67,69,76,124,166] sowie zwei methodische [98,104] und eine demoskopische Arbeit [153] schlossen, in denen entweder keine eigenen Daten vorgestellt wurden [50,51,57,134,174] oder die keine quantitativen Ergebnisse enthielten; dies waren Übersichtsartikel [1,2,34,36,63,74,75,105,117,…”