Low-dose radiation hyper-radiosensitivity in multicellular tumour spheroids

Abstract

Objective: We propose and study a new model aimed at describing the low-dose hyperradiosensitivity phenomenon appearing in the survival curves of different cell lines. Methods: The model uses the induced repair assumption, considering that the critical dose at which this mechanism begins to act varies from cell to cell in a given population. The model proposed is compared with the linear-quadratic model and the modified linear-quadratic model, which is commonly used in literature and in which the induced repair is taken into account in a heuristic way. The survival curve for the MCF-7 line of human breast cancer is measured at low absorbed doses and the uncertainties in these doses are estimated using thermoluminiscent dosemeters. Results: It is shown that these multicellular spheroids present low-dose hyperradiosensitivity. The new model permits an accurate description of the data of two human cell lines (previously published) and of the multicellular spheroids of the MCF-7 line here measured. Conclusion: The model shows enough flexibility to account for data with very different characteristics and considers in a faithful way the hypothesis of the repair induction.

Extracting the normal lung dose–response curve from clinical DVH data: a possible role for low dose hyper-radiosensitivity, increased radioresistance

“…For P 1 ( D ), α = 0.2 Gy −1 , β = 0.667 Gy −2 and α / β = 3 Gy. The value α = 0.2 Gy −1 is consistent with many in vitro measurements of cell survival (Singh et al 1994, Williams et al 2008, Guirado et al 2012) Similarly, α / β ≈ 3 Gy is a conventional assumption for normal tissues.…”

Low-Dose Radiation Induces Cell Proliferation in Human Embryonic Lung Fibroblasts but not in Lung Cancer Cells

“…Some investigators have noted the extreme sensitivity of cells to LDR, defined as hyperradiosensitivity. 17 , 18 This suggests that 2BS and NCI-H446 have different responses to LDR.…”

Radiobiological Response of Cervical Cancer Cell Line in Low Dose Region: Evidence of Low Dose Hypersensitivity (HRS) and Induced Radioresistance (IRR)

“…For this purpose ideal seeding concentration was determined by carrying out multiple initial experiments so as to prevent overlap of cells. For the experimental study, cells were plated in 24 well plates (for Cobalt 60 radiation) and 96 well plates (for radiation in linear accelerator) with different cell concentrations as described by Guirado et al, [7]. For radiation in Co60, γ rays, each well was seeded with 250 or 500 cells per well and for 6 MV and 15 MV radiation, each well was plated with 25 cells after standardization.…”

“…Different dose ranges in low dose region (5 cGy to 100 cGy) and beyond, up to 4 Gy was used. Customized phantom was made for cellular radiation using Perspex with modification of the method described by Guirado et al, [7]. The plate was placed in a Perspex slab with an inbuilt hole of the size of the plate.…”