Radiobiological model applicability in radiotherapy: single and fractionated irradiation
The effect of fractionation had been experimentally proven to increase the surviving fraction of the cells instead of single irradiation. Cell survival described by radiobiological models could be used to predict the radiosensitivity and sublethal damage repair of cells to radiation. In this stud...
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| Format: | Monograph |
| Language: | English |
| Published: |
Universiti Sains Malaysia
2016
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| Online Access: | http://eprints.usm.my/62362/ http://eprints.usm.my/62362/1/NURUL%20AKMAL%20BINTI%20ARIFFIN%20-%20e.pdf |
| Summary: | The effect of fractionation had been experimentally proven to increase
the surviving fraction of the cells instead of single irradiation. Cell survival described
by radiobiological models could be used to predict the radiosensitivity and sublethal
damage repair of cells to radiation. In this study, the linear quadratic (LQ) and multitarget
(MT) cell survival curve models were used to describe the cell survival with
single and fractionated irradiation. The applicability of both models in radiotherapy was
investigated. HeLa cells were irradiated using 6 MV photon beam with 10><10 cm2 field
size, 100 cm SSD at different doses. Standard clonogenic assay was performed to
determine the cell survival. The experimental data were fitted to the LQ and MT model
using OriginPro 9.2 software. Radiobiological parameters were evaluated from the
fitting curves generated from these models. Fitting curve of the LQ and MT models for cell survival with
single irradiation were found to be close to the experimental data. The survival curves
fitted with LQ and MT model for single irradiation displayed steep initial slope and
small shoulder. The sublethal damage repair was better for fractionated irradiation with
wider shoulder. The parameters of LQ model showed a larger a and a/p ratio whereas
for MT model showed a smaller n, Do and Dq. The parameterisation of LQ and MT model showed that single irradiation
is more effective in reducing the number of cell survive. MT model seem to be more
accurate in describing the radiosensitivity of the cells especially at high dose for both
single and fractionated irradiations because the experimental data plotted fitted closely
to the curve. The most commonly used model, LQ seem to provide unsatisfactory fitting
at high dose. |
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