Radiobiological model such as linear quadratic (LQ) is widely used in radiotherapy to predict the biophysical response of the tumour cell to the radiation. In clinical radiotherapy, LQ model is widely employed to plan treatment delivery and fractionation. Nevertheless, LQ model might not provide accurate prediction for high dose rate treatment. This study investigates the radiation cell survival responses using LQ model and alternative Multi-Target (MT) model. The experimental works were conducted in-vitro using HeLa cells that were irradiated using photon and electron beams of different energy. Cells irradiation were performed in full scatter condition and exposed to radiation doses ranges from 1 to 10 Gy. Clonogenic assay is used as an endpoint to obtain the cell survival curves which later be fitted with LQ and MT model. The results demonstrate that MT model produce the fitting curves that are closed to the experimental data compare to LQ model especially at high doses. Parameter analysis from both models indicates more biological damage inflicted by high energy electron beam. Correlation between the experimental cell survival data and radiobiological model analysis suggesting that alternative radiobiological model such as MT model could be applied in analysing cells’ radiation survival and damage in clinical radiotherapy.
The purpose of the study was to determine the effect of out-of-field photon beams radiotherapy to the cancer cell survival. In this study, HeLa and T24 cancer cells were irradiated with 6 MV and 10 MV photon beams in two different conditions, one with intercellular communication with the in-field cell and one without the communication. Cells survival was determined by clonogenic assay. In the presence of intercellular communication, the cell death was increased which indicate the presence of radiation induced bystander effects (RIBE). The effects were also dependent on the cell types and photon energy where the HeLa cells exhibit less survival compares to T24 cells and the effects were prominent at higher photon energy. This study demonstrates that the out-of-field cells in conjunction with RIBE plays important roles in the cells response towards megavoltage photon beam radiation therapy.
Gold nanoparticles (AuNPs) have been extensively investigated as dose enhancement agent to increase the lethal dose to the tumours while minimizing dose to the normal tissue. Their intriguing properties and characteristics such as small size and shape provide favorable option in increasing radiotherapy therapeutic efficiency. In this study, the effects of AuNPs size on the dose enhancement effects irradiated under megavoltage photon beams were investigated. The study was conducted in-vitro on HeLa cells using AuNPs of 5 nm and 15 nm sizes. The cells samples were incubated with AuNPs and irradiated with photon beam of energy 6 MV and 10 MV at 100 cm SSD and 10 cm x 10 cm field size. Clonogenic assay were performed to observe the dose enhancement effects on cell survival. Dose enhancement factor (DEF) were extrapolated and evaluated from the cell survival curves. The results show that both sizes of AuNPs produce dose enhancement with the larger size AuNPs of 15 nm produce more dose enhancement compare to 5 nm AuNPs for 6 MV photon beam. Dose enhancements were observed for 10 MV photon beams but DEF for both sizes AuNPs shows no differences. In conclusion, larger size AuNPs produce higher dose enhancement compare to small size of AuNPs which conclude that nanoparticles size is important factor that need to be taken into account for AuNPs to be applied in radiotherapy.
Radiotherapy has become the most important modality in treating cancer with approximately 50% of
cancer patient undergo the treatment. However, more improvement to the radiotherapy treatment
efficacy is required to deprive cancer. Assessment of tumor progress during treatment is important, to
accommodate the changes that occur during the fractionation course. The objective of this study is to
assess tumor cell damage after external beam radiotherapy by using technetium-99m
pertechnetate (99mTcOf) as a tracer. In this study, HeLa cells were irradiated with 6 MVphoton beam
with different radiation dose ranging from 0.5 Gy to 10 Gy. The irradiated cells were recultured in 6-
well plates and incubated for 10 days. After that, 2 mCi of 99mTcOf were prescribed to each cell
colonies. The viable cells were separated from the rest, and measured for 99mTcOf uptake using singlehead
gamma camera with LEHR collimation. As results, the cells survival, fractions clearly indicate
diminishing effect, to the cells at, higher dose of irradiation. Good correlation were observed between
mmTcGi uptake and survival, fraction for cells irradiated at, lower dose and less significant, correlation
were indicated at higher dose. In conclusion, there is potential for the efficacy of external beam
radiotherapy in treating cancer to be assessed by using radioisotope as a non-invasive tracer. In this
case, technetium-99m, pertechnetate (99mTcOjt) could be attached to the specific antibody so that, better
correlation, between, the cells uptake and possible cell damages could be observed.