Exploring The Measurement Of Fluorescence In Dosimetry

Object:The use of more conventional dosimeters with thermoluminescence dosimeter,Famer ionization chamber dosimeter and radiochromic film dosimeter. The operation is more simple and convenient detection with fluorescence dosimeter compared with those dosimeters that decrption.Our purpose is to explore the measurement of fluorescence in dosimetry with Aminophenyl fluorescein(APF) and Alexa Fluor 488-DNA-BHQ1.Meterials and Methods:1. APF and Alexa Fluor 488-DNA-BHQ1 was diluted with ultrapure water,irradiation of these aqueous solution samples using 160 k Vp X-rays and Co-60 γ–rays,observing the fluorescence intensity and the absorbed dose response curve. At the same time, observing the dose response curves under different concentration and p H values.The irradiated samples were stored at 4℃ from light,then tested every 20 minutes to observe the fluorescence decay. Periodic detecting the irradiated aqueous solution of fluorescent probe to observe the long-term stability of the fluorescence intensity.2. Preparation of fluorescent probes PEG-APF and MPEG-APF by modified APF with PEG and MPEG. Modified Alexa Fluor 488-DNA-BHQ1 with PEG to preparate of fluorescent probes PEG-Alexa Fluor 488-DNA-BHQ1. The response curves of the fluorescence intensity and the absorbed dose of the samples were observed by X-ray irradiation of different energies.3. Preparation of 3% agarose gel doped with PEG-APF or MPEG-APF, to make the diameter of 60 mm, the thickness of 1mm gel film. The fluorescence dose response curves of thin film samples were measured by X-ray irradiation. The fluorescence intensity of the gel film distribution of the films was observed by fluorescence imaging system after irradiation.4. Hela cell were cultured in media containing 10μmol/l APF and irradiated with241 Am α-ray. Observing the fluorescence images of the irradiated cells with fluorescencemicroscopy.Results:1.There was a good linear relationship between the fluorescence intensity and the radiation absorbed dose of the 5μmol/l APF fluorescent probe after 160 k Vp X-ray irradiation,which radiation absorbed dose within the 0-30 Gy range(R2=0.995). The radiation absorption dose response curves of the APF fluorescent probes with a concentration of 0.5μmol/l, 1μmol/l and 5μmol/l were linear. The p H value of the aqueous solution had a great influence on the fluorescence intensity. When the p H value was 4, the fluorescence was quenched completely, the fluorescence intensity was enhanced with the increase of the p H value. The fluorescence intensity of the 5μmol/l APF fluorescent probe decreased at 24 hours after irradiation, and the fluorescence intensity remained stable after 36 hours. Under the condition of 4 C, the stability of the fluorescence intensity of the sample was better.There was a good linear relationship between the fluorescence intensity and the radiation absorbed dose of 5μmol/l APF fluorescent probe after Co-60 γ–ray irradiation,which radiation absorbed dose within the 0-70 Gy range(R2=0.991).The fluorescence intensity of PEG-APF and MPEG-APF aqueous solution were weak but improved the stability after irradiation compared to APF. The linear relationship between the fluorescence intensity and the absorbed dose was good.2. There was a good linear relationship between the fluorescence intensity and the radiation absorbed dose of the Alexa Fluor 488-DNA-BHQ1 fluorescent probe after160 k Vp X-ray irradiation,which radiation absorbed dose within the 0-10 Gy range. The fluorescence intensity of△F and absorbed dose D relationship for△F =57.98 ×D(R2=0.992). The fluorescence probe concentration was 0.5μmol/l and 1μmol/l, in the dose range of 0-30 Gy, the fluorescence intensity and absorption dose of good linearity,and the fluorescence intensity △F and absorbed dose D respectively △F =29.74× D(R2 = 0.987) and △F = 56.64× D(R2 = 0.993), which could meet the needs of the measurement of single dose of radiation absorption in clinic.The fluorescence intensity tended to saturation when the irradiation dose reached 50 Gy with differentconcentrations of the probe sample. The fluorescence intensity of the fluorescent probe was increased by 20 min, and the fluorescence intensity was stable in 40~80 minutes.Under the condition of 4℃, the fluorescence intensity of the samples was weaker and more stable compared with the room temperature condition. The fluorescence intensity of the sample was stable after 24 h under 4℃ conditions. The fluorescence intensity of samples was more instable with time under room temperature.There was a good linear relationship between the fluorescence intensity and the radiation absorbed dose of the 1μmol/l Alexa Fluor 488-DNA-BHQ1 fluorescent probe after Co-60 γ–ray irradiation,which radiation absorbed dose within the 0-30 Gy range(R2=0.995). The fluorescence intensity of△F and absorbed dose D relationship for△F =57.18×D(R2=0.993).The fluorescence intensity of Alexa Fluor 488-DNA-BHQ1 fluorescent probe was not observed after modified with PEG.3. It was a good linear dose response in the range of 0-20 Gy for 3% agarose gels containing 5μmol/l APF. Immediately measuring the agarose gel after irradiation, the fluorescence intensity distribution was closed to the dose distribution. The fluorescence intensity distribution had been blurred after 15 minutes.The fluorescence intensity of 3% agarose gel containing 5μmol/l APF-PAMAMA fluorescent probes in 15 Gy dose range was linear with the absorbed dose. The agarose gel was measured immediately after irradiation and the fluorescence intensity distribution was closed to the irradiation dose distribution. The width of fluorescence distribution curve was basically unchanged, but the fluorescence intensity was decreased and the fluorescence intensity was the same as the surrounding after85 minutes.The fluorescence intensity of 3% agarose gel containing 5μmol/l MPEG-APF fluorescent probes in the range of 0-20 Gy was linear with the absorbed dose. The fluorescence intensity distribution of the agarose gel was closed to the irradiation dose distribution after irradiation. The fluorescence intensity was decreased and the fluorescence intensity was the same as the surrounding after 125 minutes. The width offluorescence distribution curve was basically unchanged in 65 mintues.5μmol/l PEG-APF fluorescent probe in 3% agarose gel containing was measured immediately after X-ray irradiation. The fluorescent intensity in the range of 0-20 Gy was linear with the absorbed dose and the distribution was closed to the irradiation dose distribution. The fluorescence intensity was decreased and the fluorescence intensity was the same as the surrounding after 185 minutes. The width of fluorescence distribution curve was basically unchanged in 85 mintues.4. It was observed that the fluorescence intensity in the cells was related to the absorbed dose.APF was not easy to enter into Hela cells and itself had greater toxicity on cells.Conclusion:1. The APF aqueous solution could be used to measure radiation absorbed dose and the dose response was linear in the range of 0-70 Gy. The dose response was linear and the fluorescence intensity of APF aqueous solution modified with PEG and MPEG were more stable2. The Alexa Fluor 488-DNA-BHQ1 aqueous solution could be used to measure radiation absorbed dose. The dose response was linear in the range of 0-30 Gy while the background fluorescence intensity was very low. The fluorescence of Alexa Fluor PEG-488-DNA-BHQ1 could not be detected.3. The 3% agarose gels contained APF-PAMAMA, MPEG-AFP and PEG-APF fluorescence pore could be used to measure the two-dimensional dose distribution.Comparatively, the performance of PEG-APF in agarose gel was the most suitable and was more suitable for two-dimensional dose measurement.4. The application of APF fluorescent probe in measuring cell radiation absorbed dose was feasible. However, the method of APF fluorescent probe enter cells was needed to be improved.