化學劑量計偵測低劑量伽傌輻射及紫外光偵測之研究

Investigation of chemical dosimeters in the low dose gamma radiation and UV radiation measurements

徐□怡(Heng-Yi Hsu)

指導教授 ： 王竹方

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(2008年)

摘要

本研究為探討化學劑量計，分別針對弗利克劑量計及二氧化鈦計量劑進行詳細的探討。有關弗利克劑量計的研究，主要針對在低劑量的部份建立一套可以校正伽瑪輻射的系統，並探討環境溫度所造成的影響。另一主要的研究則是探討以二氧化鈦溶液劑量計來建立紫外光輻射劑量的可行性。
弗利克劑量計，亦稱為硫酸亞鐵劑量計，是一種最被廣泛使用的化學劑量計。此原理為利用亞鐵離子藉由鈷六十伽瑪射線被氧化為鐵離子。被照射後的弗利克劑量計，所吸收的劑量，可以藉由鐵離子的濃度變化來偵測與觀察並加以評估。研究指出，鐵離子的吸收強度與伽瑪射線的吸收劑量成一正比關係。傳統弗利克劑量計可以使用的劑量範圍為30-400葛雷。在本實驗中，主要研究劑量範圍著重在5-30 葛雷之間，並且測試其穩定性以及探討其再現性。
此外，本研究嘗試自行合成對紫外光輻射敏感的二氧化鈦溶膠溶液，其合成方法為：將異丙基醇氧化鈦加入無水酒精（當作分散劑）及鹽酸的混合液。經過水解的過程製備完成的二氧化鈦溶膠溶液，在紫外光射源照射下，二氧化鈦溶膠溶液的顏色由無色轉變為深藍色，而在580 nm的位置產生極強的特性吸收，且與紫外光的吸收劑量呈正比關係。在本實驗中，主要探討二氧化鈦溶膠粒徑大小對濃度的影響，並找出最佳濃度之二氧化鈦溶膠劑量計。同時，找出影響二氧化鈦溶膠劑量計之參數。

關鍵字：化學劑量計; 弗利克劑量計; 二氧化鈦溶膠劑量計

關鍵字

化學劑量計 ； 弗利克劑量計 ； 二氧化鈦劑量計

並列摘要

Abstract
This research describes chemical dosimeter, and the aims of this study are Fricke dosimeter and TiO2 sol dosimeter individually. In Fricke dosimeter, the main work is to set up a calibration system for gamma radiation at low dose, and to confer the influence of environmental temperature. Another main work is the feasibility to establish the ultraviolet radiation measurement system with the TiO2 sol solution.
The Fricke dosimeter also called the ferrous sulfate dosimeter is the most useful chemical dosimeter. The principle is the oxidation of ferrous ions (Fe2+) to ferric ions (Fe3+) by 60Co γ-radiation. The absorbed dose of the irradiated Fricke dosimeter can be determined by measurement of the concentration change of Fe3+. It may be an application in γ-radiation dosimeter due to a linear relationship between the absorption intensity of Fe3+ and absorbed dose of γ-radiation. It is useable in the dose range of 30-400 Gy traditionally. In this study, the main dose ranged between 5-30 Gy in Fricke dosimeter is investigated and the stability and reproducibility are also tested.
In addition, a concentrated TiO2 sol dosimeter which is sensitive to UV-radiation is prepared in this study. The synthesis of TiO2 sols was performed by hydrolysis of titanium isopropoxide adding to the mixture solution of ethyl alcohol (as dispersing solvent) and hydrochloric acid. After aging, TiO2 sols were irradiated under UV radiation the color of TiO2 sols changed from colorless to deep blue with a characteristic absorption around 580 nm. There is a linear relationship between the absorption intensity and absorbed dose of UV radiation. The influence of particle size distribution in different concentrated TiO2 sol dosimeters is studied. The parameters in TiO2 sol dosimeter are conferred in order to find the optimum concentration.

Keywords: Chemical dosimeter; Fricke dosimeter; TiO2 sol dosimeter

並列關鍵字

chemical dosimeter ； Fricke dosimeter ； TiO2 sol dosimeter

參考文獻

[1] Jay A. LaVeme *; Development of radiation chemistry studies of aqueous solutions with heavy ions, Nuclear Instruments and Methods in Physics Research, 1996, pp.302-307.

[2] Sivakumar R.; S. Selvasekarapandian; N. Mugunthamanikandan; V. M. Raghunath; Indoor gamma dose measurements in Gudalore (India) using TLD, Applied Radiation and Isotopes 2002, 56, pp.883-889.

[5] Wang WH, Matthews KL, Teague RE; Dose rates from a cobalt=60 pool irradiator measured with Fricke dosimeters, Health Physics 2008, 94, pp. S44-S50.

[7] Ross C. K.; N. V. Klassen; K. R. Shortt; G. D. Smith; A direct comparison of water calorimetry and Fricke dosimetry, Physics in Medicine and Biology 1989, 34, pp.23-42.

[8] Fricke H.; S. Morse; The chemical action of Roentgen rays on dilute ferrosulphate solutions as a measure of dose, American Journal of Roentgenol Radium Therapy and Nuclear Medicine 1927, 18, pp.430-432.