Synthesis and evaluation of thermoluminescence properties of ZrO2:Mg for radiotherapy dosimetry

This study aimed to investigate the thermoluminescent properties of ZrO₂:Mg irradiated with a 6 MV X-ray beam and its potential application in radiotherapy dosimetry. ZrO₂ powder was synthesized using the sol–gel method and Mg was used as a dopant. Irradiations were performed with ZrO₂:Mg chips located at the center of a 10 × 10 cm² radiation field at a source surface distance of 100 cm, below a stack of solid water slabs, at the depth of maximum absorbed dose. The investigated characteristics of the material included linearity with radiation dose, reproducibility, accuracy, sensitivity and fading. Regarding the intrinsic difference of the samples, the glow curves of the investigated ZrO₂:Mg chips exposed to 1 Gy of 6 MV X-rays exhibited three or four peaks. The ZrO₂:Mg samples showed a 47% fading at 24 h after irradiation, and the reproducibility of the thermoluminescence reading of ZrO₂:Mg for equal irradiation conditions was ± 21%. The thermoluminescence response of the investigated ZrO₂:Mg samples to various absorbed doses from 0.5 to 2.5 Gy showed a gentle increase of the thermoluminescence intensity with increasing absorbed dose. The obtained results show that ZrO₂:Mg is not an appropriate candidate for X-ray photons in radiotherapy, due to low thermoluminescence peak temperature, low reproducibility, low sensitivity to various absorbed doses and significant fading.

     

Introduction a potato cultivar "sprit" as relatively resistant to main fungal pathogens causal agents of early blight and wilting on potato in Iran

Potato (Solanum tubersum L.) is one of the most human food production cultured in Iran especially Zanjan province as a temperate region. Some fungal pathogens caused severely infected on potato tubers or foliage in the majority grown areas and resulted yield losses in potato production. Recent years from 2002 to 2004 infected samples were collected from different potato grown regions in Zanjan province then cultured on PDA after surface sterilization with sodium hypochlorite. Isolated fungal pathogens were identified and study showed the main pathogens with high incidence and frequency were Alternaria solani, Fusarium oxysporum and Verticillium sp. in studied areas. The regions which used convention varieties showed more diseases than other locations which used relatively resistant races. The rate of resistance for 10 international potato varieties was studied by inoculation of them by 10(5) spores suspension of three common fungal pathogens in the field. Study showed Sprit cultivar was more resistant than others to all three common pathogens and Lady-Claire was most susceptible. Yield production of Sprit per unit of land area was also exceeded that of other cultivars by factors of 1.10 to 2.25 respectively. The results of the study helped potato growers to culture Sprit cultivar and have good yield production in Zanjan and Hamedan provinces in this year.