ABSTRACT
OBJECTIVE: This study aimed at investigating the air kerma distribution of the radiation output in two and three dimensions of three general radiographic units by physical measurements. METHODS: A 6-cm3 ionization chamber was placed at 5-cm intervals of 225 locations in a 70 × 70 cm2 x-ray beam field. The chamber was placed at a level of 30 cm above the x-ray table to measure the air kerma intensity of the x-ray output across the whole area. Three different brands of radiographic units with different anode target angles and at different tube aging stages were studied. The same exposure parameters were used for each location, and measurements were made for three different tube potentials at 60, 85, and 110 kilovoltage peaks (kV[p]). RESULTS: At the tube potential of 85 kV(p), the relative maximum percentage differences on the average air kerma measured along the central anode-cathode axis (x-axis) of the x-ray tube were found to be 31.5%, 15.5%, and 43.1% more at the cathode ends than those at the anode ends of the three radiographic units. Results of a paired samples t test (confidence intervals at 95%, two-tailed) on three of the four fixed pair-wise sampling points along the x-axis were found to be statistically significant in their relative percentage differences in air kerma intensity with respect to the central point (labeled as 35 cm) with a P value ≤.03. However, those measured at four fixed pair-wise points at 90° across the anode-cathode direction were all found to be statistically nonsignificant (P ≥ .29). Similar trends were observed for the other two tube potentials tested. From the three-dimensional displays of radiation output intensity, a similar unique pyramidal shape pattern with a skewed peak toward the cathode end was observed for all three diagnostic x-ray tubes tested. CONCLUSIONS: The anode heel effect was found to be enhanced in the x-ray tube with a smaller anode target angle, more aging, and higher tube potentials. Three-dimensional air kerma distribution maps of the three x-ray units tested were found to be similar in pattern, and this was displayed in detail regarding the extent of the anode heel effect.
ABSTRACT
Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when the CRT glasses were used due to the presence of lead in the glass. In addition, the radiation shielding contribution of CRT glasses was more pronounced when the mortar was subject to a higher level of X-ray energy.
