Ambient dose during intraoral radiography with current techniques: part 3: effect of tube voltage

Abstract

Objectives: This study was conducted to assess the impact of tube voltage on ambient dose during intraoral radiography, specifically remnant-beam transmission and scattered radiation. Methods and materials: Remnant-beam and scattered radiation doses were recorded using a phantom at tube voltages of 60, 63, 66, and 70 kV. Mathematical equations depicting their relations were then formulated, and reference values were calculated at the various voltages tested. Total ambient doses per exposure at 60 kV and at 70 kV were compared. Results: Both remnant-beam transmission and scattered radiation increased ~40% by increasing tube voltage from 60 kV to 70 kV, and the relation was linear. A remnant beam transmission reference value of 7.5% was established at 70 kV, as well as a conversion factor of 0.035µSv/mAs at one meter for scattered radiation at 60 kV. Given longer exposure times at 60 kV, total ambient dose proved higher at 60 kV than at 70 kV. Conclusion: Higher tube voltage results in higher remnant-beam transmission and more scattered radiation per workload. The relation is linear in the range between 60kV and 70 kV. Remnant-beam transmission at 70 kV is safely assessed at 7.5%. A conversion factor at 60 kV of 0.035 µSv/mAs at one meter for the scattered radiation dose can be proposed. Total ambient dose per exposure was higher at 60kV than at 70 kV.

Study of Low kV, Low Contrast Agent Dosage, and Low Contrast Agent Flow Rate Scan in Computed Tomography Angiography of Children's Liver

“…Tube voltage is positively correlated with X-ray energy. By reducing the tube voltage, X-ray photon energy decreases, leading to an increase in the X-ray attenuation coefficient of high-density substances and enhanced image contrast (28)(29)(30). In this experiment, 80 kV was used, bringing the X-ray energy closer to the K-layer electron binding energy (33.2 keV) of the iodine atom in the contrast agent.…”

Scattered Radiation Distribution Utilizing Three Different Cone-Beam Computed Tomography Devices for Maxillofacial Diagnostics: A Research Study

“…The protection against scattered radiation is a perennial concern of the scientific community, even when the radiation dose is quite low, such as during intraoral radiography [20,22,23]. A research study showed that occupationally exposed individuals presented higher incidence of thyroid cancer, especially in the past when the radiation protection measurements were not as strict [21].…”

“…Scattered radiation measurements were performed at the same distances from the CBCT devices (Figure 2). The placement positions of 451P were determined in each CBCT room based on point "0", which represented the fixed position of each CBCT device [20]. More specifically, two reference axes were drawn in the floor: the first (x-axis) represented the distance (in m) of the 451P to the right and left of the CBCT device, showing positive (right) and negative (left) values, respectively.…”

“…More specifically, two reference axes were drawn in the floor: the first (x-axis) represented the distance (in m) of the 451P to the right and left of the CBCT device, showing positive (right) and negative (left) values, respectively. The second (y-axis) represented the distance (in m) of the 451P from the CBCT device, in front of the CBCT device, perpendicular to the x-axis (Figure 2) [20].…”

“…The measurement at the height of 1 m from the floor represented the anatomical location of the gonads and the height of 1.3 m from the floor represented the anatomical location of the thyroid gland [21]. It is of importance that in the CBCT3 room, all measurements The placement positions of 451P were determined in each CBCT room based on point "0", which represented the fixed position of each CBCT device [20]. More specifically, two reference axes were drawn in the floor: the first (x-axis) represented the distance (in m) of the 451P to the right and left of the CBCT device, showing positive (right) and negative (left) values, respectively.…”