Radiation dose and image quality of CT fluoroscopy with partial exposure mode.

PURPOSE

The present study aimed to evaluate the scan technique of computed tomography (CT)-guided puncture procedures using partial exposure mode (PEM) on the radiation dose of the operator's hand and image quality.

METHODS

Radiation dose was evaluated using three types of scanning methods: one-shot scan (OS), OS with a bismuth shield added (OSBismuth), and a half-scan (i.e., PEM) capable of an adjustable exposure angle. Dose evaluation was performed using a torso phantom, while a circular phantom simulating the liver parenchyma and lesions was used for image quality evaluation. For each scanning method, four measurements were made to determine the radiation dose to the operator's hand and the dose distribution on the surface of the patient's torso; the output-dose profile was determined from five measurements. Image quality was evaluated in terms of contrast and contrast-to-noise ratio (CNR). Analysis of variance (ANOVA) or Friedman test were used for comparison between groups as appropriate. The post hoc tests were Tukey's honestly difference (HSD) test for parametric data or Wilcoxon signed rank test with Bonferroni correction for nonparametric data.

RESULTS

The PEM yielded a radiation dose to the operator's hand that was 84% (0.35 vs. 2.33 mGy) lower than that of the OS. The dose to the patient's torso was reduced by 35% and 68% for the OSBismuth and PEM, respectively, relative to that of the OS. Compared with the CNR of the other two scanning methods (OS, 2.9±0.1; OSBismuth, 2.9±0.1), the PEM increased the standard deviation and decreased the CNR (2.1±0.04, Tukey's HSD, P < 0.001 for all). Images acquired with PEM showed visibility equivalent to that of other scanning methods when window conditions were adjusted.

CONCLUSION

This study demonstrated that CT-guided puncture procedure using PEM effectively reduces the operator's exposure to radiation while minimizing image quality deterioration.