Efficacy of gonadal shielding in dose reduction for female pelvic radiography.

This study aimed to evaluate the dose reduction using gonad shielding (GS) during pelvic imaging. Three types of pelvic images (radiography, magnetic resonance and computed tomography) were fused to elucidate the three-dimensional relationship between the position of ovaries and GS. To estimate the dose received by the ovaries, the off-axis dose at any given depth was measured under two different imaging conditions using thermoluminescence dosemeters and a polymethyl methacrylate phantom. The mean ovarian depth was 8.4 cm. The mean estimated ovarian dose without an additional filter was 0.36 mGy without GS and 0.14 mGy with GS. The mean estimated ovarian dose with an additional filter was 0.24 mGy without GS and 0.10 mGy with GS. The efficacy of ovarian dose reduction should be evaluated based on the achieved ovarian dose, considering the ovarian depth and use of additional filtration, rather than the ovarian protection rate of GS.

[Verification of Effectiveness of Gonad Shielding in Female Hip Joint Radiography].

PURPOSE: It has been reported that the placement of protective equipment in female pelvic radiography is predominantly inadequate compared with that of male. We analyzed the actual situation of ovarian shielding by protective devices using X-ray, CT, and MR images obtained in the past, and evaluated the effectiveness of gonadal protection in female hip radiography. METHODS: The ovaries were contoured in MR images and the pelvic bone was extracted by CT images. The MR/CT fusion images were created using a 3D workstation. The amount of physiological fluctuation in the ovarian location was measured. The fusion images in the ray-summation display were manually superimposed with the X-ray image, and the percentage of ovaries that could be shielded by the protective device was classified into four categories: (a) complete protection, (b) partial protection, (c) failure of protection, and (d) image retaking. RESULTS: The mean and maximum ovarian fluctuations were 1.1 cm and 3.9 cm in the superior and inferior directions, respectively, and 0.7 cm and 2.0 cm in the left and right directions, respectively. The percentage of ovaries shielded was 18.9% for complete protection, 58.5% for partial protection, 15.1% for inadequate protection, and 7.5% for image retaking. CONCLUSION: The effectiveness of gonadal protection is low because the protective device could not cover the entire ovary in about 80% of the female hip radiographs.

Spontaneous brain tumor imaging of aged rat by crystal X-ray interferometer-based phase-contrast X-ray CT.

BACKGROUND: Crystal X-ray interferometer-based phase-contrast X-ray computed tomography (C-PCCT) enables the depiction of internal structures of biological tissue without contrast agents. PURPOSE: To determine the advantage of this technique in visualizing detailed morphological structures of a rare spontaneous brain tumor in an aged rat. MATERIAL AND METHODS: An aged rat's spontaneous brain tumor was imaged by C-PCCT without contrast agent. Three-dimensional (3D) images of the tumor microvasculature were reconstructed and compared with pathological pictures. RESULTS: C-PCCT depicted the tumor's various pathological features clearly, e.g. its cell density and vasculature, and blood clots caused by hemorrhaging and/or hematomas. The obtained images resembled pathological pictures with a magnification of ×20 and were used to reconstruct 3D images of the tumor vascularity up to approximately 26 µm in diameter. CONCLUSION: Since C-PCCT is able to depict various pathological conditions, it might be useful for cancer research.