In this study we present endorectal digital prostate tomosynthesis (endoDPT), a proposed method of high resolution prostate imaging using an endorectal x-ray sensor and an external x-ray source. endoDPT may be useful for visualizing the fine detail of small structures such as low dose rate brachytherapy (LDRBT) seeds that are difficult to visualize with current methods. The resolution of endoDPT was characterized through measurement of the modulation transfer function (MTF) and artifact spread function (ASF) in computational and physical phantoms. The qualitative resolution of endoDPT was assessed relative to computed tomography (CT) through imaging of LDRBT seeds implanted in ex vivo canine prostates. The x-ray sensor MTF reached 10% at 11.50 mm⁻¹, the reconstruction algorithm MTF reached a maximum at 7.08 mm⁻¹, and the ASF was 2.5 mm (full-width at half-maximum). Fine structures in LDRBT seeds like the 0.05 mm thick shell were visible with endoDPT but not CT. All endoDPT images exhibited an overshoot artifact. The measured MTFs were consistent with other studies using similar x-ray sensors and demonstrated improved resolution compared to digital breast tomosynthesis; this result was due to the smaller endoDPT x-ray sensor detection element size and quantitatively demonstrates the high resolution of endoDPT. The ASF demonstrated worse depth resolution compared to in-plane resolution, due to partial angular sampling; partial angular sampling also caused the observed overshoot artifact in the endoDPT images. However, endoDPT still was able to visualize fine structures such as the LDRBT seed shell to a much higher degree than CT. This high-resolution visualization may be useful for improvements in patient specific LDRBT dosimetry. Overall, these results indicate endoDPT is capable of high in-plane spatial resolution and is thus well poised for optimization and studies assessing clinical utility.

在这项研究中，我们提出了直肠内数字前列腺断层合成 (endoDPT)，这是一种使用直肠内 X 射线传感器和外部 X 射线源的高分辨率前列腺成像方法。EndoDPT 可用于可视化小结构的精细细节，例如使用当前方法难以可视化的低剂量率近距离放射治疗 (LDRBT) 种子。通过测量计算和物理模型中的调制传递函数 (MTF) 和伪影扩散函数 (ASF) 来表征endoDPT 的分辨率。通过对植入离体犬前列腺中的 LDRBT 种子进行成像，相对于计算机断层扫描 (CT) 评估了 EndoDPT 的定性分辨率。X 射线传感器 MTF 在 11.50 mm ^-1处达到 10%, 重建算法 MTF 在 7.08 mm ^-1处达到最大值，ASF 为 2.5 毫米（半高全宽）。LDRBT 种子中的精细结构（如 0.05 毫米厚的壳）在endoDPT 中可见，但在 CT 中看不到。所有的endoDPT 图像都表现出过冲伪影。测量的 MTF 与使用类似 X 射线传感器的其他研究一致，并且与数字乳房断层合成相比，显示出更高的分辨率；这一结果是由于较小的endoDPT X 射线传感器检测元件尺寸，并定量证明了endoDPT 的高分辨率。由于部分角度采样，ASF 表现出与面内分辨率相比更差的深度分辨率；部分角度采样还导致在 endDPT 图像中观察到的过冲伪影。然而，与 CT 相比，endoDPT 仍然能够以更高的程度可视化 LDRBT 种子壳等精细结构。