Intra-operative 3D Guidance in Prostate Brachytherapy Using a Non-isocentric C-arm

Abstract

Abstract. Intra-operative guidance in Transrectal Ultrasound (TRUS) guided prostate brachytherapy requires localization of inserted radioactive seeds relative to the prostate. Seeds were reconstructed using a typical C-arm, and exported to a commercial brachytherapy system for dosimetry analysis. Technical obstacles for 3D reconstruction on a nonisocentric C-arm included pose-dependent C-arm calibration; distortion correction; pose estimation of C-arm images; seed reconstruction; and C-arm to TRUS registration. In precision-machined hard phantoms with 40-100 seeds, we correctly reconstructed 99.8% seeds with a mean 3D accuracy of 0.68 mm. In soft tissue phantoms with 45-87 seeds and clinically realistic 15 o C-arm motion, we correctly reconstructed 100% seeds with an accuracy of 1.3 mm. The reconstructed 3D seed positions were then registered to the prostate segmented from TRUS. In a Phase-1 clinical trial, so far on 4 patients with 66-84 seeds, we achieved intra-operative monitoring of seed distribution and dosimetry. We optimized the 100% prescribed iso-dose contour by inserting an average of 3.75 additional seeds, making intra-operative dosimetry possible on a typical C-arm, at negligible additional cost to the existing clinical installation.

Robotic assistance for ultrasound-guided prostate brachytherapy

“…Generally speaking, cancerous tissues receive proportionally less dosage as more edematic fluid accumulates in the prostate. Our recent intraoperative data reveal that edema occurs immediately after needle placement begins and continues to evolve during the procedure (Jain et al, 2007). Edema typically subsides after 2-4 weeks, however by then much of the dose is already delivered due to the short half-life of the isotopes (Pd 103 =17 days, I 125 =60 days).…”

Quantification of Edematic Effects in Prostate Brachytherapy Interventions

“…What follows is that after simple binary thresholding of the two volumes, the two gravity centers are practically identical. Jain et al found this approach to be accurate to a few millimeters in intra-operative registration of C-arm fluoroscopy and TRUS of brachytherapy implants [16]. All said, we are confident that in actual clinical cases the initial pose will be conveniently determined within the capture range.…”

Miniaturized force-indentation depth sensor for tissue abnormality identification during laparoscopic surgery

“…This technique is particularly suitable for differentiating the bones from other tissues and thus has been often used in the image-guided surgery such as oral surgery [7], orthopedic surgery [8], neurosurgery [9] as well as the prostate brachytherapy [10] However, due to the cost and the radiation exposure associated with such techniques, they are not ideal for intraoperatively measuring the tissue deformation during a minimally invasive surgery.…”