Intra-operative 3D guidance and edema detection in prostate brachytherapy using a non-isocentric C-arm

Jain, A.; Deguet, A.; Iordachita, I.; Chintalapani, G.; Vikal, S.; Blevins, J.; Le, Y.; Armour, E.; Burdette, C.; Song, D.; Fichtinger, G.

doi:10.1016/j.media.2010.07.011

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Intra-operative 3D guidance and edema detection in prostate brachytherapy using a non-isocentric C-arm

A. Jain
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
- Philips Research North America, 345 Scarborough Road, NY 10510, United States
- Corresponding author at: Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States.
A. Deguet
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
I. Iordachita
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
G. Chintalapani
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
S. Vikal
- Queen’s University, 725 Goodwin Hall, Kingston, ON, Canada K7L 3N6
J. Blevins
- Acoustic MedSystems Inc., 206 Randolph St Suite 301, Champaign, IL 61820, United States
Y. Le
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
E. Armour
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
C. Burdette
- Acoustic MedSystems Inc., 206 Randolph St Suite 301, Champaign, IL 61820, United States
D. Song
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
G. Fichtinger
- Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21210, United States
- Queen’s University, 725 Goodwin Hall, Kingston, ON, Canada K7L 3N6

published online 16 August 2010.
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Research highlights

► The proposed system is the first of a kind that makes intra-operative detection of edema possible. ► It achieves a significantly more homogeneous seed distribution at low cost. ► The approach has the potential to affect a paradigm shift in clinical practice.

Abstract

Purpose

Brachytherapy (radioactive seed insertion) has emerged as one of the most effective treatment options for patients with prostate cancer, with the added benefit of a convenient outpatient procedure. The main limitation in contemporary brachytherapy is faulty seed placement, predominantly due to the presence of intra-operative edema (tissue expansion). Though currently not available, the capability to intra-operatively monitor the seed distribution, can make a significant improvement in cancer control. We present such a system here.

Methods

Intra-operative measurement of edema in prostate brachytherapy requires localization of inserted radioactive seeds relative to the prostate. Seeds were reconstructed using a typical non-isocentric C-arm, and exported to a commercial brachytherapy treatment planning system. Technical obstacles for 3D reconstruction on a non-isocentric C-arm include pose-dependent C-arm calibration; distortion correction; pose estimation of C-arm images; seed reconstruction; and C-arm to TRUS registration.

Results

In precision-machined hard phantoms with 40–100 seeds and soft tissue phantoms with 45–87 seeds, we correctly reconstructed the seed implant shape with an average 3D precision of 0.35mm and 0.24mm, respectively. In a DoD Phase-1 clinical trial on six patients with 48–82 planned seeds, we achieved intra-operative monitoring of seed distribution and dosimetry, correcting for dose inhomogeneities by inserting an average of over four additional seeds in the six enrolled patients (minimum 1; maximum 9). Additionally, in each patient, the system automatically detected intra-operative seed migration induced due to edema (mean 3.84mm, STD 2.13mm, Max 16.19mm).

Conclusions

The proposed system is the first of a kind that makes intra-operative detection of edema (and subsequent re-optimization) possible on any typical non-isocentric C-arm, at negligible additional cost to the existing clinical installation. It achieves a significantly more homogeneous seed distribution, and has the potential to affect a paradigm shift in clinical practice. Large scale studies and commercialization are currently underway.

Keywords: Fluoroscopic guidance, Prostate brachytherapy, Low cost, Edema, 3D Reconstruction