The first clinical implementation of a real-time six degree of freedom target tracking system during radiation therapy based on Kilovoltage Intrafraction Monitoring (KIM)

Doan Trang Nguyen; Ricky O'Brien; Jung-Ha Kim; Chen-Yu Huang; Lee Wilton; Peter Greer; Kimberley Legge; Jeremy T Booth; Per Rugaard Poulsen; Jarad Martin; Paul J Keall

doi:10.1016/j.radonc.2017.02.013

The first clinical implementation of a real-time six degree of freedom target tracking system during radiation therapy based on Kilovoltage Intrafraction Monitoring (KIM)

Radiother Oncol. 2017 Apr;123(1):37-42. doi: 10.1016/j.radonc.2017.02.013. Epub 2017 Mar 22.

Authors

Affiliations

¹ Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Australia.
² Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Australia.
³ Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Australia; School of Mathematical and Physical Sciences, The University of Newcastle, Australia.
⁴ School of Mathematical and Physical Sciences, The University of Newcastle, Australia.
⁵ Northern Sydney Cancer Centre, Royal North Shore Hospital, Australia.
⁶ Department of Oncology, Aarhus University Hospital, Denmark.
⁷ Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Australia. Electronic address: [email protected].

PMID: 28342648
DOI: 10.1016/j.radonc.2017.02.013

Abstract

Purpose: We present the first clinical implementation of a real-time six-degree of freedom (6DoF) Kilovoltage Intrafraction Monitoring (KIM) system which tracks the cancer target translational and rotational motions during treatment. The method was applied to measure and correct for target motion during stereotactic body radiotherapy (SBRT) for prostate cancer.

Methods: Patient: A patient with prostate adenocarcinoma undergoing SBRT with 36.25Gy, delivered in 5 fractions was enrolled in the study. 6DoF KIM technology: 2D positions of three implanted gold markers in each of the kV images (125kV, 10mA at 11Hz) were acquired continuously during treatment. The 2D→3D target position estimation was based on a probability distribution function. The 3D→6DoF target rotation was calculated using an iterative closest point algorithm. The accuracy and precision of the KIM method was measured by comparing the real-time results with kV-MV triangulation.

Results: Of the five treatment fractions, KIM was utilised successfully in four fractions. The intrafraction prostate motion resulted in three couch shifts in two fractions when the prostate motion exceeded the pre-set action threshold of 2mm for more than 5s. KIM translational accuracy and precision were 0.3±0.6mm, -0.2±0.3mm and 0.2±0.7mm in the Left-Right (LR), Superior-Inferior (SI) and Anterior-Posterior (AP) directions, respectively. The KIM rotational accuracy and precision were 0.8°±2.0°, -0.5°±3.3° and 0.3°±1.6° in the roll, pitch and yaw directions, respectively.

Conclusion: This treatment represents, to the best of our knowledge, the first time a cancer patient's tumour position and rotation have been monitored in real-time during treatment. The 6 DoF KIM system has sub-millimetre accuracy and precision in all three translational axes, and less than 1° accuracy and 4° precision in all three rotational axes.

Keywords: Intrafraction motion; Prostate SBRT treatment; Prostate cancer radiotherapy; Tumour motion; Tumour rotation; Tumour translation.

Publication types

Case Reports

MeSH terms

Adenocarcinoma / radiotherapy*
Algorithms
Computer Systems
Cone-Beam Computed Tomography / methods
Fiducial Markers
Humans
Imaging, Three-Dimensional / methods*
Male
Middle Aged
Movement
Prostatic Neoplasms / diagnostic imaging
Prostatic Neoplasms / radiotherapy*
Radiosurgery / methods*
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, Image-Guided / methods*
Reproducibility of Results
Rotation