A feasibility study of tumour motion estimate with regional deformable registration method for 4-dimensional radiation therapy of lung cancer

Department of Radiation Oncology, Mount Sinai Medical Centre, New York

Corresponding Author:

M Chao
Department of Radiation Oncology
Mount Sinai Medical Centre, New York
Tel: 212-241-6500
E-mail: ming.chao@mountsinai.org, p.e.andersen@rsyd.dk

Abstract

Keywords

Resection margin; surgical accuracy; navigation; patient-specific instruments

Ten patients with various tumour sizes and locations were retrospectively enrolled to assess the proposed technique. Estimating tumour excursion relies exclusively on the deformable registration accuracy. The lack of the ground truth makes objective assessment of the algorithm quite challenging. Commonly utilized evaluation techniques are visual inspection, digitally synthetic image experiments, and physical deformable phantoms [2,3]. We manually delineated the GTV on all slices of 4DCT to evaluate the calculation accuracy. With the multistage regional method better than 2 mm accuracy was achievable. The margin added to GTV impacts the algorithm reliability and accuracy, and is often chosen no smaller than 1.5cm. In the cases where tumour is small but immediately next to or attached to anatomy with good image contrast, the calculation could possibly be accomplished with relatively smaller margin. Computationally, the proposed approach improved efficiency by a factor of five compared to the whole image based calculation.

Our study demonstrated that the information in the region of interest is sufficient to guide the deformable registration for the tumour motion estimation with high efficiency and clinically acceptable accuracy. Although only the motion magnitude is presented, it is not difficult to derive the three dimensional movements based upon the registration results. The motion obtained could benefit 4D treatment planning [4] and eventually mitigate the deleterious impact the mobile tumour motion can have on radiotherapy of thoracic and abdominal cancer.

References

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