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Brachytherapy. 2017 Jul - Aug;16(4):847-854. doi: 10.1016/j.brachy.2017.03.006. Epub 2017 Apr 25.

Use of 3D transabdominal ultrasound imaging for treatment planning in cervical cancer brachytherapy: Comparison to magnetic resonance and computed tomography.

Author information

1
Radiation Oncology Department, CHU de Québec-Université Laval, Québec, Québec, Canada; Department of Physics, Physics Engineering and Optic, and Cancer Research Centre, Université Laval, Québec, Québec, Canada; Centre de recherche du CHU de Québec et Axe Oncologie, CHU de Québec-Université Laval, Québec, Québec, Canada.
2
Radiation Oncology Department, CHU de Québec-Université Laval, Québec, Québec, Canada.
3
Radiation Oncology Department, CHU de Québec-Université Laval, Québec, Québec, Canada; Department of Physics, Physics Engineering and Optic, and Cancer Research Centre, Université Laval, Québec, Québec, Canada; Centre de recherche du CHU de Québec et Axe Oncologie, CHU de Québec-Université Laval, Québec, Québec, Canada. Electronic address: luc.beaulieu@phy.ulaval.ca.

Abstract

PURPOSE:

To evaluate if the addition of 3D transabdominal ultrasound (3DTAUS) imaging to computed tomography (CT) can improve treatment planning in 3D adaptive brachytherapy when compared with CT-based planning alone, resulting in treatment plans closer to the ones obtained using magnetic resonance imaging (MRI)-based planning.

METHODS AND MATERIALS:

Five patients with cervical cancer undergoing brachytherapy underwent three imaging modalities: MRI, CT, and CT-3DTAUS. Volumes were delineated by a radiation oncologist and treatment plans were optimized on each imaging modality. To compare treatment plans, the dwell times optimized on MRI were transferred on CT and CT-3DTAUS images and dose parameters were reported on volumes of the receiving imaging modality. The plans optimized on CT and CT-3DTAUS were also copied and evaluated on MRI images.

RESULTS:

Treatment plans optimized and evaluated on the same imaging modalities were clinically acceptable but statistically different (p < 0.05) from one another. MR-based plans had the highest target coverage (98%) and CT-based plans the lowest (93%). For all treatment plans evaluated on MRI, the target coverage was equivalent. However, a decrease in target coverage (V100) was observed when MR-based plans were applied on CT-3DTAUS (6%) and CT (13%) with p < 0.05. An increase in the rectum/sigmoid dose (D2cc) was observed with both CT-3DTAUS-based (0.6 Gy) and CT-based planning (1 Gy) when compared with MR-based plans, whereas bladder dose stayed similar.

CONCLUSIONS:

When compared with CT-based planning, the addition of 3DTAUS to CT results in treatment plans closer to MR-based planning. Its use reduces the high-risk clinical target volume overestimation typically observed on CT, improving coverage of the target volume while reducing dose to the organs at risk.

KEYWORDS:

3D; Cervix; Computed tomography; Magnetic resonance imaging; Treatment planning; Ultrasound

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