Residual rotational set-up errors after daily cone-beam CT image guided radiotherapy of locally advanced cervical cancer

TY - JOUR

T1 - Residual rotational set-up errors after daily cone-beam CT image guided radiotherapy of locally advanced cervical cancer

AU - Laursen, Louise Vagner

AU - Elstrøm, Ulrik Vindelev

AU - Vestergaard, Anne

AU - Muren, Ludvig P

AU - Petersen, Jørgen Baltzer

AU - Lindegaard, Jacob Christian

AU - Grau, Cai

AU - Tanderup, Kari

N1 - Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

PY - 2012

Y1 - 2012

N2 - PURPOSE: Due to the often quite extended treatment fields in cervical cancer radiotherapy, uncorrected rotational set-up errors result in a potential risk of target miss. This study reports on the residual rotational set-up error after using daily cone beam computed tomography (CBCT) to position cervical cancer patients for radiotherapy treatment. METHODS AND MATERIALS: Twenty-five patients with locally advanced cervical cancer had daily CBCT scans (650 CBCTs in total) prior to treatment delivery. We retrospectively analyzed the translational shifts made in the clinic prior to each treatment fraction as well as the residual rotational errors remaining after translational correction. RESULTS: The CBCT-guided couch movement resulted in a mean translational 3D vector correction of 7.4mm. Residual rotational error resulted in a target shift exceeding 5mm in 57 of the 650 treatment fractions. Three patients alone accounted for 30 of these fractions. Nine patients had no shifts exceeding 5mm and 13 patients had 5 or less treatment fractions with such shifts. CONCLUSION: Twenty-two of the 25 patients have none or few treatment fractions with target shifts larger than 5mm due to residual rotational error. However, three patients display a significant number of shifts suggesting a more systematic set-up error.

AB - PURPOSE: Due to the often quite extended treatment fields in cervical cancer radiotherapy, uncorrected rotational set-up errors result in a potential risk of target miss. This study reports on the residual rotational set-up error after using daily cone beam computed tomography (CBCT) to position cervical cancer patients for radiotherapy treatment. METHODS AND MATERIALS: Twenty-five patients with locally advanced cervical cancer had daily CBCT scans (650 CBCTs in total) prior to treatment delivery. We retrospectively analyzed the translational shifts made in the clinic prior to each treatment fraction as well as the residual rotational errors remaining after translational correction. RESULTS: The CBCT-guided couch movement resulted in a mean translational 3D vector correction of 7.4mm. Residual rotational error resulted in a target shift exceeding 5mm in 57 of the 650 treatment fractions. Three patients alone accounted for 30 of these fractions. Nine patients had no shifts exceeding 5mm and 13 patients had 5 or less treatment fractions with such shifts. CONCLUSION: Twenty-two of the 25 patients have none or few treatment fractions with target shifts larger than 5mm due to residual rotational error. However, three patients display a significant number of shifts suggesting a more systematic set-up error.

U2 - 10.1016/j.radonc.2012.08.012

DO - 10.1016/j.radonc.2012.08.012

M3 - Journal article

C2 - 23022176

SN - 0167-8140

VL - 105

SP - 220

EP - 225

JO - Radiotherapy & Oncology

JF - Radiotherapy & Oncology

IS - 2

ER -