MRI-based tumor motion characterization and gating schemes for radiation therapy of pancreatic cancer.

Autor: Heerkens HD; Department of Radiotherapy, University Medical Center Utrecht, The Netherlands. Electronic address: h.heerkens@umcutrecht.nl., van Vulpen M; Department of Radiotherapy, University Medical Center Utrecht, The Netherlands., van den Berg CA; Department of Radiotherapy, University Medical Center Utrecht, The Netherlands., Tijssen RH; Department of Radiotherapy, University Medical Center Utrecht, The Netherlands., Crijns SP; Department of Radiotherapy, University Medical Center Utrecht, The Netherlands., Molenaar IQ; Department of Surgery, University Medical Center Utrecht, The Netherlands., van Santvoort HC; Department of Surgery, University Medical Center Utrecht, The Netherlands., Reerink O; Department of Radiotherapy, University Medical Center Utrecht, The Netherlands., Meijer GJ; Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
Jazyk: angličtina
Zdroj: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology [Radiother Oncol] 2014 May; Vol. 111 (2), pp. 252-7. Date of Electronic Publication: 2014 Apr 17.
DOI: 10.1016/j.radonc.2014.03.002
Abstrakt: Background and Purpose: To characterize pancreatic tumor motion and to develop a gating scheme for radiotherapy in pancreatic cancer.
Materials and Methods: Two cine MRIs of 60s each were performed in fifteen pancreatic cancer patients, one in sagittal direction and one in coronal direction. A Minimum Output Sum of Squared Error (MOSSE) adaptive correlation filter was used to quantify tumor motion in craniocaudal, lateral and anteroposterior directions. To develop a gating scheme, stability of the breathing phases was examined and a gating window assessment was created, incorporating tumor motion, treatment time and motion margins.
Results: The largest tumor motion was found in craniocaudal direction, with an average peak-to-peak amplitude of 15mm (range 6-34mm). Amplitude of the tumor in the anteroposterior direction was on average 5mm (range 1-13mm). The least motion was seen in lateral direction (average 3mm, range 2-5mm). The end exhale position was the most stable position in the breathing cycle and tumors spent more time closer to the end exhale position than to the end inhale position. On average, a margin of 25% of the maximum craniocaudal breathing amplitude was needed to achieve full target coverage with a duty cycle of 50%. When reducing the duty cycle to 50%, a margin of 5mm was sufficient to cover the target in 11 out of 15 patients.
Conclusion: Gated delivery for radiotherapy of pancreatic cancer is best performed around the end exhale position as this is the most stable position in the breathing cycle. Considerable margin reduction can be established at moderate duty cycles, yielding acceptable treatment efficiency. However, motion patterns and amplitude do substantially differ between individual patients. Therefore, individual treatment strategies should be considered for radiotherapy in pancreatic cancer.
(Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)
Databáze: MEDLINE
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