TY - JOUR

T1 - Feasibility of Pencil Beam Scanned Intensity Modulated Proton Therapy in Breath-hold for Locally Advanced Non-Small Cell Lung Cancer

AU - Gorgisyan, Jenny

AU - Munck Af Rosenschold, Per

AU - Perrin, Rosalind

AU - Persson, Gitte F

AU - Josipovic, Mirjana

AU - Belosi, Maria Francesca

AU - Engelholm, Svend Aage

AU - Weber, Damien C

AU - Lomax, Antony J

N1 - Copyright © 2017 Elsevier Inc. All rights reserved.

PY - 2017/12

Y1 - 2017/12

N2 - PURPOSE: We evaluated the feasibility of treating patients with locally advanced non-small cell lung cancer (NSCLC) with pencil beam scanned intensity modulated proton therapy (IMPT) in breath-hold.METHODS AND MATERIALS: Fifteen NSCLC patients who had previously received 66 Gy in 33 fractions with image guided photon radiation therapy were included in the present simulation study. In addition to a planning breath-hold computed tomography (CT) scan before the treatment start, a median of 6 (range 3-9) breath-hold CT scans per patient were acquired prospectively throughout the radiation therapy course. Three-field IMPT plans were constructed using the planning breath-hold CT scan, and the four-dimensional dose distributions were simulated, with consideration of both patient intra- and interfraction motion, in addition to dynamic treatment delivery.RESULTS: The median clinical target volume receiving 95% of the prescribed dose was 99.8% and 99.7% for the planned and simulated dose distributions, respectively. For 3 patients (20%), the dose degradation was >5%, and plan adjustment was needed. Dose degradation correlated significantly with the change in water-equivalent path lengths (P<.01) in terms of the percentage of voxels with 3-mm or more undershoot on repeat CT scans. The dose to the organs at risk was similar for the planned and simulated dose distributions. Three or fewer breath-holds per field would be required for 12 of the 15 patients, which was clinically feasible.CONCLUSIONS: For 9 of 15 NSCLC patients, IMPT in breath-hold was both dosimetrically robust and feasible to deliver regarding the treatment time. Three patients would have required plan adaption to meet the dosimetric criteria. The change in water-equivalent path length is an indicator of plan robustness and should be considered for the selection of patients for whom the plan would require adaptation.

AB - PURPOSE: We evaluated the feasibility of treating patients with locally advanced non-small cell lung cancer (NSCLC) with pencil beam scanned intensity modulated proton therapy (IMPT) in breath-hold.METHODS AND MATERIALS: Fifteen NSCLC patients who had previously received 66 Gy in 33 fractions with image guided photon radiation therapy were included in the present simulation study. In addition to a planning breath-hold computed tomography (CT) scan before the treatment start, a median of 6 (range 3-9) breath-hold CT scans per patient were acquired prospectively throughout the radiation therapy course. Three-field IMPT plans were constructed using the planning breath-hold CT scan, and the four-dimensional dose distributions were simulated, with consideration of both patient intra- and interfraction motion, in addition to dynamic treatment delivery.RESULTS: The median clinical target volume receiving 95% of the prescribed dose was 99.8% and 99.7% for the planned and simulated dose distributions, respectively. For 3 patients (20%), the dose degradation was >5%, and plan adjustment was needed. Dose degradation correlated significantly with the change in water-equivalent path lengths (P<.01) in terms of the percentage of voxels with 3-mm or more undershoot on repeat CT scans. The dose to the organs at risk was similar for the planned and simulated dose distributions. Three or fewer breath-holds per field would be required for 12 of the 15 patients, which was clinically feasible.CONCLUSIONS: For 9 of 15 NSCLC patients, IMPT in breath-hold was both dosimetrically robust and feasible to deliver regarding the treatment time. Three patients would have required plan adaption to meet the dosimetric criteria. The change in water-equivalent path length is an indicator of plan robustness and should be considered for the selection of patients for whom the plan would require adaptation.

KW - Journal Article

U2 - 10.1016/j.ijrobp.2017.08.023

DO - 10.1016/j.ijrobp.2017.08.023

M3 - Journal article

C2 - 28964587

VL - 99

SP - 1121

EP - 1128

JO - International Journal of Radiation Oncology, Biology, Physics

JF - International Journal of Radiation Oncology, Biology, Physics

SN - 0360-3016

IS - 5

ER -