Defining the margins in the radical radiotherapy of non-small cell lung cancer (NSCLC) with active breathing control (ABC) and the effect on physical lung parameters

Feasibility of the use of the Active Breathing Co ordinator™ (ABC) in patients receiving radical radiotherapy for non-small cell lung cancer (NSCLC)

“…Seventeen out of 18 patients completed a 6 ½ week radical course of radiotherapy using ABC. The mean breath hold time of 20 secs determined here was comparable with our previous study [15] and studies where the feasibility of ABC was evaluated but not combined with treatment [9,7,21]. However it was not necessary to continually use the maximum breath hold time during treatment, mean breath hold time during treatment was 10 -14…”

“…It has been speculated that the use of ABC during radical radiotherapy for lung cancer would be too demanding for patients [12,13,14]. However we have found in a previous study that lung cancer patients can maintain an average breath hold time of 20 seconds [15]. Although there are studies that report the treatment of lung cancer patients with ABC, reproducibility rather than feasibility was the focus [16,17].…”

The Use of the Active Breathing Coordinator Throughout Radical Non–Small-Cell Lung Cancer (NSCLC) Radiotherapy

“…The calculated margins in our previous work in a different patient cohort scanned but not treated with ABC during RT were 12 mm SI, 9.0 mm AP and 8.3 mm RL [24]. These margins were not applied in the current study because the reproducibility of ABC had not been determined throughout a course of radiotherapy.…”

“…The use of ABC during the computed tomography (CT) scans was tolerated by 25 out of 30 (83%) patients. The random contribution of periodic tumour motion was reduced by 90% in the superior-inferior direction compared with free-breathing, and the reduction in PTV size with ABC resulted in an 18-25% relative reduction in physical lung parameters [24].…”

Evaluation of automatic contour propagation in T2‐weighted 4DMRI for normal‐tissue motion assessment using internal organ‐at‐risk volume (IRV)

“…The full prescription dose is planned to cover the planning tumor volume (ITV+margin), which may include nearby OAR causing normal tissue toxicity 4. A planning organ‐at‐risk volume (PRV)9, 10, 11 is used to account for inter‐fractional variation in OAR position, but not intra‐fractional motion, therefore, the OAR motion has not been properly accounted for, leading uncertainties in OAR dose estimation, treatment toxicity,12, 13 and the dose‐toxicity relationship 4, 14. On the contrary, incorporating OAR motion in treatment planning may help to provide an improved OAR dose estimation and therefore optimized dose prescription for an SBRT treatment.…”