TY - JOUR
T1 - Variation in Lung Tumour Breathing Motion between Planning Four-dimensional Computed Tomography and Stereotactic Ablative Radiotherapy Delivery and its Dosimetric Implications
T2 - Any Role for Four-dimensional Set-up Verification?
AU - Ruben, J. D.
AU - Seeley, A.
AU - Panettieri, V.
AU - Ackerly, T.
PY - 2016/1
Y1 - 2016/1
N2 - Aims: To investigate variation in tumour breathing motion (TBM) between the planning four-dimensional computed tomograph (4DCT) and treatment itself for primary or secondary lung tumours undergoing stereotactic ablative radiotherapy (SABR). Materials and methods: Sixteen consecutive patients underwent planning 4DCT at least 1 week after implantation of a fiducial marker. The maximal extent of breathing motion of the intra-tumoural fiducial was measured at 4DCT and again at delivery of each SABR fraction on the linac using stereoscopic kilovoltage imaging. Displacements of the fiducial beyond planned limits were measured in three dimensions and represented as vectors. Variation in breathing motion between the planning 4DCT and treatment, and between individual SABR fractions was analysed. Results: Although TBM at treatment exceeded planned tumour motion limits for at least part of the course for all patients, 31% of patients remained consistently within 1 mm, 50% within 2 mm and 69% consistently within 3 mm of planned parameters. However, 19% of patients experienced TBM variation 5 mm or more beyond planned limits for at least one fraction. For all patients, the median displacement vector at treatment beyond the planned motion envelope was 1.0 mm (mean 2.0 mm, range 0-12.7 mm). Variation in TBM at treatment from 4DCT correlated neither with the magnitude of TBM at 4DCT nor with planning target volume size (rs = 0.13, P = 0.62; rs = 0.02, P = 0.94, respectively). Nor was TBM variation related to tumour type or lobar position (P = 0.35, P = 0.06, respectively). Inter-fraction TBM variation was modest, with an average standard deviation of 1.7 mm (0.3-8.7 mm). Conclusions: TBM variation between 4DCT and treatment and between SABR fractions was modest for most patients. However, 19% of patients experienced significant TBM variation that could be clinically relevant for those most severely affected. It seems prudent to carry out on-couch assessment of TBM at each SABR fraction to identify such patients who might benefit from respiratory gating or adaptive radiotherapy to maintain tumour motion within the planned limits.
AB - Aims: To investigate variation in tumour breathing motion (TBM) between the planning four-dimensional computed tomograph (4DCT) and treatment itself for primary or secondary lung tumours undergoing stereotactic ablative radiotherapy (SABR). Materials and methods: Sixteen consecutive patients underwent planning 4DCT at least 1 week after implantation of a fiducial marker. The maximal extent of breathing motion of the intra-tumoural fiducial was measured at 4DCT and again at delivery of each SABR fraction on the linac using stereoscopic kilovoltage imaging. Displacements of the fiducial beyond planned limits were measured in three dimensions and represented as vectors. Variation in breathing motion between the planning 4DCT and treatment, and between individual SABR fractions was analysed. Results: Although TBM at treatment exceeded planned tumour motion limits for at least part of the course for all patients, 31% of patients remained consistently within 1 mm, 50% within 2 mm and 69% consistently within 3 mm of planned parameters. However, 19% of patients experienced TBM variation 5 mm or more beyond planned limits for at least one fraction. For all patients, the median displacement vector at treatment beyond the planned motion envelope was 1.0 mm (mean 2.0 mm, range 0-12.7 mm). Variation in TBM at treatment from 4DCT correlated neither with the magnitude of TBM at 4DCT nor with planning target volume size (rs = 0.13, P = 0.62; rs = 0.02, P = 0.94, respectively). Nor was TBM variation related to tumour type or lobar position (P = 0.35, P = 0.06, respectively). Inter-fraction TBM variation was modest, with an average standard deviation of 1.7 mm (0.3-8.7 mm). Conclusions: TBM variation between 4DCT and treatment and between SABR fractions was modest for most patients. However, 19% of patients experienced significant TBM variation that could be clinically relevant for those most severely affected. It seems prudent to carry out on-couch assessment of TBM at each SABR fraction to identify such patients who might benefit from respiratory gating or adaptive radiotherapy to maintain tumour motion within the planned limits.
KW - Breathing motion
KW - Breathing movement
KW - Respiratory motion
KW - SABR
KW - Stereotactic ablative radiotherapy
UR - http://www.scopus.com/inward/record.url?scp=84948799242&partnerID=8YFLogxK
U2 - 10.1016/j.clon.2015.08.010
DO - 10.1016/j.clon.2015.08.010
M3 - Article
C2 - 26432188
AN - SCOPUS:84948799242
SN - 0936-6555
VL - 28
SP - 21
EP - 27
JO - Clinical Oncology
JF - Clinical Oncology
IS - 1
ER -