Highlights
- •DCT allows for precise characterization of tumor breathing motion.
- •Interfraction and intrafraction effects can be included in ITV definition.
- •ITV is less affected by amplitude variations than by baseline shift variations.
- •80% increase in motion range compared to that in 4DCT is caused by baseline shift.
Abstract
Purpose
To use Discrete Cosine Transform to include tumor motion variations on ITV definition
of SBRT patients.
Methods
Data from 66 patients was collected. 2D planar fluoroscopy images (FI) were available
for 54 patients. Daily CBCT projections (CBCTp) from 29 patients were employed to
measure interfraction amplitude variability. Systematic amplitude variations were
obtained from 17 patients with data from both FI and CBCTp.
Tumor motion curves obtained from FI were characterized with a Cosine model (CM),
based on cosine functions to the power of 2, 4 or 6, and DCT. Performance of both
models was evaluated by means of R2 coefficient and by comparing their results on Internal Target Volume (ITV) margins
against those calculated from original tumor motion curves.
Amplitude variations from CBCTp, as well as estimations of baseline shift variations
were added to the DCT model to account for their effect on ITV margins.
Results
DCT replicated tumor motion curves with a mean R2 values for all patients of 0.86, 0.91 and 0.96 for the lateral (LAT), anterior-posterior
(AP) and cranio-caudal (CC) directions respectively. CM yielded worst results, with
R2 values of 0.64, 0.61 and 0.74 in the three directions.
Interfraction amplitude variation increased ITV margins by a 9%, while baseline shift
variability implied a 40% and 80–100% increase for normalized values of baseline shift
of 0.2 and 0.4 respectively.
Conclusions
Probability distribution functions of tumor positions can be successfully characterized
with DCT. This permits to include tumor motion variablilities obtained from patient
population into patient specific ITVs.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Physica Medica: European Journal of Medical PhysicsAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Stereotactic body radiation therapy: The report of AAPM Task Group 101.Med Phys. 2010; 37: 4078-4101
- Frontiers in planning optimization for lung SBRT.Phys Med. 2017; 44: 163-170
- The management of respiratory motion in radiation oncology: Report of AAPM Task Group 76.Med Phys. 2006; 33: 3874-3900
- 4-dimensional computed tomography imaging and treatment planning.Semin Radiat Oncol. 2004; 14: 81-90
- Multiple “slow” CT scans for incorporating lung tumor mobility in radiotherapy planning.Int J Radiat Oncol Biol Phys. 2001; 51: 932-937
- Digital fluoroscopy to quantify lung tumor motion: potential for patient-specific planning target volumes.Int J Radiat Oncol Biol Phys. 2003; 57: 717-723
- Geometrical and dosimetrical uncertainties in hypofractionated radiotherapy of the lung: A review.Phys Med. 2017; : 36_126-139
- Planning 4-dimensional computed tomography (4DCT) cannot adequately represent daily intrafractional motion of abdominal tumors.Int J Radiat Oncol Biol Phys. 2013; 85: 999-1005
- Both four-dimensional computed tomography and four-dimensional cone beam computed tomography under-predict lung target motion during radiotherapy.Radiother Oncol. 2019; 135: 65-73
- Interfraction and intrafraction changes in amplitude of breathing motion in stereotactic liver radiotherapy.Int J Radiat Oncol Biol Phys. 2010; 77: 918-925
Bisonnette J.P. et al, Quantifying interfraction and intrafraction tumor motion in lung stereotactic body radiotherapy using respiratory-correlated cone beam computed tomography. Int J Radiat Oncol Biol Phys 75(3):688-95.
- The long- and short-term variability of breathing induced tumor motion in lung and liver over the course of a radiotherapy treatment.Radiother Oncol. 2018 Feb; 126: 339-346
- Evaluation of the intra- and interfractional tumor motion and variability by fiducial-based real-time tracking in liver stereotactic body radiation therapy.J Appl Clin Med Phys. 2018; 19: 94-100
- Inter- and Intrafractional Variation in the 3-Dimensional Positions of Pancreatic Tumors Due to Respiration Under Real-Time Monitoring.Int J Radiat Oncol Biol Phys. 2017; 98: 1204-1211
- Quantifying variability of intrafractional target motion in stereotactic body radiotherapy for lung cancers.J Appl Clin Med Phys. 2013; 14: 140-152
- Evaluation of the motion of lung tumors during stereotactic body radiation therap (SBRT) with four-dimensional computed tomography (4DCT) using real-time tumor tracking radiotherapy system (RTRT).Phys Med. 2016; 32: 305-311
Wolthaus J. W. H. et al, Comparison of different strategies to use four-dimensional computed tomography in treatment planning for lung cancer patients. Int J Radiat Oncol Biol Phys 70(4):1229-38.
George R, Vedam S. S., Chung T.D., Ramakrishnan V and Keall P. J. The application of the sinusoidal model to lung cancer patient respiratory motion. Med Phys 32 (9): 2850-61.
- Definition of internal target volumes based on planar X-ray fluoroscopic images for lung and hepatic stereotactic body radiation therapy. Comparison to inhale/exhale CT technique.J Appl Clin Med Phys. 2020; 21: 56-64
- Finding the optimal statistical model to describe target motion during radiotherapy delivery-a Bayesian approach.Phys Med Biol. 2012 May 7; 57: 2743-2755
- Discrete-Time Signal Processing.2nd Ed. Prentice Hall, Upper Saddle River, NJ1999
- A method for incorporating organ motion due to breathing into 3D dose calculations.Med Phys. 1999; 26: 715-720
- The probability of correct target dosage: dose-population histograms for deriving treatment margins in radiotherapy.Int J Radiat Oncol Biol Phys. 2000; 47: 1121-1135
- Effectiveness of a simple and real-time baseline shift monitoring system during stereotactic body radiation therapy of lung tumors.Phys Med. 2017; 43: 100-106
Article info
Publication history
Published online: April 21, 2021
Accepted:
March 31,
2021
Received in revised form:
March 25,
2021
Received:
October 16,
2020
Identification
Copyright
© 2021 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
