Background And Purpose: Vacuum cushion immobilization is commonly used during stereotactic body radiotherapy (SBRT) to reduce intrafraction motion. We investigated target and bony anatomy intrafraction motion (translations and rotations) during online adaptive SBRT on an MR-linac for pelvic/para-aortic lymph node metastases with and without vacuum cushion.
Materials And Methods: Thirty-nine patients underwent 5x7 Gy SBRT on a 1.5T MR-linac, 19 patients were treated with vacuum cushion, 19 without and 1 patient sequentially with and without. Intrafraction motion was calculated for target lymph nodes (GTVs) and nearby bony anatomy, for three time intervals (pre-position verification (PV), pre-post, PV-post, relating to the online MRI scans) per treatment fraction.
Results: Vacuum cushion immobilization significantly reduced anterior-posterior translations for the pre-PV and pre-post intervals, for bony anatomy and pre-post interval for GTV (p < 0.05). Mean GTV intrafraction motion reduction in posterior direction was 0.7 mm (95% confidence interval 0.3-1.1 mm) for pre-post interval (mean time = 32 min). Shifts in other directions were not significantly reduced. More motion occurred in pre-PV interval than in PV-post interval (mean time = 16 min for both); vacuum cushion immobilization did not reduce intrafraction motion during the beam-on period.
Conclusion: A vacuum cushion reduces GTV and bony anatomy intrafraction motion in posterior direction during pelvic/para-aortic lymph node SBRT. This motion reduction was found for the first 16 min per session. For single targets this motion can be corrected for directly with an MR-linac. Intrafraction motion was not reduced during the second half of the session, the period of radiotherapy delivery on an MR-linac. Vacuum cushion immobilization may not be necessary for patients with single lymph node oligometastases undergoing SBRT on an MR-linac.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.radonc.2020.09.021 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Does deformation of immobilization devices impact treatment accuracy in thoracic cancer radiotherapy?
J Appl Clin Med Phys
December 2024
Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.
Background: Immobilization devices are essential for maintaining accurate and repeatable patient positioning in radiotherapy. This study aimed to evaluate the setup errors and dosimetric deviation induced by the deformation of immobilization devices in thoracic cancer radiotherapy using CT-linac.
Materials And Methods: A retrospective analysis was conducted on 40 thoracic cancer patients who underwent radiotherapy, using vacuum cushion (VC) and thermoplastic mask (TM) for immobilization.
Impact of belly board immobilization devices and body mass factor on setup displacement using daily cone-beam CT in rectal cancer radiotherapy.
J Appl Clin Med Phys
November 2024
State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China.
Objective: The objective of this study is to evaluate the impact of different belly board and daily changes in patient's body-mass factor (BMF) on setup displacement in radiotherapy for rectal cancer.
Methods: Twenty-five patients were immobilized using the thermoplastic mask with belly board (TM-BB), and 30 used the vacuum bag cushion with belly board (VBC-BB), performing daily cone-beam computed tomography (CBCT) scans 625 times and 750 times, respectively. Daily pretreatment CBCT scans were registered to the planned CT images for BMF change determination and setup displacement measurement.
A prospective observational study evaluating two patient immobilisation methods in lung stereotactic radiotherapy.
Cancer Radiother
June 2024
Radiation Therapy Department, centre Léon-Bérard, 28, rue Laënnec, 69008 Lyon, France.
Purpose: The main objective of this study was to assess inter- and intrafraction errors for two patient immobilisation devices in the context of lung stereotactic body radiation therapy: a vacuum cushion and a simple arm support.
Materials And Methods: Twenty patients who were treated with lung stereotactic body radiation therapy in supine position with arms above their head were included in the study. Ten patients were setup in a vacuum cushion (Bluebag™, Elekta) and ten other patients with a simple arm support (Posirest™, Civco).
MRgFUS ablation of a recurrent tenosynovial giant cell tumor in the foot using ExAblate 2100 system in combination with patient immobilization device.
Radiography (Lond)
May 2024
Department of Radiology, Mayo Clinic, MN, USA.
Introduction: Magnetic Resonance-guided Focused Ultrasound (MRgFUS) treatment for certain anatomy locations can be extremely challenging due to patient positioning and potential motion. This present study describes the treatment of a recurrent tenosynovial giant cell tumor of the plantar forefoot using the ExAblate 2100 system in combination with patient immobilization device.
Methods: Prior to the treatment, several patient immobilization devices were investigated.
Intrafractional motion detection for spine SBRT via X-ray imaging using ExacTrac Dynamic.
Clin Transl Radiat Oncol
May 2024
Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany.
Article Synopsis
- This study aimed to evaluate intrafractional motion during spine stereotactic body radiotherapy (SBRT) without individualized immobilization by using high-accuracy X-ray monitoring.
- A total of 79 SBRT treatments were analyzed for 29 patients, where deviations from set tolerances (0.7 mm for translation and 0.5° for rotation) were tracked via the ExacTrac Dynamic System.
- The results indicated that 15% of X-ray image pairs showed significant deviations, with the most notable translational movement reaching up to 2.8 mm and rotations up to 2.6°, highlighting the importance of motion detection for improving patient safety during treatment.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!