PMID- 36893292 OWN - NLM STAT- MEDLINE DCOM- 20230510 LR - 20230510 IS - 2473-4209 (Electronic) IS - 0094-2405 (Linking) VI - 50 IP - 5 DP - 2023 May TI - Real-time motion monitoring using orthogonal cine MRI during MR-guided adaptive radiation therapy for abdominal tumors on 1.5T MR-Linac. PG - 3103-3116 LID - 10.1002/mp.16342 [doi] AB - BACKGROUND: Real-time motion monitoring (RTMM) is necessary for accurate motion management of intrafraction motions during radiation therapy (RT). PURPOSE: Building upon a previous study, this work develops and tests an improved RTMM technique based on real-time orthogonal cine magnetic resonance imaging (MRI) acquired during magnetic resonance-guided adaptive RT (MRgART) for abdominal tumors on MR-Linac. METHODS: A motion monitoring research package (MMRP) was developed and tested for RTMM based on template rigid registration between beam-on real-time orthogonal cine MRI and pre-beam daily reference 3D-MRI (baseline). The MRI data acquired under free-breathing during the routine MRgART on a 1.5T MR-Linac for 18 patients with abdominal malignancies of 8 liver, 4 adrenal glands (renal fossa), and 6 pancreas cases were used to evaluate the MMRP package. For each patient, a 3D mid-position image derived from an in-house daily 4D-MRI was used to define a target mask or a surrogate sub-region encompassing the target. Additionally, an exploratory case reviewed for an MRI dataset of a healthy volunteer acquired under both free-breathing and deep inspiration breath-hold (DIBH) was used to test how effectively the RTMM using the MMRP can address through-plane motion (TPM). For all cases, the 2D T2/T1-weighted cine MRIs were captured with a temporal resolution of 200 ms interleaved between coronal and sagittal orientations. Manually delineated contours on the cine frames were used as the ground-truth motion. Common visible vessels and segments of target boundaries in proximity to the target were used as anatomical landmarks for reproducible delineations on both the 3D and the cine MRI images. Standard deviation of the error (SDE) between the ground-truth and the measured target motion from the MMRP package were analyzed to evaluate the RTMM accuracy. The maximum target motion (MTM) was measured on the 4D-MRI for all cases during free-breathing. RESULTS: The mean (range) centroid motions for the 13 abdominal tumor cases were 7.69 (4.71-11.15), 1.73 (0.81-3.05), and 2.71 (1.45-3.93) mm with an overall accuracy of <2 mm in the superior-inferior (SI), the left-right (LR), and the anterior-posterior (AP) directions, respectively. The mean (range) of the MTM from the 4D-MRI was 7.38 (2-11) mm in the SI direction, smaller than the monitored motion of centroid, demonstrating the importance of the real-time motion capture. For the remaining patient cases, the ground-truth delineation was challenging under free-breathing due to the target deformation and the large TPM in the AP direction, the implant-induced image artifacts, and/or the suboptimal image plane selection. These cases were evaluated based on visual assessment. For the healthy volunteer, the TPM of the target was significant under free-breathing which degraded the RTMM accuracy. RTMM accuracy of <2 mm was achieved under DIBH, indicating DIBH is an effective method to address large TPM. CONCLUSIONS: We have successfully developed and tested the use of a template-based registration method for an accurate RTMM of abdominal targets during MRgART on a 1.5T MR-Linac without using injected contrast agents or radio-opaque implants. DIBH may be used to effectively reduce or eliminate TPM of abdominal targets during RTMM. CI - (c) 2023 American Association of Physicists in Medicine. FAU - Jassar, Hassan AU - Jassar H AD - Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. FAU - Tai, An AU - Tai A AD - Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. FAU - Chen, Xinfeng AU - Chen X AD - Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. FAU - Keiper, Timothy D AU - Keiper TD AD - Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. FAU - Paulson, Eric AU - Paulson E AD - Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. FAU - Lathuiliere, Fabienne AU - Lathuiliere F AD - Elekta AB, Stockholm, Sweden. FAU - Beriault, Silvain AU - Beriault S AD - Elekta AB, Stockholm, Sweden. FAU - Hebert, Francois AU - Hebert F AD - Elekta AB, Stockholm, Sweden. FAU - Savard, Laurence AU - Savard L AD - Elekta AB, Stockholm, Sweden. FAU - Cooper, David T AU - Cooper DT AD - Elekta AB, Stockholm, Sweden. FAU - Cloake, Sneha AU - Cloake S AD - Elekta AB, Stockholm, Sweden. FAU - Li, X Allen AU - Li XA AUID- ORCID: 0000-0003-2260-0245 AD - Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. LA - eng GR - MCW Fotsch Foundation and Elekta AB/ PT - Journal Article DEP - 20230316 PL - United States TA - Med Phys JT - Medical physics JID - 0425746 SB - IM MH - Humans MH - *Magnetic Resonance Imaging, Cine/methods MH - Radiotherapy Planning, Computer-Assisted MH - Magnetic Resonance Imaging/methods MH - Motion MH - *Abdominal Neoplasms/diagnostic imaging/radiotherapy MH - Respiration OTO - NOTNLM OT - MR-guided adaptive radiation therapy OT - abdominal tumor motion OT - motion monitoring with cine MRI EDAT- 2023/03/10 06:00 MHDA- 2023/05/10 06:42 CRDT- 2023/03/09 14:13 PHST- 2023/02/01 00:00 [revised] PHST- 2022/09/15 00:00 [received] PHST- 2023/02/24 00:00 [accepted] PHST- 2023/05/10 06:42 [medline] PHST- 2023/03/10 06:00 [pubmed] PHST- 2023/03/09 14:13 [entrez] AID - 10.1002/mp.16342 [doi] PST - ppublish SO - Med Phys. 2023 May;50(5):3103-3116. doi: 10.1002/mp.16342. Epub 2023 Mar 16.