TY - JOUR
T1 - Clinical Implementation and Initial Experience With a 1.5 Tesla MR-Linac for MR-Guided Radiation Therapy for Gynecologic Cancer
T2 - An R-IDEAL Stage 1 and 2a First in Humans Feasibility Study of New Technology Implementation
AU - Lakomy, David S.
AU - Yang, Jinzhong
AU - Vedam, Sastry
AU - Wang, Jihong
AU - Lee, Belinda
AU - Sobremonte, Angela
AU - Castillo, Pamela
AU - Hughes, Neil
AU - Mohammedsaid, Mustefa
AU - Jhingran, Anuja
AU - Klopp, Ann H.
AU - Choi, Seungtaek
AU - Fuller, C. David
AU - Lin, Lilie L.
N1 - Publisher Copyright:
© 2022 American Society for Radiation Oncology
PY - 2022/7/1
Y1 - 2022/7/1
N2 - Purpose: Magnetic resonance imaging–guided linear accelerator systems (MR-linacs) can facilitate the daily adaptation of radiation therapy plans. Here, we report our early clinical experience using a MR-linac for adaptive radiation therapy of gynecologic malignancies. Methods and Materials: Treatments were planned with an Elekta Monaco v5.4.01 and delivered by a 1.5 Tesla Elekta Unity MR-linac. The system offers a choice of daily adaptation based on either position (ATP) or shape (ATS) of the tumor and surrounding normal structures. The ATS approach has the option of manually editing the contours of tumors and surrounding normal structures before the plan is adapted. Here, we documented the duration of each treatment fraction; set-up variability (assessed by isocenter shifts in each plan) between fractions; and, for quality assurance, calculated the percentage of plans meeting the γ-criterion of 3%/3-mm distance to agreement. Deformable accumulated dose calculations were used to compare accumulated versus planned dose for patient treated with exclusively ATP fractions. Results: Of the 10 patients treated with 90 fractions on the MR-linac, most received boost doses to recurrence in nodes or isolated tumors. Each treatment fraction lasted a median 32 minutes; fractions were shorter with ATP than with ATS (30 min vs 42 min, P < .0001). The γ criterion for all fraction plans exceeded >90% (median, 99.9%; range, 92.4%-100%; ie, all plans passed quality assurance testing). The average extent of isocenter shift was <0.5 cm in each axis. The accumulated dose to the gross tumor volume was within 5% of the reference plan for all ATP cases. Accumulated doses for lesions in the pelvic periphery were within <1% of the reference plan as opposed to –1.6% to –4.4% for central pelvic tumors. Conclusions: The MR-linac is a reliable and clinically feasible tool for treating patients with gynecologic cancer.
AB - Purpose: Magnetic resonance imaging–guided linear accelerator systems (MR-linacs) can facilitate the daily adaptation of radiation therapy plans. Here, we report our early clinical experience using a MR-linac for adaptive radiation therapy of gynecologic malignancies. Methods and Materials: Treatments were planned with an Elekta Monaco v5.4.01 and delivered by a 1.5 Tesla Elekta Unity MR-linac. The system offers a choice of daily adaptation based on either position (ATP) or shape (ATS) of the tumor and surrounding normal structures. The ATS approach has the option of manually editing the contours of tumors and surrounding normal structures before the plan is adapted. Here, we documented the duration of each treatment fraction; set-up variability (assessed by isocenter shifts in each plan) between fractions; and, for quality assurance, calculated the percentage of plans meeting the γ-criterion of 3%/3-mm distance to agreement. Deformable accumulated dose calculations were used to compare accumulated versus planned dose for patient treated with exclusively ATP fractions. Results: Of the 10 patients treated with 90 fractions on the MR-linac, most received boost doses to recurrence in nodes or isolated tumors. Each treatment fraction lasted a median 32 minutes; fractions were shorter with ATP than with ATS (30 min vs 42 min, P < .0001). The γ criterion for all fraction plans exceeded >90% (median, 99.9%; range, 92.4%-100%; ie, all plans passed quality assurance testing). The average extent of isocenter shift was <0.5 cm in each axis. The accumulated dose to the gross tumor volume was within 5% of the reference plan for all ATP cases. Accumulated doses for lesions in the pelvic periphery were within <1% of the reference plan as opposed to –1.6% to –4.4% for central pelvic tumors. Conclusions: The MR-linac is a reliable and clinically feasible tool for treating patients with gynecologic cancer.
UR - http://www.scopus.com/inward/record.url?scp=85130370831&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85130370831&partnerID=8YFLogxK
U2 - 10.1016/j.prro.2022.03.002
DO - 10.1016/j.prro.2022.03.002
M3 - Article
C2 - 35278717
AN - SCOPUS:85130370831
SN - 1879-8500
VL - 12
SP - e296-e305
JO - Practical radiation oncology
JF - Practical radiation oncology
IS - 4
ER -