PMID- 34931447
OWN - NLM
STAT- MEDLINE
DCOM- 20220215
LR  - 20220216
IS  - 1526-9914 (Electronic)
IS  - 1526-9914 (Linking)
VI  - 23
IP  - 2
DP  - 2022 Feb
TI  - Comparison of dosimetric impact of intra-fractional setup discrepancy between 
      multiple- and single-isocenter approaches in linac-based stereotactic 
      radiotherapy of multiple brain metastases.
PG  - e13484
LID - 10.1002/acm2.13484 [doi]
LID - e13484
AB  - INTRODUCTION: Treatment of multiple brain metastases by linac-based stereotactic 
      radiotherapy (SRT) can employ either a multiple-isocenter (MI) or 
      single-isocenter (SI) approach. The purposes of this study were to evaluate the 
      dosimetric results of MI and SI approaches and compare the impacts of 
      intra-fractional setup discrepancies on the robustness of respective approaches 
      using isocenter shifts, whether the same magnitude of translational and 
      rotational effects could lead to a significant difference between the two 
      approaches. METHODS: Twenty-two patients with multiple brain metastases treated 
      by linac-based SRT were recruited. Treatment plans were computed with both the MI 
      and SI approaches. For the MI approach, the isocenter was located at the 
      geometric center of each planning target volumes (PTVs), whereas the isocenter of 
      the SI approach was located midway between the PTV centroids. To simulate the 
      intra-fractional errors, isocenter displacements including translational and 
      rotational shifts were hypothetically applied. Apart from the dosimetric outcomes 
      of the two approaches, the impact of the isocenter shifts on PTVs and organs at 
      risk (OARs) were recorded in terms of the differences (delta) in dose parameters 
      relative to the reference plan and was then compared between the MI and SI 
      approaches. RESULTS: Both MI and SI plans met the plan acceptance criteria. The 
      mean Paddick conformity index (Paddick CI) and D(max) of most OARs between MI and 
      SI plans did not show a significant difference, except that higher doses to the 
      left optic nerve and optic chiasm were found in SI plans (p = 0.03). After the 
      application of the isocenter shifts, deltaCI increased with an increase in the 
      magnitude of the isocenter shift. When comparing between MI and SI plans, the 
      deltaCIs were similar (p > 0.05) for all extents of translational shifts, but deltaCIs 
      were significantly higher in SI plans after application of all rotations 
      particularly +/-1.5 degrees  and +/-2.0 degrees  shifts. Despite the result that the majority of 
      deltaD(Max) of OARs were higher in the SI plans, only the differences in the left 
      optic nerve and chiasm showed generally consistent significance after both 
      translational >/=+/-1 mm and rotational shifts of >/=+/-1  composite function . CONCLUSION: Both MI and SI 
      approaches could produce clinically acceptable plans. However, isocenter shifts 
      brought dosimetric impacts to both MI and SI approaches and the effects increased 
      with the increase of the shift magnitude. Although similar impacts were shown in 
      plans of both approaches after translational isocenter shift, SI plans were 
      relatively more vulnerable than MI plans to rotational shifts.
CI  - (c) 2021 The Authors. Journal of Applied Clinical Medical Physics published by 
      Wiley Periodicals, LLC on behalf of The American Association of Physicists in 
      Medicine.
FAU - Tsui, Sylvia S W
AU  - Tsui SSW
AD  - Department of Clinical Oncology, Prince of Wales Hospital, Shatin, Hong Kong.
FAU - Wu, Vincent W C
AU  - Wu VWC
AD  - Department of Health Technology & Informatics, The Hong Kong Polytechnic 
      University, Hung Hom, Hong Kong.
FAU - Cheung, Jerry S C
AU  - Cheung JSC
AD  - Department of Clinical Oncology, Queen Mary Hospital, Pok Fu Lam, Hong Kong.
LA  - eng
PT  - Journal Article
DEP - 20211220
PL  - United States
TA  - J Appl Clin Med Phys
JT  - Journal of applied clinical medical physics
JID - 101089176
SB  - IM
MH  - *Brain Neoplasms/radiotherapy/surgery
MH  - Humans
MH  - Radiometry
MH  - *Radiosurgery
MH  - Radiotherapy Dosage
MH  - Radiotherapy Planning, Computer-Assisted
MH  - *Radiotherapy, Intensity-Modulated
PMC - PMC8833285
OTO - NOTNLM
OT  - SRS
OT  - SRT
OT  - intra-fractional error
OT  - isocenter shift
OT  - multiple brain metastases
OT  - multiple isocenters
OT  - single isocenter
OT  - stereotactic radiation therapy
COIS- The authors declare no conflicts of interest with respect to the content of this 
      manuscript.
EDAT- 2021/12/22 06:00
MHDA- 2022/02/16 06:00
PMCR- 2021/12/20
CRDT- 2021/12/21 07:02
PHST- 2021/04/23 00:00 [revised]
PHST- 2021/12/12 00:00 [received]
PHST- 2021/11/09 00:00 [accepted]
PHST- 2021/12/22 06:00 [pubmed]
PHST- 2022/02/16 06:00 [medline]
PHST- 2021/12/21 07:02 [entrez]
PHST- 2021/12/20 00:00 [pmc-release]
AID - ACM213484 [pii]
AID - 10.1002/acm2.13484 [doi]
PST - ppublish
SO  - J Appl Clin Med Phys. 2022 Feb;23(2):e13484. doi: 10.1002/acm2.13484. Epub 2021 
      Dec 20.