PMID- 36756023
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20230210
IS  - 2168-8184 (Print)
IS  - 2168-8184 (Electronic)
IS  - 2168-8184 (Linking)
VI  - 15
IP  - 1
DP  - 2023 Jan
TI  - Biologically Equivalent Dose Comparison Between Magnetic Resonance-Guided 
      Adaptive and Computed Tomography-Guided Internal Target Volume-Based Stereotactic 
      Body Radiotherapy for Liver Tumors.
PG  - e33478
LID - 10.7759/cureus.33478 [doi]
LID - e33478
AB  - Background and aim Magnetic resonance (MR) imaging has been increasingly adopted 
      in the field of radiotherapy, and the most advanced MR image-guided radiotherapy 
      is known as MR-guided online adaptive radiotherapy (MRgOART), which integrates 
      MRI and linac systems. Few attempts have yet been made to directly compare 
      treatment outcomes between the MRgOART and standard computed tomography 
      (CT)-guided radiotherapy (CTgRT). Besides, it is reported that the biologically 
      equivalent dose (BED) may be a good predictor of the local control (LC) and the 
      overall survival (OS) for liver tumors. The purpose of this study is to compare 
      the BEDs between the MRgOART and the CTgRT by way of virtual isotoxic planning 
      for liver tumors. The hypothesis of this study is therefore that the MRgOART 
      increases LC and OS as compared to the CTgRT. Materials and methods Using the 
      five patient cases available, isotoxic planning was performed. For CTgRT, an 
      internal target volume (ITV) was defined, and the planning target volume (PTV) 
      was created by adding an isotropic margin of 10 mm. For MRgRT, a gross tumor 
      volume (GTV) was defined, and the PTV was created by adding an isotropic margin 
      of 5 mm. Each tumor size was virtually adjusted so that the CTgRT plans resulted 
      in BED <100 Gy under the condition that the nearest organs at risk receive 
      maximum tolerated doses. Subsequently, the BED was recalculated for MRgOART plans 
      with the adjusted tumor size. Results and discussion It was found that the BEDs 
      of the MRgOART plans always exceeded 100 Gy and were approximately 20 Gy larger 
      than those of the corresponding CTgRT plans. Literature shows that superior 
      overall survival rates for liver tumors were observed when BED was >100 Gy as 
      compared to BED <100 Gy, suggesting that MR-guided adaptive planning may 
      potentially lead to better treatment outcomes for liver tumors. We have also 
      observed a case where the duodenum largely moved and abutted the liver after the 
      CT images were acquired, indicating a significant disadvantage of the standard 
      CTgRT because such abutting is not observable by the cone-beam CT immediately 
      before treatment. Conclusion A highly accelerated evidence-creation procedure to 
      suggest the clinical superiority of MRgOART has been arguably proposed with 
      promising results. The sample size is small and limits the extent to which the 
      findings in this study can be generalized. Further virtual clinical trials within 
      the radiotherapy community are awaited with more clinical outcomes data.
CI  - Copyright (c) 2023, Yoda et al.
FAU - Yoda, Kiyoshi
AU  - Yoda K
AD  - Research Physics, Elekta K.K., Tokyo, JPN.
FAU - Sato, Aya
AU  - Sato A
AD  - Application Training, Elekta K.K., Tokyo, JPN.
FAU - Miyake, Yuta
AU  - Miyake Y
AD  - Application Physics, Elekta K.K., Tokyo, JPN.
FAU - Arato, Takeru
AU  - Arato T
AD  - Application Physics, Elekta K.K., Tokyo, JPN.
FAU - Starbuck, William
AU  - Starbuck W
AD  - Clinical Marketing, Elekta Pty Ltd., North Sydney, AUS.
LA  - eng
PT  - Journal Article
DEP - 20230107
PL  - United States
TA  - Cureus
JT  - Cureus
JID - 101596737
PMC - PMC9902058
OTO - NOTNLM
OT  - biologically equivalent dose
OT  - isotoxic planning
OT  - liver tumor
OT  - mr-guided stereotactic body radiotherapy
OT  - virtual planning
COIS- The authors have declared financial relationships, which are detailed in the next 
      section.
EDAT- 2023/02/10 06:00
MHDA- 2023/02/10 06:01
PMCR- 2023/01/07
CRDT- 2023/02/09 02:21
PHST- 2023/01/07 00:00 [accepted]
PHST- 2023/02/09 02:21 [entrez]
PHST- 2023/02/10 06:00 [pubmed]
PHST- 2023/02/10 06:01 [medline]
PHST- 2023/01/07 00:00 [pmc-release]
AID - 10.7759/cureus.33478 [doi]
PST - epublish
SO  - Cureus. 2023 Jan 7;15(1):e33478. doi: 10.7759/cureus.33478. eCollection 2023 Jan.