PMID- 35499198
OWN - NLM
STAT- MEDLINE
DCOM- 20220715
LR  - 20220716
IS  - 1526-9914 (Electronic)
IS  - 1526-9914 (Linking)
VI  - 23
IP  - 7
DP  - 2022 Jul
TI  - How to estimate R50% for cranial SRS/SRT cases with overlapping 50% isodose 
      volumes: A proposed system.
PG  - e13624
LID - 10.1002/acm2.13624 [doi]
LID - e13624
AB  - Inevitably in clinical stereotactic cranial single isocenter multiple target 
      cases treated with linac-based multi-leaf collimated (MLC) delivery, one 
      encounters planning target volumes (PTVs) in close proximity with overlapping 50% 
      isodose clouds (IDC50%). In such cases, it is very difficult to separate the 
      IDC50% attributable to each individual target and, thus, assess the intermediate 
      dose conformality or R50%. Such scenarios happen regardless of what metric is 
      used to measure intermediate dose spill. Now that universal standards for 
      intermediate dose spill have been proposed, it is important to have a consistent 
      method for apportioning these overlapping IDC50% volumes to allow comparison with 
      the proposed standards when multiple PTVs have overlapping IDC50%. We propose a 
      systematic method for apportioning the IDC50% of multiple targets with 
      overlapping IDC50% based on the relative surface area of each target volume; we 
      call this the fair value estimate (FVE). This FVE system of apportionment is 
      tested for reasonableness by comparing the apportionment of multiple target 
      single isocenter stereotactic treatment with widely spaced targets where the 
      IDC50% can be obviously assigned to demonstrate that the FVE results are very 
      similar to the actual R50% results. We then demonstrate how the FVE system would 
      be applied to cases with overlapping IDC50%. We propose this FVE system for 
      consideration by the cranial stereotactic community for apportioning the 
      intermediate dose spill when that intermediate dose spill overlaps among multiple 
      targets.
CI  - (c) 2022 The Authors. Journal of Applied Clinical Medical Physics published by 
      Wiley Periodicals, LLC on behalf of The American Association of Physicists in 
      Medicine.
FAU - Desai, Dharmin D
AU  - Desai DD
AD  - Department of Radiation Oncology, CHI Memorial Hospital, Chattanooga, Tennessee, 
      USA.
FAU - Cordrey, Ivan L
AU  - Cordrey IL
AD  - Regional Cancer Center, Cumberland Medical Center, Crossville, Tennessee, USA.
LA  - eng
PT  - Journal Article
DEP - 20220502
PL  - United States
TA  - J Appl Clin Med Phys
JT  - Journal of applied clinical medical physics
JID - 101089176
SB  - IM
MH  - *Brain Neoplasms/diagnostic imaging/surgery
MH  - Humans
MH  - Particle Accelerators
MH  - *Radiosurgery/methods
MH  - Radiotherapy Dosage
MH  - Radiotherapy Planning, Computer-Assisted/methods
PMC - PMC9278687
OTO - NOTNLM
OT  - IDC50% overlap
OT  - R50%
OT  - SIMT
OT  - cranial SRS/SRT
OT  - fair value estimate
COIS- No conflicts of interest.
EDAT- 2022/05/03 06:00
MHDA- 2022/07/16 06:00
PMCR- 2022/05/02
CRDT- 2022/05/02 07:29
PHST- 2022/04/04 00:00 [revised]
PHST- 2022/03/03 00:00 [received]
PHST- 2022/04/11 00:00 [accepted]
PHST- 2022/05/03 06:00 [pubmed]
PHST- 2022/07/16 06:00 [medline]
PHST- 2022/05/02 07:29 [entrez]
PHST- 2022/05/02 00:00 [pmc-release]
AID - ACM213624 [pii]
AID - 10.1002/acm2.13624 [doi]
PST - ppublish
SO  - J Appl Clin Med Phys. 2022 Jul;23(7):e13624. doi: 10.1002/acm2.13624. Epub 2022 
      May 2.