PMID- 24119416
OWN - NLM
STAT- MEDLINE
DCOM- 20140822
LR  - 20131108
IS  - 1873-4022 (Electronic)
IS  - 1873-4022 (Linking)
VI  - 38
IP  - 4
DP  - 2013 Winter
TI  - Dosimetric errors during treatment of centrally located lung tumors with 
      stereotactic body radiation therapy: Monte Carlo evaluation of tissue 
      inhomogeneity corrections.
PG  - 436-41
LID - S0958-3947(13)00089-7 [pii]
LID - 10.1016/j.meddos.2013.06.002 [doi]
AB  - Early experience with stereotactic body radiation therapy (SBRT) of centrally 
      located lung tumors indicated increased rate of high-grade toxicity in the lungs. 
      These clinical results were based on treatment plans that were computed using 
      pencil beam-like algorithms and without tissue inhomogeneity corrections. In this 
      study, we evaluated the dosimetric errors in plans with and without inhomogeneity 
      corrections and with planning target volumes (PTVs) that were within the zone of 
      the proximal bronchial tree (BT). For 10 patients, the PTV, lungs, and sections 
      of the BT either inside or within 2cm of the PTV were delineated. Two treatment 
      plans were generated for each patient using the following dose-calculation 
      methods: (1) pencil beam (PB) algorithm without inhomogeneity correction (IC) (PB 
      - IC) and (2) PB with inhomogeneity correction (PB + IC). Both plans had 
      identical beam geometry but different beam segment shapes and monitor units (MU) 
      to achieve similar conformal dose coverage of PTV. To obtain the baseline dose 
      distributions, each plan was recalculated using a Monte Carlo (MC) algorithm by 
      keeping MUs the same in the respective plans. The median maximum dose to the 
      proximal BT and PTV dose coverage in the PB + IC plans were overestimated by 8% 
      and 11%, respectively. However, the median maximum dose to the proximal BT and 
      PTV dose coverage in PB - IC plans were underestimated by 15% and 9%. Similar 
      trends were observed in low-dose regions of the lung within the irradiated 
      volume. Our study indicates that dosimetric bias introduced by unit tissue 
      density plans cannot be characterized as underestimation or overestimation of 
      dose without taking the tumor location into account. This issue should be 
      considered when analyzing clinical toxicity data from early lung SBRT trials that 
      utilized unit tissue density for dose calculations.
CI  - (c) 2013 American Association of Medical Dosimetrists.
FAU - Altunbas, Cem
AU  - Altunbas C
AD  - Department of Radiation Oncology, University of Colorado School of Medicine, 
      Aurora, CO. Electronic address: cem.altunbas@ucdenver.edu.
FAU - Kavanagh, Brian
AU  - Kavanagh B
FAU - Dzingle, Wayne
AU  - Dzingle W
FAU - Stuhr, Kelly
AU  - Stuhr K
FAU - Gaspar, Laurie
AU  - Gaspar L
FAU - Miften, Moyed
AU  - Miften M
LA  - eng
PT  - Journal Article
DEP - 20131009
PL  - United States
TA  - Med Dosim
JT  - Medical dosimetry : official journal of the American Association of Medical 
      Dosimetrists
JID - 8908862
SB  - IM
MH  - Humans
MH  - Lung Neoplasms/*surgery
MH  - Medical Errors
MH  - Monte Carlo Method
MH  - Radiation Dosage
MH  - *Radiosurgery
MH  - Radiotherapy Planning, Computer-Assisted
OTO - NOTNLM
OT  - Inhomogeneity corrections
OT  - Lung SBRT
OT  - Monte Carlo
OT  - Pencil beam
EDAT- 2013/10/15 06:00
MHDA- 2014/08/26 06:00
CRDT- 2013/10/15 06:00
PHST- 2012/03/23 00:00 [received]
PHST- 2012/11/30 00:00 [revised]
PHST- 2013/06/05 00:00 [accepted]
PHST- 2013/10/15 06:00 [entrez]
PHST- 2013/10/15 06:00 [pubmed]
PHST- 2014/08/26 06:00 [medline]
AID - S0958-3947(13)00089-7 [pii]
AID - 10.1016/j.meddos.2013.06.002 [doi]
PST - ppublish
SO  - Med Dosim. 2013 Winter;38(4):436-41. doi: 10.1016/j.meddos.2013.06.002. Epub 2013 
      Oct 9.