PMID- 19223830
OWN - NLM
STAT- MEDLINE
DCOM- 20090618
LR  - 20211020
IS  - 1526-9914 (Electronic)
IS  - 1526-9914 (Linking)
VI  - 10
IP  - 1
DP  - 2009 Feb 5
TI  - Independent calculation of dose from a helical TomoTherapy unit.
PG  - 103-119
LID - 10.1120/jacmp.v10i1.2772 [doi]
AB  - A new calculation algorithm has been developed for independently verifying doses 
      calculated by the TomoTherapy Hi.Art treatment planning system (TPS). The 
      algorithm is designed to confirm the dose to a point in a high dose, low 
      dose-gradient region. Patient data used by the algorithm include the radiological 
      depth to the point for each projection angle and the treatment sinogram file 
      controlling the leaf opening time for each projection. The algorithm uses common 
      dosimetric functions [tissue phantom ratio (TPR) and output factor (Scp)] for the 
      central axis combined with lateral and longitudinal beam profile data to quantify 
      the off-axis dose dependence. Machine data for the dosimetric functions were 
      measured on the Hi.Art machine and simulated using the TPS. Point dose 
      calculations were made for several test phantoms and for 97 patient treatment 
      plans using the simulated machine data. Comparisons with TPS-predicted point 
      doses for the phantom treatment plans demonstrated agreement within 2% for both 
      on-axis and off-axis planning target volumes (PTVs). Comparisons with 
      TPS-predicted point doses for the patient treatment plans also showed good 
      agreement. For calculations at sites other than lung and superficial PTVs, 
      agreement between the calculations was within 2% for 94% of the patient 
      calculations (64 of 68). Calculations within lung and superficial PTVs 
      overestimated the dose by an average of 3.1% (sigma=2.4%) and 3.2% (sigma=2.2%), 
      respectively. Systematic errors within lung are probably due to the weakness of 
      the algorithm in correcting for missing tissue and/or tissue density 
      heterogeneities. Errors encountered within superficial PTVs probably result from 
      the algorithm overestimating the scatter dose within the patient. Our results 
      demonstrate that for the majority of cases, the algorithm could be used without 
      further refinement to independently verify patient treatment plans.
FAU - Gibbons, John P
AU  - Gibbons JP
AD  - Mary Bird Perkins Cancer Center, Baton Rouge, Louisiana, U.S.A.
AD  - Department of Physics and Astronomy, Louisiana State University and Agricultural 
      and Mechanical College, Baton Rouge, Louisiana, U.S.A.
FAU - Smith, Koren
AU  - Smith K
AD  - Department of Physics and Astronomy, Louisiana State University and Agricultural 
      and Mechanical College, Baton Rouge, Louisiana, U.S.A.
FAU - Cheek, Dennis
AU  - Cheek D
AD  - Mary Bird Perkins Cancer Center, Baton Rouge, Louisiana, U.S.A.
FAU - Rosen, Isaac
AU  - Rosen I
AD  - Mary Bird Perkins Cancer Center, Baton Rouge, Louisiana, U.S.A.
AD  - Department of Physics and Astronomy, Louisiana State University and Agricultural 
      and Mechanical College, Baton Rouge, Louisiana, U.S.A.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20090205
PL  - United States
TA  - J Appl Clin Med Phys
JT  - Journal of applied clinical medical physics
JID - 101089176
SB  - IM
MH  - *Algorithms
MH  - Computer Simulation
MH  - Humans
MH  - Phantoms, Imaging
MH  - Radiotherapy Dosage
MH  - Radiotherapy Planning, Computer-Assisted/*methods
MH  - Reproducibility of Results
PMC - PMC5720509
EDAT- 2009/02/19 09:00
MHDA- 2009/06/19 09:00
PMCR- 2009/02/05
CRDT- 2009/02/19 09:00
PHST- 2007/10/11 00:00 [received]
PHST- 2008/10/06 00:00 [accepted]
PHST- 2009/02/19 09:00 [entrez]
PHST- 2009/02/19 09:00 [pubmed]
PHST- 2009/06/19 09:00 [medline]
PHST- 2009/02/05 00:00 [pmc-release]
AID - ACM20103 [pii]
AID - 10.1120/jacmp.v10i1.2772 [doi]
PST - epublish
SO  - J Appl Clin Med Phys. 2009 Feb 5;10(1):103-119. doi: 10.1120/jacmp.v10i1.2772.