PMID- 28594461
OWN - NLM
STAT- MEDLINE
DCOM- 20180725
LR  - 20181202
IS  - 2473-4209 (Electronic)
IS  - 0094-2405 (Linking)
VI  - 44
IP  - 9
DP  - 2017 Sep
TI  - Evaluation of a composite Gel-Alanine phantom on an end-to-end test to treat 
      multiple brain metastases by a single isocenter VMAT technique.
PG  - 4869-4879
LID - 10.1002/mp.12400 [doi]
AB  - PURPOSE: This work aims to evaluate the application of a cylindrical phantom made 
      of dosimetric gel containing alanine pellets distributed inside the gel volume 
      during an end-to-end test of a single isocenter VMAT for simultaneous treatment 
      of multiple brain metastases. The evaluation is based on the comparison of the 
      results obtained with the composite phantom with the treatment planning system 
      (TPS) dose distribution validated by using the clinical conventional quality 
      control with point and planar dose measurements. METHODS: A cylindrical MAGIC-f 
      gel phantom containing alanine dosimeters (composite phantom) was used to design 
      the VMAT plan in the treatment planning system (TPS). The alanine dosimeters were 
      pellets with radius of 2.5 mm and height of 3 mm, and played the role of brain 
      metastasis inside the gel cylinder, which simulated the cerebral tissue. Five of 
      the alanine dosimeters were selected to simulate five lesions; five planning 
      target volumes (PTVs) were created including the dosimeters and irradiated with 
      different doses. Conventional quality assurance (QA) was performed on the TPS 
      plan and on the composite phantom; a phantom containing only gel (Gel 1 phantom) 
      was also irradiated. One day after irradiation, magnetic resonance images were 
      acquired for both phantoms on a 3T scanner. An electron spin resonance 
      spectrometer was used to evaluate alanine doses. Calibration curves were 
      constructed for the alanine and the gel dosimeters. All the gel only measurement 
      was repeated (Gel 2 phantom) in order to confirm the previous gel measurement. 
      RESULTS: The VMAT treatment plan was approved by the conventional QA. The doses 
      measured by alanine dosimeters on the composite gel phantom agreed to the TPS on 
      average within 3.3%. The alanine dose for each lesion was used to calibrate the 
      gel dosimeter measurements of the concerned PTV. Both gel dose volume histograms 
      (DVH) achieved for each PTV were in agreement with the expected TPS DVH, except 
      for a small discrepancy observed for the Gel 2 curve of PTV1 and the Gel 1 curve 
      of PTV5. In a 3D gamma analyses performed for each PTV volume independently, 
      comparing both the gels' measurements to the TPS and using 3%/3 mm, 5%/2 mm, and 
      7%/2 mm, more than 90% of the points were approved for all the PTVs, except for 
      the PTV5 comparison in the Gel 1 measurement and for the PTV2 comparison in the 
      Gel 2 measurement. A 3D gamma analysis was also applied for each PTV 
      independently, to compare both gel measurements in order to evaluate the 
      consistence of repeated gel measurements of the same plan, and more than 94.5% of 
      the points were approved. CONCLUSIONS: The composite Gel-Alanine phantom can be 
      used for the end-to-end test of a single isocenter VMAT for simultaneous 
      treatment of multiple brain metastases. The use of the alanine as the lesion 
      cores for the treatment planning provided the precise dose measurements inside 
      each lesion and allowed the conversion of the gel R2 values based on an accurate 
      dose measurement inside the target.
CI  - (c) 2017 American Association of Physicists in Medicine.
FAU - Pavoni, Juliana Fernandes
AU  - Pavoni JF
AD  - Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, Av. Bandeirantes 3900, 
      Monte Alegre, 14040-901, Ribeirao Preto, SP, Brazil.
FAU - Neves-Junior, Wellington Furtado Pimenta
AU  - Neves-Junior WFP
AD  - Hospital Sirio Libanes, R. Dona Adma Jafet 91, Bela Vista, 01308-000, Sao Paulo, 
      SP, Brazil.
FAU - da Silveira, Matheus Antonio
AU  - da Silveira MA
AD  - Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, Av. Bandeirantes 3900, 
      Monte Alegre, 14040-901, Ribeirao Preto, SP, Brazil.
FAU - Haddad, Cecilia Maria Kalil
AU  - Haddad CMK
AD  - Hospital Sirio Libanes, R. Dona Adma Jafet 91, Bela Vista, 01308-000, Sao Paulo, 
      SP, Brazil.
FAU - Baffa, Oswaldo
AU  - Baffa O
AD  - Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, Av. Bandeirantes 3900, 
      Monte Alegre, 14040-901, Ribeirao Preto, SP, Brazil.
LA  - eng
PT  - Journal Article
DEP - 20170728
PL  - United States
TA  - Med Phys
JT  - Medical physics
JID - 0425746
RN  - OF5P57N2ZX (Alanine)
SB  - IM
MH  - Alanine/*therapeutic use
MH  - Brain Neoplasms/secondary/therapy
MH  - Humans
MH  - *Phantoms, Imaging
MH  - Radiometry
MH  - Radiotherapy Dosage
MH  - Radiotherapy Planning, Computer-Assisted/*methods
OTO - NOTNLM
OT  - VMAT
OT  - MAGIC-f
OT  - alanine
OT  - gel dosimetry
OT  - tridimensional dosimetry
EDAT- 2017/06/09 06:00
MHDA- 2018/07/26 06:00
CRDT- 2017/06/09 06:00
PHST- 2016/11/01 00:00 [received]
PHST- 2017/04/28 00:00 [revised]
PHST- 2017/04/28 00:00 [accepted]
PHST- 2017/06/09 06:00 [pubmed]
PHST- 2018/07/26 06:00 [medline]
PHST- 2017/06/09 06:00 [entrez]
AID - 10.1002/mp.12400 [doi]
PST - ppublish
SO  - Med Phys. 2017 Sep;44(9):4869-4879. doi: 10.1002/mp.12400. Epub 2017 Jul 28.