Treatment planning comparison of electron arc therapy and photon intensity modulated radiotherapy for Askin's tumor of chest wall.
OBJECTIVE
A dosimetric study to quantitatively compare radiotherapy treatment plans for Askin's tumor using Electron Arc (EA) vs. photon Intensity Modulated Radiotherapy (IMRT).


METHODS
Five patients treated with EA were included in this study. Treatment plans were generated for each patient using EA and IMRT. Plans were compared using dose volume histograms (DVH) of the Planning Target Volume (PTV) and Organs at Risk (OAR).


RESULTS
IMRT resulted in superior PTV coverage, and homogeneous dose distribution compared to EA. For EA, 92% of the PTV was covered to 85% of the dose compared to IMRT in which 96% was covered to 95% of the dose. V(107) that represents the hot spot within the PTV was more in IMRT compared to EA: 7.4(+/-2)% vs. 3(+/-0.5)%, respectively. With PTVs located close to the spinal cord (SC), the dose to SC was more with EA, whereas for PTVs located away from the SC, the dose to SC was more with IMRT. The cardiac dose profile was similar to that of SC. Ipsilateral lung received lower doses with IMRT while contralateral lung received higher dose with IMRT compared to EA. For non-OAR normal tissues, IMRT resulted in large volumes of low dose regions.


CONCLUSIONS
IMRT resulted in superior PTV coverage and sparing of OAR compared to EA plans. Although IMRT seems to be superior to EA, one needs to keep in mind the volume of low dose regions associated with IMRT, especially while treating young children.
Jamema
Swamidas V
SV
Department of Medical Physics, Tata Memorial Hospital, Mumbai, India. jamemacurie@rediffmail.com
Sharma
Pramod K
PK
Laskar
Siddhartha
S
Deshpande
Deepak D
DD
Shrivastava
Shyam K
SK
D004583:Electrons; D006321:Heart / Q000528:radiation effects; D006801:Humans; D008168:Lung / Q000528:radiation effects; D018242:Neuroectodermal Tumors, Primitive / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy; D050397:Radiotherapy, Intensity-Modulated; D018228:Sarcoma, Small Cell / Q000532:radiotherapy*; D013899:Thoracic Neoplasms / Q000532:radiotherapy*; D035441:Thoracic Wall / Q000528:radiation effects