Publication Date:
2012-06-29
Description:
Background: Intensity modulated radiotherapy is an efficient radiotherapy technique to increase dose intarget volumes and decrease irradiation dose in organs at risk. This last objective is mainlyrelevant in children. However, previous results suggested that IMRT could increase low dose,factor of risk for secondary radiation induced cancer. This study was performed to comparedose distributions with 3D-radiotherapy (3D-RT) and IMRT with tomotherapy (HT) inchildren with neuroblastoma.Seven children with neuroblastoma were irradiated. Treatment plans were calculated for 3DRT,and for HT. For the volume of interest, the PTV-V95% and conformity index werecalculated. Dose constraints of all the organs at risk and integral dose were compared. Results: The conformity index was statistically better for HT than for 3D-RT. PTV-V95% constraintwas reached in 6 cases with HT compared to 2 cases with 3D-RT. For the ipsilateral kidneyof the tumor, the V12 Gy constraint was reached for 3 patients with both methods. The valueswere lower with HT than with 3D-RT in two cases and higher in one case. The threshold wasnot reached for one patient with either technique, but the value was lower with HT than with3D-RT. For the contralateral kidney of the tumors, the V12 Gy constraint was reached for allpatients with both methods. The values were lower with HT than with 3D-RT in 5 of 7children, equal in one patient and higher in one patient. The organ-at-risk volumes receivinglow doses were significantly lower with 3D-RT but larger for the highest doses, compared tothose irradiated with HT. The integral doses were not different. Conclusions: IMRT with HT allows a better conformity treatment, a more frequently acceptable PTV-V95%than 3D-RT and, concomitantly, a better shielding of the kidneys. The integral doses arecomparable between both techniques but consideration of differences in dose distributionbetween the two techniques, for the organs at risk, has to be taken in account when validatingtreatment.
Topics:
Medicine
,
Physics
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