Challenges and differences in external radiation therapy for retinoblastoma: from standard techniques to new developments.
OBJECTIVE
The purpose of this study is to calculate the treatment plans and to compare the dose distributions and dose-volume histograms (DVH) for 6 external radiotherapy techniques for the treatment of retinoblastoma as well as intensity-modulated radiotherapy (IMRT) and fractionated stereotactic radiotherapy (Cyberknife).


METHODS
Treatment plans were developed using 6 techniques, including an en face electron technique (ET), an anterior and lateral wedge photon technique (LFT), a 3D conformal (6 fields) technique (CRT), an inverse plan IMRT, tomotherapy, and conventional focal stereotactic external beam radiotherapy with Cyberknife (SBRT). Dose volume analyses were carried out for each technique.


RESULTS
All techniques except electron provided similar target coverage. When comparing conformal plan with IMRT and SBRT, there was no significant difference in planning target volume dose distribution. The mean volume of ipsilateral bony orbit received more than 20 Gy, a suggested threshold for bone growth inhibition. The V20 Gy was 73% for the ET, 57% for the LFT, 87% for the CRT, 65% for the IMRT, 66% for the tomotherapy, and 2.7% for the SBRT.


CONCLUSIONS
This work supports the potential use of IMRT and SBRT to spare normal tissues in these patients.
Department of Radiation Oncology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Ayşe
A
Hiçsönmez
Department of Radiation Oncology, Ankara Oncology Hospital, Demetevler, Ankara - Turkey.
Yıldız
Y
Güney
Department of Radiation Oncology, Ankara Oncology Hospital, Demetevler, Ankara - Turkey.
Ayşen
A
Dizman
Department of Radiation Oncology, Ankara Gülhane Military Medical Academy, Keçiöğren, Ankara - Turkey.
Bahar
B
Dirican
Department of Radiation Oncology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Yakup
Y
Arslan
Department of Radiation Oncology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Tugba
T
Atakul
Department of Radiation Oncology, Ankara Oncology Hospital, Demetevler, Ankara - Turkey.
Hasan
H
Uysal
Department of Ophthalmology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Kaan
K
Gündüz
Department of Pediatric Oncology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Nurdan
N
Taçyıldız
Department of Pediatric Oncology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Emel
E
Ünal
Department of Pediatric Oncology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Handan
H
Dinçaslan
Department of Radiation Oncology, Ankara University School of Medicine, Cebeci Hospital, Ankara - Turkey.
Meltem Nalça
MN
Andrieu
D006801:Humans; D011832:Radiation Injuries; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D012175:Retinoblastoma / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*