Simultaneous integrated vs. sequential boost in VMAT radiotherapy of high-grade gliomas.
BACKGROUND
In 20 patients with high-grade gliomas, we compared two methods of planning for volumetric-modulated arc therapy (VMAT): simultaneous integrated boost (SIB) vs. sequential boost (SEB). The investigation focused on the analysis of dose distributions in the target volumes and the organs at risk (OARs).


METHODS
After contouring the target volumes [planning target volumes (PTVs) and boost volumes (BVs)] and OARs, SIB planning and SEB planning were performed. The SEB method consisted of two plans: in the first plan the PTV received 50 Gy in 25 fractions with a 2-Gy dose per fraction. In the second plan the BV received 10 Gy in 5 fractions with a dose per fraction of 2 Gy. The doses of both plans were summed up to show the total doses delivered. In the SIB method the PTV received 54 Gy in 30 fractions with a dose per fraction of 1.8 Gy, while the BV received 60 Gy in the same fraction number but with a dose per fraction of 2 Gy.


RESULTS
All of the OARs showed higher doses (Dmax and Dmean) in the SEB method when compared with the SIB technique. The differences between the two methods were statistically significant in almost all of the OARs. Analysing the total doses of the target volumes we found dose distributions with similar homogeneities and comparable total doses.


CONCLUSIONS
Our analysis shows that the SIB method offers advantages over the SEB method in terms of sparing OARs.
Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, 81675, Munich, Germany. mfarzin1355@yahoo.com.|Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Science, Tehran, Iran. mfarzin1355@yahoo.com.
Mostafa
M
Farzin
Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, 81675, Munich, Germany. michael.molls@lrz.tum.de.
Michael
M
Molls
Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, 81675, Munich, Germany. Sabrina.Astner@gmx.de.
Sabrina
S
Astner
Institut für Medizinische Statistik und Epidemiologie, Klinikum rechts der Isar, Technische Universität München, Munich, Germany. ina.rondak@tum.de.
Ina-Christine
IC
Rondak
Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, 81675, Munich, Germany. markus.oechsner@lrz.tu-muenchen.de.
Markus
M
Oechsner
D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000473:pathology / Q000532:radiotherapy*; D001932:Brain Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D019583:Dose Fractionation, Radiation; D005260:Female; D005909:Glioblastoma / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D058958:Organs at Risk / Q000528:radiation effects; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D018714:Radiotherapy, Adjuvant; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*
High-grade glioma; Organs at risk; Sequential boost; Simultaneous integrated boost; Volumetric-modulated arc therapy