Pediatric craniospinal irradiation with a short partial-arc VMAT technique for medulloblastoma tumors in dosimetric comp
- PDF / 1,094,441 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 103 Downloads / 191 Views
Open Access
RESEARCH
Pediatric craniospinal irradiation with a short partial‑arc VMAT technique for medulloblastoma tumors in dosimetric comparison Gerhard Pollul* , Tilman Bostel, Sascha Grossmann, Sati Akbaba, Heiko Karle, Marcus Stockinger and Heinz Schmidberger
Abstract Background: This study aimed to contrast four different irradiation methods for pediatric medulloblastoma tumors in a dosimetric comparison regarding planning target volume (PTV) coverage and sparing of organs at risk (OARs). Methods: In sum 24 treatment plans for 6 pediatric patients were realized. Besides the clinical standard of a 3D-conformal radiotherapy (3D-CRT) treatment plan taken as a reference, volumetric modulated arc therapy (VMAT) treatment plans (“VMAT_AVD” vs. “noAVD” vs. “FullArc”) were optimized and calculated for each patient. For the thoracic and abdominal region, the short partial-arc VMAT_AVD technique uses an arc setup with reduced arc-length by 100°, using posterior and lateral beam entries. The noAVD uses a half 180° (posterior to lateral directions) and the FullArc uses a full 360° arc setup arrangement. The prescription dose was set to 35.2 Gy. Results: We identified a more conformal dose coverage for PTVs and a better sparing of OARs with used VMAT methods. For VMAT_AVD mean dose reductions in organs at risk can be realized, from 16 to 6.6 Gy, from 27.1 to 8.7 Gy and from 8.0 to 1.9 Gy for the heart, the thyroid and the gonads respectively, compared to the 3D-CRT treatment method. In addition we have found out a superiority of VMAT_AVD compared to the noAVD and FullArc trials with lower exposure to low-dose radiation to the lungs and breasts. Conclusions: With the short partial-arc VMAT_AVD technique, dose exposures to radiosensitive OARS like the heart, the thyroid or the gonads can be reduced and therefore, maybe the occurrence of late sequelae is less likely. Furthermore the PTV conformity is increased. The advantages of the VMAT_AVD have to be weighed against the potentially risks induced by an increased low dose exposure compared to the 3D-CRT method. Keywords: Pediatric radiation, Medulloblastoma, Craniospinal irradiation, Partial VMAT Background With an incidence of 18–20% of all brain tumors, medulloblastoma are the most common type of malign brain tumors in childhood [1, 2]. As one part of the curative treatment approach in a combined-modality, it is *Correspondence: gerhard.pollul@unimedizin‑mainz.de Department of Radiation Oncology, University Medical Center Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
recommended to irradiate the whole brain and the entire craniospinal axis [3]. The 5 year event-free survival (EFS) rate nowadays obtains values exceeding 80% for children older than three years with nondisseminated disease for concomitant radiochemotherapy (Medulloblastoma Average Risk; Cisplatin/Cyclophosphamide) [4, 5]. However, it has been turned out that any kind of radiotherapy combined with chemotherapy in childhood is a risk factor for the development of several late complications
© The Au
Data Loading...
