#Qarc medulloblastoma atlas manual#
#Qarc medulloblastoma atlas full#

Later p-value was calculated, and in both dose ranges of thecal sac volume receiving 110% and 120%, the difference in values was statistically significant. Volume receiving 100% of the dose was also calculated in both techniques mean values of this dose range was almost similar in both groups. Without FIF technique, the volume receiving 110% of the prescribed dose ranged from 39% to 74% (mean: 62.12%) and volume receiving 120% dose ranged from 8% to 28% (mean: 17.68%), whereas with FIF technique, the thecal sac volume receiving 110% of dose ranged from 2% to 18% (mean: 11%) and volume receiving 120% ranged from 0% to 2%. Paired sample t-test was used to compute the p-values for the inferential statistics. A corresponding plan without FIF technique was planned then maximum dose at the junction was noted for each patient with both plans, and the readings were evaluated. Dose-volume histogram (DVH) was used for analysis of results. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. These patients were planned with lateral craniocervical fields and posterior spinal fields using a forward-planned FIF technique.

Contouring of planning target volume (PTV) and organs at risk (OAR) was done, and planning was done on Varian EclipseTM Treatment Planning System (TPS) (Varian Medical Systems, Palo Alto, CA). These patients were treated during 2019-2020. Sixteen patients treated with three-dimensional conformal radiation therapy (3D-CRT) for CSI were retrospectively chosen for analysis.

We have started using this technique after acquiring advanced technology machines in recent years. Nowadays, FIF technique is used to feather out the dose inhomogeneity caused by multiple fields.

#Qarc medulloblastoma atlas manual#

Photon-based techniques for CSI may result in dose inhomogeneity within the treatment volume and usually require a weekly manual shift of the field junctions to minimize the possibility of spinal cord overdose. Planning craniospinal irradiation (CSI) with ''field-in-field'' (FIF) homogenization technique in combination with daily, intrafractional modulation of the field junctions is needed to avoid spinal cord overdose. 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. Furthermore the PTV conformity is increased. 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. 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. 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. We identified a more conformal dose coverage for PTVs and a better sparing of OARs with used VMAT methods. The prescription dose was set to 35.2 Gy.

#Qarc medulloblastoma atlas full#

The noAVD uses a half 180° (posterior to lateral directions) and the FullArc uses a full 360° arc setup arrangement. 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. “FullArc”) were optimized and calculated for each patient. 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. In sum 24 treatment plans for 6 pediatric patients were realized. 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).