Pediatric craniospinal irradiation with a short partial-arc VMAT technique for medulloblastoma tumors in dosimetric comparison

Pollul, Gerhard; Bostel, Tilman; Großmann, Sascha; Akbaba, Sati; Karle, Heiko; Stockinger, Marcus; Schmidberger, Heinz

doi:10.1186/s13014-020-01690-5

Cited by 15 publications

(28 citation statements)

References 51 publications

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“…3D‐CRT, VMAT, and PBS were used in this study for CSI treatment of a simulated 10‐year‐old pediatric patient using an anthropomorphic phantom. The planning target volume (PTV) was defined according to the clinical recommendations for pediatric CSI treatment: for photon treatments, the brain and the spinal cord were included in PTV, 37,38 while for the proton treatment, the PTV was larger and included also verebrae 39,40 . For patients younger than 15 years, the PTV for proton treatment includes the spine in order to reduce the risk of asymmetric growth of the developing skeleton due to dose gradients in the vertebral body 10 .…”

Section: Methodsmentioning

confidence: 99%

Out‐of‐field doses in pediatric craniospinal irradiations with 3D‐CRT, VMAT, and scanning proton radiotherapy: A phantom study

et al. 2022

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Craniospinal irradiation (CSI) has greatly increased survival rates for patients with a diagnosis of medulloblastoma and other primitive neuroectodermal tumors. However, as it includes exposure of a large volume of healthy tissue to unwanted doses, there is a strong concern about the complications of the treatment, especially for the children. To estimate the risk of second cancers and other unwanted effects,out-of -field dose assessment is necessary.The purpose of this study is to evaluate and compare out-of -field doses in pediatric CSI treatment using conventional and advanced photon radiotherapy (RT) and advanced proton therapy. To our knowledge, it is the first such comparison based on in-phantom measurements. Additionally, for out-of -field doses during photon RT in this and other studies, comparisons were made using analytical modeling. Methods: In order to describe the out-of -field doses absorbed in a pediatric patient during actual clinical treatment, an anthropomorphic phantom, which mimics the 10-year-old child, was used. Photon 3D-conformal RT (3D-CRT) and two advanced, highly conformal techniques: photon volumetric-modulated arc therapy (VMAT) and active pencil beam scanning (PBS) proton RT were used for CSI treatment. Radiophotoluminescent and poly-allyl-diglycol-carbonate nuclear track detectors were used for photon and neutron dosimetry in the phantom, respectively. Out-of -field doses from neutrons were expressed in terms of dose equivalent. A two-Gaussian model was implemented for out-of -field doses during photon RT. Results: The mean VMAT photon doses per target dose to all organs in this study were under 50% of the target dose (i.e., <500 mGy/Gy), while the mean 3D-CRT photon dose to oesophagus, gall bladder, and thyroid, exceeded that value. However, for 3D-CRT, better sparing was achieved for eyes and lungs. The mean PBS photon doses for all organs were up to three orders of magnitude lower compared to VMAT and 3D-CRT and exceeded 10 mGy/Gy only for the oesophagus, intestine, and lungs. The mean neutron dose equivalent during PBS for eight organs of interest (thyroid, breasts, lungs, liver, stomach, gall bladder, bladder, prostate) ranged from 1.2 mSv/Gy for bladder to 23.1 mSv/Gy for breasts. Comparison of out-of -field doses in this and other phantom studies found in the literature showed that a simple and fast two-Gaussian model for out-of -field doses as a function of distance from the field edge can be applied in a CSI using photon RT techniques.

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Section: Methodsmentioning

confidence: 99%

Out‐of‐field doses in pediatric craniospinal irradiations with 3D‐CRT, VMAT, and scanning proton radiotherapy: A phantom study

et al. 2022

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“…Medulloblastoma is the most common type of malignant brain tumor in childhood with an incidence of 18-20% of all brain tumors. [4] As most patients in this study are cases of Medulloblastoma, we need to know about it. For treatment purposes, patients with medulloblastoma are divided into two prognostic groups: children over 3-5 years of age with non-metastatic disease and minimal residual disease (< 1.5 cm 2 ) post-operatively comprise the standard-risk group.…”

Section: Discussionmentioning

confidence: 99%

“…Target volume delineation was performed in accordance with internationally accepted guidelines. [4] Gross tumor volume (GTV) in this case would only be any postoperative residual area and it will be of help only in the 2nd Phase of Radiation i.e. Posterior fossa Boost.…”

Section: Methodsmentioning

confidence: 99%

Field in Field Technique (FIF) Technique With Intra-fractionally Modulated Junction Shifts for Cranio-spinal Irradiation (FSI) Planning With 3D-CRT.

Sha

Hafeez

Nazim

et al. 2021

Preprint

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Background To plan craniospinal irradiation (CSI) with ‘‘field-in-field’’ (FIF) homogenization technique in combination with daily, intra-fractional modulation of the field junctions, to minimize the possibility of spinal cord overdose. 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. Nowadays FIF technique is used to feather out the dose inhomogeneity caused by multiple fields. We have started using this technique after acquiring advanced technology machines in recent years. Methods and Materials: 16 patients treated with 3D-CRT for CSI were retrospectively chosen for analysis. These patients were treated during 2016–2017. Contouring of PTV and OAR were done and planning done on Eclipse TM TPS (Varian). These patients were planned with Lateral cranio-cervical fields and posterior spinal fields using a forward-planned, FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose volume histogram (DVH) was used for analysis of results. A corresponding plan without FIF technique was planned and maximum dose at the junction was noted for each patient with both plans and the readings were evaluated. Results Plan inhomogeneity improved with FIF technique. It provided consistent dose delivery during each fraction of treatment across the junctions. The maximum doses calculated at the junction were higher in the CSI plans without FIF compared to those with FIF technique. Conclusion This paper hence proves that FIF technique is better in planning CSI.

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“…Mostly done in cases of medulloblastoma, other areas where CSI is used include anaplastic ependymoma, intracranial germinoma, PNET, and others. Medulloblastoma is the most common type of malignant brain tumor in childhood with an incidence of 18%-20% of all brain tumors [ 4 ]. As most patients in this study are cases of medulloblastoma, we need to know about it.…”

Section: Discussionmentioning

confidence: 99%

“…These images were registered with the CT simulation images using the registration option of the TPS. Target volume delineation was performed in accordance with internationally accepted guidelines [ 4 ]. Gross tumor volume (GTV) in this case would only be any postoperative residual area, and it will be of help only in the second phase of radiation, i.e., posterior fossa boost.…”

Section: Methodsmentioning

confidence: 99%

Field-in-Field Technique With Intrafractionally Modulated Junction Shifts for Craniospinal Irradiation Planning With Three-Dimensional Conformal Radiation Therapy

Hussain

Hafeez

Nazim

et al. 2021

Cureus

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Background: 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. 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. Nowadays, FIF technique is used to feather out the dose inhomogeneity caused by multiple fields. We have started using this technique after acquiring advanced technology machines in recent years.Methods and Materials: Sixteen patients treated with three-dimensional conformal radiation therapy (3D-CRT) for CSI were retrospectively chosen for analysis. These patients were treated during 2019-2020. Contouring of planning target volume (PTV) and organs at risk (OAR) was done, and planning was done on Varian Eclipse TM Treatment Planning System (TPS) (Varian Medical Systems, Palo Alto, CA). These patients were planned with lateral craniocervical fields and posterior spinal fields using a forward-planned FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose-volume histogram (DVH) was used for analysis of results. 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. Paired sample t-test was used to compute the p-values for the inferential statistics.Results: 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%. Volume receiving 100% of the dose was also calculated in both techniques; mean values of this dose range was almost similar in both groups. 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. Therefore, it proved that plan inhomogeneity improved with FIF technique. This technique provided consistent dose delivery during each fraction of treatment across the junctions. The maximum doses calculated at the junction were higher in the CSI plans without FIF compared to those with FIF technique. Conclusion:This study concludes that better dose homogeneity is achieved with FIF technique as compared to non-FIF technique, and the difference in values was statistically significant.

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Pediatric craniospinal irradiation with a short partial-arc VMAT technique for medulloblastoma tumors in dosimetric comparison

Cited by 15 publications

References 51 publications

Out‐of‐field doses in pediatric craniospinal irradiations with 3D‐CRT, VMAT, and scanning proton radiotherapy: A phantom study

Out‐of‐field doses in pediatric craniospinal irradiations with 3D‐CRT, VMAT, and scanning proton radiotherapy: A phantom study

Field in Field Technique (FIF) Technique With Intra-fractionally Modulated Junction Shifts for Cranio-spinal Irradiation (FSI) Planning With 3D-CRT.

Field-in-Field Technique With Intrafractionally Modulated Junction Shifts for Craniospinal Irradiation Planning With Three-Dimensional Conformal Radiation Therapy

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