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Contains fulltext : 232798.pdf (Publisher’s version ) (Open Access), BACKGROUND AND PURPOSE: Proton therapy is expected to outperform photon-based treatment regarding organs at risk (OAR) sparing but to date there is no method to practically measure clinical benefit. Here, we introduce the novel ROCOCO Performance Scoring System (RPSS) translating dose differences into clinically relevant endpoints and apply this to a treatment plan comparison of volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT) in 20 pilocytic astrocytoma patients. MATERIAL AND METHODS: The RPSS was developed on the basis of expert-based weighting factors and toxicity scores per OAR. The imaging datasets of 20 pilocytic astrocytoma patients having undergone radiotherapy were included in this in silico dosimetric comparison trial as proof of principle. For each of these patients, treatment plans to a total dose of 54 Gy (RBE) were generated for VMAT and IMPT and these were compared regarding radiation dose to the clinical target volume (CTV) and OARs. The RPSS was calculated for each treatment plan comparing VMAT and IMPT. RESULTS: In 40 analysed treatment plans, the average and low dose volumes to various OARs were significantly reduced when using IMPT compared to VMAT (p < 0.05). Using the RPSS, a significant difference between both treatment modalities was found, with 85% of the patients having a lower RPSS in favour of the IMPT plan. CONCLUSION: There are dosimetric differences between IMPT and VMAT in pilocytic astrocytoma patients. In absence of clinically validated NTCP models we introduce the RPSS model in order to objectively compare treatment modalities by translating dosimetric differences in potential clinical differences.

Contains fulltext : 232798.pdf (Publisher’s version ) (Open Access), BACKGROUND AND PURPOSE: Proton therapy is expected to outperform photon-based treatment regarding organs at risk (OAR) sparing but to date there is no method to practically measure clinical benefit. Here, we introduce the novel ROCOCO Performance Scoring System (RPSS) translating dose differences into clinically relevant endpoints and apply this to a treatment plan comparison of volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT) in 20 pilocytic astrocytoma patients. MATERIAL AND METHODS: The RPSS was developed on the basis of expert-based weighting factors and toxicity scores per OAR. The imaging datasets of 20 pilocytic astrocytoma patients having undergone radiotherapy were included in this in silico dosimetric comparison trial as proof of principle. For each of these patients, treatment plans to a total dose of 54 Gy (RBE) were generated for VMAT and IMPT and these were compared regarding radiation dose to the clinical target volume (CTV) and OARs. The RPSS was calculated for each treatment plan comparing VMAT and IMPT. RESULTS: In 40 analysed treatment plans, the average and low dose volumes to various OARs were significantly reduced when using IMPT compared to VMAT (p < 0.05). Using the RPSS, a significant difference between both treatment modalities was found, with 85% of the patients having a lower RPSS in favour of the IMPT plan. CONCLUSION: There are dosimetric differences between IMPT and VMAT in pilocytic astrocytoma patients. In absence of clinically validated NTCP models we introduce the RPSS model in order to objectively compare treatment modalities by translating dosimetric differences in potential clinical differences.

Contains fulltext : 232798.pdf (Publisher’s version ) (Open Access), BACKGROUND AND PURPOSE: Proton therapy is expected to outperform photon-based treatment regarding organs at risk (OAR) sparing but to date there is no method to practically measure clinical benefit. Here, we introduce the novel ROCOCO Performance Scoring System (RPSS) translating dose differences into clinically relevant endpoints and apply this to a treatment plan comparison of volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT) in 20 pilocytic astrocytoma patients. MATERIAL AND METHODS: The RPSS was developed on the basis of expert-based weighting factors and toxicity scores per OAR. The imaging datasets of 20 pilocytic astrocytoma patients having undergone radiotherapy were included in this in silico dosimetric comparison trial as proof of principle. For each of these patients, treatment plans to a total dose of 54 Gy (RBE) were generated for VMAT and IMPT and these were compared regarding radiation dose to the clinical target volume (CTV) and OARs. The RPSS was calculated for each treatment plan comparing VMAT and IMPT. RESULTS: In 40 analysed treatment plans, the average and low dose volumes to various OARs were significantly reduced when using IMPT compared to VMAT (p < 0.05). Using the RPSS, a significant difference between both treatment modalities was found, with 85% of the patients having a lower RPSS in favour of the IMPT plan. CONCLUSION: There are dosimetric differences between IMPT and VMAT in pilocytic astrocytoma patients. In absence of clinically validated NTCP models we introduce the RPSS model in order to objectively compare treatment modalities by translating dosimetric differences in potential clinical differences.

Item does not contain fulltext, BACKGROUND AND PURPOSE: To quantify renal and diaphragmatic interfractional motion in order to estimate systematic and random errors, and to investigate the correlation between interfractional motion and patient-specific factors. MATERIAL AND METHODS: We used 527 retrospective abdominal-thoracic cone beam CT scans of 39 childhood cancer patients (<18years) to quantify renal motion relative to bony anatomy in the left-right (LR), cranio-caudal (CC) and anterior-posterior (AP) directions, and diaphragmatic motion in the CC direction only. Interfractional motion was quantified by distributions of systematic and random errors in each direction (standard deviations Sigma and sigma, respectively). Also, correlation between organ motion and height was analyzed. RESULTS: Inter-patient organ motion varied widely, with the largest movements in the CC direction. Values of Sigma in LR, CC, and AP directions were 1.1, 3.8, 2.1mm for the right, and 1.3, 3.0, 1.5mm for the left kidney, respectively. The sigma in these three directions was 1.1, 3.1, 1.7mm for the right, and 1.2, 2.9, 2.1mm for the left kidney, respectively. For the diaphragm we estimated Sigma=5.2mm and sigma=4.0mm. No correlations were found between organ motion and height. CONCLUSIONS: The large inter-patient organ motion variations and the lack of correlation between motion and patient-related factors, suggest that individualized margin approaches might be required.

Item does not contain fulltext, BACKGROUND AND PURPOSE: To quantify renal and diaphragmatic interfractional motion in order to estimate systematic and random errors, and to investigate the correlation between interfractional motion and patient-specific factors. MATERIAL AND METHODS: We used 527 retrospective abdominal-thoracic cone beam CT scans of 39 childhood cancer patients (<18years) to quantify renal motion relative to bony anatomy in the left-right (LR), cranio-caudal (CC) and anterior-posterior (AP) directions, and diaphragmatic motion in the CC direction only. Interfractional motion was quantified by distributions of systematic and random errors in each direction (standard deviations Sigma and sigma, respectively). Also, correlation between organ motion and height was analyzed. RESULTS: Inter-patient organ motion varied widely, with the largest movements in the CC direction. Values of Sigma in LR, CC, and AP directions were 1.1, 3.8, 2.1mm for the right, and 1.3, 3.0, 1.5mm for the left kidney, respectively. The sigma in these three directions was 1.1, 3.1, 1.7mm for the right, and 1.2, 2.9, 2.1mm for the left kidney, respectively. For the diaphragm we estimated Sigma=5.2mm and sigma=4.0mm. No correlations were found between organ motion and height. CONCLUSIONS: The large inter-patient organ motion variations and the lack of correlation between motion and patient-related factors, suggest that individualized margin approaches might be required.

Item does not contain fulltext, BACKGROUND AND PURPOSE: To quantify renal and diaphragmatic interfractional motion in order to estimate systematic and random errors, and to investigate the correlation between interfractional motion and patient-specific factors. MATERIAL AND METHODS: We used 527 retrospective abdominal-thoracic cone beam CT scans of 39 childhood cancer patients (<18years) to quantify renal motion relative to bony anatomy in the left-right (LR), cranio-caudal (CC) and anterior-posterior (AP) directions, and diaphragmatic motion in the CC direction only. Interfractional motion was quantified by distributions of systematic and random errors in each direction (standard deviations Sigma and sigma, respectively). Also, correlation between organ motion and height was analyzed. RESULTS: Inter-patient organ motion varied widely, with the largest movements in the CC direction. Values of Sigma in LR, CC, and AP directions were 1.1, 3.8, 2.1mm for the right, and 1.3, 3.0, 1.5mm for the left kidney, respectively. The sigma in these three directions was 1.1, 3.1, 1.7mm for the right, and 1.2, 2.9, 2.1mm for the left kidney, respectively. For the diaphragm we estimated Sigma=5.2mm and sigma=4.0mm. No correlations were found between organ motion and height. CONCLUSIONS: The large inter-patient organ motion variations and the lack of correlation between motion and patient-related factors, suggest that individualized margin approaches might be required.