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Worm ES, Hansen R, Høyer M, Weber B, Mortensen H, Poulsen PR. Uniform versus non-uniform dose prescription for proton stereotactic body radiotherapy of liver tumors investigated by extensive motion-including treatment simulations. Phys Med Biol 2021; 66. [PMID: 34544071 DOI: 10.1088/1361-6560/ac2880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 09/20/2021] [Indexed: 12/24/2022]
Abstract
Compared to x-ray-based stereotactic body radiotherapy (SBRT) of liver cancer, proton SBRT may reduce the normal liver tissue dose. For an optimal trade-off between target and liver dose, a non-uniform dose prescription is often applied in x-ray SBRT, but lacks investigation for proton SBRT. Also, proton SBRT is prone to breathing-induced motion-uncertainties causing target mishit or dose alterations by interplay with the proton delivery. This study investigated non-uniform and uniform dose prescription in proton-based liver SBRT, including effects of rigid target motion observed during planning-4DCT and treatment. The study was based on 42 x-ray SBRT fractions delivered to 14 patients under electromagnetic motion-monitoring. For each patient, a non-uniform and uniform proton plan were made. The uniform plan was renormalized to be iso-toxic with the non-uniform plan using a NTCP model for radiation-induced liver disease. The motion data were used in treatment simulations to estimate the delivered target dose with rigid motion. Treatment simulations were performed with and without a repainting scheme designed to mitigate interplay effects. Including rigid motion, the achieved CTV mean dose after three fractions delivered without repainting was on average (±SD) 24.8 ± 8.4% higher and the D98%was 16.2 ± 11.3% higher for non-uniform plans than for uniform plans. The interplay-induced increase in D2%relative to the static plans was reduced from 3.2 ± 4.1% without repainting to -0.5 ± 1.7% with repainting for non-uniform plans and from 1.5 ± 2.0% to 0.1 ± 1.3% for uniform plans. Considerable differences were observed between estimated CTV doses based on 4DCT motion and intra-treatment motion. In conclusion, non-uniform dose prescription in proton SBRT may provide considerably higher tumor doses than uniform prescription for the same complication risk. Due to motion variability, target doses estimated from 4DCT motion may not accurately reflect the delivered dose. Future studies including modelling of deformations and associated range uncertainties are warranted to confirm the findings.
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Affiliation(s)
| | - Rune Hansen
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Morten Høyer
- Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Britta Weber
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.,Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Hanna Mortensen
- Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Per Rugaard Poulsen
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.,Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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2
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Ma M, Ren W, Li M, Niu C, Dai J. Dosimetric comparison of coplanar and noncoplanar beam arrangements for radiotherapy of patients with lung cancer: A meta-analysis. J Appl Clin Med Phys 2021; 22:34-43. [PMID: 33634946 PMCID: PMC8035566 DOI: 10.1002/acm2.13197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 01/06/2021] [Accepted: 01/18/2021] [Indexed: 12/25/2022] Open
Abstract
Purpose Radiotherapy plays an important role in the treatment of lung cancer, and both coplanar beam arrangements (CBA) and noncoplanar beam arrangements (NCBA) are adopted in clinic practice. The aim of this study is to answer the question whether NCBA are dosimetrically superior to CBA. Methods Search of publications were performed in PubMed, Web of Science, and the Cochran Library till March 2020. The searching terms were as following: ((noncoplanar) or ("non coplanar") or ("4pi") or ("4π")) AND (("lung cancer") or ("lung tumor") or ("lung carcinoma")) AND ((radiotherapy) or ("radiation therapy")). The included studies and extracted data were manually screened. All forest and funnel plots were carried out with RevMan software, and the Egger’s regression asymmetry tests were conducted with STATA software. Results Nine studies were included and evaluated in the meta‐analysis and treatment plans were designed with both CBA and NCBA. For the planning target volumes (PTV), D98%, D2%, the conformity index (CI), and the gradient index (GI) had no statistically significant difference. For organs‐at‐risk (OAR), V20 of the whole lung and the maximum dose of the spinal cord were significantly reduced in NCBA plans compared with CBA ones. But V10, V5, and mean dose of the whole lung, the maximum dose of the heart, and the maximum dose of the esophagus exhibited no significant difference when the two types of beam arrangements were compared. Conclusion After combining multicenter results, NCBA plans have significant advantages in reducing V20 of the whole lung and max dose of spinal cord.
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Affiliation(s)
- Min Ma
- National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Wenting Ren
- National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Minghui Li
- National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Chuanmeng Niu
- National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jianrong Dai
- National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Hansen AT, Poulsen PR, Høyer M, Worm ES. Isotoxic dose prescription level strategies for stereotactic liver radiotherapy: the price of dose uniformity. Acta Oncol 2020; 59:558-564. [PMID: 31833432 DOI: 10.1080/0284186x.2019.1701200] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Introduction: To find the optimal dose prescription strategy for liver SBRT, this study investigated the tradeoffs between achievable target dose and healthy liver dose for a range of isotoxic uniform and non-uniform prescription level strategies.Material and methods: Nine patients received ten liver SBRT courses with intrafraction motion monitoring during treatment. After treatment, five VMAT treatment plans were made for each treatment course. The PTV margin was 5 mm (left-right, anterior-posterior) and 10 mm (cranio-caudal). All plans had a mean CTV dose of 56.25 Gy in three fractions, while the PTV was covered by 50%, 67%, 67 s% (steep dose gradient outside CTV), 80%, and 95% of this dose, respectively. The 50%, 67 s%, 80%, and 95% plans were then renormalized to be isotoxic with the standard 67% plan according to a Lyman-Kutcher-Burman normal tissue complication probability model for radiation induced liver disease. The CTV D98 and mean dose of the iso-toxic plans were calculated both without and with the observed intrafraction motion, using a validated method for motion-including dose reconstruction.Results: Under isotoxic conditions, the average [range] mean CTV dose per fraction decreased gradually from 21.2 [20.5-22.7] Gy to 15.5 [15.0-16.6] Gy and the D98 dose per fraction decreased from 20.4 [19.7-21.7] Gy to 15.0 [14.5-15.5] Gy, as the prescription level to the PTV rim was increased from 50% to 95%. With inclusion of target motion the mean CTV dose was 20.5 [16.5-22.5] Gy (50% PTV rim dose) and 15.4 [13.9-16.7] Gy (95% rim dose) while D98 was 17.8 [7.4-20.6] Gy (50% rim dose) and 14.6 [8.8-15.7] Gy (95% rim dose).Conclusion: Requirements of a uniform PTV dose come at the price of excess normal tissue dose. A non-uniform PTV dose allows increased CTV mean dose at the cost of robustness toward intrafraction motion. The increase in planned CTV dose by non-uniform prescription outbalanced the dose deterioration caused by motion.
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Affiliation(s)
- Anders T. Hansen
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | - Per R. Poulsen
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
- The Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Morten Høyer
- The Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Esben S. Worm
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
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Daw S, Hasenclever D, Mascarin M, Fernández-Teijeiro A, Balwierz W, Beishuizen A, Burnelli R, Cepelova M, Claviez A, Dieckmann K, Landman-Parker J, Kluge R, Körholz D, Mauz-Körholz C, Wallace WH, Leblanc T. Risk and Response Adapted Treatment Guidelines for Managing First Relapsed and Refractory Classical Hodgkin Lymphoma in Children and Young People. Recommendations from the EuroNet Pediatric Hodgkin Lymphoma Group. Hemasphere 2020; 4:e329. [PMID: 32072145 PMCID: PMC7000476 DOI: 10.1097/hs9.0000000000000329] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 11/14/2019] [Accepted: 11/22/2019] [Indexed: 01/21/2023] Open
Abstract
The objective of this guideline is to aid clinicians in making individual salvage treatment plans for pediatric and adolescent patients with first relapse or refractory (R/R) classical Hodgkin lymphoma (cHL). While salvage with standard dose chemotherapy followed by high dose chemotherapy and autologous stem cell transplant is often considered the standard of care in adult practice, pediatric practice adopts a more individualized risk stratified and response adapted approach to salvage treatment with greater use of non-transplant salvage. Here, we present on behalf of the EuroNet Pediatric Hodgkin Lymphoma group, evidence and consensus-based guidelines for standardized diagnostic, prognostic and response procedures to allocate children and adolescents with R/R cHL to stratified salvage treatments.
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Affiliation(s)
- Stephen Daw
- Children and Young People's Cancer Services, University College Hospital London, London, UK
| | - Dirk Hasenclever
- Institute of Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
| | - Maurizio Mascarin
- AYA and Pediatric Radiotherapy Unit, Centro di Riferimento Oncologico, Aviano, Italy
| | - Ana Fernández-Teijeiro
- Unit of Pediatric Onco-Hematology, Hospital Universitario Virgen Macarena, Seville, Spain
| | - Walentyna Balwierz
- Department of Pediatric Oncology and Hematology, Institute of Pediatrics, Jagiellonian University Medical College, Krakow, Poland
| | - Auke Beishuizen
- Prinses Máxima Centrum voor Kinderoncologie, Utrecht, The Netherlands
| | - Roberta Burnelli
- Section of Pediatrics, Azienda Ospedaliero-Universitaria di Ferrara, Ferrara, Italy
| | - Michaela Cepelova
- Department of Pediatric Hematology and Oncology, University Hospital Motol, Czech Republic
| | - Alexander Claviez
- University Hospital Schleswig Holstein, Department of Pediatric and Adolescent Medicine, Pediatric Hematology, Oncology and Stem Cell Transplantation, Kiel, Germany
| | - Karin Dieckmann
- Department of Radiation Oncology, Medical University of Vienna, Vienna
| | | | - Regine Kluge
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany
| | - Dieter Körholz
- Pädiatrische Hämatologie und Onkologie, Zentrum für Kinderheilkunde der Justus-Liebig-Universität Gießen, Gießen, Germany
| | - Christine Mauz-Körholz
- Pädiatrische Hämatologie und Onkologie, Zentrum für Kinderheilkunde der Justus-Liebig-Universität Gießen, Gießen, Germany
| | | | - Thierry Leblanc
- University of Edinburgh and Department of Pediatrics, Royal Hospital for Sick Children, Edinburgh, Scotland, UK
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Stereotactic body radiotherapy in patients with hepatocellular carcinoma in a multimodal treatment setting. Strahlenther Onkol 2019; 196:334-348. [DOI: 10.1007/s00066-019-01540-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 10/23/2019] [Indexed: 12/24/2022]
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Kim ST, An HJ, Kim JI, Yoo JR, Kim HJ, Park JM. Non-coplanar VMAT plans for lung SABR to reduce dose to the heart: a planning study. Br J Radiol 2019; 93:20190596. [PMID: 31625759 DOI: 10.1259/bjr.20190596] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE This study aimed to compare the plan quality of non-coplanar partial arc (NPA) volumetric modulated arc therapy (VMAT) to that of coplanar partial arc (CPA) VMAT for stereotactic ablative radiotherapy (SABR) for lung cancer. METHODS A total of 20 patients treated for lung cancer with the SABR VMAT technique and whose lung tumors were close to the heart were retrospectively selected for this study. For the CPA VMAT, three coplanar half arcs were used while two coplanar half arcs and one noncoplanar arc rotating 315°-45° with couch rotations of 315° ± 5° were used for the NPA VMAT. For each patient, identical CT image sets and identical structures were used for both the CPA and NPA VMAT plans. Dose-volumetric parameters of each plan were analyzed. RESULTS For the planning target volume and both lungs, no statistically significant differences between the CPA and NPA VMAT plans were observed in general. For the heart, average values of D0.1cc of the CPA and NPA VMAT plans were 29.42 ± 13.37 and 21.71 ± 9.20 Gy, respectively (p < 0.001). For whole body, the mean dose and the gradient index of the CPA VMAT plans were 1.2 ± 0.5 Gy and 4.356 ± 0.608 while those of the NPA VMAT plans were 1.1 ± 0.5 Gy and 4.111 ± 0.480, respectively (both with p < 0.001). CONCLUSION The NPA VMAT proposed in this study showed more favorable plan quality than the CPA VMAT plans for lung SABR with tumors located close to the heart. ADVANCES IN KNOWLEDGE For lung SABR, NPA VMAT can reduce doses to the heart as well as whole-body irradiation.
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Affiliation(s)
- Sang-Tae Kim
- Nuclear Emergency Division, Radiation Protection and Emergency Preparedness Bureau, Nuclear Safety and Security Commission, Seoul, Korea
| | - Hyun Joon An
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea.,Department of Biomedical Sciences, Seoul National University, Seoul, Korea
| | - Jung-In Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
| | - Jae-Ryong Yoo
- Radiation Emergency Medicine Regulation Team, National Radiation Emergency Medical Center, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Hak Jae Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea.,Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea.,Robotics Research Laboratory for Extreme Environments, Advanced Institute of Convergence Technology, Suwon, Korea
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Mazzola R, Ruggieri R, Figlia V, Rigo M, Giaj Levra N, Ricchetti F, Nicosia L, Corradini S, Alongi F. Stereotactic body radiotherapy of central lung malignancies using a simultaneous integrated protection approach : A prospective observational study. Strahlenther Onkol 2019; 195:719-724. [PMID: 30689026 DOI: 10.1007/s00066-018-01419-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/22/2018] [Indexed: 12/11/2022]
Abstract
AIM It is recognized that stereotactic body radiotherapy (SBRT) for centrally located lung metastases is affected by higher rates of severe toxicity. In the present study, we report the clinical outcomes following a novel intensity-modulated radiotherapy prescription dose, termed simultaneous integrated protection (SIP), for nearby organs at risk (OARs). MATERIALS AND METHODS The prescribed total doses of SBRT were 70 Gy in 10 fractions and 60 Gy in 8 fractions. For ultra-centrally located lesions, a dose of 60 Gy in 10 fractions was delivered. The main planning instructions were: (1) to remain within the limits of the given dose constraints for an OAR; (2) to make use of the maximum possible dose to the OARs to minimize dose inhomogeneity for the Planning Target Volume (PTV). SBRT-related toxicity was prospectively assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v4.0. The primary clinical endpoint was the SBRT-related toxicity. Secondary endpoint was local control. RESULTS Forty patients affected by a single central malignancy were analyzed. The median follow-up was 20 months (range, 6-58 months). Acute and late clinical pulmonary toxicity ≥grade 2 was recorded in 2 out of 40 patients (5%) and 3 out of 40 patients (7%), respectively. No patient experienced cardiac toxicity. No narrowing or stenosis of any airway or vessel was registered. One-year local control rate was 91%. The median time to local progression was 13 months (range, 6-46 months). CONCLUSION SBRT using a PTV-SIP approach for single central lung metastases achieved low SBRT-related toxicity with acceptable local control.
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Affiliation(s)
- Rosario Mazzola
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy.
| | - Ruggero Ruggieri
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy
| | - Vanessa Figlia
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy
| | - Michele Rigo
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy
| | - Niccolò Giaj Levra
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy
| | - Francesco Ricchetti
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy
| | - Luca Nicosia
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy
| | | | - Filippo Alongi
- Radiation Oncology, IRCCS, Sacro Cuore-Don Calabria Hospital, Negrar-Verona, Italy.,University of Brescia, Brescia, Italy
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Zehentmayr F, Sprenger M, Rettenbacher L, Wass R, Porsch P, Fastner G, Pirich C, Studnicka M, Sedlmayer F. Survival in early lung cancer patients treated with high dose radiotherapy is independent of pathological confirmation. Thorac Cancer 2019; 10:321-329. [PMID: 30618120 PMCID: PMC6360228 DOI: 10.1111/1759-7714.12966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Approximately 15% of lung cancer patients are diagnosed in early stages. Microscopic proof of disease cannot always be obtained because of comorbidity or reluctance to undergo invasive diagnostic procedures. In the current study, survival data of patients with and without pathology are compared. METHODS One hundred and sixty three patients with NSCLC I-IIb (T3 N0) treated between 2002 and 2016 were eligible: 123 (75%) had pathological confirmation of disease, whereas 40 (25%) did not. In accordance with international guidelines, both groups received radiotherapy. Comorbidity was assessed with the Charlson Comorbidity Index (CCI). RESULTS The median follow-up was 28.6 months (range: 0.3-162): 66 (40%) patients are still alive, while 97 (59%) patients died: 48 (29%) cancer-related deaths and 49 (30%) from causes other than cancer. Median overall survival (OS) in patients without pathological confirmation was 58.6 months (range: 0.5-162), which did not differ from those with microscopic proof of disease (39.4 months, range: 0.3-147.5; logrank P = 0.481). Median cancer-specific survival (CSS) also did not differ at 113.4 months (range: 0.5-162) in the non-confirmation group (logrank P = 0.763) versus 51.5 months (range: 3.7-129.5) in patients with pathology. In Cox regression, a CCI of ≥ 3 was associated with poor OS (hazard ratio 2.0; range 1.2-3.4; P = 0.010) and CSS (hazard ratio 2.0; 1.0-4.0; P = 0.043). CONCLUSION OS and CSS in early lung cancer patients depend on comorbidity rather than on pathological confirmation of disease.
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Affiliation(s)
- Franz Zehentmayr
- Department of Radiation Oncology, Paracelsus Medical University, SALK, Salzburg, Austria.,radART, Paracelsus Medical University, Salzburg, Austria
| | - Martin Sprenger
- Postgraduate Public Health Program, Medical University of Graz, Graz, Austria
| | - Lukas Rettenbacher
- Department of Nuclear Medicine, Paracelsus Medical University, SALK, Salzburg, Austria
| | - Romana Wass
- Department of Pneumology, Paracelsus Medical University, SALK, Salzburg, Austria
| | - Peter Porsch
- Department of Pneumology, Paracelsus Medical University, SALK, Salzburg, Austria
| | - Gerd Fastner
- Department of Radiation Oncology, Paracelsus Medical University, SALK, Salzburg, Austria
| | - Christian Pirich
- Department of Nuclear Medicine, Paracelsus Medical University, SALK, Salzburg, Austria
| | - Michael Studnicka
- Department of Pneumology, Paracelsus Medical University, SALK, Salzburg, Austria
| | - Felix Sedlmayer
- Department of Radiation Oncology, Paracelsus Medical University, SALK, Salzburg, Austria.,radART, Paracelsus Medical University, Salzburg, Austria
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SBRT planning for spinal metastasis: indications from a large multicentric study. Strahlenther Onkol 2018; 195:226-235. [PMID: 30353349 DOI: 10.1007/s00066-018-1383-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 10/08/2018] [Indexed: 12/31/2022]
Abstract
BACKGROUND The dosimetric variability in spine stereotactic body radiation therapy (SBRT) planning was investigated in a large number of centres to identify crowd knowledge-based solutions. METHODS Two spinal cases were planned by 48 planners (38 centres). The required prescription dose (PD) was 3 × 10 Gy and the planning target volume (PTV) coverage request was: VPD > 90% (minimum request: VPD > 80%). The dose constraints were: planning risk volume (PRV) spinal cord: V18Gy < 0.35 cm3, V21.9 Gy < 0.03 cm3; oesophagus: V17.7 Gy < 5 cm3, V25.2 Gy < 0.03 cm3. Planners who did not fulfil the protocol requirements were asked to re-optimize the plans, using the results of planners with the same technology. Statistical analysis was performed to assess correlations between dosimetric results and planning parameters. A quality index (QI) was defined for scoring plans. RESULTS In all, 12.5% of plans did not meet the protocol requirements. After re-optimization, 98% of plans fulfilled the constraints, showing the positive impact of knowledge sharing. Statistical analysis showed a significant correlation (p < 0.05) between the homogeneity index (HI) and PTV coverage for both cases, while the correlation between HI and spinal cord sparing was significant only for the single dorsal PTV case. Moreover, the multileaf collimator leaf thickness correlated with the spinal cord sparing. Planners using comparable delivery/planning system techniques produced different QI, highlighting the impact of the planner's skills in the optimization process. CONCLUSION Both the technology and the planner's skills are fundamentally important in spine SBRT planning optimization. Knowledge sharing helped to follow the plan objectives.
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