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Radonic S, Schneider U, Besserer J, Meier VS, Rohrer Bley C. Risk adaptive planning with biology-based constraints may lead to higher tumor control probability in tumors of the canine brain: A planning study. Phys Med 2024; 119:103317. [PMID: 38430675 DOI: 10.1016/j.ejmp.2024.103317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 11/27/2023] [Accepted: 02/06/2024] [Indexed: 03/05/2024] Open
Abstract
BACKGROUND Classical radiation protocols are guided by physical dose delivered homogeneously over the target. Protocols are chosen to keep normal tissue complication probability (NTCP) at an acceptable level. Organs at risk (OAR) adjacent to the target volume could lead to underdosage of the tumor and a decrease of tumor control probability (TCP). The intent of our study was to explore a biology-based dose escalation: by keeping NTCP for OAR constant, radiation dose was to be maximized, allowing to result in heterogeneous dose distributions. METHODS We used computed tomography datasets of 25 dogs with brain tumors, previously treated with 10x4 Gy (40 Gy to PTV D50). We generated 3 plans for each patient: A) original treatment plan with homogeneous dose distribution, B) heterogeneous dose distribution with strict adherence to the same NTCPs as in A), and C) heterogeneous dose distribution with adherence to NTCP <5%. For plan comparison, TCPs and TCP equivalent doses (homogenous target dose which results in the same TCP) were calculated. To enable the use of the generalized equivalent uniform dose (gEUD) metric of the tumor target in plan optimization, the calculated TCP values were used to obtain the volume effect parameter a. RESULTS As intended, NTCPs for all OARs did not differ from plan A) to B). In plan C), however, NTCPs were significantly higher for brain (mean 2.5% (SD±1.9, 95%CI: 1.7,3.3), p<0.001), optic chiasm (mean 2.0% (SD±2.2, 95%CI: 1.0,2.8), p=0.010) compared to plan A), but no significant increase was found for the brainstem. For 24 of 25 of the evaluated patients, the heterogenous plans B) and C) led to an increase in target dose and projected increase in TCP compared to the homogenous plan A). Furthermore, the distribution of the projected individual TCP values as a function of the dose was found to be in good agreement with the population TCP model. CONCLUSION Our study is a first step towards risk-adaptive radiation dose optimization. This strategy utilizes a biologic objective function based on TCP and NTCP instead of an objective function based on physical dose constraints.
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Affiliation(s)
- Stephan Radonic
- Department of Physics, University of Zurich, Zurich, Switzerland; Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
| | - Uwe Schneider
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapie Hirslanden AG, Rain 34, Aarau, Switzerland
| | - Jürgen Besserer
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapie Hirslanden AG, Rain 34, Aarau, Switzerland
| | - Valeria S Meier
- Department of Physics, University of Zurich, Zurich, Switzerland; Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Carla Rohrer Bley
- Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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De Saint-Hubert M, Boissonnat G, Schneider U, Bäumer C, Verbeek N, Esser J, Wulff J, Stuckmann F, Suesselbeck F, Nabha R, Dabin J, Vasi F, Radonic S, Rodriguez M, Simon AC, Journy N, Timmermann B, Thierry-Chef I, Brualla L. Complete patient exposure during paediatric brain cancer treatment for photon and proton therapy techniques including imaging procedures. Front Oncol 2023; 13:1222800. [PMID: 37795436 PMCID: PMC10546320 DOI: 10.3389/fonc.2023.1222800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/21/2023] [Indexed: 10/06/2023] Open
Abstract
Background In radiotherapy, especially when treating children, minimising exposure of healthy tissue can prevent the development of adverse outcomes, including second cancers. In this study we propose a validated Monte Carlo framework to evaluate the complete patient exposure during paediatric brain cancer treatment. Materials and methods Organ doses were calculated for treatment of a diffuse midline glioma (50.4 Gy with 1.8 Gy per fraction) on a 5-year-old anthropomorphic phantom with 3D-conformal radiotherapy, intensity modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT) and intensity modulated pencil beam scanning (PBS) proton therapy. Doses from computed tomography (CT) for planning and on-board imaging for positioning (kV-cone beam CT and X-ray imaging) accounted for the estimate of the exposure of the patient including imaging therapeutic dose. For dose calculations we used validated Monte Carlo-based tools (PRIMO, TOPAS, PENELOPE), while lifetime attributable risk (LAR) was estimated from dose-response relationships for cancer induction, proposed by Schneider et al. Results Out-of-field organ dose equivalent data of proton therapy are lower, with doses between 0.6 mSv (testes) and 120 mSv (thyroid), when compared to photon therapy revealing the highest out-of-field doses for IMRT ranging between 43 mSv (testes) and 575 mSv (thyroid). Dose delivered by CT ranged between 0.01 mSv (testes) and 72 mSv (scapula) while a single imaging positioning ranged between 2 μSv (testes) and 1.3 mSv (thyroid) for CBCT and 0.03 μSv (testes) and 48 μSv (scapula) for X-ray. Adding imaging dose from CT and daily CBCT to the therapeutic demonstrated an important contribution of imaging to the overall radiation burden in the course of treatment, which is subsequently used to predict the LAR, for selected organs. Conclusion The complete patient exposure during paediatric brain cancer treatment was estimated by combining the results from different Monte Carlo-based dosimetry tools, showing that proton therapy allows significant reduction of the out-of-field doses and secondary cancer risk in selected organs.
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Affiliation(s)
| | | | - Uwe Schneider
- Physik Institut, Universitat Zürich, Zürich, Switzerland
| | - Christian Bäumer
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
- Radiation Oncology and Imaging, German Cancer Consortium DKTK, Essen, Germany
- Department of Physics, TU Dortmund University, Dortmund, Germany
| | - Nico Verbeek
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
| | - Johannes Esser
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
- Faculty of Mathematics and Science Institute of Physics and Medical Physics, Heinrich-Heine University, Düsseldorf, Germany
| | - Jörg Wulff
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
| | - Florian Stuckmann
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
| | - Finja Suesselbeck
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
| | - Racell Nabha
- Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Jérémie Dabin
- Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Fabiano Vasi
- Physik Institut, Universitat Zürich, Zürich, Switzerland
| | | | - Miguel Rodriguez
- Hospital Paitilla, Panama City, Panama
- Instituto de Investigaciones Científicas y de Alta Tecnología INDICASAT-AIP, Panama City, Panama
| | | | - Neige Journy
- INSERM U1018, Paris Sud-Paris Saclay University, Villejuif, France
| | - Beate Timmermann
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
- Radiation Oncology and Imaging, German Cancer Consortium DKTK, Essen, Germany
- Faculty of Medicine, University of Duisburg-Essen, Essen, Germany
- Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Isabelle Thierry-Chef
- Barcelona Institute of Global Health (ISGlobal), Barcelona, Spain
- University Pompeu Fabra, Barcelona, Spain
- CIBER Epidemiología y Salud Pública, Madrid, Spain
| | - Lorenzo Brualla
- West German Proton Therapy Centre Essen WPE, Essen, Germany
- West German Cancer Centre (WTZ), Essen, Germany
- Radiation Oncology and Imaging, German Cancer Consortium DKTK, Essen, Germany
- Faculty of Medicine, University of Duisburg-Essen, Essen, Germany
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Radonic S, Besserer J, Rohrer Bley C, Schneider U, Meier VS. A concept for anisotropic PTV margins including rotational setup uncertainties and its impact on the tumor control probability in canine brain tumors. Biomed Phys Eng Express 2022; 8. [PMID: 35981496 DOI: 10.1088/2057-1976/ac8a9f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/18/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE In this modelling study, we pursued two main goals. The first was to establish a new CTV-to-PTV expansion which considers the closest and most critical organ at risk (OAR). The second goal was to investigate the impact of the planning target volume (PTV) margin size on the tumor control probability (TCP) and its dependence on the geometrical setup uncertainties. The aim was to achieve a smaller margin expansion close to the OAR while allowing a moderately larger expansion in less critical areas further away from the OAR and whilst maintaining the TCP. APPROACH Imaging data of radiation therapy plans from pet dogs which had undergone radiation therapy for brain tumor were used to estimate the clinic specific rotational setup uncertainties. A Monte-Carlo methodology using a voxel-based TCP model was used to quantify the implications of rotational setup uncertainties on the TCP. A combination of algorithms was utilized to establish a computational CTV-to-PTV expansion method based on probability density. This was achieved by choosing a center of rotation close to an OAR. All required software modules were developed and integrated into a software package that directly interacts with the Varian Eclipse treatment planning system. MAIN RESULTS Several uniform and non-isotropic PTVs were created. To ensure comparability and consistency, standardized RT plans with equal optimization constraints were defined, automatically applied and calculated on these targets. The resulting TCPs were then computed, evaluated and compared. SIGNIFICANCE The non-isotropic margins were found to result in larger TCPs with smaller margin excess volume. Further, we presented an additional application of the newly established CTV-to-PTV expansion method for radiation therapy of the spinal axis of human patients.
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Affiliation(s)
- Stephan Radonic
- Department of Physics, University of Zurich Faculty of Science, Winterthurerstrasse 190, Zurich, ZH, 8057, SWITZERLAND
| | - Jürgen Besserer
- Radiotherapy Hirslanden, Hirslanden Klinik Hirslanden, Witelikerstrasse 40, Zurich, Zürich, 8032, SWITZERLAND
| | - Carla Rohrer Bley
- Division of Radiation Oncology, Small Animal Department, University of Zurich Vetsuisse Faculty, Winterthurerstrasse 260, Zurich, Zürich, 8057, SWITZERLAND
| | - Uwe Schneider
- Radiotherapy Hirslanden, Hirslanden Klinik Hirslanden, Witellikerstrasse 40, Zurich, Zürich, 8032, SWITZERLAND
| | - Valeria Sabina Meier
- Division of Radiation Oncology, Small Animal Department, University of Zurich Vetsuisse Faculty, Winterthrerstrasse 260, Zurich, Zürich, 8057, SWITZERLAND
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De Saint-Hubert M, Verbeek N, Bäumer C, Esser J, Wulff J, Nabha R, Van Hoey O, Dabin J, Stuckmann F, Vasi F, Radonic S, Boissonnat G, Schneider U, Rodriguez M, Timmermann B, Thierry-Chef I, Brualla L. Validation of a Monte Carlo Framework for Out-of-Field Dose Calculations in Proton Therapy. Front Oncol 2022; 12:882489. [PMID: 35756661 PMCID: PMC9213663 DOI: 10.3389/fonc.2022.882489] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 05/04/2022] [Indexed: 11/30/2022] Open
Abstract
Proton therapy enables to deliver highly conformed dose distributions owing to the characteristic Bragg peak and the finite range of protons. However, during proton therapy, secondary neutrons are created, which can travel long distances and deposit dose in out-of-field volumes. This out-of-field absorbed dose needs to be considered for radiation-induced secondary cancers, which are particularly relevant in the case of pediatric treatments. Unfortunately, no method exists in clinics for the computation of the out-of-field dose distributions in proton therapy. To help overcome this limitation, a computational tool has been developed based on the Monte Carlo code TOPAS. The purpose of this work is to evaluate the accuracy of this tool in comparison to experimental data obtained from an anthropomorphic phantom irradiation. An anthropomorphic phantom of a 5-year-old child (ATOM, CIRS) was irradiated for a brain tumor treatment in an IBA Proteus Plus facility using a pencil beam dedicated nozzle. The treatment consisted of three pencil beam scanning fields employing a lucite range shifter. Proton energies ranged from 100 to 165 MeV. A median dose of 50.4 Gy(RBE) with 1.8 Gy(RBE) per fraction was prescribed to the initial planning target volume (PTV), which was located in the cerebellum. Thermoluminescent detectors (TLDs), namely, Li-7-enriched LiF : Mg, Ti (MTS-7) type, were used to detect gamma radiation, which is produced by nuclear reactions, and secondary as well as recoil protons created out-of-field by secondary neutrons. Li-6-enriched LiF : Mg,Cu,P (MCP-6) was combined with Li-7-enriched MCP-7 to measure thermal neutrons. TLDs were calibrated in Co-60 and reported on absorbed dose in water per target dose (μGy/Gy) as well as thermal neutron dose equivalent per target dose (μSv/Gy). Additionally, bubble detectors for personal neutron dosimetry (BD-PND) were used for measuring neutrons (>50 keV), which were calibrated in a Cf-252 neutron beam to report on neutron dose equivalent dose data. The Monte Carlo code TOPAS (version 3.6) was run using a phase-space file containing 1010 histories reaching an average standard statistical uncertainty of less than 0.2% (coverage factor k = 1) on all voxels scoring more than 50% of the maximum dose. The primary beam was modeled following a Fermi–Eyges description of the spot envelope fitted to measurements. For the Monte Carlo simulation, the chemical composition of the tissues represented in ATOM was employed. The dose was tallied as dose-to-water, and data were normalized to the target dose (physical dose) to report on absorbed doses per target dose (mSv/Gy) or neutron dose equivalent per target dose (μSv/Gy), while also an estimate of the total organ dose was provided for a target dose of 50.4 Gy(RBE). Out-of-field doses showed absorbed doses that were 5 to 6 orders of magnitude lower than the target dose. The discrepancy between TLD data and the corresponding scored values in the Monte Carlo calculations involving proton and gamma contributions was on average 18%. The comparison between the neutron equivalent doses between the Monte Carlo simulation and the measured neutron doses was on average 8%. Organ dose calculations revealed the highest dose for the thyroid, which was 120 mSv, while other organ doses ranged from 18 mSv in the lungs to 0.6 mSv in the testes. The proposed computational method for routine calculation of the out-of-the-field dose in proton therapy produces results that are compatible with the experimental data and allow to calculate out-of-field organ doses during proton therapy.
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Affiliation(s)
- Marijke De Saint-Hubert
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Nico Verbeek
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany
| | - Christian Bäumer
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Radiation Oncology and Imaging, German Cancer Consortium DKTK, Heidelberg, Germany.,Department of Physics, TU Dortmund University, Dortmund, Germany
| | - Johannes Esser
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Mathematics and Science Institute of Physics and Medical Physics. Heinrich-Heine University, Düsseldorf, Germany
| | - Jörg Wulff
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany
| | - Racell Nabha
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Olivier Van Hoey
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Jérémie Dabin
- Research in Dosimetric Applications, Belgian Nuclear Research Center (SCK CEN), Mol, Belgium
| | - Florian Stuckmann
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,Faculty of Mathematics and Science Institute of Physics and Medical Physics. Heinrich-Heine University, Düsseldorf, Germany.,Klinikum Fulda GAG, Universitätsmedizin Marburg, Fulda, Zurich, Germany
| | - Fabiano Vasi
- Physik Institut, Universität Zürich, Zürich, Switzerland
| | | | | | - Uwe Schneider
- Physik Institut, Universität Zürich, Zürich, Switzerland
| | - Miguel Rodriguez
- Hospital Paitilla, Panama City, Panama.,Instituto de Investigaciones Cientificas y de Alta Tecnología INDICASAT-AIP, Panama City, Panama
| | - Beate Timmermann
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany.,Radiation Oncology and Imaging, German Cancer Consortium DKTK, Heidelberg, Germany.,Department of Particle Therapy, University Hospital Essen, Essen, Germany
| | - Isabelle Thierry-Chef
- Radiation Programme, Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain.,University Pompeu Fabra, Barcelona, Spain.,CIBER Epidemiología y Salud Pública, Madrid, Spain
| | - Lorenzo Brualla
- West German Proton Therapy Centre Essen WPE, Essen, Germany.,West German Cancer Center (WTZ), Essen, Germany.,Faculty of Medicine, University of Duisburg-Essen, Essen, Germany
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Hennet M, Radonic S, Schneider U, Hartmann M. Retrospective evaluation of a robust hybrid planning technique established for irradiation of breast cancer patients with included mammary internal lymph nodes. Radiat Oncol 2022; 17:76. [PMID: 35428265 PMCID: PMC9013158 DOI: 10.1186/s13014-022-02039-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 03/22/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
The irradiation of breast cancer patients with included internal mammary lymph nodes challenges radiation planning with regard to robustness and protection of OARs. In this publication, a feasible hybrid radiation technique is presented with a retrospective dosimetric and radiobiological analysis of patient data of our institute from 2016 to 2020 and robustness analysis.
Methods
The proposed hybrid irradiation technique consists of two IMRT tangents and two partial VMAT fields. The retrospective dosimetric and radiobiological evaluation are made for 217 patient treatments (right- and left-sided). The robustness is evaluated regarding an artificial swelling from 0.4 to 1.5 cm for a random example patient and compared to a pure VMAT planning technique with use of a virtual bolus. The out of field stray dose is calculated for a selected patient plan and compared to alternative radiation techniques.
Results
The coverage D95% of the PTVEval (with breast swelling of 1.5 cm) changes for the hybrid plan from 96.1 to 92.1% of prescribed dose and for the pure VMAT plan from 94.3 to 87%. The retrospective dosimetric evaluation of patient irradiations reveals a Dmean for total lung 6.5 ± 0.9 Gy (NTCP[Semenenko 2008] 2.8 ± 0.5%), ipsilateral lung 10.9 ± 1.5 Gy, contralateral lung 2.2 ± 0.6 Gy, heart 2.1 ± 1.1 Gy (ERR[Schneider 2017] 0.02 ± 0.17%) and contralateral breast 1.7 ± 0.6 Gy. The scatter dose of the hybrid irradiation technique is higher than for pure VMAT and lower than for pure IMRT irradiation.
Conclusions
The feasibility of the proposed planning technique is shown by treating many patients with this technique at our radiotherapy department. The hybrid radiation technique shows a good sparing of the OARs in the retrospective analysis and is robust with regards to a breast swelling of up to 1.5 cm. The slightly higher stray dose of the hybrid technique compared to a pure VMAT technique originates from higher number of MUs and lower conformity.
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Hauri P, Radonic S, Vasi F, Ernst M, Sumila M, Mille MM, Lee C, Hartmann M, Schneider U. Development of whole-body representation and dose calculation in a commercial treatment planning system. Z Med Phys 2021; 32:159-172. [PMID: 34301443 PMCID: PMC9948842 DOI: 10.1016/j.zemedi.2021.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 05/03/2021] [Accepted: 05/10/2021] [Indexed: 10/20/2022]
Abstract
For the epidemiological evaluation of long-term side effects of radiotherapy patients, it is important to know the doses to organs and tissues everywhere in the patient. Computed tomography (CT) images of the patients which contain the anatomical information are sometimes available for each treated patient. However, the available CT scans usually cover only the treated volume of the patient including the target and surrounding anatomy. To overcome this limitation, in this work we describe the development of a software tool using the Varian Eclipse Scripting API for extending a partial-body CT to a whole-body representation in the treatment planning system for dose calculation. The whole-body representation is created by fusing the partial-body CT with a similarly sized whole-body computational phantom selected from a library containing 64 phantoms of different heights, weights, and genders. The out-of-field dose is calculated with analytical models from the literature and merged with the treatment planning system-calculated dose. To test the method, the out-of-field dose distributions on the computational phantoms were compared to dose calculations on whole-body patient CTs. The mean doses, D2% and D98% were compared in 26 organs and tissues for 14 different treatment plans in 5 patients using 3D-CRT, IMRT, VMAT, coplanar and non-coplanar techniques. From these comparisons we found that mean relative differences between organ doses ranged from -10% and +20% with standard deviations of up to 40%. The developed method will help epidemiologists and researchers estimate organ doses outside the treated volume when only limited treatment planning CT information is available.
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Affiliation(s)
- Pascal Hauri
- Department of Physics, University of Zurich, Zurich, Switzerland,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Stephan Radonic
- Department of Physics, University of Zurich, Zurich, Switzerland,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland,Corresponding author: Stephan Radonic, Department of Physics, University of Zurich, Zurich, Switzerland
| | - Fabiano Vasi
- Department of Physics, University of Zurich, Zurich, Switzerland,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Marina Ernst
- Department of Physics, University of Zurich, Zurich, Switzerland
| | - Marcin Sumila
- Department of Physics, University of Zurich, Zurich, Switzerland,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Matthew M. Mille
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, USA
| | - Matthias Hartmann
- Department of Physics, University of Zurich, Zurich, Switzerland,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Uwe Schneider
- Department of Physics, University of Zurich, Zurich, Switzerland,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
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Radonic S, Besserer J, Meier V, Bley CR, Schneider U. A Novel Analytical Population Tumor Control Probability Model Includes Cell Density and Volume Variations: Application to Canine Brain Tumor. Int J Radiat Oncol Biol Phys 2021; 110:1530-1537. [PMID: 33838213 DOI: 10.1016/j.ijrobp.2021.03.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 02/05/2021] [Accepted: 03/10/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE Tumor control probability (TCP) models based on Poisson statistics characterize the distribution of surviving clonogens. Thus enabling the calculation of TCP for individuals. To mathematically describe clinically observed survival data of patient cohorts it is necessary to extend the Poisson TCP model. This is typically done by either incorporating variations of model parameters or by using an empirical logistic model. The purpose of this work is the development of an analytical population TCP model by mechanistic extension of the Possion model. METHODS AND MATERIALS The frequency distribution of gross tumor volumes was used to incorporate tumor volume variations into the TCP model. Additionally the tumor cell density variation was incorporated. Both versions of the population TCP model were fitted to clinical data and compared to existing literature. RESULTS It was shown that clinically observed brain tumor volumes of dogs undergoing radiotherapy are distributed according to an exponential distribution. The average gross tumor volume size was 3.37 cm3. Fitting the population TCP model including the volume variation using linear-quadratic and track-event model yieldedα=0.36Gy--1a, β=0.045Gy--2, a=0.9yr--1, TD=5.0d,and p=.36Gy--1, q=0.48Gy--1, a=0.80yr--1, TD=3.0d, respectively. Fitting the population TCP model including both the volume and cell density variation yielded α=0.43Gy--1, β=0.0537Gy--2, a=2.0yr--1, TD=3.0d, σ=2.5,and p=.43Gy--1, q=0.55Gy--1, a=2.0yr--1, TD=2.0d, σ=3.0,respectively. CONCLUSIONS Two sets of radiobiological parameters were obtained which can be used for quantifying the TCP for radiation therapy of brain tumors in dogs. We established a mechanistic link between the poisson statistics based individual TCP model and the logistic TCP model. This link can be used to determine the radiobiological parameters of patient specific TCP models from published fits of logistic models to cohorts of patients.
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Affiliation(s)
- Stephan Radonic
- Department of Physics, University of Zurich, Zurich, Switzerland; Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
| | - Jürgen Besserer
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapy Hirslanden, Rain 32, Aarau, Switzerland
| | - Valeria Meier
- Department of Physics, University of Zurich, Zurich, Switzerland; Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | | | - Uwe Schneider
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapy Hirslanden, Rain 32, Aarau, Switzerland
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Meier V, Staudinger C, Radonic S, Besserer J, Schneider U, Walsh L, Rohrer Bley C. Reducing margins for abdominopelvic tumours in dogs: Impact on dose-coverage and normal tissue complication probability. Vet Comp Oncol 2021; 19:266-274. [PMID: 33372354 PMCID: PMC8247346 DOI: 10.1111/vco.12671] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/08/2020] [Accepted: 12/21/2020] [Indexed: 12/19/2022]
Abstract
Image‐guided, intensity modulated radiation therapy (IG‐IMRT) reduces dose to pelvic organs at risk without losing dose coverage to the planning target volume (PTV) and might permit margin reductions potentially resulting in lower toxicity. Appropriate PTV margins have not been established for IG‐IMRT in abdominopelvic tumours in dogs, and herein we explore if our usual PTV 5 mm margin can be reduced further. Datasets from dogs that underwent IG‐IMRT for non‐genitourinary abdominopelvic neoplasia with 5 mm‐PTV expansion were included in this retrospective virtual study. The clinical target volumes and organs at risk (OAR) colon, rectum, spinal cord were adapted to each co‐registered cone‐beam computed tomography (CBCT) used for positioning. New treatment plans were generated and smaller PTV margins of 3 mm and 4 mm evaluated with respect to adequate dose coverage and normal tissue complication probability (NTCP) of OAR. Ten dogs with a total of 70 CBCTs were included. Doses to the OAR of each CBCT deviated mildly from the originally planned doses. In some plans, insufficient build‐up of the high dose‐area at the body surface was found due to inadequate or missing bolus placement. Overall, the margin reduction to 4 mm or 3 mm did not impair dose coverage and led to significantly lower NTCP in all OAR except for spinal cord delayed myelopathy. However, overall NTCP for spinal cord was very low (<4%). PTV‐margins depend on patient immobilization and treatment technique and accuracy. IG‐IMRT allows treatment with very small margins in the abdominopelvic region, ensuring appropriate target dose coverage, while minimizing NTCP.
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Affiliation(s)
- Valeria Meier
- Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Department of Physics, University of Zurich, Zurich, Switzerland
| | - Chris Staudinger
- Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Stephan Radonic
- Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Department of Physics, University of Zurich, Zurich, Switzerland
| | - Jürgen Besserer
- Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Department of Physics, University of Zurich, Zurich, Switzerland.,Radiation Oncology, Hirslanden Clinic, Zurich, Switzerland
| | - Uwe Schneider
- Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Department of Physics, University of Zurich, Zurich, Switzerland.,Radiation Oncology, Hirslanden Clinic, Zurich, Switzerland
| | - Linda Walsh
- Department of Physics, University of Zurich, Zurich, Switzerland
| | - Carla Rohrer Bley
- Division of Radiation Oncology, Small Animal Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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