Oliver Jäkel

German Cancer Research Center | DKFZ · Division of Medical Physics in Radiation Oncology

Objective: In this contribution we present a special Fano test for charged particles in presence of magnetic fields in the MC code TOPAS, as well as the determination of magnetic field correction factors k B for Farmer-type ionization chambers using proton beams. Approach: Customized C++ extensions for TOPAS were implemented to model the special F...

Objective : This work investigates the use of Al 2 O 3 :C and Al 2 O 3 :C,Mg optically stimulated luminescence (OSL) detectors to determine both the dose and the radiation quality in light ion beams. The radiation quality is here expressed through either the linear energy transfer (LET) or the closely related metric Q eff , which depends on the par...

Background: Interest in spatial fractionation radiotherapy has exponentially increased over the last decade as a significant reduction of healthy tissue toxicity was observed by mini-beam irradiation. Published studies, however, mostly use rigid mini-beam collimators dedicated to their exact experimental arrangement such that changing the setup or...

Background Patients with locally-advanced non-small-cell lung cancer (LA-NSCLC) are often ineligible for surgery, so that definitive chemoradiotherapy (CRT) represents the treatment of choice. Nevertheless, long-term tumor control is often not achieved. Intensification of radiotherapy (RT) to improve locoregional tumor control is limited by the det...

Purpose: To describe performance measurements, adaptations and time stability over 20 months of a diagnostic MR scanner for integration into MR-guided photon and particle radiotherapy. Material and methods: For realization of MR-guided photon and particle therapy (MRgRT/MRgPT), a 1.5 T MR scanner was installed at the Heidelberg Ion Beam Therapy...

Objective: We propose an integration scheme for a biomechanical motion model into a deformable image registration. We demonstrate its accuracy and reproducibility for adaptive radiation therapy in the head and neck region. Approach: The novel registration scheme for the bony structures in the head and neck regions is based on a previously developed...

Background: Magnetic resonance-guided proton therapy is promising, as it combines high-contrast imaging of soft tissue with highly conformal dose delivery. However, proton dosimetry in magnetic fields using ionization chambers is challenging since the dose distribution as well as the detector response are perturbed. Purpose: This work investigat...

Particle therapy is a well established clinical treatment of tumors. More than one hundred particle therapy centers are in operation world-wide. The advantage of using hadrons like protons or carbon ions as particles for tumor irradiation is the distinct peak in the depth-dependent energy deposition, which can be exploited to accurately deposit dos...

Purpose: Helium ions offer intermediate physical and biological properties to the clinically used protons and carbon ions. This work presents the commissioning of the first clinical treatment planning system (TPS) for helium ion therapy with active beam delivery to prepare the first patients' treatment at the INSTITUTION-XXX METHODS: : Through col...

Purpose : Surface guided Radiotherapy (SGRT) has been intensively investigated to ensure correct patient positioning during a radiotherapy course. Although the implementation is well defined for photon beam facilities, only a few analyses have been published for ion beam therapy centers. To investigate the accuracy, reliability and efficiency of SG...

Particle therapy is a well established clinical treatment of tumors. More than one hundred particle therapy centers are in operation world wide. The advantage of using hadrons like protons or carbon ions as particles for tumor irradiation is the distinct peak in the depth dependent energy deposition, which can be exploited to accurately deposit dos...

Background: Radiation fields encountered in Proton Therapy (PT) and Ion-Beam Therapy (IBT) are characterized by a variable Linear Energy Transfer (LET), which lead to a variation of Relative Biological Effectiveness and also affects the response of certain dosimeters. Therefore, reliable tools to measure LET are advantageous to predict and correct...

Purpose/Objective(s) Differentiation between radiation-induced lung fibrosis (RILF) and tumor local recurrence (LR) remains challenging in SBRT treated NSCLC patients. We aimed to integrate spatially and time-resolved 4D radiomics with dosiomics biomarkers to develop a novel robust multi-omics classifier of LR vs RILF. Materials/Methods 210 NSCLC...

Fast and accurate predictions of uncertainties in the computed dose are crucial for the determination of robust treatment plans in radiation therapy. This requires the solution of particle transport problems with uncertain parameters or initial conditions. Monte Carlo methods are often used to solve transport problems especially for applications wh...

Background This study aimed to compare the results of irradiation with protons versus irradiation with carbon ions in a raster scan technique in patients with skull base chordomas and to identify risk factors that may compromise treatment results. Methods A total of 147 patients (85 men, 62 women) were irradiated with carbon ions (111 patients) or...

Background Radiotherapy with ion beams has been demonstrated to yield excellent clinical results in some clinical studies but is currently the single most expensive form of radiotherapy. The analysis of the cost-effectiveness is therefore of special relevance.Objective What is the current state of knowledge on the cost-effectiveness of ion beam the...

This review focuses on reference dosimetry of proton and light ion beams used for cancer treatments. The background is the recommendation from the International Atomic Energy Agency in the Technical Report Series 398 and the recent publication of the International Commission on Radiation Units and Measurements Report 93 (Prescribing, Recording, and...

Purpose: A clinical implementation of ion-beam radiography (iRad) is envisaged to provide a method for on-couch verification of ion-beam treatment plans. The aim of this work is to introduce and evaluate a method for quantitative water-equivalent thickness (WET) measurements for a specific helium-ion imaging system for WETs that are relevant for i...

Fluorescent Nuclear Track Detectors (FNTDs) are biocompatible passive detectors and a promising tool for neutron dosimetry applications, such as in-phantom measurements within the scope of ion therapy. Sensitivity differences between individual detectors however complicate the post-irradiation analysis process, making detector comparability and con...

Fiducial markers are used for image guidance to verify the correct positioning of the target for the case of tumors that can suffer interfractional motion during proton therapy. The markers should be visible on daily imaging, but at the same time, they should produce minimal streak artifacts in the CT scans for treatment planning and induce only sl...

Clonogenic survival assay constitutes the gold standard method for quantifying radiobiological effects. However, it neglects cellular radiation response variability and heterogeneous energy deposition by ion beams on the microscopic scale. We introduce “Cell-Fit-HD4D” a biosensor that enables a deconvolution of individual cell fate in response to t...

The advantageous depth dose profile of ion beams together with state of the art beam delivery and treatment planning systems allow for highly conformal tumor treatments in patients. First treatments date back to 1954 at the Lawrence Berkley Laboratory (LBL) and in Europe, ion beam therapy started in the mid-90ies at the Paul-Scherrer Institute (PSI...

Within two studies, kQ factors for two Farmer-type ionization chambers have been experimentally determined by means of water calorimetry in the entrance channel (EC) of a monoenergetic carbon-ion beam [1] and for a passively modulated spread-out Bragg peak (SOBP) [2]. Both studies were performed at the Heidelberg Ion Beam Therapy Center (HIT) using...

Improvements in image-guided-radiotherapy (IGRT) enable accurate and precise radiotherapy treatments of moving tumors in the abdomen while simultaneously sparing healthy tissue. However, the lack of validation tools for newly developed IGRT hybrid devices such as MR-Linac is an open issue. This study presents an abdominal phantom with respiratory o...

Purpose: Non-invasive methods to monitor carbon-ion beams in patients are desired to fully exploit the advantages of carbon-ion radiotherapy. Prompt secondary ions produced in nuclear fragmentations of carbon ions are of particular interest for monitoring purposes as they can escape the patient, and thus be detected and tracked to measure the radi...

Fast and accurate predictions of uncertainties in the computed dose are crucial for the determination of robust treatment plans in radiation therapy. This requires the solution of particle transport problems with uncertain parameters or initial conditions. Monte Carlo methods are often used to solve transport problems especially for applications wh...

Objective: The purpose of this study is to estimate the energy and angular distribution of secondary neutrons inside a phantom in hadron therapy, which will support decisions on detector choice and experimental setup design for in-phantom secondary neutron measurements. Approach: Dedicated Monte Carlo simulations were implemented, considering cl...

Objective:To present an efficient uncertainty quantification method for range and set-up errors in Monte Carlo (MC) dose calculations. Further, we show that uncertainty induced by interplay and other dynamic influences may be approximated using suitable error correlation models.Approach:We introduce an importance (re-)weighting method in MC history...

Self-developing radiochromic film is widely used in radiotherapy QA procedures. To compensate for typical film inhomogeneities, the triple channel analysis method is commonly used for photon-irradiated film. We investigated the applicability of this method for GafchromicTMEBT3 (Ashland) film irradiated with a clinically used carbon-ion beam. Calibr...

The high precision and conformity of intensity-modulated particle therapy (IMPT) comes at the cost of susceptibility to treatment uncertainties in particle range and patient set-up. Dose uncertainty quantification and mitigation, which is usually based on sampled error scenarios, however becomes challenging when computing the dose with computationa...

The dosimetry of carbon-ion beams based on calibrated ionization chambers still shows a significantly higher uncertainty compared to high-energy photon beams, a fact influenced mainly by the uncertainty of the correction factor for the beam qualitykQ. Due to a lack of experimental data,kQfactors in carbon-ion beams used today are based on theoretic...

Purpose: Ion beam radiotherapy offers enhances dose conformity to the tumor volume while better sparing healthy tissue compared to conventional photon radiotherapy. However, the increased dose gradient also makes it more sensitive to uncertainties. While the most important uncertainty source is the patient itself, the beam delivery is also subject...

2043 Background: Unique radiobiological and physical properties of carbon ion radiotherapy (CIRT) may be favorably utilized to improve outcome in recurrent High-Grade Glioma (rHGG). There are currently no standardized criteria for stratification of rHGG patients for re-irradiation (re-RT). This study evaluated the impact of morphological data (radi...

Large amounts of high quality biophysical data are needed to improve current biological effects models but such data are lacking and difficult to obtain. The present study aimed to more efficiently measure the spatial distribution of relative biological effectiveness (RBE) of charged particle beams using a novel high-accuracy and high-throughput ex...

An experimental campaign was carried out at the NASA Space Radiation Laboratory to perform an additional, independent dosimetric characterization of the beams of protons, helium and carbon ions for radiobiological experiments. The campaign was undertaken by the request and with the support from the National Cancer Institute, U.S. In this initial ph...

Background: To investigate deviations between planned and applied treatment doses for hypofractionated prostate radiotherapy and to quantify dosimetric accuracy in dependence of the image guidance frequency. Methods: Daily diagnostic in-room CTs were carried out in 10 patients in treatment position as image guidance for hypofractionated prostate r...

Ionization chamber-based dosimetry for carbon-ion beams still shows a significantly higher standard uncertainty than high-energy photon dosimetry. This is mainly caused by the high standard uncertainty of the correction factor for beam quality k_Q,Q0 . Due to a lack of experimental data, the given values for k_Q,Q0 are based on theoretical calculat...

Background: The targeting accuracy of proton therapy (PT) for moving soft-tissue tumours is expected to greatly improve by real-time magnetic resonance imaging (MRI) guidance. The integration of MRI and PT at the treatment isocenter would offer the opportunity of combining the unparalleled soft-tissue contrast and real-time imaging capabilities of...

Background and purpose Proton therapy may be promising for treating non-small-cell lung cancer due to lower doses to the lung and heart, as compared to photon therapy. A reported challenge is degradation, i.e., a smoothing of the depth-dose distribution due to heterogeneous lung tissue. For pencil beams, this causes a distal falloff widening and a...

Background and purpose: To analyze divergences between the planned and applied treatment doses for post-prostatectomy radiotherapy to the prostatic fossa on a voxel-by-voxel basis based on interfractional anatomic variations and imaging frequency. Materials and methods: For 10 patients receiving intensity-modulated postoperative radiotherapy to th...

The dosimetric advantages of ion therapy come at the cost of an increased sensitivity to range inaccuracies in the treatment planning and delivery stages. This prompts the development of imaging techniques capable of an accurate assessment of the relative stopping power (RSP). We investigate carbon ion imaging based on a prototype integration-mode...

Background and purpose: To analyze deviations of the applied from the planned doses on a voxel-by-voxel basis for definitive prostate cancer radiotherapy depending on anatomic variations and imaging frequency. Materials and methods: Daily in-room CT imaging was performed in treatment position for 10 patients with prostate cancer undergoing inten...

Proton and ion beam therapy has been introduced in the Lawrence Berkeley National Laboratory in the mid-1950s, when protons and helium ions have been used for the first time to treat patients. Starting in 1972, the scientists at Berkeley also were the first to use heavier ions (carbon, oxygen, neon, silicon and argon ions). The first clinical ion b...

Background and purpose: To compare the relative biological effectiveness (RBE)-weighted dose distributions in the target volume of chordoma and chondrosarcoma patients when using two different versions of the local effect model (LEM I vs. IV) under identical conditions. Materials and methods: The patient collective included 59 patients treated w...

A new practical method to determine the ion recombination correction factor ( k_s ) for plane-parallel and Farmer-type cylindrical chambers in particle beams is investigated. Experimental data were acquired in passively scattered and scanned particle beams and compared with theoretical models developed by Boag and/or Jaffé. The new metho...

To mark the International Year of the Periodic Table, nine Physics World journalists have picked their favourite chemical element and argued their case on the Physics World blog.

Background: Commissioning of treatment planning systems (TPS) and beam delivery for scanned light ion beams is an important quality assurance task. This requires measurement of large sets of high quality dosimetric data in anthropomorphic phantoms to benchmark the TPS and dose delivery under realistic conditions. Method: A novel measurement setu...

Carbon ion radiotherapy is an attractive alternative to conventional radiotherapy, especially in case of deep-seated and radio-resistant tumors. As a consequence of inelastic nuclear reactions between primary particles and patient's tissues, the primary carbon ions may undergo nuclear fragmentation. The resulting decrease of primary ions and produc...

Background and purposes: Carbon ion radiotherapy (CIRT) with raster scanning technology is a promising treatment for lung cancer and thoracic malignancies. Determining normal tissue tolerance of organs at risk is of utmost importance for the success of CIRT. Here we report the relative biological effectiveness (RBE) of CIRT as a function of dose a...

Dieser Abschnitt gibt einen Überblick über Qualitäts- und Risikomanagement in der Strahlentherapie. Es werden dazu die regulatorischen Grundlagen und Konzepte vorgestellt sowie die verwendeten Begriffe erläutert. Beispielhaft werden anschließend einige praktische Aspekte der Qualitätssicherung für verschiedene Verfahren der Strahlentherapie sowie e...

Eine Strahlenbehandlung läuft stets nach einem vor Behandlungsbeginn festgelegten Verfahren, der sogenannten „Bestrahlungstechnik“, ab.

Die Entwicklung der Strahlentherapie von den empirischen Anfängen hin zu einer hochpräzisen, quantitativ planbaren Therapie wäre ohne die Entwicklung moderner Bildgebungsverfahren nicht möglich gewesen. So ist auch die Röntgen-CT-Bildgebung noch immer eine wesentliche Voraussetzung zur exakten Dosisberechnung. Nach der Einführung der bildgeführten...

Background/aim: Carbon ion radiotherapy (CIRT) offers high conformality and ability to dose-escalate skull base chordomas, with promising clinical data. However, it is an imperative measure to economically justify the use of such high-priced new technologies. Herein, we investigated the cost-effectiveness of CIRT compared to photon radiotherapy (P...

Clinical/methodical issue: As a standard, today's radiation therapy is based on CT images which are used for therapy planning. These images are obtained once before therapy starts and serve as a basis to obtain the position and shape of the target volume. As the patient has to be positioned anew for each fraction, deviations of the tumor position...

Background: Uncertainties associated with the delivery of treatment to moving organs might compromise the accuracy of treatment. This study explores the impact of intra-fractional anatomical changes in pancreatic patients treated with charged particles delivered using a scanning beam. The aim of this paper is to define the potential source of unce...

Background: Ion beam radiotherapy provides potential for increased dose conformation to the target volume. To translate it into a clinical advantage, it is necessary to guarantee a precise alignment of the actual internal patient geometry with the treatment beam. This is in particular challenging for inter- and intrafractional variations, includin...

Background: With the advance of modern irradiation techniques, the role of radiotherapy (RT) for intracranial meningioma has increased significantly throughout the past years. Despite that tumor's generally favorable outcome with local control rates of up to 90% after ten years, progression after RT does occur. In those cases, re-irradiation is of...

Background: The present work aimed to analyze the feasibility of a shuttle-based MRI-guided radiation therapy (MRgRT) in the treatment of pelvic malignancies. Patients and methods: 20 patients with pelvic malignancies were included in this prospective feasibility analysis. Patients underwent daily MRI in treatment position prior to radiotherapy...

Background: To evaluate the impact of68Ga-DOTATOC-PET on treatment planning and sparing of normal tissue in the treatment of skull base meningioma with advanced photons and protons. Methods: From the institutional database consisting of 507 skull base meningiomas 10 patients were chosen randomly for the present analysis. Target volume definition...