Water calorimetry-basedfactors for Farmer-type ionization chambers in the SOBP of a carbon-ion beam.

The dosimetry of carbon-ion beams based on calibrated ionization chambers (ICs) 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 quality. Due to a lack of experimental data,factors in carbon-ion beams used today are based on theoretical calculations whose standard uncertainty is three times higher than that of photon beams. To reduce their uncertainty, in this work,factors for two ICs were determined experimentally by means of water calorimetry for the spread-out Bragg peak of a carbon-ion beam, these factors are presented here for the first time.

Triple channel analysis of Gafchromic EBT3 irradiated with clinical carbon-ion beams.

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 GafchromicEBT3 (Ashland) film irradiated with a clinically used carbon-ion beam.

Effect of timing, technique and molecular features on brain control with local therapies in oncogene-driven lung cancer.

Background: The improved efficacy of tyrosine kinase inhibitors (TKI) mandates reappraisal of local therapy (LT) for brain metastases (BM) of oncogene-driven non-small-cell lung cancer (NSCLC).

Patients And Methods: This study included all epidermal growth factor receptor-mutated (EGFR, n = 108) and anaplastic lymphoma kinase-rearranged (ALK, n = 33) TKI-naive NSCLC patients diagnosed with BM in the Thoraxklinik Heidelberg between 2009 and 2019. Eighty-seven patients (62%) received early LT, while 54 (38%) received delayed (n = 34; 24%) or no LT (n = 20; 14%).

Quality assurance method for monitoring of lateral pencil beam positions in scanned carbon-ion radiotherapy using tracking of secondary ions.

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 to uncertainties.

Joint Optimization of Photon-Carbon Ion Treatments for Glioblastoma.

Purpose: Carbon ions are radiobiologically more effective than photons and are beneficial for treating radioresistant gross tumor volumes (GTV). However, owing to a reduced fractionation effect, they may be disadvantageous for treating infiltrative tumors, in which healthy tissue inside the clinical target volume (CTV) must be protected through fractionation. This work addresses the question: What is the ideal combined photon-carbon ion fluence distribution for treating infiltrative tumors given a specific fraction allocation between photons and carbon ions?

Methods And Materials: We present a method to simultaneously optimize sequentially delivered intensity modulated photon (IMRT) and carbon ion (CIRT) treatments based on cumulative biological effect, incorporating both the variable relative biological effect of carbon ions and the fractionation effect within the linear quadratic model.

Carbon ion radiotherapy eradicates medulloblastomas with chromothripsis in an orthotopic Li-Fraumeni patient-derived mouse model.

Background: Medulloblastomas with chromothripsis developing in children with Li-Fraumeni Syndrome (germline TP53 mutations) are highly aggressive brain tumors with dismal prognosis. Conventional photon radiotherapy and DNA-damaging chemotherapy are not successful for these patients and raise the risk of secondary malignancies. We hypothesized that the pronounced homologous recombination deficiency in these tumors might offer vulnerabilities that can be therapeutically utilized in combination with high linear energy transfer carbon ion radiotherapy.

Imaging Artifacts of Nonadhesive Liquid Embolic Agents in Conventional and Cone-beam CT in a Novel in Vitro AVM Model.

Background: A major drawback of liquid embolic agents (LEAs) is the generation of imaging artifacts (IA), which may represent a crucial obstacle for the detection of periprocedural hemorrhage or subsequent radiosurgery of cerebral arteriovenous malformations (AVMs). This study aimed to compare the IAs of Onyx, Squid and PHIL in a novel three-dimensional in vitro AVM model in conventional computed tomography (CT) and cone-beam CT (CBCT).

Methods: Tubes with different diameters were configured in a container resembling an AVM with an artificial nidus at its center.

Longitudinal MRI study after carbon ion and photon irradiation: shorter latency time for myelopathy is not associated with differential morphological changes.

Background: Radiation-induced myelopathy is a severe and irreversible complication that occurs after a long symptom-free latency time if the spinal cord was exposed to a significant irradiation dose during tumor treatment. As carbon ions are increasingly investigated for tumor treatment in clinical trials, their effect on normal tissue needs further investigation to assure safety of patient treatments. Magnetic resonance imaging (MRI)-visible morphological alterations could serve as predictive markers for medicinal interventions to avoid severe side effects.

Effectiveness of fractionated carbon ion treatments in three rat prostate tumors differing in growth rate, differentiation and hypoxia.

Purpose: To quantify the fractionation dependence of carbon (C) ions and photons in three rat prostate carcinomas differing in growth rate, differentiation and hypoxia.

Material And Methods: Three sublines (AT1, HI, H) of syngeneic rat prostate tumors (R3327) were treated with six fractions of either C-ions or 6 MV photons. Dose-response curves were determined for the endpoint local tumor control within 300 days.

The RBE in ion beam radiotherapy: In vivo studies and clinical application.

Ion beams used for radiotherapy exhibit an increased relative biological effectiveness (RBE), which depends on several physical treatment parameters as well as on biological factors of the irradiated tissues. While the RBE is an experimentally well-defined quantity, translation to patients is complex and requires radiobiological studies, dedicated models to calculate the RBE in treatment planning as well as strategies for dose prescription. Preclinical in vivo studies and analysis of clinical outcome are important to validate and refine RBE-models.

Solving problems is smart, preventing them is wise: Lessons learned from the 2nd International DKFZ Conference on Cancer Prevention.

The 2nd International DKFZ Conference on Cancer Prevention (CCP2020) organized by the German Cancer Research Center (DKFZ) was held as a virtual event on 17-18 September 2020. The event gathered experts on cancer prevention from around the world with the aim of generating a stimulating interchange of opinions between clinicians and basic researchers working in the field. The talks and posters of the conference fueled exciting discussions and debates about the state of the art of cancer prevention and provided a comprehensive outlook on the many aspects of the field.

Severe skin toxicity during whole-brain radiotherapy, targeted therapy, and additional drug intake including St. John's wort skin oil.

Background: Metastatic non-small cell lung cancer (NSCLC) often requires a multimodal treatment including chemotherapy, targeted therapy and radiotherapy. In addition to this, many patients take supportive drugs. Since only scarce data on possible interactions between radiotherapy and pharmaceutical or herbal drugs exist, description of clinical cases is of special interest.

Analytical modeling of depth-dose degradation in heterogeneous lung tissue for intensity-modulated proton therapy planning.

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, , a smoothing of the depth-dose distribution due to heterogeneous lung tissue. For pencil beams, this causes a distal falloff widening and a peak-to-plateau ratio decrease, not considered in clinical treatment planning systems.

Prognostic impact of gross tumor volume during radical radiochemotherapy of locally advanced non-small cell lung cancer-results from the NCT03055715 multicenter cohort study of the Young DEGRO Trial Group.

Background: In radical radiochemotherapy (RCT) of inoperable non-small-cell lung cancer (NSCLC) typical prognostic factors include T- and N-stage, while there are still conflicting data on the prognostic relevance of gross tumor volume (GTV) and particularly its changes during RCT. The NCT03055715 study of the Young DEGRO working group of the German Society of Radiation Oncology (DEGRO) evaluated the prognostic impact of GTV and its changes during RCT.

Methods: A total of 21 university centers for radiation oncology from five different European countries (Germany, Switzerland, Spain, Belgium, and Austria) participated in the study which evaluated n = 347 patients with confirmed (biopsy) inoperable NSCLC in UICC stage III A/B who received radical curative-intent RCT between 2010 and 2013.

Consolidation Immunotherapy After Platinum-Based Chemoradiotherapy in Patients With Unresectable Stage III Non-Small Cell Lung Cancer-Cross-Sectional Study of Eligibility and Administration Rates.

Introduction: The PACIFC trial demonstrated a significant benefit of durvalumab consolidation immunotherapy (CIT) after definitive platinum-based chemoradiotherapy (P-CRT) for survival in stage III non-small cell lung cancer (NSCLC). It is unknown how many patients are eligible in clinical practice to receive CIT according to PACIFIC criteria compared to real administration rates and what influencing factors are.

Patients And Methods: We analyzed 442 patients with unresectable stage III NSCLC who received P-CRT between 2009 and 2019 regarding CIT eligibility rates according to PACIFIC criteria and administration rates since drug approval.

Development of phantom materials with independently adjustable CT- and MR-contrast at 0.35, 1.5 and 3 T.

Quality assurance in magnetic resonance (MR)-guided radiotherapy lacks anthropomorphic phantoms that represent tissue-equivalent imaging contrast in both computed tomography (CT) and MR imaging. In this study, we developed phantom materials with individually adjustable CT value as well as [Formula: see text]- and [Formula: see text]-relaxation times in MR imaging at three different magnetic field strengths. Additionally, their experimental stopping power ratio (SPR) for carbon ions was compared with predictions based on single- and dual-energy CT.

Long short-term memory networks for proton dose calculation in highly heterogeneous tissues.

Purpose: To investigate the feasibility and accuracy of proton dose calculations with artificial neural networks (ANNs) in challenging three-dimensional (3D) anatomies.

Methods: A novel proton dose calculation approach was designed based on the application of a long short-term memory (LSTM) network. It processes the 3D geometry as a sequence of two-dimensional (2D) computed tomography slices and outputs a corresponding sequence of 2D slices that forms the 3D dose distribution.

Optimal beam angle selection and knowledge-based planning significantly reduces radiotherapy dose to organs at risk for lung cancer patients.

Background: Lung cancer patients struggle with high toxicity rates. This study investigates if IMRT plans with individually set beam angles or uni-lateral VMAT plans results in dose reduction to OARs. We investigate if introduction of a RapidPlan model leads to reduced dose to OARs.

Safety and Efficacy of Stereotactic Body Radiotherapy in Ultracentral Lung Tumors Using a Risk-optimized Fractionation Scheme.

Background: Delivery of stereotactic body radiotherapy (SBRT) to ultracentral lung tumors remains a major challenge, with potentially excessive SBRT-related toxicity. This study investigates a risk-optimized approach to ultracentral SBRT in an elderly and comorbid patient cohort.

Patients And Methods: Analysis encompassed 129 patients (mean age: 70 ± 11 years, median Charlson comorbidity index: 4 [range, 3-5]) following risk-adapted SBRT to central or ultracentral primary and secondary lung tumors between 2012 and 2019 (78 central, 51 ultracentral).

Technical Note: ADAM PETer - An anthropomorphic, deformable and multimodality pelvis phantom with positron emission tomography extension for radiotherapy.

Objective: To develop an anthropomorphic, deformable and multimodal pelvis phantom with positron emission tomography extension for radiotherapy (ADAM PETer).

Methods: The design of ADAM PETer was based on our previous pelvis phantom (ADAM) and extended for compatibility with PET and use in 3T magnetic resonance imaging (MRI). The formerly manually manufactured silicon organ surrogates were replaced by three-dimensional (3D) printed organ shells.

On the feasibility of absolute 3D dosimetry using LiF thermoluminescence detectors and polymer gels on a 0.35T MR-LINAC.

Background And Purpose: As shown in our previous study, highly accurate absolute dosimetry in 3D is feasible by combining polymer gels (PG) with thermoluminescence dosimetry (TLD). In this setup, the thermoluminescence (TL)-based point dose information is used to renormalize the PG. This new PG-TLD reference system is now extended to measurements in magnetic fields.

High Doses of Photons and Carbon Ions Comparably Increase Vascular Permeability in R3327-HI Prostate Tumors: A Dynamic Contrast-Enhanced MRI Study.

Carbon- (12C-) ion radiotherapy exhibits enhanced biological effectiveness compared to photon radiotherapy, however, the contribution of its interaction with the vasculature remains debatable. The effect of high-dose 12C-ion and photon irradiation on vascular permeability in moderately differentiated rat prostate tumors was compared using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Syngeneic R3327-HI rat prostate tumors were irradiated with a single dose of either 18 or 37 Gy 12C ions, or 37 or 75 Gy 6-MV photons (sub-curative and curative dose levels, respectively).

Progression of Pulmonary Function and Correlation with Survival Following Stereotactic Body Radiotherapy of Central and Ultracentral Lung Tumors.

Stereotactic body radiotherapy (SBRT) to central and ultracentral lung tumors carries a risk of excessive toxicity. This study analyzed changes in pulmonary function tests (PFT) and their correlation with overall survival (OS) in 107 patients following central ( = 62) or ultracentral ( = 45) lung SBRT. Ultracentral location was defined as planning target volume overlap with the proximal bronchial tree (PBT).

CT-based attenuation correction of whole-body radiotherapy treatment positioning devices in PET/MRI hybrid imaging.

Objective: To implement computed tomography (CT)-based attenuation maps of radiotherapy (RT) positioning hardware and radiofrequency (RF) coils to enable hybrid positron emission tomography/magnetic resonance imaging (PET/MRI)-based RT treatment planning.

Materials And Methods: The RT positioning hardware consisted of a flat RT table overlay, coil holders for abdominal scans, coil holders for head and neck scans and an MRI compatible hip and leg immobilization device. CT images of each hardware element were acquired on a CT scanner.