The aim of the guideline presented in this article is to unify the test parameters for image quality evaluation and radiation output in all types of cone-beam computed tomography (CBCT) systems. The applications of CBCT spread over dental and interventional radiology, guided surgery and radiotherapy. The chosen tests provide the means to objectively evaluate the performance and monitor the constancy of the imaging chain. Experience from all involved associations has been collected to achieve a consensus that is rigorous and helpful for the practice. The guideline recommends to assess image quality in terms of uniformity, geometrical precision, voxel density values (or Hounsfield units where available), noise, low contrast resolution and spatial resolution measurements. These tests usually require the use of a phantom and evaluation software. Radiation output can be determined with a kerma-area product meter attached to the tube case. Alternatively, a solid state dosimeter attached to the flat panel and a simple geometric relationship can be used to calculate the dose to the isocentre. Summary tables including action levels and recommended frequencies for each test, as well as relevant references, are provided. If the radiation output or image quality deviates from expected values, or exceeds documented action levels for a given system, a more in depth system analysis (using conventional tests) and corrective maintenance work may be required.

ObjectiveTo assess the reliability of ADC measurements in vitro and in cervical lymph nodes of healthy volunteers.MethodsWe used a GE 1.5 T MRI scanner and a first ice-water phantom according to recommendations released by the Quantitative Imaging Biomarker Alliance (QIBA) for assessing ADC against reference values. We analysed the target size effect by using a second phantom made of six inserted spheres with diameters ranging from 10 to 37 mm. Thirteen healthy volunteers were also scanned to assess the inter- and intra-observer reproducibility of volumetric ADC measurements of cervical lymph nodes.ResultsOn the ice-water phantom, the error in ADC measurements was less than 4.3 %. The spatial bias due to the non-linearity of gradient fields was found to be 24 % at 8 cm from the isocentre. ADC measure reliability decreased when addressing small targets due to partial volume effects (up to 12.8 %). The mean ADC value of cervical lymph nodes was 0.87.10-3 ± 0.12.10-3 mm2/s with a good intra-observer reliability. Inter-observer reproducibility featured a bias of -5.5 % due to segmentation issues.ConclusionADC is a potentially important imaging biomarker in oncology; however, variability issues preclude its broader adoption. Reliable use of ADC requires technical advances and systematic quality control.Key Points• ADC is a promising quantitative imaging biomarker.• ADC has a fair inter-reader variability and good intra-reader variability.• Partial volume effect, post-processing software and non-linearity of scanners are limiting factors.• No threshold values for detecting cervical lymph node malignancy can be drawn.Electronic supplementary materialThe online version of this article (10.1007/s00330-017-5265-2) contains supplementary material, which is available to authorized users.

Rationale Radiation therapy is widely used for cancer treatment but its efficacy is limited by radioresistance and by damages caused to adjacent normal tissues. Active research aims at maximizing tumor eradication while reducing side-effects with theranostic nanoparticles that act as radioenhancers in situ. Ferromagnetic materials have been identified as promising nanotools for image-guided radiotherapy. Here, we investigated the potential of RGD-tagged magnetosomes (magnetosomes@RGD), bacterial biogenic magnetic nanoparticles naturally coated by a biological membrane and genetically engineered to express a RGD peptide, as tumour enhancers to conventional radiotherapy and proton therapy. Methods The potential of native and RGD-functionalized magnetosomes to enhance the effects of ionizing radiations was assessed in a DNA fragmentation assay and in melanoma and colorectal cancer cells using in vitro clonogenic assays. The in vivo radiotherapy enhancement efficacy of the magnetosomes@RGD was explored in preclinical models of melanoma-bearing mice treated with either X-rays or protons. Results Native and RGD-tagged magnetosomes similarly enhanced radiation-induced DNA damage. On cancer cells, both magnetoprobes were able to boost the killing efficacy of radiotherapy, although to a much larger extent with the magnetosomes@RGD enhancing the mortality by 2.5 fold in melanoma cells and by 2.9 fold in colorectal cancer cells. In vivo treatment of melanomabearing mice with magnetosomes@RGD prior to X-rays led to a 65% reduction in tumor development compared to radiotherapy alone (31%). Comparatively, a more effective tumor 3 growth inhibition (77%) was observed in combining RGD-decorated nanoprobes to proton therapy. The radioenhancing potential of magnetosomes@RGD was further evidenced by the DNA damage observed in the nanoscale vicinity of magnetosomes within the treated lesions. Conclusions Our results show efficacy of magnetosomes functionalized with a RGD peptide as tumor radioenhancers to both X-rays and protons in vivo and strengthen the interest of developing biogenic magnetoparticles for multimodal nanomedicine for cancer therapy.

Purpose: Respiratory-gated positron emission tomography (PET)/computed tomography protocols reduce lesion smearing and improve lesion detection through a synchronized acquisition of emission data. However, an objective assessment of image quality of the improvement gained from respiratorygated PET is mainly limited to a three-dimensional (3D) approach. This work proposes a 4D numerical observer that incorporates both spatial and temporal informations for detection tasks in pulmonary oncology. Methods: The authors propose a 4D numerical observer constructed with a 3D channelized Hotelling observer for the spatial domain followed by a Hotelling observer for the temporal domain. Realistic 18 F-fluorodeoxyglucose activity distributions were simulated using a 4D extended cardiac torso anthropomorphic phantom including 12 spherical lesions at different anatomical locations (lower, upper, anterior, and posterior) within the lungs. Simulated data based on Monte Carlo simulation were obtained using 4 application for tomographic emission (GATE). Fifty noise realizations of six respiratory-gated PET frames were simulated by GATE using a model of the Siemens Biograph mMR scanner geometry. PET sinograms of the thorax background and pulmonary lesions that were simulated separately were merged to generate different conditions of the lesions to the background (e.g., lesion contrast and motion). A conventional ordered subset expectation maximization (OSEM) reconstruction (5 iterations and 6 subsets) was used to obtain: (1) gated, (2) nongated, and (3) motion-corrected image volumes (a total of 3200 subimage volumes: 2400 gated, 400 nongated, and 400 motion-corrected). Lesion-detection signal-to-noise ratios (SNRs) were measured in different lesion-to-background contrast levels (3.5, 8.0, 9.0, and 20.0), lesion diameters (10.0, 13.0, and 16.0 mm), and respiratory motion displacements (17.6-31.3 mm). The proposed 4D numerical observer applied on multiple-gated images was compared to the conventional 3D approach applied on the nongated and motion-corrected images. Results: On average, the proposed 4D numerical observer improved the detection SNR by 48.6% (p < 0.005), whereas the 3D methods on motion-corrected images improved by 31.0% (p < 0.005) as compared to the nongated method. For all different conditions of the lesions, the relative SNR measurement (Gain = SNR Observed /SNR Nongated ) of the 4D method was significantly higher than one from the motion-corrected 3D method by 13.8% (p < 0.02), where Gain 4D was 1.49 ± 0.21 and Gain 3D was 1.31 ± 0.15. For the lesion with the highest amplitude of motion, the 4D numerical observer yielded the highest observer-performance improvement (176%). For the lesion undergoing the smallest motion amplitude, the 4D method provided superior lesion detectability compared with the 3D method, which provided a detection SNR close to the nongated method. The investigation on a structure of the 4D numerical observer showed that a Laguerre-Gaussian channel matrix with a volumetric 3D function y...