A novel radioguided surgery (RGS) technique for cerebral tumors using β(-) radiation is being developed. Checking for a radiotracer that can deliver a β(-) emitter to the tumor is a fundamental step ...in the deployment of such a technique. This paper reports a study of the uptake of (90)Y-DOTATOC in meningiomas and high-grade gliomas (HGGs) and a feasibility study of the RGS technique in these types of tumor. Estimates were performed assuming the use of a β(-) probe under development with a sensitive area 2.55 mm in radius to detect 0.1-mL residuals.
Uptake and background from healthy tissues were estimated on (68)Ga-DOTATOC PET scans of 11 meningioma patients and 12 HGG patients. A dedicated statistical analysis of the DICOM images was developed and validated. The feasibility study was performed using full simulation of emission and detection of the radiation, accounting for the measured uptake and background rate.
All meningioma patients but one with an atypical extracranial tumor showed high uptake of DOTATOC. In terms of feasibility of the RGS technique, we estimated that by administering a 3 MBq/kg activity of radiotracer, the time needed to detect a 0.1-mL remnant with 5% false-negative and 1% false-positive rates is less than 1 s. Actually, to achieve a detection time of 1 s the required activities to administer were as low as 0.2-0.5 MBq/kg in many patients. In HGGs, the uptake was lower than in meningiomas, but the tumor-to-nontumor ratio was higher than 4, which implies that the tracer can still be effective for RGS. It was estimated that by administering 3 mBq/kg of radiotracer, the time needed to detect a 0.1-mL remnant is less than 6 s, with the exception of the only oligodendroma in the sample.
Uptake of (90)Y-DOTATOC in meningiomas was high in all studied patients. Uptake in HGGs was significantly worse than in meningiomas but was still acceptable for RGS, particularly if further research and development are done to improve the performance of the β(-) probe.
The interaction of the incoming beam radiation with the patient body in hadrontherapy treatments produces secondary charged and neutral particles, whose detection can be used for monitoring purposes ...and to perform an on-line check of beam particle range. In the context of ion-therapy with active scanning, charged particles are potentially attractive since they can be easily tracked with a high efficiency, in presence of a relatively low background contamination. In order to verify the possibility of exploiting this approach for in-beam monitoring in ion-therapy, and to guide the design of specific detectors, both simulations and experimental tests are being performed with ion beams impinging on simple homogeneous tissue-like targets (PMMA). From these studies, a resolution of the order of few millimeters on the single track has been proven to be sufficient to exploit charged particle tracking for monitoring purposes, preserving the precision achievable on longitudinal shape. The results obtained so far show that the measurement of charged particles can be successfully implemented in a technology capable of monitoring both the dose profile and the position of the Bragg peak inside the target and finally lead to the design of a novel profile detector. Crucial aspects to be considered are the detector positioning, to be optimized in order to maximize the available statistics, and the capability of accounting for the multiple scattering interactions undergone by the charged fragments along their exit path from the patient body. The experimental results collected up to now are also valuable for the validation of Monte Carlo simulation software tools and their implementation in Treatment Planning Software packages.
•Compact gamma camera based on a CdTe semiconductor hybrid pixel detector.•This probe can be adopted for various radioguided surgery tasks.•A semiconductor detector bump-bonded to a photon-counting ...CMOS readout circuit and a coded aperture collimator.
The aim of this work was to assess the performance of a prototype compact gamma camera (MediPROBE) based on a CdTe semiconductor hybrid pixel detector, for coded aperture imaging. This probe can be adopted for various tasks in nuclear medicine such as preoperative sentinel lymph node localization, breast imaging with 99mTc radiotracers and thyroid imaging, and in general in radioguided surgery tasks. The hybrid detector is an assembly of a 1-mm thick CdTe semiconductor detector bump-bonded to a photon-counting CMOS readout circuit of the Medipix2 series or energy-sensitive Timepix detector. MediPROBE was equipped with a set of two coded aperture masks with 0.07-mm or 0.08-mm diameter holes. We performed laboratory measurements of field of view, system spatial resolution, and signal-difference-to-noise ratio, by using gamma-emitting radioactive sources (109Cd, 125I, 241Am, 99mTc). The system spatial resolution in the lateral direction was 0.56 mm FWHM (coded aperture mask with holes of 0.08 mm and a 60 keV source) at a source-collimator distance of 50 mm and a field of view of 40 mm by side. Correspondingly, the longitudinal resolution in 3D source localization tasks was about 3 mm. MediPROBE showed a significant improvement in terms of spatial resolution when equipped with the high-resolution coded apertures, with respect to the performance previously reported with 1–2 mm pinhole apertures as well as with respect to adopting a 0.35 mm pinhole aperture.
This work presents a direct comparison of two pixel detectors: a charge-integrating flat panel imager coupled to a CsI:Tl scintillator and a hybrid silicon detector of Medipix2 type, working in a ...single-photon counting mode. The comparison concerns image quality in terms of system-spatial resolution,
signal-to-noise ratio and contrast in imaging of small biological objects. It will be shown that, at photon energies below 40
keV and for low attenuating biological objects, single-photon counting detectors are more appropriate for small-animal imaging than flat panel devices right due to better spatial resolution,
signal-to-noise ratio and contrast.
Abstract Charged particle therapy is a technique for cancer treatment that exploits hadron beams, mostly protons and carbon ions. A critical issue is the monitoring of the beam range so to check the ...correct dose deposition to the tumor and surrounding tissues. The design of a new tracking device for beam range real-time monitoring in pencil beam carbon ion therapy is presented. The proposed device tracks secondary charged particles produced by beam interactions in the patient tissue and exploits the correlation of the charged particle emission profile with the spatial dose deposition and the Bragg peak position. The detector, currently under construction, uses the information provided by 12 layers of scintillating fibers followed by a plastic scintillator and a pixelated Lutetium Fine Silicate (LFS) crystal calorimeter. An algorithm to account and correct for emission profile distortion due to charged secondaries absorption inside the patient tissue is also proposed. Finally detector reconstruction efficiency for charged particle emission profile is evaluated using a Monte Carlo simulation considering a quasi-realistic case of a non-homogenous phantom.
We report on the tests of a prototype (MediSPECT) system developed at University & INFN Napoli, for Single Photon Emission Computed Tomography (SPECT) imaging on small animals with a small Field of ...View (FoV) and high spatial resolution. MediSPECT is a SPECT imaging system based on a 1-mm-thick CdTe pixel detector, bump-bonded to the Medipix2 CMOS readout circuit operating in single-photon counting. The CdTe detector has 256×256 square array of pixels arranged with a 55
μm pitch, for a sensitive area of 14×14
mm
2. In its present version, this system implements a single detector head, mounted on a rotating gantry. For preliminary testing and calibration of the acquisition equipment and image reconstruction algorithms, 90 projections of a γ-ray point source (
109Cd) through a single pinhole (diameter 0.4
mm; radius of rotation about 2.5
cm; focal length about 4.5
cm) were acquired for 20
min each in a step-and-shoot mode. Capillaries, 800
μm in diameter, were arranged in a Y-shape to form a more complex phantom (
125I, 1
mm pinhole diameter, 45 projections, each acquired for 25
min). Images were reconstructed with a custom algorithm implementing standard OS-EM with center of rotation correction and spatial resolution of 0.2
mm over a FoV of 2
mm was obtained.
Charged Particle Therapy is a technique for cancer treatment that exploits hadron beams, mostly protons and carbons. A critical issue is the monitoring of the dose released by the beam to the tumor ...and to the surrounding tissues. We present the design of a new tracking device for monitoring on-line the dose in ion therapy through the detection of secondary charged particles produced by the beam interactions in the patient tissues. In fact, the charged particle emission shape can be correlated with the spatial dose release and the Bragg peak position. The detector uses the information provided by 12 layers of scintillating fibers followed by a plastic scintillator and a small calorimeter made of a pixelated Lutetium Fine Silicate crystal. Simulations have been performed to evaluate the achievable spatial resolution and a possible application of the device for the monitoring of the dose profile in a real treatment is presented.
J Nucl Med 2015 56:8A A novel radio guided surgery (RGS) technique for cerebral tumors using
$\beta^{-}$ radiation is being developed. Checking the availability of a
radio-tracer that can deliver a ...$\beta^{-}$ emitter to the tumor is a
fundamental step in the deployment of such technique. This paper reports a
study of the uptake of 90Y labeled (DOTATOC) in the meningioma and the high
grade glioma (HGG) and a feasibility study of the RGS technique in these cases.
In this work we present the study of applicability of a desktop size radiographic/tomographic X-ray system for real-time microscopy and micro-tomography in the fields of biology, entomology, botanic ...and medical imaging. The apparatus is made up of the single photon counting pixel silicon detector, Medipix2 (matrix of 256×256 square pixels of 55 μm pitch) and a microfocus X-ray tube with a minimum spot size of 5 μm and a tungsten anode. The system has been used for observations of time-dependent processes inside living and still biological and organic samples. Excellent contrast and spatial resolution (micrometer scale) were obtained as a combination of a) low photon energy (40 kVp X-ray tube voltage), b) single photon counting operation, witch avoids integration of dark current c) energy discrimination in each pixel, allowing noise rejection and providing high SNR, d) high effective dynamic range for long exposures, which allows for high signal with high SNR, e) implementation of an original procedure for the energy response calibration of each pixel of the detector matrix, f) high speed read-out hardware and software, which opens the possibility to perform real-time studies of biological processes permitting, e.g., observation of morphological changes, mutations or metamorphosis of living animals and plants. Static and dynamic images of a parasite life cycle from the larva stage to pupa stage are presented here, as well as an in vivo computed tomography of the parasite living inside its host.
A novel radio guided surgery (RGS) technique for cerebral tumors using \(\beta^{-}\) radiation is being developed. Checking the availability of a radio-tracer that can deliver a \(\beta^{-}\) emitter ...to the tumor is a fundamental step in the deployment of such technique. This paper reports a study of the uptake of 90Y labeled (DOTATOC) in the meningioma and the high grade glioma (HGG) and a feasibility study of the RGS technique in these cases.
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