A Compton camera prototype for prompt gamma medical imaging

Thirolf, P.; Aldawood, S.; Böhmer, M.; Bortfeldt, J.; Castelhano, I.; Dedes, G.; Fiedler, F.; Gernhäuser, R.; Golnik, C.; Helmbrecht, S.; Hueso-González, F.; Kolff, H. van der; Kormoll, T.; Lång, Christian; Liprandi, S.; Lutter, R.; Marinsek, T.; Maier, L.; Pausch, G.; Petzoldt, J.; Römer, K.; Schaart, Dennis R.; Parodi, Katia

doi:10.1051/epjconf/201611705005

Cited by 22 publications

(23 citation statements)

References 8 publications

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“…LYSO:Ce crystals, however, are not well suited for Compton telescopes because of the inferior energy resolution. In another recent study, a resolution of 5.5 mm FWHM at 662 keV has been obtained for a 30 mm thick LaBr 3 :Ce crystal [16], which is a very promising result for a crystal of such thickness. In this paper, we report the position resolution measured for 81 keV and 356 keV gamma-rays using 20 mm and 10 mm thick CeBr 3 crystals coupled to a 4×4 array of silicon photomultipliers (SiPMs).…”

Section: Introductionmentioning

confidence: 86%

Localisation of gamma-ray interaction points in thick monolithic CeBr 3 and LaBr 3 :Ce scintillators

Ulyanov¹,

Morris²,

Roberts³

et al. 2017

Nuclear Instruments and Methods in Physics Research Section A:

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Localisation of gamma-ray interaction points in monolithic scintillator crystals can simplify the design and improve the performance of a future Compton telescope for gamma-ray astronomy. In this paper we compare the position resolution of three monolithic scintillators: a 28 × 28 × 20 mm 3 (length × breadth × thickness) LaBr 3 :Ce crystal, a 25 × 25 × 20 mm 3 CeBr 3 crystal and a 25 × 25 × 10 mm 3 CeBr 3 crystal. Each crystal was encapsulated and coupled to an array of 4 × 4 silicon photomultipliers through an optical window. The measurements were conducted using 81 keV and 356 keV gamma-rays from a collimated 133 Ba source. The 3D position reconstruction of interaction points was performed using artificial neural networks trained with experimental data. Although the position resolution was significantly better for the thinner crystal, the 20 mm thick CeBr 3 crystal showed an acceptable resolution of about 5.4 mm FWHM for the x and y coordinates, and 7.8 mm FWHM for the z-coordinate (crystal depth) at 356 keV. These values were obtained from the full position scans of the crystal sides. The position resolution of the LaBr 3 :Ce crystal was found to be considerably worse, presumably due to the highly diffusive optical interface between the crystal and the optical window of the enclosure. The energy resolution (FWHM) measured for 662 keV gamma-rays was 4.0% for LaBr 3 :Ce and 5.5% for CeBr 3 . The same crystals equipped with a PMT (Hamamatsu R6322-100) gave an energy resolution of 3.0% and 4.7%, respectively.

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Section: Introductionmentioning

confidence: 86%

Localisation of gamma-ray interaction points in thick monolithic CeBr 3 and LaBr 3 :Ce scintillators

Ulyanov¹,

Morris²,

Roberts³

et al. 2017

Nuclear Instruments and Methods in Physics Research Section A:

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“…Since the Compton camera (CC) was first proposed for medical imaging (Todd et al , 1974), many researchers have studied its use for a wide range of medical applications, including 2D and 3D imaging of prompt gamma (PG) emission from a patient during proton radiotherapy as a means of providing in vivo verification of the delivered proton beam range (Frandes et al , 2010; Gillam et al , 2011; Golnik et al , 2016; Hueso-Gonzalez et al , 2016; Kim et al , 2013; Kormoll et al , 2011; Krimmer et al , 2015; Llosa et al , 2012; Lojacono et al , 2013; McCleskey et al , 2015; Munoz et al , 2017; Peterson et al , 2010; Polf et al , 2015; Richard et al , 2011; Robertson et al , 2011; Roellinghoff et al , 2014; Rohling et al , 2017; Seo et al , 2010; Solevi et al , 2016; Thirolf et al , 2016; Thirolf et al , 2014). In standard Compton imaging, information pertaining to the energy deposited by and spatial coordinates of gammas that interact at least twice in the stages of a CC is used to create the images.…”

Section: Introductionmentioning

confidence: 99%

“…The point of gamma emission is constrained to lie on the surface of a cone (or cone segment if the Compton scattered electron is tracked (Kim et al, 2012; Kurosawa et al, 2012; Thirolf et al, 2016)), called the cone-of-origin, with an opening angle equal to θ 1 , whose vertex corresponds to the first interaction location and whose axis is defined by v 1 . The cone-of-origin is used to produce an image of the measured gamma emission using either back projection or statistical image reconstruction methods.…”

Section: Introductionmentioning

confidence: 99%

3D prompt gamma imaging for proton beam range verification

Draeger¹,

Mackin²,

Peterson³

et al. 2018

Phys. Med. Biol.

121

100

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We tested the ability of a single Compton camera (CC) to produce 3-dimensional (3D) images of prompt gammas (PGs) emitted during the irradiation of a tissue-equivalent plastic phantom with proton pencil beams for clinical doses delivered at clinical dose rates. PG measurements were made with a small prototype CC placed at three different locations along the proton beam path. We evaluated the ability of the CC to produce images at each location for two clinical scenarios: (1) the delivery of a single 2 Gy pencil beam from a hypo-fractionated treatment (~9 × 10 protons), and (2) a single pencil beam from a standard treatment (~1 × 10 protons). Additionally, the data measured at each location were combined to simulate measurements with a larger scale, clinical CC and its ability to image shifts in the Bragg peak (BP) range for both clinical scenarios. With our prototype CC, the location of the distal end of the BP could be seen with the CC placed up to 4 cm proximal or distal to the BP distal falloff. Using the data from the simulated full scale clinical CC, 3D images of the PG emission were produced with the delivery of as few as 1 × 10 protons, and shifts in the proton beam range as small as 2 mm could be detected for delivery of a 2 Gy spot. From these results we conclude that 3D PG imaging for proton range verification under clinical beam delivery conditions is possible with a single CC.

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“…Key ingredient of the -source reconstruction is the determination of the -ray interaction position in the scintillator, which is read out by a 256-fold segmented multi-anode photomultiplier tube (PMT). From simulations an angular resolution of about 1.5 o for the photon source reconstruction can be expected for the energy range around 3 -5 MeV, provided that a spatial resolution of 3 mm can be reached in the absorbing scintillator [1]. Therefore, particular effort was dedicated to characterize this latter property as a function of the -ray energy.…”

Section: Sub-3mm Spatial Resolution From a Large Monolithic Labr 3 (Cmentioning

confidence: 99%

Sub-3mm spatial resolution from a large monolithic LaBr₃ (Ce) scintillator

Liprandi

Mayerhofer

Aldawood

et al. 2017

Current Directions in Biomedical Engineering

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A Compton camera prototype for ion beam range monitoring via prompt (< 1 ns) gamma detection in hadron therapy is being developed and characterized at the Medical Physics Department of LMU Munich. Co photon sources were used for 2D irradiation scans (step size 0.5 mm) as prerequisite for studying the performance of the "k-Nearest-Neighbors" algorithm developed at TU Delft [2] (together with its variant "Categorical Average Pattern", CAP) and extending its applicability into the energy range beyond the original 511 keV. In this paper we present our most recent interaction position analysis in the absorbing scintillator, leading to a considerably improved value for the spatial resolution: systematic studies were performed as a function of the k-NN parameters and the PMT segmentation. A trend of improving spatial resolution with increasing photon energy was confirmed, resulting in the realization of the presently optimum spatial resolution of 2.9(1) mm @1.3 MeV, thus reaching the design specifications of the Compton camera absorber. The specification goal was reached also for a reduced PMT segmentation of 8x8 anode segments (each with 6x6 mm 2 active area), thus allowing to reduce the complexity of the signal processing while preserving the performance.

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A Compton camera prototype for prompt gamma medical imaging

Cited by 22 publications

References 8 publications

Localisation of gamma-ray interaction points in thick monolithic CeBr 3 and LaBr 3 :Ce scintillators

Localisation of gamma-ray interaction points in thick monolithic CeBr 3 and LaBr 3 :Ce scintillators

3D prompt gamma imaging for proton beam range verification

Sub-3mm spatial resolution from a large monolithic LaBr₃ (Ce) scintillator

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A Compton camera prototype for prompt gamma medical imaging

Cited by 22 publications

References 8 publications

Localisation of gamma-ray interaction points in thick monolithic CeBr 3 and LaBr 3 :Ce scintillators

Localisation of gamma-ray interaction points in thick monolithic CeBr 3 and LaBr 3 :Ce scintillators

3D prompt gamma imaging for proton beam range verification

Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator

Contact Info

Product

Resources

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Sub-3mm spatial resolution from a large monolithic LaBr₃ (Ce) scintillator