AU2021204807A1

AU2021204807A1 - System & method for high-accuracy radioactive source localisation

Info

Publication number: AU2021204807A1
Application number: AU2021204807A
Authority: AU
Inventors: Mohammed Al Towairqi; Terry Braddock; Anatoly Rozenfeld
Original assignee: University of Wollongong
Current assignee: University of Wollongong
Priority date: 2021-07-09
Filing date: 2021-07-09
Publication date: 2023-02-02
Also published as: AU2023223008A1

Abstract

Patent Application: System & method for high-accuracy ionising radiation source localisation By Mohammed Al Towairqi, Anatoly Rozenfeld and Terry Braddock ABSTRACT: A fibre optic data acquisition system and methods for using the system to perform ionising radiation detection and measurement are described and claimed. The claimed system and operating methods are useful and optimised for clinical radiotherapy practice, but can also be applied in fields such as radiation safety and dose monitoring. When used in the most optimum configuration, the inventive system comprises hardware and software capable of deducing radioactive source location in a "solid" object to an accuracy of better than +/-2 mm in 3 mutually orthogonal directions. UoWAustralia ABSTRACT System & method for high-accuracy ionising radiation source localisation 8-07-2021 p.1/1 3 46 - ~7 1 9 1 24a 17 20 P/S 9L-WFZA8 15

Description

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Patent Application:

Description: System & method for high-accuracy ionising radiation source localisation

By Mohammed Al Towairqi, Anatoly Rozenfeld and Terry Braddock

Introduction/Background:

Using radioactive sources or concentrated beams of ionising radiation such as X-rays for irradiating tumorous areas of a human or animal body as a key part of cancer-curing therapy is well-known in the medical physics art, and a large number of devices and systems have been described and claimed in patent applications and granted patents. A big challenge in the field arises from the irradiating rays or particles being invisible, which makes it more difficult to assure that doses are being delivered to the desired regions and with the desired intensity and total dose deposition. A further challenge is that other living tissue in the field of the radiation interacts with the radiation and can absorb it, otherwise impede it (eg: by scattering) or even enhance it (eg: by back-scattering). Similar considerations apply when radioactive sources or concentrated beams of ionising radiation are being used in other applications (for example, but not limited to: radioactive tracing, radioactive waste disposal and use of industrial-scale high-intensity lasers which can cause ionisation).

The Inventors' research has discovered that a novel combination of recent technologies can be skilfully combined in a non-obvious manner to give a powerful, accurate, convenient, and very cost effective system and technique for assuring accurate detection and dose-measurement of ionising radiation.

The unique combination of fibre optics and other elements in the invention, and the technique for applying the invention can save time and complexity in detection, dose measurement, radiotherapy treatments, personnel safety and calibration procedures.

The Key Problem being addressed:

The invention addresses the key problem that accurate sensors and methods are needed for measuring ionising radiation doses delivered to specific regions during clinical radiotherapy sessions, and assuring that optimal doses are delivered to the region of interest, while minimising doses to all surrounding regions. It also a desirable feature to have real-time monitoring of doses rather than merely accumulating a record of what total dose was delivered and accessing this record only after the irradiation/therapy session has finished. The components and methods of the invention are also applicable to other activities such as assuring radiation safety, personnel dose monitoring, radioactive tracing, radioactive waste disposal and use of industrial-scale, high intensity lasers, which thus fall within the scope of the invention.

Known Prior Art involving related inventions:

Some of the prior art in the field of radiotherapy in particular teaches the convenience and usefulness of applying fibre optics in the area of patient dose measurement. Relevant background UoWAustralia Description: System &method for high-accuracy ionising radiation source localisation 8-07-2021 p. 1 /10 prior art includes:

RU 2012 154932 27/2014 (State Atomic Energy Corporation Rosatom, Federal State Unitary Enterprise "Russian Federal Nuclear Center - All-Russian Research Institute of Experimental Physics" FSUE RFNC-VNIIEF) RU 2016 138041 29018 (HOUTWAST Guillaume HOUTWAST and Dirk BINNECAMP, KONINKLEIKE PHILIPS N.V.) WO 2013 040646 (Suchowerska, McKenzie and Naseri/ University of Sydney) CN 207318732U (University of Sun Yat Sen) WO 2018 043383 KuraRay Co. (Japan) JP 2019 219278 20//2018 (Hitachi Ltd., Japan) JP 2019 219305 21/6/2018 (Hitachi Ltd., Japan) AU 2018 2307718/2018 (Sean Cavanaugh/ International Private Bank LLC) AU 2018 206828 20/7/2018 (Covidien LP) AU 2020 201134 17/2/2020 (Margin-Clear) LT2018 025 11/7/2018 (University of Vilniaus, Lithuania) KR 2019 0139365 (Myong Geun Yoon & Sun Young Moon/ University of Korea Research & Business Foundation)

Key Features of the Invention:

The authors' research has built further on previous reports that systems using a scintillating material coupled to a clear optical fibre can accurately gauge doses of ionization which are delivered during clinical radiotherapy. When coupled in a non-obvious way with novel, purpose-designed and appropriately-packaged amplifiers and novel downstream data acquisition and storage means, an inventive, very convenient, user-friendly, non-bulky and quite portable system has been constructed and trialled in a range of controlled laboratory and clinical conditions. The inventive system and method can also be applied in other ionising radiation detection and measurement applications. The system also possesses other synergistic advantages such as ease of calibration, cost-effectiveness, portability and long-range tolerance to radiation hardening effects. Although some of these aspects are taught by previous literature, no previous system teaches the combined, holistic and synergistic advantages of the inventors' total system. Furthermore, existing literature teaches many kinds of systems and capabilities which provide a wide range of options and combinations, but it is not obvious, even for practitioners well skilled in the relevant arts, to choose and combine the exact combination of steps and features which comprise this invention. The system and method of applying the invention has the novel capability of being used to determine ("localise") the source position and measure doses simultaneously because, if we locate the source accurately within a few mm tolerance then we can easily calculate the dose through applying known radiotherapy absorbed dose formalisms. The inventive system can hence also be used as an All-n-One HDR source localiser and dosimeter.

How the invention Solves the Problem:

The Inventors' research has verified that a suite of related problems such as detecting, measuring and localising sources of ionising radiation can be accurately and cost-effectively solved by applying and integrated system comprised of scintillating materials coupled to clear optical fibres which are subsequently fed to a novel amplifier or set of parallel amplifiers which makes the apparatus a versatile multichannel realtime system. The signal amplification stage of this system has photodiode UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 2/10 front-ends and a unique combination of downstream data storage, processing and display facilities. By this means, an amplification system typically used for amplifying electrical signals is transformed into a dose detection, measurement and/or localisation system, initially activated by light intensity rather than by presentation of electrical charges or currents.

The invention hence makes an effective unified solution that is efficient, convenient, cost-effective and accurate for users.

Brief explanation of the drawing figures:

Figure 1: Item # Explanation 1 Stereotactic/Orienting frame for cannulae and radiation detector fibres 2 cannulae for guiding and locating radiation detector fibres 3 optically scintillating fibre segment 4 practical length of clear optical fibre 4a A "Control" or "Background" fibre which can be coupled/connected to any desired photodiode input 5 optical coupler 5a optical coupler for additional signal input channels 6 photodiode light receiver(s) 5a Further photodiode light receiver(s) 6 further photodiode light receivers 7 electrical signal amplifier- could work in charge, voltage, current, impedance or trans-impedance modes 8 power supply for electrical amplifier. Shown as an external unit for clarity, but may be included within the electrical signal amplifier outer enclosure (with appropriate screening) if desired 9 signal transmission means for further downstream processing 10 analog-to-digital signal converter. As with item #8, this feature/capability may be installed integrally within the outer enclosure of item #7 11 appropriate signal receiving apparatus for further processing, data storage and display. This item could be, as a non-limiting example, a laptop computer. 13 signal transmission means to a suitable display device

14 signal transmission means for further use of data generated by the system. This feature could be, as a non-limiting example, a USB or Ethernet" or optical fibre cable connected to a local network or internet 15 data display device 17 surface/boundary of physical body wherein it is desired to sense radiation 18 inner volume at depth where ionising radiation source is located 20 Optional in-built source for calibrating the operation of the light signal receiving input and electrical amplifier system channels

Figure 2: Item # Explanation (Other items have same identifications as in Fig. 1)

UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 3/10

29 Pipe conveying fluid 41,42&43 further pipes conveying fluid 35, 36, 46, 47, 48, 49, 50 & 51 Control valves 50 Arrow indicating direction of fluid flow 31,32 Location markers

Figure 3: (Other items have same identifications as in earlier Figures) Item # Explanation 29 Pipe undergoing analysis 30 various sections of pipe #29 at various lengths successively along the pipe (the pipe is shown sectioned for clarity, to "telescope" more length into the finite sized diagram) 31,32 Are reference location markers at the extreme ends of pipe #29

Figure 4: (Other items have same identifications as in earlier Figures) Item # Explanation 4a, 4a1& 4a2 Detecting fibres chosen to monitor a "background" location 4, 4.3a Detecting fibres chosen to monitor the "hottest" location 4, 4.3b, 4.3c Detecting fibres chosen to monitor other adjacent locations 73 A key asset of interest: by non-limiting example, an inner containment vessel of a nuclear reactor 76 the "hottest" location of interest: by non-limiting example, immediately adjacent a nuclear reactor 71, 72,74,75 other locations of interest for radiation intensity monitoring

The Best Way of Applying the invention:

The invention is quite versatile, and can be embodied in various formats from simple to more complex in order to satisfy users' varied requirements. The best way of applying the system and method of the invention in a fairly simple and exemplary, but by no means limiting format, is depicted in Figure 1. Fig. 1 shows a minimalist but exemplary embodiment of the inventive system for the purposes of illustrative but non-limiting example.

(( Figure 1: An exemplary embodiment of the inventive system ))

Item #17 in the drawing will typically be the skin surface of a patient receiving radiotherapy treatment. The region #18 indicated in the drawing will typically be an interior region of a patient receiving radiotherapy treatment, although it could equally well be an animal being treated, or a solid or gel object in which it is desired to study radiation fields. Item 1 in the drawing is a Stereotactic/Orienting framework for fixing and assuring the 3D location and orientation of operative cannulae for accepting radiation sources and small-diameter detectors UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 4/10 such as fibre optic detectors. Items 2 are a multiplicity of cannulae, the exact number being chosen as required to fulfil the desired source localisation measurements at the desired level of accuracy. In the ideal embodiment, the items #4 will be a sufficient number of shielded optical fibres tipped by scintillating fibre sections (items #3). The shielded optical fibres are optically coupled by couplers (items 5 and 5a) accurately interfacing them to photodiode receivers (items 6 and/or 6a). The equipment box 7 is generally designated as an "Amplifier" (or "Amplifiers") as would be readily understood by one skilled in the relevant arts, and contains suitable amplifier circuits to accurately convert light signals from the desired plurality of shielded optical fibres into electrical signals. The main equipment housing (7) may however contain additional useful circuitry such as signal filters, integrators, power supply (shown here as an optional separate unit, item 8) or A-2-D convertors (shown here as an optional separate unit, item 10). Although the main amplifier box (7) is depicted with 4 input channels, the reader should understand that it is desirable for the purposes of the invention to have multiple parallel input channels, but the total number of inputs included can be anywhere from 2 upwards without departing from the spirit and scope of the invention. If it is chosen to install any required A-D convertors inside item 7, item 10 may instead be a datalogging device or even a complete computer. Similarly, item #15 may be merely a data display device or a complete computer with appropriate software installed and running. Amplified signals from the amplifier module (7) are transmitted via line 9 to further downstream data processing and storage devices. Item #11 is a further item accessing the data stream from the signal amplifiers (item 7). Item 11may be a datalogger, a computer, a mobile phone with appropriate software or a memory storage device for storing acquired data. In the most ideal embodiment, the inventors have used transimpedance amplifiers to create the data stream needed for applying the inventive method. However, without departing from the principle and scope of the invention, charge, voltage or current amplifiers can be used for the same purpose. If desired, one of the fibre optic lines (4 or 4a) can be designated and dedicated as a "Control" or "Background" fibre, to monitor stray or "background" radiation levels experienced in a desired vicinity such as a patient couch, the operators' room or a bench holding the main equipment housing (item #7). If desired, the amplifier box (7) can be setup/programmed to automatically subtract "background" signal levels from the signal levels produced by the other channels. The data transmission lines 9, 13 and 14 can be any required formats as would be well understood by one skilled in modern data collection, datalogging, storage, processing and display technologies such as USB cables, LAN, Etherneti", Firewire etc. They can also represent "wireless" data transmission systems such as WiFiTM Bluetooth metc. The shielded optical fibres (4 and 4a) may be of any length desired for operator convenience, with a "tradeoff" between various practical aspects such as cost, convenience of equipment location and overall attenuation of the fibres. However, as a practical guide, it is convenient to use lengths such as m so that the system components (7, 8, 9, 10, 11, 13, 14 & 15) are well away from any possible stray ionising radiation. By this means, measurement or radiotherapy staff can operate the inventive apparatus in a completely separated shielded room to minimise occupational radiation dose. When used according to the inventive method, a desired number of shielded optical fibres (items 4 and 4a) with scintillating fibre detector tips are deployed into cannulae (items 2) in the region where it is desired to locate a radioactive source. A sufficient number of such fibres with detecting scintillators need to be deployed so as to give the desired accuracy in computing (by received intensity measurement) the position of the nearby radiation source (usually deployed at a location UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 5/10 inside the patient (item 18) during a radiotherapy session). The inventors have developed appropriate software programs enabling the downstream processing devices (10, 11 and/or 15) to be capable of converting relative signal strengths from the various optical fibre signals into an accurate estimate of where the original radiation source is located. With an appropriate "triangulation" style algorithmic approach, abundant calibration trials and data records, the inventors have proven it possible to reliably and repeatedly guarantee knowledge of source position in 3D space. In most cases, the inventive system and operating method with associated software could determine radioactive source position for typical X-ray or gamma radiation within +/- 2 mm in mutually orthogonal x, y and z directions. In ideal cases this uncertainty was reduced to +/-1 mm in mutually orthogonal x, y and z directions.

A key novel and inventive advantage of the claimed method is the use of photodiodes on the "front end" of the signal amplifier system (item 7). Up until this point, the received signals in the optical fibres are light (i.e. optical) signals rather than "electrical" signal, and are relatively immune to electrical interference. The amplifier(s) (item 7) then convert these signals accurately into corresponding electrical (and digital) signals suitable for easy and convenient processing by further equipment such as dataloggers and computers further downstream (items 10, 11& 15).

Using the inventive system according to the inventive method requires the inventive signal amplifier system (item 7) to first be "calibrated" so that the exact transmission and conversion efficiencies of the optical fibres and channels used are accurately known. In this way, a received pulse of ionising radiation at the scintillating fibre end of the system (items 3) of a known energy, wavelength and time duration will be known to produce a particular voltage and/or current (or electrical charge) down the signal path (9). Once these transmission and conversion efficiencies are known accurately, because of the photodiode "front end" of the inventive signal amplifier system, a NON-ONISING signal (light rather than X-ray or gamma radiation) can be used to stimulate the signal amplifier(s) and produce electrical signals (transmitted down cable/path 9). By this means, the relative sensitivities of the multiplicity of receiving channels of the module 7 can be quickly checked (or "calibrated") without needing any exposure by the system components (or its operators) to ionising radiation. This reveals a very novel and inventive feature of the claimed system.

Another key novel feature of the invention is that ALL of the components shown in the exemplary embodiment of Fig. 1 (even the radioactive source, which may be a radioactive "seed" rather than an X-ray LINAC) can be battery-operated without "mains" power, and hence the entire system may be completely mobile and portable.

Procedure for operating the invention:

Primary calibration: The system needs first to undergo "primary calibration" in accordance with legal regulations in the environment in which it is to be used. An appropriate configuration of the system (as would be understood by the managers and operators who are to apply the system) needs to be exposed to a known, traceable dose of ionising radiation in a controlled environment. Scintillating Fibre detector elements abutted to chosen lengths of clear transmitting optical fibre (in whatever quantity is desired, with appropriate terminations to accurately mate with the optical couplers of item 7) need UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 6/10 to be deployed in the known radiation field, and the final output quantity of the chosen parameter of interest (charge, voltage or current etc.) need to be measured and recorded. Allowances may also need to be made and recorded in detail for other operation-sensitive parameters such as the environmental temperature in the region of the scintillating fibre(s), plain fibre(s) and equipment boxes (particularly item #7 in the figure). These critical settings needing accurate measurement and recording also include the power supply voltage applied to the equipment, the gain, offset, dc shift, filter settings of any of components (items 7, 8, 10 &/or 11), as would be readily understood by people skilled in the relevant calibration, standards, traceability, legal records and electronic arts. The inventive system in a minimalist embodiment may have only one high-gain, high-accuracy, low noise amplifier, with individual light pulse/intensity signals from multiple detecting fibres being sequentially presented to that amplifier. Alternatively, the more ideal embodiment of the inventive system is supplied with two or more high-gain, high-accuracy, low-noise amplifiers, with individual light pulse/intensity signals from multiple detecting fibres being amplified simultaneously in parallel with each other. This embodiment requires less switching and allows a parallel data stream to be processed closer to realtime, with less process/programming/queuing delays. The primary calibration procedures for individual system components and total end-to-end performance need to be repeated at regular intervals in accordance with local and relevant legal statutory regulations of relevant authorities (Health department, national standards authority etc.)

Secondary calibration: The system is given "secondary calibration" at frequent intervals, appropriate to its intended usage. This requirement is more practical, but is still a strategic and legal necessity, although it may involve legal regulations at a much lower level than the primary calibration requirements. The required frequency of applying the secondary calibration procedure is expected to be far lower than the need for primary calibration. (By way of non-limiting example, the primary calibration may be required annually, whereas the secondary calibration may be demanded quarterly (three-monthly) or every 100 patient hours of therapy). It is in this secondary calibration procedure that the novel inventive aspects of the claimed inventive system really shine. NO calibrated levels of ionising radiation are necessary. Neither is any ionising radiation needed at all. None of the usual scintillating fibre detector elements or lengths of clear transmitting optical fibre are needed either. Instead, a calibrated Light-emitting diode (LED) element of known wavelength and intensity levels is used to present light to the chosen optical coupler(s) and photodiode channel(s) of the amplifier(s) (item 7). This calibrated Light-emitting diode (LED) element may even be integrally housed in the unit 7 (indicated by item 20 in the drawing), and only connected to an input coupler when required. As in the primary calibration procedure, the final output quantity of the chosen parameter (charge, voltage or current etc.) needs to be measured and recorded when activated by the calibrated LED. Allowances may also need to be made and recorded in detail for other operation-sensitive parameters such as the environmental temperature in the region of the equipment boxes (particularly item #7 in the figure). Once again, other known critical settings may need accurate measurement and recording, such as the power supply voltage applied to the equipment, the gain, offset, dc shift, filter settings of any internal components (items 7, 8, 10 &/or 11), as would be readily understood by people skilled in the relevant calibration, standards, traceability, legal records and electronic arts. UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 7/10

Quick calibration: day-to-day system checks: Once the "secondary calibration" of the inventive system has been carried out and recorded, a "quick calibration" of the system can be carried out anytime before using the system for a set of measurements. Once again, the crucially convenient, novel and inventive aspect of this procedure for the inventive system is that it does not require any ionising radiation. The purpose of such a "quick calibration" is to rapidly and conveniently verify system performance details, for example (but not limited to) to check that the overall "gain" or end-to-end sensitivity of the system has not changed, or to check that the relative gain of two adjacent signal channels has not "drifted" beyond previously measured gain values, within the limits of experimental/system performance error. The capability of the inventive system to be so quickly and easily calibration-checked in this manner is one of its most attractive and novel features. It has a huge advantage of minimising the need of operating staff to be exposed to "hard" (i.e. ionising) radiation. There is a concomitant saving of wear-&-tear on the fibre components of the system also (i.e. scintillating fibres sections and shielded clear fibres with the terminators).

Use of the Inventive system in a clinical radiotherapy dose situation: Once the above calibrations of the inventive system has been carried out and recorded, the system can be used to aid measurements of positions of a radioactive source(s), including extended sources.

In a clinical radiotherapy treatment scenario, the inventive system can be used for extremely accurate radioactive source localisation. In such an application, the inventive system is used in conjunction (but not limited to) a stereotactic-style physical positioning reference system such as the one minimally outlined in Fig. 1 (item #1). This framework allows accurately-known positioning in "x" and "y" orientations (although those skilled in application of 3D geometry will understand that different labels for these coordinates in a chosen frame of reference could be equally used, without departing from the spirit and scope of the invention). Accurate positioning of devices such as radioactive source "pellet" source and the lengths of scintillating detecting fibres (items #3) in the remaining dimension ("z", by means of non-limiting example) can then be done by known standard means (not part of the invention) such as ultrasound, 3D X-ray CT scanning or MRI (Magnetic resonance imaging.

When the inventive system is used in combination with accurate primary physical positioning systems as described, the known positions of the plurality of scintillating fibre-tipped optical fibres and the known response of the inventive system (primary calibration) can be used to accurately deduce the position of a radioactive source in reasonable proximity to the scintillating fibre-tips of the invention. Signal processing by the various devices that comprise the inventive system, and use of an appropriate algorithm (which we have pioneered and perfected), permits the inventive system to accurately deduce the radioactive source position in 3D space and relative to the other primary referenced devices (cannulae located in accurately known position in the stereotactic arrangement).

Our inventive method includes a novel algorithm which is applied to process the received signal data in order to accurately deduce the source localisation. If the radioactive source position is estimated accurately within a few mm tolerance, then we can easily calculate the dose at a small region of interest nearby by applying accepted algorithmic codes such as the TG-43 HDR Brachytherapy formalism. The system hence displays the novel feature of being an All-n-One source localiser and dosimeter.

In non-clinical applications of the inventive system and method, strict primary positioning

UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 8/10 referencing system such as the stereotactic frame may not be necessary, as the users of the application may be satisfied with accuracies far broader such as +/- 2 cm or even +/- 0.5 m.

A scenario demonstrating an exemplary alternative embodiment of the inventive system: The inventive system may be employed for further novel applications such as, by way of non-limiting example, detection of pipe blockages in an industrial fluid transfer situation.

Use of the inventive system to provide a novel and highly useful capability for the detection of pipe blockages in an industrial fluid transfer situation is illustrated by means of the following exemplary scenario:

Fig. 2 shows a field of pipes transferring fluids. Fig. 2 is merely diagrammatic for the purpose of illustration, and is not limited by scale. Items 29, 41, 42 & 43 are pipes conveying the said fluids, which may be (but not limited to) water, oil, natural gas, ethene gas, petroleum fractions etc. Arrows (50) indicate the flow direction of the fluids, while items # 35, 26 and 46 - 51 inclusive are fluid control valves. Hence, for example, the locating reference points 31 and 32 along pipe #29 may be 50 apart or 500 m apart or 15 km apart.

(( Figure 2: An exemplary industrial situation where the inventive system can be innovatively applied))

Field engineers have determined from fluid flowrate/time observations that there is a blockage in pipe #29, somewhere between valves # 35 and 36. The blockage is suspected to be a broken piece of gasket or valve segment or a chunk of dirt/rock which may have entered the system during some previous maintenance activity. It is desired to locate WHERE in the # 29 pipe the blockage is located. If the blockage location is known to an accuracy of +/- 1 m or better, maintenance engineers have the capability to remove a short section of pipe in the troubled region and weld in an unblocked, fully functional section of replacement pipe. To do this, they have access to quantities of a suitable radioactive tracer species which is capable of suspending (or dissolving) in the fluid carried by the pipe of interest. They intend to use the inventive fibre-optic system and method for source localisation to "map" the intensity of radiotracer radiation at various locations along the #29 pipeline between reference points 31 and 32, to deduce where the blockage is located.

The advantage they gain by using the inventive system is that the equipment of the inventive system is all portable and capable of being operated in a remote location without available "mains" power and in an industrially "noisy" setting. A further advantage is that the inventive system has a multi channel components capable of measuring source strength at a multiplicity of locations simultaneously. This allows multiple segments of the pipeline to be measured simultaneously (as indicated by the alternative successive locations numbered 30 in Fig. 3).

(( Figure 3: An exemplary alternative embodiment of the inventive system for radioactive tracing))

During the measurements, a "control" optical fibre line (items 4a in Fig. 3) may optionally be used to detect "background" levels of optical signal generated by - for example - natural radioactivity in the general region of the testing. UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 9/10

By applying the inventive system, the pipeline operators can save time, money and materials by locating the few metres of the pipeline containing the trouble, instead of having to replace the entire (for example) 2 km section of pipe (which may be underground and significantly difficult to access).

A further exemplary embodiment of the inventive system: The inventive system may be employed for further novel applications such as, by way of non-limiting example, the monitoring of hazardous locations. Figure 4 shows an exemplary setup for applying the system for such a use. Using the inventive system, a plurality of previously-calibrated fibre detectors (4 and 4a) can be deployed to a number of areas which it is desired to monitor. The fibres are mated appropriately with a suitable multiplicity of photodiode inputs on the inventive photodiode/amplifier/signal processing apparatus (item 7). By this means, radiation levels at a multiplicity of locations may be monitored over short or long times, with near-instantaneous readout of intensity levels from the multiplicity of locations. Information about, or derived from, these intensity levels can be displayed appropriately to operators at a suitable shielded location remote from the "hottest" of monitored areas (eg: 73, 76). In a further variation of this embodiment, the inventive system with its plurality of previously calibrated fibre detectors (4 and 4a) can be arrayed around a moving, shielded operator (or mobile robotic device) which can then move to survey a set of areas of interest. By this means, radiation levels at a suite of locations adjacent to the operator or robot may be monitored with near instantaneous readout of intensity levels. Information about, or derived from, these intensity levels can be displayed to operator(s) in a suitable format and may activate alerts, alarms etc.

((Figure4: A further exemplary embodiment of the inventive system: monitoring radiologically hazardous areas ))

UoWAustralia Description: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 10/10

Claims

CLAIMS: System & method for high-accuracy ionising radiation source localisation By Mohammed Al Towairqi, Anatoly Rozenfeld and Terry Braddock We Claim:

1. An integrated system for detecting an ionising radiation field by using 2 or more optical "detecting fibres", each comprising a segment of scintillating material optically coupled to a clear optical fibre which is in turn coupled to a photodiode receiver at the front-end of a reasonably high-gain, low-noise amplifier(s). The electrical outputs of these amplifier(s) is suitably processed (eg: filtered, digitised, integrated) by components of the inventive system and routed to appropriate data processing, analysis, storage and display means for display to one or more operators or therapists.

2. An integrated system for accurately quantifying dose received in an ionising radiation field by using 2 or more optical "detecting fibres", each comprising a segment a segment of scintillating material optically coupled to a clear optical fibre which is in turn coupled to a photodiode receiver at the front end of a high-gain, low-noise amplifier or suite of parallel amplifiers. The electrical output of these amplifiers is suitably processed (eg: digitised) and routed to appropriate processing, analysis, storage and display means for displaying results in a convenient format to one or more operators or therapists.

3. An integrated system for quantifying dose received at multiple locations throughout an ionising radiation field by using a plurality of fibre detectors, each having a segment of scintillating material optically coupled to a clear optical fibre which is in turn coupled to a photodiode receiver channel in a high-gain, low-noise amplifier system. The electrical outputs of one or a plurality of such amplifiers is suitably processed (eg: filtered,digitised) and routed to appropriate data processing and storage means to produce results displayed to one or more operators.

4. An integrated system as per any of the previous claims, whereby the system is used in tandem with accurate positioning hardware (such as, but not limited to, a stereotactic grid, guiding cannulae and/or a CT scanner) and has appropriate algorithmic software included which is capable of accurately determining radioactive source location to better than +/- 2 mm accuracy in mutually orthogonal x, y or z directions.

5. An integrated system as per any of the previous claims, whereby the system is capable of accurately determining radioactive source location to better than +/- 1 mm accuracy in mutually orthogonal x, y or z directions.

6. An integrated system as per any of the previous claims, whereby the calibration of the system is capable of being quickly and easily checked by measuring the response of its input channels to a known, previously-calibrated optical, non-ionising radiation source which may be included within the system packaging.

7. An integrated system as per any of the previous claims, whereby the system includes optical fibre(s) used as reference(s) for providing a signal(s) derived from unwanted "background", "baseline" or "noise" optical signal contributions (eg: from fluorescence or Cerenkov emission or electrical interference) which can then be readily subtracted from other signals presented to the photodiode front end and of interest to the operator(s). UoWAustralia Claims: System &method for high-accuracy ionising radiation source localisation 8-07-2021 p. 1 /3

8. An integrated system as per any of the previous claims, whereby the system is equipped and packaged to be utilised for REAL-TIME or, at least, near-real-time absorbed radioactive dose measurements or radioactive source localisation in a clinical radiotherapy or high doserate radiotherapy (HDR) brachytherapy setting and wherein the amplifier(s) within the system are specifically trans-impedance or trans-conductance amplifiers.

9. An integrated system as per any of the previous claims, whereby the light-transmission components of the optical fibres of the said system are composed of substantially organic materials.

10. An integrated system as per any of the previous claims, whereby the system is equipped and packaged to be utilised for radioactive source detection, activity level, dose or doserate measurements in a radioactive tracing, environmental safety or personnel safety application.

11. An integrated system as per any of the previous claims, whereby the system is equipped and packaged to be utilised for REAL-TIME or, at least, near-real-time absorbed radioactive dose measurement, radioactivity measurement or radioactive source localisation, in a setting wherein multiple locations (and hence multiple signal channels) are monitored optically and signals proportional (or substantially proportion to) received dose are routed to measuring/monitoring equipment located substantially far away (eg: 3m, 5m, 10m, 20m, 50m) from any ionising radiation source.

12. A METHOD of operating an integrated system for detecting and characterising an ionising radiation field by using 2 or more optical detecting fibres, each comprising a segment of scintillating material optically coupled to a clear optical fibre which is in turn coupled to a photodiode receiver at the front-end of a reasonably high-gain, low-noise amplifier. The method includes using the resultant electrical output of this amplifier with suitable processing (eg: filtering, integration, digitisation) by components of the inventive system for routing to appropriate analysis and data retention means for display to one or more operators.

13. A METHOD of operating an integrated system for quantifying dose received at multiple locations in an ionising radiation field by using 2 or more optical detecting fibres, each comprising a segment of scintillating material optically coupled to a clear optical fibre which is in turn coupled to a photodiode receiver at the front-end of a reasonably high-gain, low noise amplifier. The method includes using the electrical output of this amplifier with suitable processing (eg: digitisation) by components of the inventive system for routing to appropriate analysis and data retention means for display to one or more operators.

14. A METHOD of operating an integrated system for quantifying dose received at multiple locations throughout an ionising radiation field by using 3 or more fibre detectors coupled to photodiode receivers at the front-end of a reasonably high-gain, low-noise amplifier configured to work in trans-impedance or trans-conductance mode. The method includes using the electrical outputs of these amplifiers with suitable post-processing (eg: filtering, digitisation) by components of the inventive system for routing to appropriate further processing, analysis and data storage and display means for display to one or more operators or therapists.

15. A METHOD of operating an integrated system as per any of the previous claims, whereby the system comprises hardware and software capable of accurately performing radioactive source localisation to better than +/- 2 mm accuracy in mutually orthogonal x, y or z directions.

16. A METHOD of operating an integrated system as per any of the previous claims, whereby the system comprises hardware and software capable of accurately performing radioactive source localisation to better than +/- 1 mm accuracy in mutually orthogonal x, y or z directions.

17. A METHOD of operating an integrated system as per any of the previous claims, whereby the method includes a quick and easy system calibration procedure by exposing the sensors of

UoWAustralia Claims: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 2 /3 the system to optical, non-ionising radiation which may be integrally included within the system packaging.

18. A METHOD of operating an integrated system as per any of the previous claims, whereby the method includes use of optical fibre(s) used as reference(s) for providing a signal(s) useful so that unwanted "background", "baseline" or "noise" signal contributions (eg: from fluorescence or Cerenkov emission or electrical interference) can be readily monitored, recorded and optionally subtracted from other signals presented to the photodiode front end and of interest to the operator(s).

19. A METHOD of operating an all-in-one integrated system as per any of the previous claims, for accurate dose measurement or radioactive source localisation accurate to +/- 1mm, or at least +/- 2 mm in 3 mutually-orthogonal directions in a clinical radiotherapy setting.

20. A METHOD of operating an integrated system as per any of the previous claims, to be utilised for radioactive source detection, activity level, dose or doserate measurements in a radioactive tracing, environmental safety or personnel safety application.

UoWAustralia Claims: System & method for high-accuracy ionising radiation source localisation 8-07-2021 p. 3/3