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Proceedings of the 13th IFAC Conference on Proceedings of Devices the 13thand IFACEmbedded Conference on online at www.sciencedirect.com Programmable Systems Available Programmable Embedded Systems May 13-15, 2015. Cracow, Poland Proceedings of Devices the 13thand IFAC Conference on May 13-15, 2015. Cracow, Poland Programmable Devices and Embedded Systems May 13-15, 2015. Cracow, Poland

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IFAC-PapersOnLine 48-4 (2015) 153–158

Real Time Breathing Signal Measurement: Real Time Breathing Signal Measurement: Current Methods Real Time Breathing Signal Measurement: Current Methods Current Methods J. Grepl*, M. Penhaker**, J. Kubíček**, A. Liberda**, A. Selamat***, J. Majerník****, R. Hudák*****

J. Grepl*, M. Penhaker**, J. Kubíček**, A. Liberda**, A. Selamat***, J. Majerník****, R. Hudák***** J. Grepl*, M.*VSB Penhaker**, J. Kubíček**, Liberda**,Engineering, A. Selamat***, Majerník****, R. Hudák***** – TU Ostrava, Faculty ofA.Mechanical Dep.J.337/IT4 Innovations, *VSB – TU Ostrava, Faculty of Mechanical Engineering, Dep. 337/IT4 Innovations, Ostrava, Czech Republic (email: [email protected]) Ostrava, Czech Republic of (email: [email protected]) *VSB––TU TUOstrava, Ostrava, Faculty of Mechanical Engineering, Dep. 337/IT4 Innovations, **VSB FEECS/ Department Cybernetics and Biomedical Engineering, **VSB – TU Ostrava, FEECS/ Department of Cybernetics and Biomedical Engineering, Ostrava, Czech Republic (email: [email protected]) Ostrava, Czech Republic (email: [email protected], [email protected]) Ostrava, Czech Republic (email: [email protected], [email protected]) **VSB – TU Ostrava, FEECS/ Department of Cybernetics and Biomedical Engineering, ***UTM-IRDA Center of Excellence, UTM and Faculty of Computing, Universiti Teknologi Malaysia, Johor Bahru ***UTM-IRDA Center of Excellence, UTM and Faculty of Computing, Universiti Teknologi Malaysia, Johor Bahru Ostrava, Czech Republic (email: [email protected], [email protected]) ****Dep. of Medical Informatics, Faculty of Medicine, Pavol Jozef Šafarik University in Košice, ****Dep. of Medical Informatics, Faculty of Medicine, Pavol Jozef Šafarik University in Košice, ***UTM-IRDA Center of Excellence, and Faculty of Computing, Universiti Teknologi Malaysia, Johor Bahru SlovakUTM Republic (email: [email protected]) Slovak Republic (email: [email protected]) ****Dep. of Medical Informatics, Faculty of Medicine, Pavol of Jozef Šafarik University in Košice, ***** Dep. of Instrumental and Biomedical Engineering, Faculty Mechanical Engineering, TU Košice, ***** Dep. of InstrumentalSlovak and Biomedical Engineering, Faculty of Mechanical Engineering, TU Košice, Republic [email protected]) Slovak Republic (email: (email: [email protected]) Republic (email: [email protected]) ***** Dep. of InstrumentalSlovak and Biomedical Engineering, Faculty of Mechanical Engineering, TU Košice, Slovak Republic (email: [email protected]) Abstract: Oncological diseases count for the most severe problems tackling population of today. There Abstract: count for the most severe tackling population of today. There are variousOncological methods to diseases treat those, radiotherapy being oneproblems of the most efficient ones, which is mainly are various methods to treat those, radiotherapy being one of the most efficient ones, which is mainly Abstract: Oncological diseases count for the most severe problems tackling population of today. There because of highly advanced instrumentation. Yet still some important physiological parameters of human because highly advanced Yet still some physiological parameters human are methods to treatinstrumentation. those,significant radiotherapy being oneimportant of theand most efficient ones, which of is mainly bodyvarious areof overlooked, despite their impact on efficiency safety of medical intervention. body areof overlooked, despiteinstrumentation. their significant Yet impact efficiency andphysiological safety of medical intervention. because highly advanced stillon some important parameters of human Keywords: breathing; signal; their radiotherapy; respiration; oncology. © 2015, (International of Automatic Hostingand by safety Elsevier All rights reserved. body areIFAC overlooked, despite significant impactControl) ononcology. efficiency ofLtd. medical intervention. Keywords: breathing; signal;Federation radiotherapy; respiration; Keywords: breathing; signal; radiotherapy; respiration; oncology.

2. PHYSIOLOGY OF BREATHING 2. PHYSIOLOGY OF BREATHING The breathing system comprises system for exchange of 2. PHYSIOLOGY OF aBREATHING The system system for of gasesbreathing (lungs) and the comprises pump to aventilate the exchange lungs. This gases (lungs) and the pump to ventilate the lungs. This The breathing system comprises a system for exchange of system provides three essential functions: ventilation system provides three essential functions: ventilation gases (lungs) and the pump to ventilate the lungs. This (mechanisms of gas exchange between the ambient (mechanisms gas exchange between theventilation ambient system provides three essential functions: atmosphere andoflungs), diffusion (exchange of gases between atmosphere and lungs), diffusion (exchange of gases between (mechanisms of gas exchange between the the alveolar air and blood) and perfusion (blood flow ambient through the alveolar airadult and blood) and perfusion (blood flow litres through atmosphere lungs), diffusion (exchange of gases between lungs). Eachand consumes approximately 0.25 of lungs). Each adult consumes approximately 0.25 litres of the alveolar air and blood) and perfusion (blood flow through oxygen per minute on average and exhales about 0.2 litres of oxygen per minute on average and exhales about 0.2 litres of lungs). dioxide. Each adult carbon Eachconsumes 1 litre of approximately blood contains 0.25 aboutlitres 3 ml of carbon Each 1average litre ofand blood contains about 3 ml of oxygen dioxide. peroxygen. minute onFundamental exhales about litres dispersed importance is0.2given to dispersed oxygen. Fundamental importance is given to carbon dioxide. Each 1 litre of blood contains about 3 ml by of transport of oxygen in red blood cells ensured transport of oxygen in red blood cells ensured by dispersed oxygen. Fundamental importance is given to haemoglobin. The main task of control functions is to secure haemoglobin. The main task of control functions is to secure transport of oxygen in red blood cells ensured by the balance between metabolic need of organism and the balance between metabolic needfunctions of organism and haemoglobin. The main task ofetcontrol is to secure ventilation of lungs (Penhaker al. 2004). ventilation of lungs (Penhaker et al. 2004). the balance between metabolic need of organism and Ventilation lungs(Penhaker ensures et exchange air between the ventilation ofof al. 2004).of Ventilation oflungs lungsand ensures exchange of air isbetween ambient atmosphere alveoli. This exchange enabled the by ambient atmosphere and alveoli. This exchange is by Ventilation of lungs ensures exchange of air between the flow of air through the respiratory tract alongenabled pressure flow of air through the respiratory tract along pressure ambient atmosphere and alveoli. This exchange is enabled by gradients. The path from terminal bronchioles to alveoli also gradients. The path from terminal bronchioles to alveoli also flow of air through the respiratory tract along pressure lays importance on diffusion and breathing gases diffuse lays importance onfrom diffusion breathing to gases diffuse gradients. The path terminal bronchioles alveoli also from/to alveolar membrane alongand concentration gradients. from/to alveolar membrane along concentration gradients. lays importance on diffusion and breathing gases diffuse Air enters the respiratory through the nosegradients. or mouth. It from/to alveolar membranetract along concentration Air respiratory tract through or mouth. It thenenters travelsthe into pharynx (gullet), wherethe thenose respiratory tract then travels into pharynx (gullet), where the respiratory tract Air enters the respiratory tract through the nose or mouth. It crosses with the digestive system, further into larynx, the crosses with the pharynx digestive system, further the then travels (gullet), where the into respiratory tract trachea, the into bronchi and through bronchioles all larynx, the way to trachea, the bronchi and through bronchioles all larynx, the of waythe to crosses with the digestive system, further into alveoli. Besides the supply and discharge air alveoli. Besides the supply and discharge of air trachea, the bronchi and through bronchioles all the way to to/from alveoli, the respiratory tract also plays other vital to/from alveoli, the respiratory tract also plays other vital alveoli. Besides the supply and discharge of air roles: roles: to/from alveoli, the respiratory tract also plays other vital roles:¥ the respiratory tract purifies air; ¥ the respiratory tract purifies air; ¥ the ambient air temperature is adapted to the body ¥ the ambient and airtract temperature is adapted to the body respiratory air; temperature the purifies air is humidified; the air is humidified; ¥ temperature the ambient and air temperature is adapted to the body temperature and the air is humidified;

1. INTRODUCTION 1. INTRODUCTION The current medical1. practice is literally flooded with vast INTRODUCTION The current practice is provide literally quality floodedservices with vast quantities of medical appliances able to to quantities of appliances able to provide quality services to The current medical practice is literally flooded with even vast end users in many cases, this rule definitely proves right end inofmany cases, definitely proves right even quantities appliances able toforprovide quality services to moreusers in radiotherapy. If this onlyrule utilisation of the ionising more in radiotherapy. If this onlyrule fordefinitely utilisation of theright ionising end users in many cases, proves even radiation to cure oncological diseases the requirements laid radiation to cure requirements laid more radiotherapy. If only for utilisation of the ionising on theinquality of oncological design and diseases safe use the of these devices are on the quality of design and safe use of these devices are radiation to cure oncological diseases the requirements laid much higher, when compared to other fields of medical much higher, when compared to other fields of medical on the quality of design and safe use of these devices are instrumentation, which is obviously reflected also in the cost instrumentation, which is obviously reflected also in the cost much higher, when compared to other fields of medical of such equipment. However, the current manufacturers of of such equipment. However, the current manufacturers of instrumentation, which isfollow obviously reflected also radiotherapy appliances proven trends, as in farthe as cost any radiotherapy appliances follow proven trends, as far as any of such equipment. However, the current manufacturers of additional functionalities of radiotherapy equipment are additional functionalities ofareradiotherapy equipment are radiotherapy appliances follow proven trends, as far as any concerned, that is why there still some outstanding issues concerned, that why therenecessary. still some outstanding additional functionalities ofareradiotherapy equipmentissues are to be resolved toisthe extent to be resolved extent concerned, thattoisthe why therenecessary. are still some outstanding issues One such problems seennecessary. on radiotherapy equipment deals to be of resolved to the extent One such problems seen on radiotherapy deals with of monitoring of breathing activity that equipment has an express with monitoring of breathing activity that has an express One of such problems seen on radiotherapy deals mechanical impact on positioning of equipment tissue during mechanical impact on complicates positioning of has tissue during with monitoring of breathing activity medical that an express radiotherapy, which even intervention radiotherapy, which even complicates intervention mechanical impact positioning of tissue on patients reluctant tooncollaborate withmedical medical staff.during Such on patients reluctant to collaborate with medical staff. Such radiotherapy, which even complicates medical intervention situations involve monitoring of body parts movement of a situations monitoring of body parts movement offora on patientsinvolve reluctant to collaborate with medical breathing patient with automatic targeting of staff. spotsSuch breathing patient with automatic targeting of spots situations involve monitoring of body parts movement offora application of the ionising radiation from the instrument application of the ionising radiation from the instrument breathing patient with automatic targeting of spots for itself. itself. application of the ionising radiation from the instrument The question is: what are the current techniques and methods itself. The question is: what are the current used techniques and methods for real-time monitoring of breath in radiology? Are for real-time monitoring of breath used in radiology? Are The question is: what are the current techniques and methods these methods sufficient? What are their disadvantages? Is these methods sufficient? What are their disadvantages? Is for real-time monitoring of breath used in radiology? Are there any space for development of a new type of multithere any space for development of a new type of multithese methods sufficient? What are their disadvantages? Is purpose measurement device for continuous real-time purpose measurement device for continuous real-time there any space for development of a new type of multimeasuring of breath to provide essential information to the measuring of breath to provide information to the purpose staff? measurement device essential for continuous real-time medical medical staff? measuring of breath to provide essential information to the medical staff?

2405-8963 © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. Copyright IFAC responsibility 2015 153Control. Peer review©under of International Federation of Automatic Copyright © IFAC 2015 153 10.1016/j.ifacol.2015.07.024 Copyright © IFAC 2015

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The basic types of breathing are:

bronchi guide the air flow and its even distribution into lungs; the lymphoid tissue forms a barrier within respiratory tract to prevent infection; generation of voice on vocal chords caused by the flow of air during exhalation.

¥ ¥ ¥ ¥ ¥ ¥ ¥

3. BREATHING MECHANISM There is a cavity between the lungs and thoracic wall - the interpleural cavity. When the thoracic wall is intact, this cavity between the thoracic wall and lungs contains underpressure, compared to the atmospheric pressure negative pressure. Following a calm exhalation (exspirium), this interpleural pressure will be lower than the atmospheric pressure by about 4 mmHg.

Eupnoea – normal relaxed breathing. Apnoea – temporary suspension of breathing. Oligopnoea (bradypnoea) – abnormally infrequent respiration. Polypnoea – accelerated respiration. Tachypnoea – rapid breathing. Dyspnoe – shortness of breath. Orthopnoea – heavy breathlessness – the patient is unable when lying, he/she needs to stand or sit up instead. 4. BIOLOGICAL SIGNALS

A signal is generally defined as a vehicle to carry some kind of information. Signals are mostly various physical quantities. Biological signal can be then defined as special type of signal originating in a live organism and it must be stochastic. Biological signal can be induced by the very life expressions of an organism (native) or by external physical effects on an organism (evoked). The nature (physical fundamentals) and method of origin will class biological signals into several groups (Krejcar et al. 2010).

Lungs have the tendency towards shrinking due to elasticity of lung tissue – retraction force of lungs. This force is opposed by elasticity of the chest. Upon inhalation (inspirium), the negative pressure inside the interpleural cavity becomes more negative due to the effect generated by muscle inspiration force against the lung retraction force. As the lungs communicate with atmospheric pressure via the respiratory tract, suction of air into lungs occurs. Suction of air persists, until the pressure inside lungs equals the atmospheric pressure level.

As mentioned above, biological signals may differ in nature (they may be based on different physical fundamentals) to aid their division. The essential types of biological signals and their most typical representatives are listed below:

Inspirium (inhalation) is always an active operation, as it involves inspiration (inhalation) muscles. Calm breathing involves the main inspiration muscles only, yet intensive inspiration will also include the auxiliary inspiration muscles. Relaxation of the inspiration muscles is followed by expiration (exhalation), when the retraction force of lungs starts prevailing and the pressure in lungs will increase in comparison with the ambient atmospheric pressure that results in flow of air from lungs through clear respiratory tract into the environment. Expiration is passive operation during calm breathing, which means that expiration (exhalation) muscles are not active and the volume of air exchanged in lungs is about 0.5 l, yet these muscles will be involved in action during intense expiration (Figure 1). The whole of this cycle, i.e. alternating of inspiration and expiration, is defined as the breathing cycle and it is repeated at the frequency of 8-28 cycles per minute (Schmid et al. 2004).

Bioelectric signal (ECG, EEG, EMG, EOG, etc.). Bioimpedance signal (condition and nature of tissue). ¥ Biomagnetic signal (measurement of magnetic fields of body parts - MKG, MEG, MMG, MOG). ¥ Biomechanical (blood pressure, cardiac output, respiration frequency, tissue volumes). ¥ Bioacoustic signal (heart sound). ¥ Biochemical signal (concentration of O2, CO2 in blood or breath, pH). ¥ Other bio signals (body temperature). Respiration is a complex biological process that can act as a source of biological signals by itself or it can affect other biological signals developing within the field affected by respiration activity. Typical representatives of basic types of biological signals originating from the breathing activity itself are the following signals identified by respiration physiology: ¥ ¥

¥ ¥ ¥ ¥ ¥ ¥ Figure 1. Breathing mechanism. 154

bioimpedance (change in volume and structure of lung tissue); biomechanical (changes in volume of chest and abdominal areas, volumes, capacity and flows of respiration gases); bioacoustic (sounds generated by flow of air through the respiratory tract); biomechanical (concentration of respiration gas in breath or blood); bioelectric (operations of respiration muscles); other signals (temperature changes in the vicinity of respiratory tract inlets).

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5.5 Bioimpedance signals

Biological signals affected by breathing activity include mainly the ECG signal subject to strong influence of changes in tissue structure during respiration, as it belongs to bioelectric signals. That is related to the bioimpedance signal mentioned above, whereas changes in impedance definitely affect the electric activity of cardiac muscle measured.

Bioimpedance signals are described as carriers of information about characteristics of tissue (volume, perfusion or type of particular tissue, etc.) and one can therefore consider changes of impedance in the chest area during respiration associated with changes in volume perfusion, mainly in muscles in this area, as well as contents due to exchange of respiration gases. This agenda also includes a certain part of ECG affected by respiration, when the monitoring aims at demonstration of changes in chest impedance directly using the ECG signal obtained. Similarly to monitoring of bioelectric signals, this monitoring also requires a conductive connection to the patient's body by means of electrodes (Havlík et al. 2012).

5. METHODS FOR MONITORING OF BIOLOGICAL SIGNALS IN BREATHING ACTIVITY 5.1 Biomechanical signals Biomechanical signals are the visually best perceived expressions of breathing, these deal mainly with changes in volume in thoracic and abdominal areas (movement of respiratory muscles) that are usually measured using various elastic bands of different designs (e.g. resistance bands or piezoelectric bands) or the methods of so called whole-body plethysmography. On the contrary, volumes, flow rates and capacities of respiration gases are not that easy to control by visual inspection, yet spirometry still remains the most frequent method used for examination of pulmonary ventilation.

6. RADIOTHERAPY Radiotherapy is a special clinical method for treatment of malignities with ionising radiation. Radiotherapy obviously includes processing of an exposure plan for precise determination of suitable amount of radiation depending on the defined tumorous volume with minimum damage and to protect healthy tissue. That results in destruction of the tumour, restoration of life quality and extension of the patient's life.

5.2 Bioacoustics signals

Besides this curative (aimed at the final cure of the patient) purpose, radiotherapy is also employed in treatment of malignant tumours as palliative care (enhancement of patient's life, not just its mere extension) with essential focus on elimination of disease signs, especially pain, worse integrity of body parts or ill functioning of body organs.

Bioacoustic signals are examined with stethoscope during inspection of the respiratory tract. The electronic method to measure this expression of respiratory activity would be implementation of a microphone. 5.3 Biochemical signals

The objective of radiotherapy is to apply a lethal dose into a tumour corresponding with not only clinically and macroscopically identified volume, as well as those areas, where it’s assumed microscopic spread. The scope of potential microscopic spread of tumour can be determined pursuant to histological finding and knowledge of behaviour of the particular tumour type. Such area of assumed microscopic spread defines the so called safety or biological border around the tumorous deposit to define the target clinical volume (Figure 2).

Biochemical signals relevant to respiration deal mainly with concentration and partial pressure exerted by oxygen and carbon dioxide CO2 in the inhaled/exhaled air or directly in patient's blood. The content of carbon dioxide CO2 in the inhaled/exhaled air is most often subject to measurements using a capnograph, i.e. the capnography method. One the other hand, measurement of blood saturation with oxygen is usually conducted using the pulse oximetry method. These signals are mainly measured in relevance with proper ventilation check or they are included within the spirometry examination. 5.4 Bioelectric signals Bioelectric signals originate from electric events that occur on membranes of irritant cells. Simultaneous activity of these cells generates the bioelectric signal. These signals are mostly measured on the surface of human body using surface electrodes, some cases allow application of invasive method with sub-surface micro electrodes. Bioelectric signals associated with respiration include EMG of the respiratory muscle activity, respectively the respiratory part of ECG (the ECG signal itself acts as interfering element in this case), caused mainly by change in impedance tissue around the chest.

Figure 2. Determination of target volume in radiotherapy There are situations in practice, when a tumorous deposit, including its biological border (target clinical volume, changes its position depending on patient's movement due to physiological activities, e.g. respiration, swallowing, filling of bladder. The patient's contours may also change during 155



exposure or within more frequent exposure to radiation at the same spot, where the patient's position may not be precisely reproducible. Those are the reasons, why the target clinical volume has been extended with another so called position tumour border to define a larger planned target volume (Spurný at el 1999).

7.1 The breath holding technique The breath holding technique is one of the probably most common and "the simplest" methods for radiotherapy in areas with expected location of tumorous deposit (especially the area affected by respiration activity). This method involves delivering of the dose required into the relevant volume, while the tumorous deposit (holding of patient's breath), which reduces the planned target volume significantly, therefore saving the healthy tissue in its vicinity, to enable delivery of greater dose of radiation with better accuracy. The usual procedure focuses on a static tumour during deep inspiration (inhalation), as the density of pulmonary tissue will be lower during inhalation and its volume will be greater, which results in lower exposure of healthy tissue. This method depends on good coordination of the patient and medical staff, otherwise the breath activity of patients needs to be monitored. One of the devices for detection of breathing activity is the so called ABC (Active Breathing Coordinator) using a valve to control respiration conditions and monitoring the breathing process with a digital spirometer (Figure 4A); however, some patients may be experiencing certain discomfort or even limitations when using this device (Figure 4B).

Furthermore, the so called curative volume has been defined to include the minimum required deposit (curative) dose and the final so called exposed volume comprising the total volume and healthy tissue irradiated with less than 50% dose. 7. CURRENT METHODS FOR RESPIRATION MEASUREMENTS IN RADIOTHERAPY As already mentioned above in chapter referring to radiotherapy, if there is a tumorous deposit within the area affected by physiological activities causing the tissue to move (the pectoral or abdominal area in this case) the exposure plan needs to involve a larger volume, resulting in higher probability of irradiation on healthy tissue. In situation of designing a lesser planned target volume could result both in unnecessary exposure of both healthy tissue (Figure 3C) in case of a sudden unpredicted movement as well as a failure to kill all the tumorous cells within the area of clinical target volume (Figure 3B). This may result in necessary repetition of therapy and the associated higher radiation load on the patient.

Figure 4. Active Breathing Coordinator (Elekta 2015) 7.2 The tracking technique The tracking technique is based on monitoring of movement by means of external or internal sensors and adaptation of the radiation harness depending on such movement. This method is fairly demanding as far as finance and technologies are concerned, that is why this solution has been implemented in the Cyberknife or Calypso System equipment. Whereas Cyberknife is based on tracking of external sensors copying the patient's movement (Figure 5A), then Calypso System uses an implantable "beacon" (Figure 5C) to transmit non-ionising electromagnetic radiation and this signal is tracked by other features within the system (Figure 5B), the movement of which interrupts the radiation harness.

Figure 3. A) Location of tumour when stationary, B) and C) Location of tumour when moving There are currently several systems, methods and even radiotherapy devices dealing with respiration issues or generally the issues associated with movement of the tumour deposit during radiotherapy. However, the main problems relevant to these solutions include extension of the therapy planning process as well as prolongation of the treatment itself, which may have a negative impact on patient especially with respect to comfort and health condition, lack of comfort during therapy that may change numerous conditions essential to guarantee success of the whole process, the last but not the least are the financial and technological demands associated with the solution in place. The most important methods for dealing with these issues are described below.

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Figure 5. A CyberKnife made by ACCURAY (Accuray 2015), B. Electromagnetic field of the Calypso system (Varian 2015), C. Approximately 8.5 mm large implantable transmitters of the Calypso system. 7.3 The gating technique

Figure 7. 4D CT recording (Appleyard 2015)

The gating technique is based on the principle that involves interruptions of the ionising radiation harness with respect to selected sections of the breathing cycle (Figure 6). The technology behind this method mostly involves reflection of the infra-red ray from the reflective stack fixed onto patient's chest. The movement of this reflective stack helps assess the stages of patient's breath and the ionising radiation harness is activated within the stages required.

Another method for monitoring of respiration and breathing movements is change recognition in a video image, for example. This method is fairly demanding with respect to hardware and software equipment, it is therefore more costly and ranks among rather experimental methods than those widely used in practice (Hudák et al. 2012). 8. CONCLUSION Continuous measurement of breathing in real time belongs to vital aspects of radiotherapy in oncology. It actually provides the necessary information about the existing location of target deposit in a specific period. Poor knowledge of this information may result in unnecessary exposure of healthy tissue instead of the target deposit. This article provides a description of the fundamental physiology of breathing together with the mechanical principle. Further explanations concerned types of biological signals and their potential tracking methods. The last but not the least part dealt with listing of methods for breathing measurement implemented by various manufacturers of radiotherapy equipment in their products. The main disadvantage of technologies for breath measurement applied by those manufacturers is the fact these can be utilised in combination with their own equipment and cannot be installed on other equipment at medical workplaces. That is a problem, as hospitals are mostly fitted with equipment originating from different manufactures in practice. That prevents transfer of data obtained through breath measurement and their utilisation during the course of treatment is therefore severely limited. Another advantage is the frequent occurrence of silhouettes on the resultant images due to application of materials impassable by X-rays.

Figure 6. Gating technique 7.4 The 4D CT method The 4D CT method is rather a procedure for significant alteration of radiotherapy planning. This is 3D CT recording of the area with tumour deposit in time during particular stages of breathing. Such imaging of the tumour movement plays a great role in planning of the entire radiotherapy and the overall result of therapy in general. A drafted 4D plan can be applied for interruption of ionising radiation harness and minimising of deficiencies associated with respiration activity in radiotherapy (Figure 7).

Further research should focus on development of versatile system for breathing measurement in real time. Correct selection of the biological signal type and the methods for its monitoring could help with designing of the measurement system compatible with all the radiological equipment at most medical workplaces. Emphasis should be laid on high comfort for patients and preventing of any increase of the 157



already high stress load during treatment, with attention to simplicity and intuitiveness of use of equipment by medical staff. The new measurement system should ensure significant elimination of the above-mentioned disadvantages suffered by the existing techniques for breath measurement. Its low cost would also contribute towards rapid spread of such equipment to multiple workplaces, resulting in potentially fast improvement of accuracy and efficiency of radiotherapy.

VŠB - Technická univerzita Ostrava, 320 s. ISBN 80248-0751-3. Schmid, M, Conforto, S, Bibbo, D & D'Alessio, T 2004, 'Respiration and postural sway: detection of phase synchronizations and interactions', Human Movement Science, vol. 23, no. 2, pp. 105-19. Spurný, V. Šlmapa, P. 1999 Moderní radioterapeutické metody: Základy radisoterapie - VI. Díl. Brno: Institut pro další vzdělávání pracovníků ve zdravotnictví, 118 s. ISBN 80-7013-267-1. Varian 2015, Calypso Extracranial Tracking. Available from:

One may therefore conclude that these is still some space for new advanced systems in the field of versatile monitoring of breathing. Their functioning principle for elimination of disadvantages of the existing methods may be based on the whole range of biological signals and methods implemented for their monitoring. That makes the development of a versatile and self-contained system feasible. ACKNOWLEDGMENT The work and the contributions were supported by the project SP2015/179 'Biomedicínské inženýrské systémy XI', and this paper has been elaborated in the framework of the project „Support research and development in the Moravian-Silesian Region 2014 DT 1 - Research Teams“(RRC/07/2014). Financed from the budget of the Moravian-Silesian Region. The paper was elaborated in the framework of the IT4Innovations Centre of Excellence project, reg. no. CZ.1.05/1.1.00/02.0070, supported by the Operational Programme Research and Development for Innovation,' funded by the Structural Funds of the European Union and the state budget of the Czech Republic. REFERENCES Accuray 2015, Cyberknife. Available from: Appleyard, R. 2015, 4D Computed Tomography. Available from: Elekta 2015, Active Breathing Coordinator. Available from: Havlík, J. Fousek, O. Ložek, M. 2012. Patient monitoring using bioimpedance signal. In Information Technology in Bio- and Medical Informatics. Heidelberg: Springer, p. 171-172. ISBN 978-3-642-32394-2. Hudák, R. Živčák, J. Kaťuch, P. Goban, B. 2012. Biomedical Applications of Diagnostics and Measurements by Industrial Computer Tomography In: Aspects of Computational Intelligence: Theory and Applications. Germany: Springer, P. 335-355. - ISBN 978-3-64230667-9. Krejcar, O. Penhaker, M. Janckulik, D. Motalova, L. 2010 Performance Test of Multiplatform Real Time Processing of Biomedical Signals. In Proceedings of 8th IEEE International Conference on Industrial Informatics, Osaka, Japan. NJ: IEEE Conference Publishing Services, pp. 825-839. ISSN: 19354576, ISBN: 978-142447300-7. Penhaker, M. Imramovský, M. Tiefenbach, P. Kobza, F. 2004 Lékařské diagnostické přístroje: Učební texty. Ostrava:

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