Sentinel lymph node biopsy has become standard practice in the surgical treatment of early stage malignancies. In mammary carcinoma conservative surgery, constant research is made on this technique. The aim is to perform less and less invasive surgical procedures, with smaller and smaller probability of post-operative complications for the patient. On this matter, key aspects are duration of the intervention, surgeon’s skill with the detection instrument, which is commonly called “gamma probe”, and quality of the instrument itself. During this thesis work, electronics and firmware of an intraoperative gamma probe prototype have been developed, with the aim of providing surgeons with a handy and easy-to-use tool for such procedures. Thanks to a peculiar geometrical structure of the detection head of the instrument (involving three detection channels suitably oriented), which has been previously designed and patented, the instrument shows a field-of-view greater than 180°. This provides immediate feedback on the direction with most uptake of the radiopharmaceutical that has been injected into the patient during pre-operative procedures, thus strongly reducing intervention times. With respect to other commercially available gamma probes, an unconventional readout technique has been implemented. Starting from current pulses generated by gamma photons impinging on the three detectors, the time instants measured in correspondence of the crossing of a set voltage threshold are exploited in order to retrieve the energy associated to the isotope contained within the radiopharmaceutical. Anytime that the detected event is related to such an energy value, evidence of it is displayed on the instrument control unit, giving feedback about the direction where it comes from. In order to reject radiation coming from different sources, the instrument is periodically calibrated by a nuclear medicine physicist. The chosen readout technique led to deep reductions in terms of area occupation and energy consumption of the probe electronics, with respect to a previous version of the instrument developed by the customer. The compact size and weight allowed additional improvements in the device ergonomics, also thanks to the development of a novel wireless version. In this implementation, the instrument is battery powered and communicates with its control unit via Bluetooth.
La biopsia del linfonodo sentinella è diventata ormai parte integrante della terapia chirurgica per tumori maligni alle fasi iniziali. Nella chirurgia conservativa del carcinoma mammario, tale tecnica è costante oggetto di ricerca. L’obiettivo è effettuare interventi di chirurgia sempre meno invasivi e con sempre più bassa probabilità di complicazioni post-operatorie per il paziente. A tal proposito, sono elementi chiave la durata dell’intervento, l’abilità del chirurgo nell’utilizzo dello strumento di rivelazione, detto comunemente “sonda gamma”, e la qualità di quest’ ultimo. In questo lavoro di tesi è stata sviluppata l’elettronica ed il firmware di un prototipo di sonda gamma intraoperatoria, con l’obiettivo di equipaggiare il chirurgo durante queste operazioni con uno strumento ergonomico e di facile utilizzo. In particolare, grazie ad una geometria particolare della testa di rivelazione precedentemente studiata e brevettata, la quale prevede tre canali di rivelazione opportunamente disposti, è stato provato il raggiungimento di un campo visivo dello strumento superiore a 180°. Ciò permette di avere un riscontro immediato circa la direzione con maggior punto di accumulo del radiofarmaco iniettato nel paziente in fase preoperatoria, riducendo notevolmente la durata dell’operazione. Rispetto alle altre sonde gamma disponibili commercialmente, una tecnica di acquisizione non convenzionale è stata implementata. Essa, partendo da impulsi di corrente generati dai fotoni gamma incidenti sui tre rivelatori, sfrutta una misura del tempo di attraversamento di una soglia di tensione prefissata per ricostruire l’energia associata all’isotopo contenuto nel radiofarmaco. Ogni volta che l’evento rilevato viene associato a tale valore di energia, viene tenuto conto di esso sull’unità centrale dello strumento, la quale da’ riscontro al chirurgo in fase operatoria sulla direzione da cui è arrivato. Al fine di rigettare la radiazione proveniente da altre eventuali fonti, lo strumento è periodicamente calibrato da un fisico medico. La tecnica di acquisizione utilizzata ha permesso di tagliare notevolmente gli spazi occupati dall’elettronica ed i consumi energetici, rispetto alla precedente versione del dispositivo. Ciò ha permesso di elevare ulteriormente l’ergonomia dello strumento, sviluppandone una nuova versione comunicante con l’unità centrale senza filo. In tale sua versione, lo strumento di rivelazione è alimentato via batteria e comunica con l’unità centrale via Bluetooth.
Compact non-imaging gamma probe for sentinel lymph node detection with high field-of-view
FRATI, SIMONE
2017/2018
Abstract
Sentinel lymph node biopsy has become standard practice in the surgical treatment of early stage malignancies. In mammary carcinoma conservative surgery, constant research is made on this technique. The aim is to perform less and less invasive surgical procedures, with smaller and smaller probability of post-operative complications for the patient. On this matter, key aspects are duration of the intervention, surgeon’s skill with the detection instrument, which is commonly called “gamma probe”, and quality of the instrument itself. During this thesis work, electronics and firmware of an intraoperative gamma probe prototype have been developed, with the aim of providing surgeons with a handy and easy-to-use tool for such procedures. Thanks to a peculiar geometrical structure of the detection head of the instrument (involving three detection channels suitably oriented), which has been previously designed and patented, the instrument shows a field-of-view greater than 180°. This provides immediate feedback on the direction with most uptake of the radiopharmaceutical that has been injected into the patient during pre-operative procedures, thus strongly reducing intervention times. With respect to other commercially available gamma probes, an unconventional readout technique has been implemented. Starting from current pulses generated by gamma photons impinging on the three detectors, the time instants measured in correspondence of the crossing of a set voltage threshold are exploited in order to retrieve the energy associated to the isotope contained within the radiopharmaceutical. Anytime that the detected event is related to such an energy value, evidence of it is displayed on the instrument control unit, giving feedback about the direction where it comes from. In order to reject radiation coming from different sources, the instrument is periodically calibrated by a nuclear medicine physicist. The chosen readout technique led to deep reductions in terms of area occupation and energy consumption of the probe electronics, with respect to a previous version of the instrument developed by the customer. The compact size and weight allowed additional improvements in the device ergonomics, also thanks to the development of a novel wireless version. In this implementation, the instrument is battery powered and communicates with its control unit via Bluetooth.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/147378