In vivo dosimetry for radiotherapy with semiconductor diodes and optically stimulated luminescent dosimeters in 60Co photon beams

U ovom radu opisano je ispitivanje svojstava, priprema i primjena poluvodičkih dioda i optički stimuliranih luminiscentnih dozimetara (OSLD) za in vivo dozimetriju u konvencionalnoj vanjskoj radioterapiji. Cilj istraživanja bio je utvrditi primjenljivost novog OSL dozimetrijskog sustava s pasivnim detektorima od aluminijevog oksida dopiranog ugljikom (Al2O3:C) u kliničkim uvjetima. Ispitivanje dozimetrijskih svojstava detektora provedeno je u terapijskom području doza dobivenih 60Co fotonskim snopovima a uključivalo je, između ostalog, određivanje linearnosti odziva na dozu i reproducibilnosti mjerenja, zatim kalibraciju i određivanje korekcijskih faktora za primjenu u nereferentnim uvjetima. Za OSLD-e je dodatno ispitano slabljenje OSL signala s vremenom, stupanj osiromašenja signala u ponovljenim očitanjima i ovisnost odziva o akumuliranoj dozi. Analizirani su rezultati velikog broja kliničkih in-vivo mjerenja ulaznih doza različitih anatomskih lokalizacija i uvjeta zračenja dobivenih s oba dozimetrijska sustava. Pokazalo se da je ispitivani OSL dozimetrijski sustav pogodan za in vivo dozimetriju te su predloženi postupci za pripremu, kalibraciju i optimalni način upotrebe, koji su potrebni pri uvođenju programa in vivo dozimetrije s OSL detektorima u radioterapiji.This thesis describes characterization, basic dosimetric properties investigation and application of semiconductor diodes and optically stimulated luminescence dosimeters (OSLDs) for in vivo dosimetry in conventional external beam radiotherapy. The aim of this reasearch was to test the performance and suitability of the new commercial dosimetry system based on carbon doped aluminum oxide (Al2O3:C) passive OSLDs in clinical conditions. Investigation was performed with 60Co photon beams within the range of typical therapeutic doses. It included determination of detectors response linearity, measurement reproducibility, comparison of calibration methods and determination of correction factors for use in nonreferent conditions. In addition, for OSLDs, specific features such as depletion of OSL signal with multiple readouts, fading and detector response with acumulated dose, were explored. Large number of entrance dose in vivo measurements were performed with both dosimetry system and results were analyzed regarding different anatomical localization, irradiation techniques and other irradiation conditions during the actual treatment of patients. The investigated OSL dosimetry system proves to be convenient for in vivo dosimetry in radiotherapy and this work presents guidelines in their characterization, calibration and optimal way of use, which are important for the implementation of an in vivo dosimetry program in a clinical environment

Razlika histološkog gradusa karcinoma endometrija u kiretaži i histerektomiji – presječna studija

Objectives: To determine the compatibility rate between histological grades of endometrial carcinoma in curettage and hysterectomy and to determine how quantity of material, given by the method of fractional hysterectomy, affects the compatibility between histological grades in the two methods. Material and methods: The study included 102 patients with endometrioid endometrial cancer who underwent methods of fractional curettage and hysterectomy. Data regardingthepathohistological status of uterine tissue was obtained from the available medical records. Information on age andclinical diagnoses were obtained from referrals for pathohistologicaltissue examination. The age of the subjects was determined at the time when the tissue samples were taken for analysis. Data on the amount of material was obtained from the description of macroscopic evaluation of the given material. Results: Most subjects had grade II endometrioid endometrial cancer (47.1 % and 50 %). Most of the respondents had a medium deficient material obtained by fractional curettage (40.2 %). There was no statistically significant difference between the histological grade determined after the fractional curettage and hysterectomy. There were no statistically significant differences in histological grade in the sample obtained by fractional curettage and hysterectomy depending on the amount of material in fractional curettage. Conclusions: There was no statistically significant differences in the grade of endometrial cancer in samples obtained by the fractional curettage and hysterectomy. The correspondence is higher in higher tumor grade (III), and lower in lower tumor grades (I, II). The amount of material did not affect the grade deviation in the sample obtained by fractional curettage and hysterectomy.Cilj: Ispitati podudarnost histološkog gradusa endometrioidnog karcinoma endometrija u uzorcima dobivenim frakcioniranom kiretažom i histerektomijom te ispitati utječe li količina materijala dobivenog frakcioniranom kiretažom na podudarnost histoloških gradusa. Materijal i metode: U istraživanje su bile uključene 102 pacijentice oboljele od endometrioidnog karcinoma endometrija. Iz dostupne medicinske dokumentacije prikupljeni su arhivski podatci o patohistološkom nalazu tkiva maternice dobivenog metodom frakcionirane kiretaže i histerektomijom. Iz uputnice za patohistološki pregled tkiva dobiveni su podatci o dobi i uputnim kliničkim dijagnozama. Podatci o količini materijala dobiveni su iz opisa makroskopske procjene prikupljenog materijala. Rezultati: Najveći broj ispitanica imao je gradus II endometrioidnog karcinoma endometrija (47,1 % i 50 %). Najveći dio ispitanica imao je srednje obilan materijal dobiven frakcioniranom kiretažom (40,2 %). Nije uočena statistički značajna razlika između histološkog gradusa utvrđenog nakon frakcionirane kiretaže i nakon histerektomije, kao ni u histološkom gradusu između uzoraka dobivenih frakcioniranom kiretažom i histerektomijom s obzirom na količinu kiretiranog materijala. Zaključci: Nije bilo statistički značajne razlike u određenim gradusima karcinoma endometrija u uzorcima dobivenima metodom frakcionirane kiretaže i histerektomije. Podudarnost je veća u višem gradusu tumora (III), a manja u nižem gradusu tumora (I, II). Količina materijala nije utjecala na odstupanje gradusa u uzorku dobivenom frakcioniranom kiretažom i histerektomijom

Radioterapija raka prostate vođena magnetskom rezonancom: nova paradigma liječenja

Radiotherapy is one of the key treatment modalities for primary prostate cancer. During the last decade, significant advances were made in radiotherapy technology leading to increasing both physical and biological precision. Being a loco-regional treatment approach, radiotherapy requires accurate target dose deposition while sparing surrounding healthy tissue. Conventional radiotherapy is based on computerized tomography (CT) images both for radiotherapy planning and image-guidance, however, shortcomings of CT as soft tissue imaging tool are well known. Nowadays, our ability to further escalate radiotherapy dose using hypofractionation is limited by uncertainties in CT-based image guidance and verification. Magnetic resonance imaging (MRI) is a well established imaging method for pelvic organs. In prostate cancer specifically, MRI accurately depicts prostate zonal anatomy, rectum, bladder, and pelvic floor structures with previously unseen precision owing to its sharp soft tissue contrast. The advantages of including MRI in the clinical workflow of prostate cancer radiotherapy are multifold. MRI allows for true adaptive radiotherapy to unfold based on daily MRI images taken before, during and after each radiotherapy fraction. It enables accurate dose escalation to the prostate and intraprostatic tumor lesions. Technically, MRI high-strength magnetic field and linear accelerator high energy electromagnetic beams are hardly compatible, and important efforts were made to overcome these technical challenges and integrate MRI and linear accelerator into one single treatment device, called MRI-linac. Different systems are produced by two leading vendors in the field and currently, there are around 100 MRI-linacs worldwide in clinical operations. In this narrative review paper, we discuss historical perspective of image guidance in radiotherapy, basic elements of MRI, current clinical developments in MRI-guided prostate cancer radiotherapy, and challenges associated with the use of MRI-linac in clinical practice.Radioterapija je temelj liječenja raka prostate. Radioterapija je zadnjih godina značajno napredovala što je omogućilo njenu preciznost. Radioterapija zahtjeva točnu isporuku radioterapijske doze na tumor uz maksimalnu poštedu okolnog zdravog tkiva. Konvencionalna radioterapija se bazira na slikama kompjuterizirane tomografije (CT) za sve faze radioterapijskog procesa, iako su slike CT-a slabe rezolucije za prikaz mekih tkiva. Danas je naša sposobnost da još više podižemo radioterapijsku dozu limitirana nedovoljnom jasnoćom CT slika. Magnetska rezonanca (MR) za razliku od CT-a ima odličan kontrast za meka tkiva zdjelice te odlično oslikava prostatu i zdjelične strukture. Mnoge su prednosti uključenja MR u radioterapijski proces raka prostate. MR omogućava pravu adaptivnu radioterapiju na osnovi MR slika uzetih prije, tijekom i nakon radioterapije. Omogućuje eksalaciju doze na intraprostatičke tumorske strukture. Napredak tehnike je omogućio integraciju snažnog magnetskog polja MR-a i visokoenergetskih X-zraka linearnog akceleratora u jedan jedinstveni uređaj - MRI-linac. Dva su MR-linac komercijalna sustava dostupna na tržištu, a u svijetu ima instalirano preko 100 ovakvih uređaja. U ovom preglednom članku razmatramo razvoj slikovnog vođenja u radioterapiji, trenutno stanje magnetom vođene radioterapije raka prostate, kao i izazove u primjeni ove inovativne metode

Dozimetrijska verifikacija radioterapijskih planova intezitet-modulirajuće radioterapije u bolesnika s rakom prostate

Intensity modulated radiotherapy (IMRT) has become widely used as a standard radiation therapy technique for the treatment of localized prostate cancer. The transition from conformal radiotherapy (3D CRT) to a more complex IMRT technique triggered the need for more thorough verification of the accuracy in the dose delivery. In this work we present the clinical workflow and the results of patient specific quality assurance (PSQA) procedures for 40 prostate cancer patients who have been treated with step and shot IMRT ever since its implementation in our routine clinical practice. PSQA procedures include dosimetric verification of each treatment plan with dedicated rotational phantom and high-resolution matrix detector system Octavius 4D (PTW Freiburg) that allows three-dimensional comparison of the calculated and delivered radiation dose distribution. Our results proved the compliance with the universal tolerance limits recommended for those procedures (1), assuring the safety of the treatment and providing the possibility for the adoption of more stringent constraints in the future.Radioterapija moduliranog intenziteta (eng. intensity modulated radiotherapy –IMRT) u posljednjem desetljeću je postala uobičajena radioterapijska metoda za terapiju lokaliziranih karcinoma prostate. Prelazak s konformalne radioterapije na napredniju i tehnički složeniju IMRT tehniku, donio je i potrebu za detaljnijom i sveobuhvatnom provjerom točnosti isporuke doze zračenja. U ovom radu predstavljamo provođenje postupaka dozimetrijske verifikacije radioterapijskih planova poznatih pod engleskim nazivom patient specific QA (PSQA) te rezultate za 40 bolesnika s karcinomom prostate koji su primili IMRT terapiju. U tu svrhu koristimo posebni dozimetrijski sustav s rotacijskim fantomom i visoko razlučivom detektorskom matricom, Octavius 4D (PTW Freiburg). Pokazalo se kako su sva dobivena odstupanja između planirane i mjerene trodimenzionalne raspodjele doze bila unutar preporučenih tolerancija (1) što nam daje povjerenje u sigurnost provođenja ovakve terapije te otvara mogućnost za primjenu strožijih ograničenja u budućnosti

Exposure of Croatian Population to Radiopharmaceuticals

Cilj je ovoga preglednog rada prikazati aktualno stanje opterećenosti stanovništva Republike Hrvatske ozračivanjem zbog izlaganja otvorenim izvorima ionizirajućeg zračenja u medicinske svrhe. U nedostatku relevantnih statističkih pokazatelja nije moguće validirano prikazati efektivnu dozu po stanovniku RH zbog medicinskog izlaganja radionuklidima čiji je unos u ljudsko tijelo defi niran jednokratnim injektiranjem često i vrlo velikih aktivnosti, izvršena je jednostavna procjena kako bi se upozorilo na potrebu ozbiljnijeg istraživanja i utvrđivanja referentnih nivoa izloženosti za defi nirane vrste dijagnostičkih pretraga. Uz vrlo slobodnu pretpostavku da se u RH godišnje obavi do 35.000 dijagnostičkih pregleda uporabom radionuklida procijenjena efektivna doza po stanovniku RH zbog izlaganja dijagnostičkim kratkoživućim radionuklidima velike početne aktivnosti iznosi od 6,8 do 7,9 μSv po stanovniku.The aim of this paper is to call attention to the exposure of Croatian population to open sources of ionising radiation used in medical diagnostics, radiopharmaceuticals in particular, whose initial activity is very high. Without proper exposure monitoring, it is not possible to establish the effective dose per capita, but we have estimated it to be between 6.8 μSv and 7.0 μSv for this type of internal exposure, based on a very loose assumption that about 35,000 diagnostic procedures with radiopharmaceuticals are performed in Croatia every year. This calls for further research that would eventually lead to limiting the doses received through exposure to radiopharmaceuticals

Violinističke škole

Diplomski rad predstavlja osnovna načela violinističke škole Ivana Galamiana, komparira ih sa suvremenim violinističkim metodama, te detaljno obrađuje najvažnije metodičke i interpretativne postavke škole

Violinističke škole

Diplomski rad predstavlja osnovna načela violinističke škole Ivana Galamiana, komparira ih sa suvremenim violinističkim metodama, te detaljno obrađuje najvažnije metodičke i interpretativne postavke škole

Violinističke škole

Diplomski rad predstavlja osnovna načela violinističke škole Ivana Galamiana, komparira ih sa suvremenim violinističkim metodama, te detaljno obrađuje najvažnije metodičke i interpretativne postavke škole