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.
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.
There are still controversies about the benefit of surgery after concurrent radiochemotherapy (CRT) for locally advanced cervical cancer. The aim of this study was to evaluate toxicity, local tumor ...control and overall survival of surgery after CRT in stage IB-IIB cervical cancer.
Between 2002 and 2008, 24 patients with stage IB-IIB cervical cancer were treated with external-beam radiotherapy concomitantly with chemotherapy. High-dose rate brachytherapy fractions were given once weekly. Radical hysterectomy was undertaken after a median of 42 days.
Overall survival at five years was estimated at 75% (95% confidence interval=52-88%) and sustained thereafter through to 8.9 years. No patient experienced local failure in the surgical bed. Postoperative complications were recorded in two patients.
Surgery after CRT in stage IB-IIB cervical cancer is safe and leads to better local control of the disease and overall survival.
Background The aim of this study was to determine the possible predictive value of various dosimetric parameters on the development of hypothyroidism (HT) in patients with head and neck squamous cell ...carcinoma (HNSCC) treated with (chemo)radiotherapy. Patients and methods This study included 156 patients with HNSCC who were treated with (chemo)radiotherapy in a primary or postoperative setting between August 2012 and September 2017. Dose-volume parameters as well as V10 toV70, D02 to D98, and the VS10 to VS70 were evaluated. The patients' hormone status was regularly assessed during follow-up. A nomogram (score) was constructed, and the Kaplan-Maier curves and Log-Rank test were used to demonstrate the difference in incidence of HT between cut-off values of specific variables. Results After a median follow-up of 23.0 (12.0-38.5) months, 70 (44.9%) patients developed HT. In univariate analysis, VS65, Dmin, V50, and total thyroid volume (TTV) had the highest accuracy in predicting HT. In a multivariate model, HT was associated with lower TTV (OR 0.31, 95% CI 0.11-0.87, P = 0.026) and Dmin (OR 9.83, 95% CI 1.89-108.08, P = 0.042). Hypothyroidism risk score (HRS) was constructed as a regression equation and comprised TTV and Dmin. HRS had an AUC of 0.709 (95% CI 0.627-0.791). HT occurred in 13 (20.0%) patients with a score < 7.1 and in 57 (62.6%) patients with a score > 7.1. Conclusions The dose volume parameters VS65, Dmin, V50, and TTV had the highest accuracy in predicting HT. The HRS may be a useful tool in detecting patients with high risk for radiation-induced hypothyroidism.
In relatively recent paleographic studies, a new type of the Glagolitic script, namely triangular type, was introduced as being older than the rounded type (commonly considered as the oldest known ...type) with possible mixing of letter types in the early period of Glagolitic writing. That hypothesis, drawn from the so-called generative model, has been lacking of a quantitative analysis. Here, we report on such an analysis in which the forms of the original letters carved in two among oldest stone tablets are compared to the models of the triangular and rounded letters. To calculate similarity measures, two different approaches were used. In the first approach, we use the standard correlator systems that are fast but sensitive to various letter deformations. The second approach, via calculating Fourier–Jacobi image moments, is rather slow but possesses invariance to input image deformations. To accelerate the entire recognition and classification process of the later approach, we introduced so-called sensitivity vector consisting of those moments that are robust to rotational and scale change deformations of input image. Although different in details, both approaches indicate presence of a mixture of both letter types supporting thus one of the hypothesis claims.
SUMMARY
Intraluminal high dose rate brachytherapy (ILHDR BT) is one of several effective modalities for palliation of advanced esophageal cancer. Thirty patients with endoscopic‐proven, mostly ...locally advanced, squamous cell carcinoma of the esophagus, not involving the gastroesophageal junction and without distant metastases, were included in this analysis. Twenty‐nine patients received two ILHDR BT sessions of 8 Gy within a week and one patient received only one session. All patients were followed monthly. Outcomes included quality of life (QOL), symptoms control: dysphagia, regurgitation, odynophagia, and chest or back pain, as well as, overall survival. Through 4 months of follow‐up, QOL was statistically improved (having lowered scores) in regards to feelings (P= 0.013), sleeping (P= 0.032), eating (P= 0.020), and social life (P= 0.002). The most significantly improved symptom was dysphagia (P < 0.006), with a reduction of 0.52 units or one‐half grade. Regurgitation, odynophagia, and pain were lower during follow‐up but were not statistically significant. The median overall survival from death of any cause was 165 days (with a 95% confidence interval of 128–195 days). In conclusion, ILHDR BT of advanced squamous esophageal cancer consisting of two out‐patient procedures is very successful in achieving the primary objectives of the patients to reduce dysphagia and improve QOL.
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.
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. Key words: prostate IMRT, patient specific QA Radioterapija moduliranog intenziteta (eng intensity modulated radiotherapy -IMRT) u posljednjem desetljecu je postala uobicajena radioterapijska metoda za terapiju lokaliziranih karcinoma prostate. Prelazak s konformalne radioterapije na napredniju i tehnicki slozeniju IMRT tehniku, donio je i potrebu za detaljnijom i sveobuhvatnom provjerom tocnosti isporuke doze zracenja. U ovom radu predstavljamo provodenje postupaka dozimetrijske verifikacije radio terapijskih 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 razlucivom detektorskom matricom, Octavius 4D (PTW Freiburg). Pokazalo se kako su sva dobivena odstupanja izmedu planirane i mjerene trodimenzionalne raspodjele doze bila unutar preporucenih tolerancija (1) sto nam daje povjerenje u sigurnost provodenja ovakve terapije te otvara mogucnost za primjenu strozijih ogranicenja u buducnosti. Kljucne rijeci: radioterapija moduliranog intenziteta (IMRT) karcinoma prostate, dozimetrijska verifikacija plana, patient specific QA (PSQA)
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.
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