Adjuvant radiotherapy post microvascular reconstructive surgery (MRS) for patients with locally advanced head and neck cancer – when and how?

For many decades palliation (radiotherapy, chemotherapy or symptomatic treatment) was the only therapeutic solu­tion for locally very advanced head and neck cancer. In the mid 70s, H. Buncke carried out pioneering microvascular reconstructive surgery (MRS) as a radical treatment. Since that time, the MRS has been accepted around the world as a successful radical therapy, not only for head and neck (H&N) cancers. A part of the H&N cancers need however post­-MRS radiotherapy (RT). Based on the 20 year experience of the Institute of Oncology in Gliwice with MRS (about 2500 patients), D. Bula has defined local recurrence risk factors. Dutch studies convincingly documented the prognostic value of the estimated molecular profiles of the resected margins as additional risk factors. The use of conventional 2.0 Gy/ fraction post-MRS-RT result in a high risk of the inserted reconstructive flap necrosis or rejection. Therefore, a novel IMRT­-VMAT technique with 50 Gy given in 1.5–1.6 Gy/fraction has been designed which allows to almost eliminate the flap from the irradiated volume and therefore minimizes recurrence and/or flap rejection to almost zero. The present paper shows objectively selected a cluster of patients being the candidate to post-MRS safe and effective VMAT radiotherapy

Adjuvant radiotherapy post microvascular reconstructive surgery (MRS) for patients with locally advanced head and neck cancer – when and how?

For many decades palliation (radiotherapy, chemotherapy or symptomatic treatment) was the only therapeutic solu­tion for locally very advanced head and neck cancer. In the mid 70s, H. Buncke carried out pioneering microvascular reconstructive surgery (MRS) as a radical treatment. Since that time, the MRS has been accepted around the world as a successful radical therapy, not only for head and neck (H&N) cancers. A part of the H&N cancers need however post­-MRS radiotherapy (RT). Based on the 20 year experience of the Institute of Oncology in Gliwice with MRS (about 2500 patients), D. Bula has defined local recurrence risk factors. Dutch studies convincingly documented the prognostic value of the estimated molecular profiles of the resected margins as additional risk factors. The use of conventional 2.0 Gy/ fraction post-MRS-RT result in a high risk of the inserted reconstructive flap necrosis or rejection. Therefore, a novel IMRT­-VMAT technique with 50 Gy given in 1.5–1.6 Gy/fraction has been designed which allows to almost eliminate the flap from the irradiated volume and therefore minimizes recurrence and/or flap rejection to almost zero. The present paper shows objectively selected a cluster of patients being the candidate to post-MRS safe and effective VMAT radiotherapy

Frakcjonowana radioterapia stereotaktyczna CyberKnifeTM chorych na raka gruczołu krokowego — prezentacja metody

A significant technological development of radiotherapy in the last several years has enabled the implementation indaily practice of highly specialized procedures for accurate imaging and precise irradiation for patients with prostatecancer.Due to the numerous reports on the low value of the alpha/beta ratio for prostate cancers, using such technologygives an opportunity to implement hypofractionated radiotherapy safely.This article presents the first Polish implementation of CyberKnifeTM based stereotactic radiotherapy for prostatecancer patients.Eligibility for treatment includes low risk prostate cancer patients with good performance status and biopsy confirmed prostate cancer. Preparing the patient for IGRT procedures includes transrectal implantation of golden markers and patient immobilization using a vacuum pillow.Treatment planning was based on the fusion of computed tomography and magnetic resonance imaging. Verification of prostate position was performed by localization of implanted markers using two orthogonal kilovoltage beams and detectors.The dose of 7.25 Gy per fraction to a total dose of 36.25 Gy was used to irradiate the prostate tumor with a margin. The organs at risk are rectum, bladder, femoral heads and the urethra.A comparative analysis of the doses used in conventional and hypofractionated radiation therapy after estimation as the normalized total dose (NTD) and the biologically effective dose (BED) was made.Estimation of the risk of adverse effects in healthy tissues, both for acute and late reactions, justifies using stereotactic fractionated radiotherapy for patients suffering from prostate cancer.Reduction of total treatment time is justified from an economic as well as an ethical point of view.Znaczny postęp technologiczny radioterapii w ostatnich kilkunastu latach umożliwił wdrożenie do codziennej praktykiwysokospecjalistycznych procedur, umożliwiających dokładne obrazowanie i precyzyjną realizację leczenia chorych naraka gruczołu krokowego. Z uwagi na liczne doniesienia dotyczące niskich wartości współczynnika alfa/beta dla rakówstercza, dysponując opisaną technologią możemy realizować w bezpieczny sposób hipofrakcjonowaną radykalnąradioterapię. W poniższym artykule zaprezentowano pierwszą w Polsce metodę leczenia chorych z rozpoznaniemraka gruczołu krokowego z zastosowaniem frakcjonowanej radioterapii stereotaktycznej przy użyciu CyberKnife.Kryteria kwalifikacji do leczenia obejmują chorych z grupy tzw. niskiego ryzyka, w dobrym stanie ogólnym i potwierdzonymw biopsji rakiem gruczołu krokowego. Przygotowanie chorego polega na implantacji drogą transrektalnązłotych znaczników do stercza i wykonaniu unieruchomienia przy pomocy materaca próżniowego.Planowanie leczenia przeprowadzono w oparciu o fuzję tomografii komputerowej i rezonansu magnetycznego.Weryfikacji ułożenia chorego dokonywano za pomocą implantowanych znaczników do stercza z zastosowaniemsystemu dwóch układów detektorów i lamp rentgenowskich o prostopadłych do siebie osiach wiązek.Stosowano dawkę frakcyjną 7,25 Gy w pięciu frakcjach do dawki całkowitej 36,25 Gy w objętości gruczołu krokowegoz marginesem. Organami krytycznymi podczas radioterapii są odbytnica, pęcherz moczowy, główki kości udowychoraz cewka moczowa.W poniższym artykule dokonano porównawczej analizy dawek stosowanych w radioterapii konwencjonalnej i hipofrakcjonowanejpo przeliczeniu znormalizowanej dawki całkowitej (NTD) oraz dawki efektywnej biologicznie (BED).Obliczone dawki w guzie oraz w narządach krytycznych, zarówno dla odczynów wczesnych, jak i późnych, uzasadniajązastosowanie radioterapii z użyciem CyberKnife u chorych z rozpoznaniem raka gruczołu krokowego. Skrócenie całkowitegoczasu leczenia zmniejsza obciążenie chorego wielotygodniowym leczeniem i jest uzasadnione z przyczynekonomicznych

The influence of dose calculation algorithms on TCP in radiotherapy

W planowaniu rozkładu dawki w radioterapii stosowane są różne algorytmy obliczające. Najprostsze z nich, stosowane od wielu lat, dają dobrą zgodność: obliczenia – pomiar, ale tylko w przypadku najprostszych modeli, np. w ośrodku o jednorodnej gęstości. Wraz z rozwojem technik obliczeniowych pojawiły się algorytmy, które uwzględniały coraz więcej zjawisk fizycznych oddziaływania promieniowania z materią. Różnice pomiędzy dawkami obliczonymi i zmierzonymi, dla bardzo wyrafinowanych sytuacji klinicznych, są coraz mniejsze, mieszczą się granicach niepewności metody. Czy zatem dokładność obliczeń może mieć wpływ na wyniki radioterapii? Aby odpowiedzieć na to pytanie, należy rozkłady dawek fizycznych połączyć z dawkami biologicznie równoważnymi i obliczyć prawdopodobieństwo miejscowego wyleczenia. Skorzystano z modelu liniowo-kwadratowego oraz modelu Poissona. Wykonane obliczenia wskazują, że istnieje wpływ algorytmu obliczającego na prawdopodobieństwo miejscowego wyleczenia. Jednak jest on uzależniony od lokalizacji guza nowotworowego. W sytuacji, kiedy różnice gęstości w napromienianej objętości nie są zbyt duże – najprostsze i najbardziej zaawansowane modele wyliczają podobne dawki, czyli nie wykazują wpływu na prawdopodobieństwo miejscowego wyleczenia. Jednak w sytuacji dużych różnic w gęstościach, prostsze modele mogą znacznie zafałszować rozkłady dawek, co przekłada się na TCP.In the radiotherapy treatment planning, different calculation algorithms are used. Can the accuracy of calculations affect the results of radiotherapy? Physical dose distributions should be combined with biologically equivalent doses and calculated the local control probability. The Linear-Quadratic model and the Poisson model were used. The dose calculations indicates that there is an effect of a computing algorithm on the local control probability. However, it depends on the location of the tumor. In the case of large differences in densities, more simple models can significantly distort dose distribution, which affects the TCP

Integral dose: Comparison between four techniques for prostate radiotherapy

AimComparisons of integral dose delivered to the treatment planning volume and to the whole patient body during stereotactic, helical and intensity modulated radiotherapy of prostate.BackgroundMultifield techniques produce large volumes of low dose inside the patient body. Delivered dose could be the result of the cytotoxic injuries of the cells even away from the treatment field. We calculated the total dose absorbed in the patient body for four radiotherapy techniques to investigate whether some methods have a potential to reduce the exposure to the patient.Materials and methodsWe analyzed CyberKnife plans for 10 patients with localized prostate cancer. Five alternative plans for each patient were calculated with the VMAT, IMRT and TomoTherapy techniques. Alternative dose distributions were calculated to achieve the same coverage for PTV. Integral Dose formula was used to calculate the total dose delivered to the PTV and whole patient body.ResultsAnalysis showed that the same amount of dose was deposited to the treated volume despite different methods of treatment delivery. The mean values of total dose delivered to the whole patient body differed significantly for each treatment technique. The highest integral dose in the patient's body was at the TomoTherapy and CyberKnife treatment session. VMAT was characterized by the lowest integral dose deposited in the patient body.ConclusionsThe highest total dose absorbed in normal tissue was observed with the use of a robotic radiosurgery system and TomoTherapy. These results demonstrate that the exposure of healthy tissue is a dosimetric factor which differentiates the dose delivery methods

The Effectiveness and Toxicity of Frameless CyberKnife Based Radiosurgery for Parkinson’s Disease—Phase II Study

Frame-based stereotactic radiosurgery (SRS) has an established role in the treatment of tremor in patients with Parkinson’s disease (PD). The low numbers of studies of frameless approaches led to our prospective phase 2 open-label single-arm clinical trial (NCT02406105), which aimed to evaluate the safety and efficacy of CyberKnife frameless SRS. Twenty-three PD patients were irradiated on the area of the thalamic ventral nuclei complex with gradually increasing doses of 70 to 105 Gy delivered in a single fraction. After SRS, patients were monitored for tremor severity and the toxicity of the treatment. Both subjective improvement and dose-dependent efficacy were analysed using standard statistical tests. The median follow-up was 23 months, and one patient died after COVID-19 infection. Another two patients were lost from follow-up. Hyper-response resulting in vascular toxicity and neurologic complications was observed in two patients irradiated with doses of 95 and 100 Gy, respectively. A reduction in tremor severity was observed in fifteen patients, and six experienced stagnation. A constant response during the whole follow-up was observed in 67% patients. A longer median response time was achieved in patients irradiated with doses equal to or less than 85 Gy. Only two patients declared no improvement after SRS. The efficacy of frameless SRS is high and could improve tremor control in a majority of patients. The complication rate is low, especially when doses below 90 Gy are applied. Frameless SRS could be offered as an alternative for patients ineligible for deep brain stimulation; however, studies regarding optimal dose are required