Znalost dávky na kůži pacienta a v hloubkách od povrchu kůže do hloubky maxima dávky je pro klinické využití fotonových svazků lineárního urychlovače velmi důležitá. Hodnoty těchto dávek závisí nejen na kvalitě svazku a jeho kolimaci, ale také na modifikátorech svazku, jako jsou klíny, bloky, a zejména na užití pomůcek pro fixaci pacienta. Měření uvedených dávek in vivo je velmi složité, a proto se hodnoty těchto dávek obvykle stanovují měřením na fantomech. Cílem této práce bylo ověřit metodu, která by při stávajícím přístrojovém vybavení pracoviště umožnila odhadnout dávku na kůži a průběh dávky v přechodové oblasti pro různé klinické situace. Práce uvádí hodnoty naměřené ve fotonových svazcích lineárního urychlovače Clinac 2100 C.
Knowledge of absorbed dose in the skin of a patient and in the build-up region in the photon beams of linear accelerators is very important in the clinical practice of radiotherapy. The values of these doses depend not only on the quality of the beam and its collimation, but also on the use of beam modifiers, such as wedges, beam shaping blocks and especially on the means of patient immobilisation. In vivo determination of the skin and build-up dose is very difficult and assessment of their values is usually performed on phantoms. The aim of the present work was to verify a method, allowing the use of available equipment for evaluation of skin and build up dose in different clinical situations. Actual doses measured in photon beams of linear accelerator Clinac 2100 C are presented.
BACKGROUND AND AIMS: As treatments for primary cancers continue to improve life expectancy, unfortunately, brain metastases also appear to be constantly increasing and life expectancy for patients with brain metastases is low. Longer survival and improved quality of life may be achieved using localised radiological and surgical approaches in addition to low dose corticosteroids. Stereotactic brain radiotherapy is one rapidly evolving localized radiation treatment. This article describes our experience with stereotactic radiotherapy using a linear accelerator. METHODS: We reviewed patients treated with stereotactic radiotherapy, from the time of its introduction into daily practice in our Department of Oncology in 2014. We collected the data on patient treatment and predicted survival based on prognostic indices and actual patient outcome. RESULTS: A total of 10 patients were treated by stereotactic radiotherapy, in one case in combination with whole brain radiotherapy and hippocampal sparing. There was no significant treatment related toxicity during the treatment or follow-up and due to the small number of fractions, the overall tolerance of the treatment was excellent. The patient intrafractional movement in all cases was under 1 mm suggesting that 1 mm margin around the CTV to create the PTV is sufficient and also that patient immobilization using the thermoplastic mask compared with invasive techniques, is feasible. We also found that prognostic indices such as the Graded Prognostic Assessment provide accurate predictions of patient survival. CONCLUSIONS: Based on our current evidence, patients with brain metastases fit enough, should be considered for stereotactic radiotherapy treatment.
- MeSH
- Particle Accelerators MeSH
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Brain Neoplasms mortality radiotherapy secondary MeSH
- Radiosurgery instrumentation mortality MeSH
- Retrospective Studies MeSH
- Aged MeSH
- Feasibility Studies MeSH
- Treatment Outcome MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
PURPOSE: The aim of this study was to determine small field correction factors for a synthetic single-crystal diamond detector (PTW microDiamond) for routine use in clinical dosimetric measurements. MATERIALS AND METHODS: Correction factors following small field Alfonso formalism were calculated by comparison of PTW microDiamond measured ratio MQclinfclin/MQmsrfmsrwith Monte Carlo (MC) based field output factors ΩQclin,Qmsrfclin,fmsrdetermined using Dosimetry Diode E or with MC simulation itself. Diode measurements were used for the CyberKnife and Varian Clinac 2100C/D linear accelerator. PTW microDiamond correction factors for Leksell Gamma Knife (LGK) were derived using MC simulated reference values from the manufacturer. RESULTS: PTW microDiamond correction factors for CyberKnife field sizes 25-5 mm were mostly smaller than 1% (except for 2.9% for 5 mm Iris field and 1.4% for 7.5 mm fixed cone field). The correction of 0.1% and 2.0% for 8 mm and 4 mm collimators, respectively, needed to be applied to PTW microDiamond measurements for LGK Perfexion. Finally, PTW microDiamond MQclinfclin/MQmsrfmsrfor the linear accelerator varied from MC corrected Dosimetry Diode data by less than 0.5% (except for 1 × 1 cm2field size with 1.3% deviation). CONCLUSIONS: Regarding low resulting correction factor values, the PTW microDiamond detector may be considered an almost ideal tool for relative small field dosimetry in a large variety of stereotactic and radiosurgery treatment devices.
- MeSH
- Particle Accelerators * MeSH
- Diamond * MeSH
- Uncertainty MeSH
- Radiosurgery instrumentation MeSH
- Radiometry MeSH
- Publication type
- Journal Article MeSH
Technical equipment of radiotherapeutic wards is presently supplemented with irradiators on the principle of a linear accelerator. The paper briefly describes the principle of linear accelerator with standing wave and its basic technical parameters. Data on electric, mechanic and densitometric properties of this apparatus and accessories are presented. Therapeutic beams of bremsstrahlung and electron radiation were characterized in the whole range of energy, i.e. 0.961 and 3.204 pJ (6 and 20 MV) for bremsstrahlung and 0.961 to 3.364 pJ (6 to 21 MeV) for electron radiation. In the last part the performed hygienic measurements are also described.
- MeSH
- Particle Accelerators * MeSH
- Publication type
- English Abstract MeSH
- Journal Article MeSH
The aim of this study was to compare radiosurgical treatment plan quality of a linear accelerator with Leksell Gamma Knife (LGK) for pituitary adenoma irradiation. Thirty pituitary adenoma patients were evaluated in this study. Treatment plans were prepared on LGK and stereotactic linear accelerator Varian TrueBeam STx. Volumetric Modulated Arc Therapy (VMAT) plans (21 plans with 2 coplanar arcs and 9 plans with 4 non-coplanar arcs) were calculated for linear accelerator. All the plans were evaluated in terms of conformity, selectivity, gradient index and organ at risk (OAR) sparing. VMAT produced dosimetrically comparable treatment plans to LGK regarding conformity and selectivity (New Conformity Index (NCI): 1.76 ± 0.65 for 4 arc VMAT, 2.33 ± 1,16 for 2 arc VMAT and 1.96 ± 0.71 for LGK; Selectivity Index (SI): 0.63 ± 0.16 for 4 arc VMAT, 0.51 ± 0.16 for 2 arc VMAT and 0.58 ± 0.17 for LGK). Gradient index (GI) was superior for LGK plans (GI: 2.74 ± 0.20 for LGK and 5.28 ± 2.29 for 4 arc VMAT). OAR sparing for optics, brainstem, and hypophysis was similar for both modalities while target volume coverage was maintained the same. Finally, treatment time resulted in favor of VMAT plans (in this study VMAT plans were almost 5 times faster than LGK treatment regarding beam on time). According to the results of this study stereotactic linear accelerator with VMAT treatment could be used as a reasonable alternative to LGK for pituitary adenoma radiosurgery but only if the same head fixation method accuracy and target volume delineation are maintained for both modalities.
- MeSH
- Particle Accelerators MeSH
- Radiotherapy Dosage MeSH
- Humans MeSH
- Pituitary Neoplasms * radiotherapy MeSH
- Brain Neoplasms * surgery MeSH
- Radiotherapy Planning, Computer-Assisted MeSH
- Radiosurgery * MeSH
- Radiotherapy, Intensity-Modulated * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
V moderní rádioterapii se při optimalizaci dávkové distribuce stále více uplatňují dynamické techniky. Jednou z těchto technik, užívaných u klinických lineárních urychlovačů, je dynamický kHn. Dodání předepsané dávky je řízeno a kontrolováno řídícím a kontrolním systémem urychlovače. Klinická aplikace dynamických klínuje vázána na použití plánovacího systému (TPS). V případě použití TPS CadPlan není k výpočtu polí s dynamickými klíny nutno provádět dodatečná měření, pole s dynamickými kliny jsou modelována na základě dat otevřených polí. V práci je uvedeno srovnáni výsledků výpočtů profilů, křivek hloubkových dávek a klínových faktorů ozařovacích polí lineárního urychlovače Clinac 600C s dynamickými klíny, provedených plánovacím systémem CadPlan v. 3.1.3, s hodnotami týchž parametrů, naměřenými ve vodním fantomu WeUhofer. Dosažené výsledky svědčí o tom, že správnost výpočtů dat polí s dynamickými klíny vyhovuje náročným požadavkům soudobé rádioterapie.
Enhanced dynamic wedge is one of the dynamic delivery techniques in radiotherapy, which allows optimizing final dose distribution. Treatment planning the above-mentioned technique is done with the help of a treatment planning system (TPS). Calculation accuracy of commercially available TPS CadPlan has been performed for a variety of fields with enhanced dynamic wedge. Data calculated by TPS were compared with measurements in water phantom. The comparison based on percentage Lose curves and transversal profiles indicated, that for all calculation points the agreement between calculation and measurement was better than 2% or 4 mm respectively.
- Keywords
- volumetric modulated arc therapy, Octavius QA system,
- MeSH
- Particle Accelerators MeSH
- Radiotherapy Setup Errors prevention & control MeSH
- Film Dosimetry instrumentation MeSH
- Humans MeSH
- Head and Neck Neoplasms radiotherapy MeSH
- Prostatic Neoplasms radiotherapy MeSH
- Radiotherapy Planning, Computer-Assisted * MeSH
- Radiometry standards instrumentation MeSH
- Radiotherapy, Intensity-Modulated * methods standards instrumentation MeSH
- Reproducibility of Results MeSH
- Quality Control * MeSH
- Rotation MeSH
- Gamma Rays MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Publication type
- Evaluation Study MeSH
