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Comparision of beam data requirements for MLC commissioning on a TPS

100%

Solaiappan G., Singaravelu G., Prakasarao A., Supe S.

Polish Journal of Medical Physics And Engineering

2008

vol. 14

issue 2

63-77

The treatment planning system (TPS) has become a key element in the radiotherapy process with the introduction of computer tomography (CT) based 3D conformal treatment planning. Commissioning of a MLC on a TPS either for conformal radiotherapy or intensity modulated radiation therapy (IMRT) requires beam data to be generated on a linear accelerator. Most of the TPS require these beam data to be generated with routine collimator jaws. However some TPS demand the data to be provided for MLC shaped fields. This prompted us to investigate whether beam data with jaws differ than that with MLC and whether the jaw based beam data would suffice for the commissioning of a MLC on a TPS.Beam data like percentage depth dose (PDD), cross beam profiles and output factors was acquired for jaws and MLC defined square fields for 6, 10 and 23 MV photon beams. Percentage depth dose and cross beam profiles were acquired with a radiation field analyzer RFA-200, CC13-S ion chambers with active volume of 0.13 cm3 and OmniPro-Accept software from Scanditronix-Wellhofer. A Medtec-TG51 water tank with Max-4000 electrometer and 0.6 cc PTW ionization chamber and a mini phantom from Standard Imaging was utilized for output measurements for millennium-120 MLC (Varian Medical Systems) and SRS diode detector (Scanditronix-Wellhofer) of 0.6 mm diameter of active area and 0.3 mm of active volume thickness for micro-MLC (BrainLab).The difference in PDD in the build-up region for millennium MLC was ±1.0% for 6 MV photons. For 10 MV photons the PDD difference was within ±4.0%. The difference in PDD for 23 MV photons ranged from 0% to 40.0%. PDD difference from build-up depth to about 28 cm was within ±1.0%. Difference in PDD crossed ±1.0% at 30 cm depth for 6 MV photons. The difference in PDD in the build-up region for mMLC was ±8.0% for 6 MV photons. For the smallest field size studied with micro-MLC i.e. 0.6 × 0.6 cm2 difference in PDD was more than ±1.0% in the build-up region and beyond a depth of 8.0 cm. The profiles for jaws and MLC agreed within the umbra region. However in the penumbra region small differences in doses were observed. The collimator scatter factor (Sc), phantom scatter factor (Sp) and output factor values for MLC were different that those for jaws.The differences in beam characteristics could have implication for intensity modulated radiation therapy and stereotactic radiosurgery in terms of dose in the build up region, exit dose, dose to the planning target volume (PTV) and organ at risk (OAR). Impact of these dosimetric differences between jaw and MLC needs to be further studied in terms of dose volume histograms for PTV and OAR and its further impact on tumor control probability (TCP) and normal tissue complication probability (NTCP).

Oznaczenia klasycznych markerów nowotworowych u chorych na nowotwory złośliwe narządu rodnego

45%

Kozakiewicz B., Stefaniak M., Dmoch-Gajzlerska E.

Current Gynecologic Oncology

2012

vol. 10

issue 3

226-235

Since the 1970s we are witnessing a continuing search for new markers that would assist in the treatment and follow- up of patients with malignant tumors. First reports on benefits of assessment of tumor markers authored by Goldman and Freedman date back to 1965. Discovery of the first carcinoembryonic antigen (CEA) initiate an era of search for substances, still insufficiently sensitive and specific as to be used to screen tumors, but increasingly helpful in the assessment of treatment effects. This paper discusses the role of tumor markers, increasingly often referred to as “classic” in the monitoring of tumors. We present an update on markers with the longest history in oncology practice, e.g. CEA and on the recently introduced marker TATI. Selection of markers was made based on their role in three basic processes taking place in tumor cells, i.e. proliferation, differentiation and apoptosis. We highlight novel and expanding fields of research – genomics and proteomics, which appear to be the future of oncology. They are extremely useful in the evaluation of molecular prognostic factors, enabling implementationof individually tailored targeted therapies in cancer patients. We discuss classic markers and the few known cancer- specific substances. To sum-up, we state that understanding of the role of more sensitive and more specific markers in oncology may contribute to a more personalized treatment and thus may improve the outcome in cancer patients.

Od lat siedemdziesiątych XX wieku nieustannie poszukuje się nowych markerów, które mogą być pomocne w leczeniu i kontroli po jego ukończeniu u chorych na nowotwory złośliwe. Po raz pierwszy przydatność określania markerów nowotworowych opisali Goldman i Freedman w 1965 roku. Oznaczyli pierwszy marker CEA (karcynoembrionalny) i tak zapoczątkowali erę odkryć substancji o wciąż niezadowalającej czułości i swoistości, aby mogły być używane do skriningu chorób nowotworowych, lecz coraz bardziej przydatnych w ocenie efektu leczenia. W pracy opisano zastosowanie markerów nowotworowych coraz częściej określanych mianem klasycznych w procesie śledzenia chorób nowotworowych. Zaprezentowano najnowsze informacje o markerach najdłużej stosowanych w praktyce onkologicznej, na przykład CEA, jak również o nowo wykorzystywanym markerze TATI. Doboru markerów dokonano na podstawie ich udziału w trzech procesach toczących się w komórkach nowotworowych: proliferacji, różnicowaniu i obumieraniu komórek. Zwrócono uwagę na rozwijające się nowe dyscypliny nauki – genomikę i proteomikę, stanowiące przyszłość onkologii. Są one niezwykle pomocne w określeniu molekularnych czynników predykcyjnych umożliwiających stosowanie leczenia celowanego u chorych na nowotwory złośliwe. Opisano markery klasyczne, a także nieliczne markery molekularne występujące w różnych nowotworach. W podsumowaniu stwierdzono, że poznanie natury markerów o znaczącej czułości i swoistości w chorobach nowotworowych może wpłynąć na personalizację leczenia i tą drogą na poprawę wyleczeń chorych na nowotwory złośliwe.

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1 Current Gynecologic Oncology

1 Polish Journal of Medical Physics And Engineering

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1 Dmoch-Gajzlerska E.

1 Kozakiewicz B.

1 Prakasarao A.

1 Singaravelu G.

1 Solaiappan G.

1 Stefaniak M.

1 Supe S.

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Comparision of beam data requirements for MLC commissioning on a TPS

Oznaczenia klasycznych markerów nowotworowych u chorych na nowotwory złośliwe narządu rodnego