Purpose: Test and comparison of various 2-D real-time detectors for dosimetric quality assurance (QA) of intensity-modulated radiotherapy (IMRT) with the vision to replace radiographic films for 2-D dosimetry.
Material And Methods: All IMRT treatment plans were created with the Konrad software (Siemens OCS). The final dose calculation was also carried out in Konrad. A Mevatron Primus (Siemens OCS) linear accelerator which provides 6-MV and 15-MV highenergy photon beams was used for the delivery of segmented multileaf-modulated IMRT. Three different 2-D detectors, each based on a different physical (interaction) principle, were tested for the field-related IMRT verification: (1) the MapCheck diode system (Sun Nuclear), (2) the I'mRT QA scintillation detector (Scanditronix/Wellhöfer), and the Seven29 ionization chamber array (PTW). The performance of these detector arrays was evaluated against IMRT dose distributions created and calculated with Konrad and the results obtained were compared with film measurements performed with radiographic films (EDR2, Kodak). Additionally, measurements were performed with point detectors, such as diamond, diodes (PTW) and ionization chambers (PTW, Scanditronics/ Wellhöfer) and radiochromic films (GafChromic film MD55, ISP).
Results: The results obtained with all three 2-D detector systems were in good agreement with calculations performed with the treatment-planning system and with the standard dosimetric tools, i.e., films or various point dose detectors. It could be shown that all three systems offer dosimetric characteristics required for performing field-related IMRT QA with relative dose measurements. The accuracy of the 2-D detectors was mostly +/- 3% normalized to dose maximum for a wide dynamic range. The maximum deviations did not exceed +/- 5% even in regions with a steep dose gradient. The main differences between the detector systems were the spatial resolution, the maximal field size, and the ability to perform absolute dosimetric measurements.
Conclusion: Commercial 2-D detectors have the potential to replace films as an "area detector" for field-related verification of IMRT. The on-line information provided by the respective systems can even improve the efficiency of the QA procedures.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1007/s00066-005-1381-z | DOI Listing |
Rev Sci Instrum
December 2024
J-PARC Center, Japan Atomic Energy Agency, 2-4, Shirakata, Tokai-mura, Ibaraki, Japan.
A gas-sheet beam profile monitor enabling non-destructive two-dimensional profile measurements of a high-intensity beam by capturing an image of a beam-induced fluorescence was developed. For quantitative profile measurements, the monitor's response function comprising, e.g.
View Article and Find Full Text PDFTalanta
January 2025
College of Ocean Food and Biological Engineering, Jimei University, Xiamen, 361021, China. Electronic address:
Organophosphorus pesticides (OPPs) present in tea infusions pose a serious threat to human health. In this study, a sensitive method for the determination of OPPs was developed based on a direct-immersion solid-phase microextraction (DI-SPME) probe. By fine adjustment of the ratio and one-step polymerization of dihydroxy-functionalized zirconium-based metal-organic framework UiO-66-(OH) and divinylbenzene-N-vinyl pyrrolidone (DVB-NVP) microspheres, the DVB-NVP@ UiO-66-(OH) (D-N@U) composite with an optimal hydrophilic-lipophilic balance (HLB) was achieved.
View Article and Find Full Text PDFRadiat Oncol
July 2024
Department of Radiation Oncology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Background: Conventional single-energy CT can only provide a raw estimation of electron density (ED) for dose calculation by developing a calibration curve that simply maps the HU values to ED values through their correlations. Spectral CT, also known as dual-energy CT (DECT) or multi-energy CT, can generate a series of quantitative maps, such as ED maps. Using spectral CT for radiotherapy simulations can directly acquire ED information without developing specific calibration curves.
View Article and Find Full Text PDFAppl Radiat Isot
July 2024
Northwest Institute of Nuclear Technology, Xi'an, 710024, China.
Precise determination of half-lives of Tm and Tm are important for their application in nuclear medicine diagnostics, nuclear forensics, and other nuclear data measurements. We produced Tm and Tm sources using an α-particle beam bombarded Ho target and a series purification steps. A series of 173 measurements was performed over a period of 44 days using a high-purity germanium (HPGe) detector to track the count rate change as a function of time by following the 207.
View Article and Find Full Text PDFJ Microsc
September 2024
Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, UK.
Here we show that compressive sensing allows 4-dimensional (4-D) STEM data to be obtained and accurately reconstructed with both high-speed and reduced electron fluence. The methodology needed to achieve these results compared to conventional 4-D approaches requires only that a random subset of probe locations is acquired from the typical regular scanning grid, which immediately generates both higher speed and the lower fluence experimentally. We also consider downsampling of the detector, showing that oversampling is inherent within convergent beam electron diffraction (CBED) patterns and that detector downsampling does not reduce precision but allows faster experimental data acquisition.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!