Evaluation of relative transmitted dose for a step and shoot head and neck intensity modulated radiation therapy using a scanning liquid ionization chamber electronic portal imaging device
| Autor: | Eva Bezak, Mohammad Mohammadi |
|---|---|
| Přispěvatelé: | Bezak, Eva, Mohammadi, Mohammadi |
| Rok vydání: | 2012 |
| Předmět: |
lcsh:Medical physics. Medical radiology. Nuclear medicine
Step and shoot transmitted dose map business.industry lcsh:R895-920 Biophysics Radiation Intensity-modulated radiation therapy segmented intensitymodulated radiation therapy scanning liquid ionization chamber electronic portal imaging device Portal imaging head and neck treatment Ionization chamber Calibration Head and neck treatment Medicine Original Article Radiology Nuclear Medicine and imaging Head and neck Nuclear medicine business Radiation treatment planning segmented intensity modulated radiation therapy Biomedical engineering |
| Zdroj: | Journal of Medical Physics, Vol 37, Iss 1, Pp 14-26 (2012) Journal of Medical Physics / Association of Medical Physicists of India |
| ISSN: | 0971-6203 |
| DOI: | 10.4103/0971-6203.92716 |
| Popis: | The dose delivery verification for a head and neck static intensity modulated radiation therapy (IMRT) case using a scanning liquid ionization chamber electronic portal imaging device (SLIC-EPID) was investigated. Acquired electronic portal images were firstly converted into transmitted dose maps using an in-house developed method. The dose distributions were then compared with those calculated in a virtual EPID using the Pinnacle3 treatment planning system (TPS). Using gamma evaluation with the DDmax and DTA criteria of 3%/2.54 mm, an excellent agreement was observed between transmitted dose measured using SLIC-EPID and that calculated by TPS (gamma score approximately 95%) for large MLC fields. In contrast, for several small subfields, due to SLIC-EPID image blurring, significant disagreement was found in the gamma results. Differences between EPID and TPS dose maps were also observed for several parts of the radiation subfields, when the radiation beam passed through air on the outside of tissue. The transmitted dose distributions measured using portal imagers such as SLIC-EPID can be used to verify the dose delivery to a patient. However, several aspects such as accurate calibration procedure and imager response under different conditions should be taken into the consideration. In addition, SLIC-EPID image blurring is another important issue, which should be considered if the SLIC-EPID is used for clinical dosimetry verification. Refereed/Peer-reviewed |
| Databáze: | OpenAIRE |
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