TG-51: Experience from 150 institutions, common errors, and helpful hints
| Autor: | Ramesh C. Tailor, Geoffrey S. Ibbott, William F. Hanson |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
medicine.medical_specialty
Electrons Photon energy calibration protocol Imaging phantom 030218 nuclear medicine & medical imaging Radiotherapy High-Energy 03 medical and health sciences 0302 clinical medicine Clinical Protocols Oncology Service Hospital TG‐51 medicine Calibration Radiation Oncology Physics Humans Dosimetry Radiology Nuclear Medicine and imaging Medical physics Instrumentation Physics Protocol (science) Clinical Trials as Topic Photons Radiation dosimetry Medical Errors plane‐parallel chamber United States National Institutes of Health (U.S.) 030220 oncology & carcinogenesis Ionization chamber |
| Zdroj: | Journal of Applied Clinical Medical Physics |
| ISSN: | 1526-9914 |
| Popis: | The Radiological Physics Center (RPC) is a resource to the medical physics community for assistance regarding dosimetry procedures. Since the publication of the AAPM TG-51 calibration protocol, the RPC has responded to numerous phone calls raising questions and describing areas in the protocol where physicists have had problems. At the beginning of the year 2000, the RPC requested that institutions participating in national clinical trials provide the change in measured beam output resulting from the conversion from the TG-21 protocol to TG-51. So far, the RPC has received the requested data from approximately 150 of the approximately 1300 institutions in the RPC program. The RPC also undertook a comparison of TG-21 and TG-51 and determined the expected change in beam calibration for ion chambers in common use, and for the range of photon and electron beam energies used clinically. Analysis of these data revealed two significant outcomes: (i) a large number (approximately 1/2) of the reported calibration changes for photon and electron beams were outside the RPC's expected values, and (ii) the discrepancies in the reported versus the expected dose changes were as large as 8%. Numerous factors were determined to have contributed to these deviations. The most significant factors involved the use of plane-parallel chambers, the mixing of phantom materials and chambers between the two protocols, and the inconsistent use of depth-dose factors for transfer of dose from the measurement depth to the depth of dose maximum. In response to these observations, the RPC has identified a number of circumstances in which physicists might have difficulty with the protocol, including concerns related to electron calibration at low energies (R50 |
| Databáze: | OpenAIRE |
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