Tolerance levels of CT number to electron density table for photon beam in radiotherapy treatment planning system
| Autor: | Yasushi Nagata, Hiroshige Nozaki, Yusuke Ochi, Kosaku Habara, Minoru Nakao, Daisuke Kawahara, Takeo Nakashima, Yoshiharu Morimoto, Fumika Hosono, Shuichi Ozawa, Akito Saito, Toru Yoshizaki, Kiyoshi Yamada, Masahiro Hayata, Kentaro Miki, Katsunori Yogo |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Electron density
Materials science Adipose tissue Electrons quality assurance Table (information) Imaging phantom flattening‐filter‐free beam 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine tolerance level Neoplasms Calibration medicine Technical Note Humans Radiology Nuclear Medicine and imaging electron density Instrumentation 87.55.d Photons Radiation business.industry Phantoms Imaging Radiotherapy Planning Computer-Assisted Radiotherapy Dosage Radiotherapy treatment planning CT number medicine.anatomical_structure 030220 oncology & carcinogenesis 87.55.Qr Cortical bone Radiotherapy Intensity-Modulated Technical Notes Particle Accelerators Nuclear medicine business Tomography X-Ray Computed Beam (structure) Algorithms |
| Zdroj: | Journal of Applied Clinical Medical Physics |
| ISSN: | 1526-9914 |
| Popis: | The accuracy of computed tomography number to electron density (CT‐ED) calibration is a key component for dose calculations in an inhomogeneous medium. In a previous work, it was shown that the tolerance levels of CT‐ED calibration became stricter with an increase in tissue thickness and decrease in the effective energy of a photon beam. For the last decade, a low effective energy photon beam (e.g., flattening‐filter‐free (FFF)) has been used in clinical sites. However, its tolerance level has not been established yet. We established a relative electron density (ED) tolerance level for each tissue type with an FFF beam. The tolerance levels were calculated using the tissue maximum ratio (TMR) and each corresponding maximum tissue thickness. To determine the relative ED tolerance level, TMR data from a Varian accelerator and the adult reference computational phantom data in the International Commission on Radiological Protection publication 110 (ICRP‐110 phantom) were used in this study. The 52 tissue components of the ICRP‐110 phantom were classified by mass density as five tissues groups including lung, adipose/muscle, cartilage/spongy‐bone, cortical bone, and tooth tissue. In addition, the relative ED tolerance level of each tissue group was calculated when the relative dose error to local dose reached 2%. The relative ED tolerances of a 6 MVFFF beam for lung, adipose/muscle, and cartilage/spongy‐bone were ±0.044, ±0.022, and ±0.044, respectively. The thicknesses of the cortical bone and tooth groups were too small to define the tolerance levels. Because the tolerance levels of CT‐ED calibration are stricter with a decrease in the effective energy of the photon beam, the tolerance levels are determined by the lowest effective energy in useable beams for radiotherapy treatment planning systems. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text