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Tolerance levels of mass density for CT number calibration in photon radiation therapy
- Source :
- Journal of Applied Clinical Medical Physics
- Publication Year :
- 2019
- Publisher :
- Wiley, 2019.
-
Abstract
- Computed tomography (CT) data are required to calculate the dose distribution in a patient’s body. Generally, there are two CT number calibration methods for commercial radiotherapy treatment planning system (RTPS), namely CT number‐relative electron density calibration (CT‐RED calibration) and CT number‐mass density calibration (CT‐MD calibration). In a previous study, the tolerance levels of CT‐RED calibration were established for each tissue type. The tolerance levels were established when the relative dose error to local dose reached 2%. However, the tolerance levels of CT‐MD calibration are not established yet. We established the tolerance levels of CT‐MD calibration based on the tolerance levels of CT‐RED calibration. In order to convert mass density (MD) to relative electron density (RED), the conversion factors were determined with adult reference computational phantom data available in the International Commission on Radiological Protection publication 110 (ICRP‐110). In order to validate the practicability of the conversion factor, the relative dose error and the dose linearity were validated with multiple RTPSes and dose calculation algorithms for two groups, namely, CT‐RED calibration and CT‐MD calibration. The tolerance levels of CT‐MD calibration were determined from the tolerance levels of CT‐RED calibration with conversion factors. The converted RED from MD was compared with actual RED calculated from ICRP‐110. The conversion error was within ±0.01 for most standard organs. It was assumed that the conversion error was sufficiently small. The relative dose error difference for two groups was less than 0.3% for each tissue type. Therefore, the tolerance levels for CT‐MD calibration were determined from the tolerance levels of CT‐RED calibration with the conversion factors. The MD tolerance levels for lung, adipose/muscle, and cartilage/spongy‐bone corresponded to ±0.044, ±0.022, and ±0.045 g/cm3, respectively. The tolerance levels were useful in terms of approving the CT‐MD calibration table for clinical use.
- Subjects :
- Organs at Risk
Dose linearity
Calibration (statistics)
87.55.Qr
Photon radiation therapy
Dose distribution
mass density
030218 nuclear medicine & medical imaging
photon radiation therapy
03 medical and health sciences
Radiation Protection
0302 clinical medicine
tolerance level
Ct number
Image Processing, Computer-Assisted
Humans
Radiation Oncology Physics
Radiology, Nuclear Medicine and imaging
radiation treatment planning
87.55.d
Instrumentation
Mathematics
Photons
Radiation
Phantoms, Imaging
Radiotherapy Planning, Computer-Assisted
Conversion factor
Radiotherapy Dosage
Radiotherapy treatment planning
030220 oncology & carcinogenesis
Calibration
Tissue type
Tomography, X-Ray Computed
Algorithms
CT number calibration
Biomedical engineering
Subjects
Details
- ISSN :
- 15269914
- Volume :
- 20
- Database :
- OpenAIRE
- Journal :
- Journal of Applied Clinical Medical Physics
- Accession number :
- edsair.doi.dedup.....3972fc40e008b80d8d2995d214ecef2a