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Selection of bone dosimetry models for application in Monte Carlo simulations to provide CT scanner-specific organ dose coefficients
| Content Provider | Scilit |
|---|---|
| Author | Jansen, Jan T. M. Shrimpton, Paul C. Holroyd, John Richard Edyvean, Sue |
| Copyright Year | 2018 |
| Description | Journal: Physics in Medicine & Biology This is the second paper arising from a project concerning the application of Monte Carlo simulations to provide scanner-specific organ dose coefficients for modern CT scanners. The present focus is centred on the bone dosimetry models that have been developed. Simulations have been performed in photon only transport mode, with the assumption of electron equilibrium. This approximation breaks down for doses to active marrow and endosteum since the target cells are localised within tens of micrometre from bone tissue and dose enhancement functions are necessary to correct for the additional dose from photoelectric electrons created in adjacent material. The dose enhancement models used previously in publications NRPB-SR250 (Jones & Shrimpton 1993) and ORNL-TM8381 (Cristy & Eckerman 1987) have been implemented and compared with the contemporary approaches of Johnson et al. (2011) and ICRP Publication 116 (ICRP 2010) that are being adopted in the present project. In addition, the calculation of dose to endosteum in the medullary cavity is reviewed and updated using electron mode simulations. For the purposes of quality assurance and comparison, the various dose enhancement functions have been applied in relation to the NRPB18+DJ and HPA18+ stylised hermaphrodite phantoms and also the adult male and female voxel phantoms recommended in ICRP Publication 110 (ICRP 2009), for exposure from three CT scanners modelled previously. Contemporary results for standard examinations on the head and trunk calculated for these latter phantoms demonstrate moderate increases (modal value +18%) in active marrow dose coefficients relative to values derived from data published in NRPB-SR250. A similar analysis in relation to endosteum dose coefficients shows larger reductions (modal value −46%), owing at least in part to changes in assumed location of the target cells. Even larger changes are apparent for both of these dose coefficients in relation to examination of the upper legs (−39% and −94%, respectively). However, resultant changes in any values of effective dose will be less owing to the low weighting factors applied for these tissues. |
| Related Links | http://iopscience.iop.org/article/10.1088/1361-6560/aac717/pdf |
| ISSN | 00319155 |
| e-ISSN | 13616560 |
| DOI | 10.1088/1361-6560/aac717 |
| Journal | Physics in Medicine & Biology |
| Issue Number | 12 |
| Volume Number | 63 |
| Language | English |
| Publisher | IOP Publishing |
| Publisher Date | 2018-05-22 |
| Access Restriction | Open |
| Subject Keyword | Journal: Physics in Medicine & Biology Bone Dosimetry Ct Scanner Dose Enhancement Factors Monte Carlo Simulation Stylised and Voxel Phantoms |
| Content Type | Text |
| Resource Type | Article |
| Subject | Radiology, Nuclear Medicine and Imaging Radiological and Ultrasound Technology |
