RADAR Reference Adult, Pediatric, and Pregnant Female Phantom Series for Internal and External Dosimetry

Abstract

A new generation of reference computational phantoms, based on image-based models tied to the reference masses defined by the International Commission on Radiological Protection (ICRP) for dose calculations, is presented. Methods Anatomic models based on nonuniform rational b-spline modeling techniques were used to define reference male and female adults, 15-y-olds, 10-y-olds, 5-y-olds, 1-y-olds, newborns, and pregnant women at 3 stages of gestation, using the defined reference organ masses in ICRP publication 89. Absorbed fractions and specific absorbed fractions for internal emitters were derived using standard Monte Carlo radiation transport simulation codes. Results Differences were notable between many pairs of organs in specific absorbed fractions because of the improved realism of the models, with adjacent organs usually closer and sometimes touching. Final estimates of absorbed dose for radiopharmaceuticals, for example, were only slightly different overall, as many of the differences were small and most pronounced at low radiation energies. Some new important organs were defined (salivary glands, prostate, eyes, and esophagus), and the identity of a few gastrointestinal tract organs changed. Conclusion A new generation of reference models for standardized internal and external dose calculations has been defined. The models will be implemented in standardized software for internal dose calculations and be used to produce new standardized dose estimates for radiopharmaceuticals and other applications.

New Fetal Dose Estimates from 18F-FDG Administered During Pregnancy: Standardization of Dose Calculations and Estimations with Voxel-Based Anthropomorphic Phantoms

“…The present study sought to establish new standard fetal doses from 18 F-FDG administration during pregnancy, using realistic voxel-based anthropomorphic phantoms (16). The value found in early pregnancy (2.5E-2 mGy/MBq) is comparable to the current standard value (2.2E-2 mGy/MBq) estimated from monkey data (2).…”

“…By contrast, the fetuses of the first and second trimester are significantly smaller in the new phantoms (85 and 1,114 g, compared with 458 and 1,642 g, respectively), and thus the doses were higher (170% and 135%, respectively). Dose differences are also partly explained by the different disposition of the organs inside the voxel-based phantoms, which tend to be more closely associated than those in the old phantoms (16).…”

“…The time-integrated activities were entered into OLINDA/EXM software using both the version 1.1 (17), which contains the old anthropomorphic phantoms of Cristy and Eckerman, and the version 2.0, which contains the more realistic RADAR phantoms (16). For women in early pregnancy, the dose to the uterus was calculated using the anthropomorphic phantom of the nonpregnant woman.…”

High-grade cervical dysplasia in pregnancy – psychological and medical challenges

“…In order to standardize all external and internal dosages, a new generation of models is under development using standardized software for internal dose calculations based on the dose estimates for radiopharmaceuticals (12).…”

A set of 4D pediatric XCAT reference phantoms for multimodality research

“…Voxelized phantoms, [16][17][18] which are based on segmented patient data, provide a realistic anatomy; however, their voxelized nature limits anatomical variations and motion. Hybrid phantoms [19][20][21][22][23][24] combine the advantages of voxelized and mathematical phantoms: they are based on segmented patient data to create a realistic anthropomorphic anatomy, and use nonuniform rational B-spline (NURBS) surfaces and polygon meshes to define each anatomical object, so that organ variations and movement are easily performed with rigid and nonrigid transformations. However, due to the time-consuming process of development, the number of existing hybrid phantoms is limited, most modeling adults with few pediatric anatomies.…”