The MCART radiation physics core: the quest for radiation dosimetry standardization

Abstract

Dose-related radiobiological research results can only be compared meaningfully when radiation dosimetry is standardized. To this purpose, the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored Medical Countermeasures Against Radiological Threats (MCART) consortium recently created a Radiation Physics Core (RPC) as an entity to assume responsibility of standardizing radiation dosimetry practices among its member laboratories. The animal research activities in these laboratories use a variety of ionizing photon beams from several irradiators such as 250-320 kVp x-ray generators, Cs irradiators, Co teletherapy machines, and medical linear accelerators (LINACs). In addition to this variety of sources, these centers use a range of irradiation techniques and make use of different dose calculation schemes to conduct their experiments. An extremely important objective in these research activities is to obtain a Dose Response Relationship (DRR) appropriate to their respective organ-specific models of acute and delayed radiation effects. A clear and unambiguous definition of the DRR is essential for the development of medical countermeasures. It is imperative that these DRRs are transparent between centers. The MCART RPC has initiated the establishment of standard dosimetry practices among member centers and is introducing a Remote Dosimetry Monitoring Service (RDMS) to ascertain ongoing quality assurance. This paper will describe the initial activities of the MCART RPC toward implementing these standardization goals. It is appropriate to report a summary of initial activities with the intent of reporting the full implementation at a later date.

Figure 1

Figure 1a. Percent Mortality vs. Dose of TBI in rhesus macaques. Figure 1b. Radiation dose response relationship of C57BL/6 mice

Figure 1

Figure 1a. Percent Mortality vs. Dose of TBI in rhesus macaques. Figure 1b. Radiation dose response relationship of C57BL/6 mice

Figure 2

MCART RPC organizational chart. The abbreviations used are as follows: - UMB: University of Maryland, Baltimore, RPC: Radiation Physics Core, H: Hematopoietic, GI: GastroIntestinal, ARS: Acute Radiation Syndrome, DEARE: Delayed effects of Acute Radiation Exposure.

Figure 3

Figure 3a. Mouse Phantom with holding capacity of 3 nanoDots with one dot mark on top. Figure 3b. Mouse Phantom with holding Capacity of 6 nanoDots with two dot marks on Top. Figure 3c. Mouse phantoms with ion chamber receptacles.

Figure 3

Figure 3a. Mouse Phantom with holding capacity of 3 nanoDots with one dot mark on top. Figure 3b. Mouse Phantom with holding Capacity of 6 nanoDots with two dot marks on Top. Figure 3c. Mouse phantoms with ion chamber receptacles.

Figure 3

Figure 3a. Mouse Phantom with holding capacity of 3 nanoDots with one dot mark on top. Figure 3b. Mouse Phantom with holding Capacity of 6 nanoDots with two dot marks on Top. Figure 3c. Mouse phantoms with ion chamber receptacles.

Figure 4

Figure 4a. Beam Quality measurement Figure 4b. Dose Linearity measurement

Figure 4

Figure 4a. Beam Quality measurement Figure 4b. Dose Linearity measurement

Figure 5

Pre-Irradiation Dosimetry Log, to record output QA to be performed prior to each irradiation.

Figure 6

A sample prescription form to be filled out prior to animal irradiation.

Figure 7

Removable Pb shields used for lung irradiation. Pb sheets A and E are 8 cm wide; B, C, and D are each 4 cm wide. The width of the gap is changed by moving section E and A.

Figure 8

A sample of intra-irradiation port film clearly showing extent of lung being irradiated. The occurrences of less than 100% lung irradiations are indicated by ‘X’ marks.