Evaluation of UVA emission from X-ray megavoltage-irradiated tissues and phantoms.

In this study, we develop a UVA-imaging technique to quantify relative UVA CL produced by bulk tissues and other phantoms upon clinical X-ray megavoltage irradiation. 
 UVA CL emission (320-400nm) was quantified in tissue samples of porcine and poultry and in two kinds of solid waters (SW): brown (Standard Imaging, Virtual Waters and white (CIRS, Diagnostic Therapy), and in 1% agarose gels variously doped with absorbing dye. Quantification was achieved through cumulative imaging of the samples placed in a dark, light-blocking chamber during irradiation on a Varian 21 EX accelerator. UVA imaging required a specialized high-sensitivity cooled camera equipped with UVA lenses and a filter. At 15MV, white SW emitted 66 ± 5%, 64 ± 5% and 76 ± 3% less UVA than chicken, pork loin and pork belly respectively. Similar under-response was observed at 6MV. Brown SW had 21 ± 8% less UVA emission than white SW at 15MV, and negligible emission at 6MV. Agarose samples (1% by weight) doped with 250ppm India ink exhibited equivalent UVA CL emission to chicken breast (within 8%). 
 The results confirm that for the same absorbed dose, SW emits less UVA light than the tissue samples, indicating that prior in vitro studies utilizing SW as the CL-generating source may have underestimated the RECA therapeutic effect. Agarose doped with 250ppm India ink is a convenient tissue-equivalent phantom for further work. PMID: 31505474 [PubMed - as supplied by publisher]
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research