Radiation, Volume 3, Issue 4 (December 2023) – 3 articles

Nuclear sites require regular measurements of the air, soil, and groundwater to ensure the safety of the surrounding environment from potentially hazardous levels of contamination. Although high-energy beta and gamma emitters can often be detected instantly using fixed dosimeters, the detection of low-energy beta emitters is a difficult challenge, especially in groundwater, as its radiation is easily self-absorbed by the surrounding medium. Therefore, it is common practice to sample groundwater and transfer it to a laboratory for analysis using Liquid Scintillation Counting. This work demonstrates a new detector design for the real-time monitoring of tritiated water, a weak beta emitter. This design utilizes a flow cell filled with a granulated scintillator to maximize the surface area of the sample. The cavity is made from plastic sheets, which allow rapid manufacture using readily available lamination sheets. A column of SiPMs in coincidence counting mode has been implemented to reduce noise and allow future extensions to the flow cell for greater detection rates while allowing the detector to fit within limited spaces such as groundwater monitoring boreholes. Using multiple concentrations of tritiated water, this detector has been validated and calibrated, obtaining a minimum detection activity of 26.356 ± 0.889 Bq/mL for a 1-day counting period. Full article

Background: The Chernobyl nuclear disaster is still considered the worst nuclear accident in history. The particles were dispersed over the former USSR and large parts of Western Europe, leading to radioactive exposure to more than 10 million people. Radioactivity is a risk factor for the development of basal cell carcinoma (BCC), since radiation-induced mutations in both Sonic hedgehog (Shh) signaling pathway genes and TP53 have been described. Methods: We present the case of a patient with a history of radiation exposure following the 1986 Chernobyl accident who presented to our outpatient clinic with recurrent basal cell carcinoma in the facial region. Case: The patient presented to our clinic with two facial lesions suspicious for BCC. Although there were no typical risk factors, 11 BCCs had previously been removed. The patient had been building shelters for the construction workers working on the sarcophagus around the destroyed reactor immediately after the 1986 accident. Staging using an 18F-FDG-PET/CT as well as ultrasound of the abdomen revealed no other tumor manifestations. Diagnostic excision of the two facial lesions was performed, and a histopathological workup revealed BCC at the right temporal region and acanthopapillomatosis with no sign of malignancy at the corner of the mouth. After presentation to the tumor board, complete resection of the BCC was initiated. Conclusions: This case demonstrates the value of early use of 18F-FDG-PET/CT in staging/restaging to visualize BCC location, local spread and potential metastases or secondary tumors and to aid in the decision for therapeutic management. Full article

Synchrotron Microbeam Radiation Therapy (MRT) is an innovative technique that spatially segments the synchrotron radiation field for cancer treatment. A microbeam peak dose is often hundreds of times the dose in the valley (the sub-millimeter region between the peaks of the microbeams). Peak and valley doses vary with increasing depth in tissue which effects tumor dose coverage. It remains to be seen whether the peak or valley is the primary factor in MRT cancer control. This study investigates how unilateral MRT doses can be modulated using a bolus, and identifies the valley dose as a primary factor in MRT cancer control. Fischer rats bearing 9 L gliosarcoma tumors were irradiated with MRT at the Imaging and Medical Beam Line of the Australian Synchrotron. MRT valley doses of 8–15 Gy (250–1040 Gy peak doses) were used to treat tumors with and without a 5 mm dose-modulating bolus. Long-term survival depended on the valley dose primarily (92% correlation), and the use of the bolus reduced the variance in animal survival and improved to the mean survival of rats treated with MRT by 47% and 18% using 15 Gy and 8 Gy valley doses, respectively. Full article