Modern conformal radiation therapy using techniques such as modulation, image guidance and motion management have changed the face of radiotherapy today offering superior conformity, efficiency, and reproducibility to clinics worldwide. This review assesses the impact of these advanced radiotherapy techniques on patient toxicity and survival rates reported from January 2017 to September 2020. The main aims are to establish if dosimetric and efficiency gains correlate with improved survival and reduced toxicities and to answer the question ‘What is the clinical evidence for the most effective implementation of VMAT?’. Compared with 3DCRT, improvements have been reported with VMAT in prostate, locally advanced cervical carcinoma and various head and neck applications, leading to the shift in technology to VMAT. Other sites such as thoracic neoplasms and nasopharyngeal carcinomas have observed some improvement with VMAT although not in line with improved dosimetric measures, and the burden of toxicity and the incidence of cancer related deaths remain high, signaling the need to further mitigate toxicity and increase survival. As technological advancement continues, large randomised long-term clinical trials are required to determine the way-forward and offer site-specific recommendations. These studies are usually expensive and time consuming, therefore utilising pooled real-world data in a prospective nature can be an alternative solution to comprehensively assess the efficacy of modern radiotherapy techniques.

Exposure to electromagnetic radiation (EMR) from intermediate frequency sources has increased exponentially in recent years. The consequences of this exposure on biological systems are prompting scientists to study the effects on human health. This current study aimed to determine the effects of intermediate frequency (150 kHz) EMR exposure on the vital organs of female Sprague Dawley rats. The EMR group (n = 10 animals) was exposed to a frequency of 150 kHz with an intensity of 65 ± 15 μW/cm² for two months. The control group (n = 10 animals) was exposed to an intensity of 35 ± 15 nW/cm². Haematological, histochemical, gross, and histopathological profiles of all major organs of all animals were then performed using standard procedures. All major organs generally showed no significant detectable effects in either the control or EMR groups. However, gross and histopathological examinations revealed the effects of EMR on the liver and lungs, which showed inflammatory changes without significant biochemical/haematological manifestations. In addition, a significant increase in serum sodium level and a decrease in serum urea level were also observed in the EMR group. It can be concluded that the current frequency and duration of exposure trigger the changes in the liver and lungs but are not sufficient to cause clinical and functional manifestations. Therefore, a long-term exposure study might be helpful to determine the effects of 150 kHz IF EMR on these organs.

The effects of low-dose radiation exposure remain a controversial topic in radiation biology. This study compares early (0.5, 4, 24, 48, and 72 h) and late (5, 10, and 15 cell passages) post-irradiation changes in γH2AX, 53BP1, pATM, and p-p53 (Ser-15) foci, proliferation, autophagy, and senescence in primary fibroblasts exposed to 100 and 2000 mGy X-ray radiation. The results show that exposure to 100 mGy significantly increased γH2AX, 53BP1, and pATM foci only at 0.5 and 4 h post irradiation. There were no changes in p-p53 (Ser-15) foci, proliferation, autophagy, or senescence up to 15 passages post irradiation at the low dose.

An open question in radiobiology concerns whether low doses of radiation are harmful or if cells are able to tolerate such exposure with minimal or no disruption. This issue is relevant for evaluating public health risks associated with the increasing number of medical computed tomography (CT) diagnostic procedures. This study evaluated the impact of CT scan-level exposure on human adipose mesenchymal stem cells (hMSCs) by measuring DNA damage responses (γH2AX, 53BP1, pATM foci), proliferation (Ki-67), senescence (β-galactosidase), and multiple gene expressions. Responses to one or five CT exposures were compared to a 2 Gy X-ray dose at intervals from 1 h to 10 passages post-irradiation. It was shown that CT scan briefly increased DNA damage markers but showed no significant long-term effects. A high dose of 2 Gy X-ray exposure caused sustained DNA damage, decreased proliferation, increased senescence, and significant changes in hundreds of genes even after several cell generations. After a single CT exposure, gene expression changes were minimal, while high-dose exposure led to strong activation of DNA repair and stress response pathways. Five CT scans caused a slight activation of LIF and HSPA1B genes, but these effects were minor compared to the high-dose group. All detected effects from CT scans were not observed by ten cell passages, whereas high-dose effects persisted. In conclusion, typical CT scan exposures have only short-term, mild effects on hMSCs, while high-dose radiation causes lasting cellular and genetic changes.

The growing use of computed tomography (CT) in medicine requires a better understanding of how low-dose radiation affects human stem cells. This study investigated the long-term consequences of CT-level radiation on the secretory profile of human adipose-derived mesenchymal stem cells (AD-MSCs). AD-MSCs were exposed to radiation regimens simulating a single or multiple head CT scans, or to a single 2 Gy therapeutic dose, and their secretion of 41 cytokines, chemokines, and growth factors was monitored during long-term culture. At the early passage, AD-MSCs receiving a single 2 Gy dose showed a coordinated increase in several lymphocyte-regulating cytokines compared to cells exposed to multiple CT scans. However, these initial differences were not sustained. Long-term culturing led to a progressive and widespread decrease in the secretion of 26 cytokines, chemokines, and growth factors across all groups. By the latest passage, all irradiated cells showed a generalized reduction in secretory function compared to non-irradiated controls. These findings demonstrate that while different radiation regimens trigger distinct immediate responses, long-term culture results in a broad decline of the AD-MSCs secretome, which is accentuated by prior radiation exposure. This underscores the importance of assessing long-term consequences to fully evaluate the functional impact of diagnostic radiation on stem cells.

International Conference on Emerging Trends in Engineering and Technology (IConETech-2020)