Biological and Mechanical Synergies to Deal With Proton Therapy Pitfalls: Minibeams, FLASH, Arcs, and Gantryless Rooms

Proton therapy has advantages and pitfalls comparing with photon therapy in radiation therapy. Among the limitations of protons in clinical practice we can selectively mention: uncertainties in range, lateral penumbra, deposition of higher LET outside the target, entrance dose, dose in the beam path, dose constraints in critical organs close to the target volume, organ movements and cost. In this review, we combine proposals under study to mitigate those pitfalls by using individually or in combination: (a) biological approaches of beam management in time (very high dose rate “FLASH” irradiations in the order of 100 Gy/s) and (b) modulation in space (a combination of mini-beams of millimetric extent), together with mechanical approaches such as (c) rotational techniques (optimized in partial arcs) and, in an effort to reduce cost, (d) gantry-less delivery systems. In some cases, these proposals are synergic (e.g., FLASH and minibeams), in others theyare hardly compatible (mini-beam and rotation). Fixed lines have been used in pioneer centers, or for specific indications (ophthalmic, radiosurgery,…), they logically evolved to isocentric gantries. The present proposals to produce fixed lines are somewhat controversial. Rotational techniques, minibeams and FLASH in proton therapy are making their way, with an increasing degree of complexity in these three approaches, but with a high interest in the basic science and clinical communities. All of them must be proven in clinical applications

Scope of PET imaging in the evaluation of cardiac tumors

Cardiac and pericardial masses can be categorized as neoplastic (either benign or malignant), non-neoplastic (such as thrombus or pericardial cysts), or normal variants of the cardiac structure. Diagnosing these masses can be challenging, and various imaging modalities are available, with each of them having advantages and pitfalls. Echocardiography is typically the first test used for the evaluation and detection of cardiac masses, as it is widely accessible, portable, and provides a comprehensive assessment of cardiac function and valves without the use of ionizing radiation. However, it may not be helpful in some cases, such as evaluating the extracardiac extension of the mass or characterizing tissue. On the other hand, cross-sectional imaging can provide a three-dimensional data set with excellent spatial resolution. Still, it requires ionizing radiation and intravenous iodinated contrast, and its functional evaluation of the heart may be relatively limited. 18F-FDG PET/CT helps determine 18F-FDG PET/CT is a crucial molecular imaging modality to assess and differentiate benign and malignant cardiac tumors noninvasively and helps in treatment planning and prognostication. Currently, studies evaluating the role of 18F-FDG PET/CT in cardiac tumors are limited to case reports and single center studies

Potential of radiosensitizing agents in cancer chemo-radiotherapy

Potential of herbs and other plant-based formulations have been increasingly recognized in prevention and treatment of human diseases including cancer. There exist enormous prospect for screening and evaluation of herbal/plant products for developing effective radiosensitization and radioprotection relevant to nuclear research program. Investigations in our laboratory have focused on the mechanism of activity of variety of anticancer and antioxidant agents, namely, Eugenol, (EU), Ellagic acid (EA), Triphala (TPL), Tocopherol Succinate (TOS) and Arachidonic acid on normal and cancer cells with view to design effective protocols in practical radioprotection and cancer radiotherapy. This paper is mainly focused on studies on cytotoxic effects on cancer cell lines. Results have shown that these agents produced radiosensitizing action involving oxidative damage, membrane alteration and damage to nucleic acid in various human cell lines. Studies were performed employing fluorescence probes and electron spin resonance methods and gel electrophoresis protocols. It has been found that cytotoxic effect was induced by initiating membrane oxidative damage and by triggering intracellular generation of reactive oxygen species (ROS) by gamma radiation in combination with phytochemicals like TPL, EA and TOS in tumor cell line Ehrlich Ascites (EAC), Human cervical (HeLa) and breast (MCF-7) cells. Membrane damage and ROS generation was measured by DPH and DCF-FDA fluorescent probes respectively after exposure to low to moderate doses of gamma radiation. This talk will present the cytotoxic effects of phytochemicals in combination with ionizing radiation. It is emphasized that modulation of membrane peroxidative damage and intra cellular ROS may help achieve efficient killing of cancer cells which may provide a new approach to developing effective treatment of cancer