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Narici L. Light flashes and other sensory illusions perceived in space travel and on ground, including proton and heavy ion therapies. Z Med Phys 2024; 34:44-63. [PMID: 37455230 PMCID: PMC10919968 DOI: 10.1016/j.zemedi.2023.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/18/2023]
Abstract
Most of the astronauts experience visual illusions, apparent flashes of light (LF) in absence of light. The first reported observation of this phenomenon was in July 1969 by Buzz Aldrin, in the debriefing following the Apollo 11 mission. Several ground-based experiments in the 1970s tried to clarify the mechanisms behind these light flashes and to evaluate possible related risks. These works were supported by dedicated experiments in space on the following Apollo flights and in Low Earth Orbit (LEO). It was soon demonstrated that the LF could be caused by charged particles (present in the space radiation) traveling through the eye, and, possibly, some other visual cortical areas. In the 1990s the interest in these phenomena increased again and additional experiments in Low Earth Orbit and others ground-based were started. Recently patients undergoing proton and heavy ion therapy for eye or head and neck tumors have reported the perception of light flashes, opening a new channel to investigate these phenomena. In this paper the many LF studies will be reviewed, presenting an historical and scientific perspective consistent with the combined set of observations, offering a single comprehensive summary aimed to provide further insights on these phenomena. While the light flashes appear not to be a risk by themselves, they might provide information on the amount of radiation induced radicals in the astronauts' eyes. Understanding their generation mechanisms might also support radiation countermeasures development. However, even given the substantial progress outlined in this paper, many questions related to their generation are still under debate, so additional studies are suggested. Finally, it is also conceivable that further LF investigations could provide evidence about the possible interaction of single particles in space with brain function, impacting with the crew ability to optimally perform a mission.
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Affiliation(s)
- Livio Narici
- Department of Physics, University of Rome Tor Vergata & INFN Tor Vergata, Rome, Italy; Italian Space Agency (ASI), Rome, Italy.
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Saito T, Mizumoto M, Oshiro Y, Miyamoto T, Kamizawa S, Nakamura M, Ishida T, Makishima H, Numajiri H, Nakai K, Sakae T, Sakurai H. Synchronization of light flash with the irradiation pulse in proton beam therapy: A case report. Tech Innov Patient Support Radiat Oncol 2023; 27:100218. [PMID: 37485049 PMCID: PMC10362298 DOI: 10.1016/j.tipsro.2023.100218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/26/2023] [Accepted: 07/06/2023] [Indexed: 07/25/2023] Open
Abstract
The correlation between sensory light flash and proton beam delivery was evaluated by measuring the timing of pulse beam delivery and light flash sensing using an event recorder in an 83-year-old patient receiving proton beam therapy (PBT) for nasopharyngeal adenoid cystic carcinoma. The treatment dose was 65 Gy (RBE) in 26 fractions with 2 ports, and both beams included the visual pathway (retina, optic nerve, chiasma). Measurements were obtained in 13 of the 26 fractions. The patient sensed a light flash in all 13 fractions and pressed the recorder button for 426 of the 430 pulsed beam deliveries, giving a sensing rate of 99.1%. The median duration of button-pressing of 0.3 s was almost the same as that of the beam pulse of 0.2 s, with a reaction time lag of 0.35 s. These results suggest a consistency between light flash during PBT and the timing of irradiation.
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Affiliation(s)
- Takashi Saito
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | - Masashi Mizumoto
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | - Yoshiko Oshiro
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
- Department of Radiation Oncology, Tsukuba Medical Center Hospital, Tsukuba, Japan
| | - Toshio Miyamoto
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | - Satoshi Kamizawa
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | | | - Toshiki Ishida
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | | | - Haruko Numajiri
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | - Kei Nakai
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | - Takeji Sakae
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
| | - Hideyuki Sakurai
- Department of Radiation Oncology, University of Tsukuba, Tsukuba, Japan
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Narici L, Titova E, Obenaus A, Wroe A, Loredo L, Schulte R, Slater JD, Nelson GA. Multiple sensory illusions are evoked during the course of proton therapy. LIFE SCIENCES IN SPACE RESEARCH 2020; 26:140-148. [PMID: 32718680 DOI: 10.1016/j.lssr.2020.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/10/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
Visual illusions from astronauts in space have been reported to be associated with the passage of high energy charged particles through visual structures (retina, optic nerve, brain). Similar effects have also been reported by patients under proton and heavy ion therapies. This prompted us to investigate whether protons at the Loma Linda University Proton Therapy and Research Center (PTRC) may also affect other sensory systems beside evoking similar perceptions on the visual system. A retrospective review of proton radiotherapy patient records at PTRC identified 29 sensory reports from 19 patients who spontaneously reported visual, olfactory, auditory and gustatory illusions during treatment. Our results suggest that protons can evoke neuronal responses sufficient to elicit conscious sensory illusion experiences, in four senses (auditory, taste, smell, and visual) analogous to those from normal sensory inputs. The regions of the brain receiving the highest doses corresponded with the anatomical structures associated with each type of illusion. Our findings suggest that more detailed queries about sensory illusions during proton therapy are warranted, possibly integrated with quantitative effect descriptions (such as electroencephalography) and can provide additional physiological basis for understanding the effects of protons on central nervous system tissues, needed for radiation risk assessment in advance of deep space human exploration.
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Affiliation(s)
- Livio Narici
- Department of Physics, University of Rome, Tor Vergata, Rome, Italy; INFN sect Tor Vergata, Rome Italy
| | - Elena Titova
- Departments of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States; Krasnoyarsk State Medical University, Krasnoyarsk, Russian Federation
| | - André Obenaus
- Departments of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States; Departments of Radiation Medicine, Loma Linda University School of Medicine, Loma Linda, CA, United States; Department of Pediatrics, University of California Irvine, Irvine, CA, United States.
| | - Andrew Wroe
- Departments of Radiation Medicine, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Lilia Loredo
- Departments of Radiation Medicine, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Reinhard Schulte
- Departments of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Jerry D Slater
- Departments of Radiation Medicine, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Gregory A Nelson
- Departments of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States; Departments of Radiation Medicine, Loma Linda University School of Medicine, Loma Linda, CA, United States
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