Light flashes during proton and photon radiotherapy: A multicenter prospective observational study

Mizumoto, Masashi; Oshiro, Yoshiko; Miyamoto, Toshio; Sumiya, Taisuke; Murakami, M.; Baba, Keiichiro; Shimizu, Shunsuke; Iizumi, Takashi; Numajiri, Haruko; Nakai, Kei; Okumura, Toshiyuki; Maruo, Kazushi; Sakae, Takeji; Sakurai, Hideyuki

doi:10.1016/j.tipsro.2021.11.003

Cited by 8 publications

(24 citation statements)

References 11 publications

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“…In our previous study on Cherenkov light during RT, younger age was significantly associated with a sense of light during RT or PBT [ 4 ]. The reason was unclear, but it may simply be that younger patients have sharper sensations that cause them to sense light and odor more frequently during RT or PBT.…”

Section: Discussionmentioning

confidence: 99%

“…Obinata et al also found seven of 191 patients were aware of olfactory sensations during RT [ 3 ]. Our prospective observational study indicated that >50% of patients in whom the retina was irradiated have a visual sensation during photon RT or proton beam therapy (PBT), whereas <5% of those without retinal irradiation had a visual sensation [ 4 ]. The dose to the retina and younger patients were significant factors that showed an association with a visual sensation.…”

Section: Introductionmentioning

confidence: 99%

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Olfactory Sensations During Proton and Photon Radiotherapy: A Multicenter Prospective Observational Study

Mizumoto¹,

Oshiro²,

Sumiya³

et al. 2022

Cureus

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Purpose: Patients often report a sense of smell during radiation therapy (RT), but the details of these events are not well understood. The purpose of the study was to evaluate events of smell during photon RT and proton beam therapy (PBT).Methods and materials: The subjects were all adult patients (≥20 years old) treated with photon RT or PBT at two centers from January 2019 to August 2020, with the exclusion of those with communication difficulties or olfactory abnormality. The presence of smell, odor type, intensity (five levels), and time period was examined prospectively using a weekly checklist.Results: A total of 649 courses were examined in 620 patients who received photon RT (n=415) or PBT (n=205). A smell during the procedure was sensed by 51 patients (8.2%). In multivariate logistic regression analysis, nasal cavity dose (p=0.002), age (p<0.001), and photon RT (p=0.018) were identified as significant factors associated with a sense of smell. Smell occurred in only 23/515 patients (4.5%) in whom the nasal cavity was not irradiated, but in 4/19 (21.1%) and 24/86 (27.9%) with nasal cavity maximum isodose lines of 10%-50% and 60%-100%, respectively. Patients who received photon RT sensed a smell (43/415; 10.4%) more frequently than those treated with PBT (8/205; 3.9%). Of the 51 patients who sensed a smell, 32 (63%) reported a burnt smell, eight (16%) a chemical smell, two (4%) a sour smell, and nine another smell (copier machine, sweet, garbage, etc.).Conclusions: The sense of a smell appears to be common during RT and this sensation is significantly associated with the nasal cavity dose, younger age, and photon RT.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Olfactory Sensations During Proton and Photon Radiotherapy: A Multicenter Prospective Observational Study

Mizumoto¹,

Oshiro²,

Sumiya³

et al. 2022

Cureus

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“…Evaluations were made for the presence or absence of light flash or odor during irradiation. Light flash and odor were evaluated using a survey checklist that was completed each week ( 4 ).…”

Section: Methodsmentioning

confidence: 99%

“…Cherenkov light is thought to be the main cause of the light flash during irradiation, but no clear conclusion has been reached ( 8 – 10 ). A trace amount of ozone generated by radiation therapy is likely to be the main cause of odor during radiation therapy, but it is difficult to detect this small amount of ozone and similarly there is no clear conclusion on the source of the odor ( 1 , 4 ).…”

Section: Introductionmentioning

confidence: 99%

“…Light flash and odor during irradiation may mainly occur in radiotherapy for brain or head and neck tumors ( 1 – 4 ). In our previous survey of light flash and odor during irradiation using a common checklist, we found that light flash was experienced by 55% of adults if the retina was included in the irradiation range, but only by 7% if the retina was not in this range ( 4 ).…”

Section: Introductionmentioning

confidence: 99%

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Light flash and odor during proton beam therapy for pediatric patients: a prospective observational study

et al. 2022

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Light flash and odor during radiation therapy are well-known phenomena, but the details are poorly understood, particularly in pediatric patients. Therefore, we conducted a prospective observational study of these events in pediatric patients (age ≤20 years old) who received radiotherapy at our center from January 2019 to November 2021. Light flash and odor were evaluated using a patient-reported checklist including the presence, strength, and duration of the phenomenon, and color of light or type of odor. 53 patients who received proton therapy (n=47) and photon radiotherapy (n=6) were enrolled in this study. The median age of the patients was 10, ranged from 5 to 20. The patients who was able to see the light flash was 4, and all of them received retina irradiation. This was equivalent to 57% of the patients who received radiotherapy to retina (n=7). The light was bright and colored mainly blue and purple, which seemed to be consistent with Cherenkov light. Odor was sensed by 9 (17%) patients, and seven patients of the 9 received nasal cavity irradiation. This was equivalent to 41% of the patients who received nasal cavity irradiation (n=17). Other 2 patients received proton therapy to brain tumor. The odors were mainly described as plastic, burnt and disinfectant, which may be caused by ozone generated during irradiation. These data suggest that pediatric patients with retinal and nasal cavity irradiation frequently sense light flashes or odor. So adequate care is necessary so that these patients are not worried about this phenomenon.

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Abnormal visual and olfactory sensations during radiation therapy: a prospective study

et al. 2023

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Purpose Patients sometimes report phosphene and phantosmia during radiation therapy (RT). However, the detail features and related factors are not well understood. Our prospective study aimed to investigate the characteristics of phantosmias and phosphenes, to identify factors that influence the occurrence, intensity and hedonic (pleasantness/unpleasantness) ratings of such sensations during RT. Methods We included a total of 106 patients (37 women), who underwent RT in regions of the brain, ear, nose, throat (ENT), and other areas of the body for a duration of 43 ± 5 days. Medical history and treatment parameters were collected in a structured medical interview. Olfactory function was measured using the Sniffin’ Stick Odor Identification Test at baseline. Phantosmia and phosphene were recorded weekly based on a self-report questionnaire. Results There were 37% of the patients experiencing phantosmias, 51% experiencing phosphenes, and 29% simultaneously experiencing both sensations. Phosphenes were typically perceived as a flashily blue, white and/or purple light, phantosmias were typically perceived as a chemical-like, metallic or burnt smell. Younger age (F = 7.81, p < 0.01), radiation in the brain region (χ2 = 14.05, p = 0.02), absence of taste problems (χ2 = 10.28, p = 0.01), and proton RT (χ2 = 10.57, p = 0.01) were related to these abnormal sensations. History of chemical/dust exposure predicted lower intensity (B = −1.52, p = 0.02) and lower unpleasantness (B = 0.49, p = 0.03) of phantosmia. In contrast, disease (tumor) duration (B = 0.11, p < 0.01), food allergy (B = 2.77, p < 0.01), and epilepsy (B = −1.50, p = 0.02) influence phosphenes intensity. Analgesics intake predicted a higher pleasantness of the phosphenes (B = 0.47, p < 0.01). Conclusions Phantosmias and phosphenes are common during RT. The treatment settings and individual arousal level influence the occurrence, intensity and hedonic of such abnormal sensations. Phantosmias and phosphenes may involve more central neural than peripheral mechanism, and they could be elicited with activation of areas that are not regarded to be part of the olfactory or visual network.

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Light flashes during proton and photon radiotherapy: A multicenter prospective observational study

Cited by 8 publications

References 11 publications

Olfactory Sensations During Proton and Photon Radiotherapy: A Multicenter Prospective Observational Study

Olfactory Sensations During Proton and Photon Radiotherapy: A Multicenter Prospective Observational Study

Light flash and odor during proton beam therapy for pediatric patients: a prospective observational study

Abnormal visual and olfactory sensations during radiation therapy: a prospective study

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