Radiation, Volume 4, Issue 3 (September 2024) – 7 articles

Vibrational spectroscopic techniques, such as Fourier transform infrared (FTIR) absorption and Raman spectroscopy (RS), offer unique and detailed biochemical fingerprints by detecting specific molecular vibrations within samples. These techniques provide profound insights into the molecular alterations induced by ionising radiation, which are both complex and multifaceted. This paper reviews the application of rapid and label-free vibrational spectroscopic methods for assessing biological radiation responses. These assessments span from early compartmentalised models such as DNA, lipid membranes, and vesicles to comprehensive evaluations in various living biological models, including tissues, cells, and organisms of diverse origins. The review also discusses future perspectives, highlighting how the field is overcoming methodological limitations. RS and FTIR have demonstrated significant potential in detecting radiation-induced biomolecular alternations, which may facilitate the identification of radiation exposure spectral biomarkers/profiles. Full article

X-ray fluoroscopy causes relatively high radiation exposure to physicians, radiation professionals, and patients. Understanding the behavior of scattered radiation is crucial for reducing occupational exposure. We developed a system for estimating radiation exposure during fluoroscopy by monitoring the position of the physician using a depth camera for radiation protection education. The dose distribution of scattered radiation in an X-ray room was simulated using Monte Carlo code. The data were displayed using augmented reality markers, and the dose at each joint point location was estimated using body tracking. Additional functions were created, such as displaying arbitrary two-dimensional cross-sections. The system performance ranged from 9.0 to 11.0 FPS with or without motion and a protective apron. The estimated doses were 0.93 to 1.21 times the measured doses for all joint points, except for the chest and pelvis. The estimated doses for the chest and pelvis were lower than the measured dose, with the minimum values being 0.72 and 0.60 times lower for the chest and pelvis, respectively. The system provides valuable insight into the estimation of radiation dose at joint points based on the physician’s position and movements, the physician’s optimal fluoroscopy location, and warning of dangerous exposure doses. Full article

Nanotechnology has provided considerable advancements in an array of disciplines. Recently, it has been shown that ferumoxytol, a magnetite (Fe₃O₄) nanoparticle, can be oxidized by ionizing radiation. Ferumoxytol nanoparticles have high stability, and thus can be hypothesized that they have dosimetric potential. In this study, it has been observed that xylenol orange, a colorimetric detector of Fe³⁺ used for conventional Fricke dosimetry, was not able to detect radiolytic changes in ferumoxtyol. Electron paramagnetic resonance (EPR) spectroscopy was more readily able to evaluate the oxidation of ferumoxytol. EPR spectroscopy revealed that oxidation of 500 nM ferumoxytol in H₂O was linear up to 20 Gy. This concentration, however, was unable to estimate the delivered dose from a Small Animal Radiation Research Platform system, as a 6 Gy dose was estimated to be 1.37 Gy, which represents a 79.2% underestimation of the dose delivered. Thus, while the high stability of Fe₃O₄ nanoparticles is attractive for use in pre-clinical radiation dosimetry, further radiochemical evaluation may be required before considering them for this application. Full article

Background: Pelvic reirradiation of de novo rectal or anal cancer after prior prostate cancer RT poses a significant risk of urinary and rectal fistula. In this report we describe the use of a rectal spacer to improve dosimetry and reduce this risk. Methods: Patients undergoing anorectal radiotherapy (RT) after prior prostate RT who had a rectal spacer placed prior to RT were identified in a prospective database. Patient, disease, and treatment characteristics were collected for these patients. Survival data were calculated from the end of RT. Radiation was delivered with intensity-modulated radiation therapy (IMRT) or proton beam therapy (PBT) following rectal spacer placement. Results: Rectal spacer placement with hydrogel injected transperineally under transrectal ultrasound guidance was successful in all five patients. MR/CT simulation 1–2 weeks post-spacer placement and IMRT or PBT delivered to a dose of 36–50 Gy in 24–30 fractions once or twice daily were tolerated well by all patients. The V100% of the PTV ranged from 62–100% and mean rectal and bladder dose ranged from 39–46 Gy and 16–40 Gy, respectively. At the last follow-up, three patients were alive and without evidence of disease up to 48 months out from treatment. There were no acute or late grade 3 or higher toxicities observed, but acute grade 2 proctitis was observed in all patients. Conclusions: The use of a rectal spacer placement to improve dosimetry of IMRT and PBT after prior prostate RT is safe and feasible in appropriately selected anorectal cancer patients. Full article

A 98-year-old patient with cognitive impairment and a history of squamous cell carcinoma of the nasal pyramid was referred to the radiation oncology department of our institution’s hospital given that surgery was not recommended. The lesion was sized 6 × 6 cm, ulcerated, and bleeding; was significantly impairing the patient’s health-related quality of life, causing pain; and was not responsive to analgesics, including opioids. The patient experienced deterioration of her general conditions, with a Karnofsky performance status of 40. A single radiotherapy (RT) fraction was delivered on a weekly basis for 3 weeks, up to a total dose of 21 Gy, using a VMAT technique (7 Gy/fraction). The patient was given three fractions of radiotherapy, during which she received continuous assistance due to episodes of mental disorientation and an altered sense of consciousness. One month after the conclusion of the treatment, the patient exhibited a nearly complete clinical response, with full pain relief and an improved health-related quality of life. This favourable clinical outcome was maintained for a period of four months following the conclusion of RT. A brief review was performed on the role of hypofractionated radiation therapy in elderly patients with locally advanced skin cancer of the head and neck region. Full article

Aim: To evaluate patient satisfaction outcomes with respect to pain, discomfort, and quality of life with hematology/oncology referrals undergoing CT-guided bone marrow biopsy and compare these scores with those of patients undergoing in-office biopsy. Methods: A retrospective chart review was performed over 2 years with all patients who underwent CT-guided bone marrow biopsy at our university set-up. Age, gender, BMI, radiation dose (CTDI/DLP), number of in-office biopsies, number of CT-guided biopsies, type/amount of moderate sedation used, technical and pathologic success rates, and complication rates were recorded. All patients who underwent both in-office and CT-guided biopsy were contacted by telephone to answer a brief survey regarding pain, discomfort, quality of life, and future preference with respect to each biopsy. Results: A total of 32 patients underwent CT-guided bone marrow biopsy. Moderate sedation was utilized for all CT patients, and 19 patients underwent both in-office and CT-guided biopsies. Upon surveying the 19 patients who underwent both kinds of biopsies, on a scale of 1–10 (10 = highest discomfort and highest pain), the patients on an average reported 7.8 for in-office vs. 2.1 for CT for the discomfort level (p < 0.001) and 7.9 vs. 1.7 for the pain (p < 0.001). The patients reported an average quality-of-life score of 82 (out of a scale of 100) after CT procedures and 53 for in-office (p < 0.001). All patients reported that they would prefer CT-guided procedures with sedation versus in-office procedures in the future. Conclusion: CT-guided bone marrow biopsy is the preferred and more comfortable procedure, especially in low-pain-tolerant patients, although it involves more cost, conscious sedation, and radiation exposure. Full article

Current radiation dosimeters sometimes face accuracy limitations or provide only cumulative doses over long periods. To contribute to this area, we developed a portable monitor that measures the energy spectrum and dose of gamma rays in real time. To achieve this, we used an improved sequential Bayesian estimation algorithm. The dose rate was then derived from the energy spectrum by applying a flux-to-dose conversion coefficient. The monitor consists mainly of a CsI(Tl) scintillator and a multi-pixel photon counter (MPPC). In developing this device, we focused on striking a balance between measurement accuracy, ease of use, and portability. As an essential aspect of the research, we investigated the influence of the CsI(Tl) crystal size on the performance of the monitor to determine an optimal size. This was accomplished by calculating the detection efficiency and energy resolution through experimental measurements using standard gamma-ray sources and simulations using MCNP5. Within the scope of the research, detector response functions were created for each crystal size for an energy range of 10 keV to 3 MeV. Considering an optimal balance of detection efficiency and energy resolution alongside a compact size suitable for portable applications, the crystal measuring 2.6 × 2.6 × 1.3 cm³ was deemed preferable. Full article