Quantitative Radiomics Approach to Assess Acute Radiation Dermatitis in Breast Cancer Patients

We applied a radiomics approach to skin surface images to objectively assess radiodermatitis in patients undergoing radiotherapy for breast cancer. A prospective cohort study of 20 patients was conducted. Skin surface images in normal, polarised, and UV modes were acquired using a skin analysis device before starting radiotherapy (‘before RT’), 7 days after the first treatment ('RT_D7'), on ‘RT_D14’, and 10 days after radiotherapy ended (‘after RT_D10’). Eighteen types of radiomic feature ratios were calculated. We measured skin doses in ipsilateral breasts using OSLDs on the first day of radiotherapy. Clinical evaluation of acute radiodermatitis was performed using the RTOG scoring criteria on ‘RT_D14’ and ‘after RT_D10’. Several statistical analysis methods were used to test the performance of radiomic features as indicators of radiodermatitis evaluation. As the skin was damaged by radiation, the energy for normal mode and sum variance for polarised and UV modes decreased significantly for ipsilateral breasts. The radiomic feature ratios at ‘RT_D7’ had strong correlations to skin doses and those at ‘RT_D14’ and ‘after RT_D10’ with statistical significance. The energy for normal mode and sum variance for polarised and UV modes demonstrated the potential to evaluate and predict acute radiation, which assists in its appropriate management.

Dosimetric Comparison of Exposure Pathways to Human Organs and Tissues in Radon Therapy

Three therapeutic applications are presently prescribed in the radon spas in Gastein, Austria: exposure to radon in a thermal bath, exposure to radon vapor in an exposure chamber (vapor bath), and exposure to radon in the thermal gallery, a former mine. The radiological exposure pathways to human organs and tissues in these therapeutic radon applications are inhalation of radon and radon progeny via the lungs, radon transfer from water or air through the skin, and radon-progeny deposition on the skin in water or air. The objectives of the present study were to calculate radon and radon-progeny doses for selected organs and tissues for the different exposure pathways and therapeutic applications. Doses incurred in red bone marrow, liver, kidneys, and Langerhans cells in the skin may be correlated with potential therapeutic benefits, while doses to the lungs and the basal cells of the skin indicate potential carcinogenic effects. The highest organ doses among the three therapeutic applications were produced in the thermal gallery by radon progeny via inhalation, with lung doses of 5.0 mSv, and attachment to the skin, with skin doses of 4.4 mSv, while the radon contribution was less significant. For comparison, the primary exposure pathways in the thermal bath are the radon uptake through the skin, with lung doses of 334 μSv, and the radon-progeny attachment to the skin, with skin doses of 216 μSv, while the inhalation route can safely be neglected.

A Collaborative Experience: Implementation of an Optimised Tc-99m Generator Assembly Process

Technetium-99m (Tc-99m) has a six-hour half-life making customer transportation times a challenge. ANSTO (Australia's Nuclear Science and Technology Organisation) Health Products group has overcome this by delivering the parent isotope Molybdenum-99 (Mo-99), which has a half-life of sixty-six hours, in shielded GENTECH™ generators. As part of ANSTO's questioning attitude, an augmented risk assessment was undertaken to identify any potential exposure risks of the GENTECH™ assembly process. The evaluation identified potential areas of improvement in contamination control for the manual handling of the generator leads. Upon further analysis, contamination events from the generator leads had the potential for skin doses above the threshold for skin tissue reactions. Additional substitution and administrative controls were designed to mitigate the risks identified. The effectiveness of the new controls was assessed for efficiency in the manufacturing process through mock trials and fitness for use in a pharmaceutical cleanroom environment. The implemented controls were monitored, and data from each run was gathered. This data included; changes in radiological conditions and dosimetry results. Upon implementation, there was an observable decrease in glove contamination. The decrease verified that there was a reduction in the risk of skin contamination events. The data analysis was used to model the dose averted, which revealed a reduction in potential extremity dose to production workers. This paper aims to show the optimisation within an approved process through the implementation of engineering and administrative controls, resulting in a dose reduction to workers.

Evaluation of skin doses for cone-beam computed tomography in dentomaxillofacial imaging: A preclinical study

Purpose Evaluation of skin organ doses in six different cone-beam computed tomography scanners (CBCT) dedicated to dentomaxillofacial imaging. Our hypothesis is that the dose varies between different devices, protocols and skin areas. Materials and methods An anthropomorphic adult head and neck phantom was used to which a dosimeter (Waterproof Farmer® Chamber, PTW, Freiburg, Germany) was attached to anatomic landmarks of both parotid glands, both ocular lenses, the thyroid gland and the neurocranium. CBCT examinations were performed on six different CBCT devices dedicated to dentomaxillofacial imaging with standard settings and, if available, also in high dose settings. Measurements were repeated five times each. Results The measured mean skin doses ranged from 0.48 to 2.21 mGy. The comparison of the region based dose evaluation showed a high correlation between the single measurements. Furthermore, the distribution of doses between regions was similar in all devices, except that four devices showed side differences for the dose of the parotid region and one device showed side differences for the lens region. The directly exposed regions, such as the parotid glands, showed significant higher values than the more distant regions like the neurocranium. When comparing examination protocols, a significant difference between the standard dose and the high dose acquisitions could be detected. But also a significant dose difference between the different CBCTs could be shown. 3D Accuitomo 170 (Morita, Osaka, Japan) showed the highest absorbed mean dose value for standard settings with 2.21 mGy, especially at the directly exposed regions and their adjacent organs. The lowest mean value for standard settings was achieved with VGi evo (NewTom, Verona, Italy) with 0.48 mGy. Conclusion Repeated measurements of skin organ doses in six different CBCT scanners using a surface dosimeter showed side differences in distribution of dose in five devices for the parotid and lens region. Additionally, significant dose differences between the devices could be detected. Further studies should be performed to confirm these results.

Skin dose measurement and estimating the dosimetric effect of applicator misplacement in gynecological brachytherapy: A patient and phantom study

OBJECTIVES: To evaluate skin dose differences between TPS (treatment planning system) calculations and TLD (thermo-luminescent dosimeters) measurements along with the dosimetric effect of applicator misplacement for patients diagnosed with gynecological (GYN) cancers undergoing brachytherapy. METHODS: The skin doses were measured using TLDs attached in different locations on patients’ skin in pelvic regions (anterior, left, and right) for 20 patients, as well as on a phantom. In addition, the applicator surface dose was calculated with TLDs attached to the applicator. The measured doses were compared with TPS calculations to find TPS accuracy. For the phantom, different applicator shifts were applied to find the effect of applicator misplacement on the surface dose. RESULTS: The mean absolute dose differences between the TPS and TLDs results for anterior, left, and right points were 3.14±1.03, 6.25±1.88, and 6.20±1.97 %, respectively. The mean difference on the applicator surface was obtained 1.92±0.46 %. Applicator misplacements of 0.5, 2, and 4 cm (average of three locations) resulted in 9, 36, and 61%, dose errors respectively. CONCLUSIONS: The surface/skin differences between the calculations and measurements are higher in the left and right regions, which relate to the higher uncertainty of TPS dose calculation in these regions. Furthermore, applicator misplacements can result in high skin dose variations, therefore it can be an appropriate quality assurance method for future research.

Feasibility of commercially available underwear during radiation therapy for breast cancer: build-up and surface dose measurements

Aim: When patients receive radiation therapy for breast cancer, they need to take off their underwear to avoid build-up effects. However, it is a mental burden for female patients to take off their underwear at every fraction of radiation therapy. The purpose of this study was to investigate whether commercially available thin underwear can be worn during radiation therapy for breast cancer. Materials and methods: In this phantom study, we investigated whether commercially available underwear can be worn during radiation therapy for breast cancer using six thin non-disposable brassieres and one disposable paper brassiere. The dose increase rate (ΔD) was calculated by measuring skin doses with or without each brassiere. Results: The mean ΔD values of six non-disposable brassieres were 13.5% (9.0–21.8%), whereas that of disposable ones was 2.0%. Findings: Due to the risk of excessive radiation to the skin, wearing commercially available underwear is not recommended during radiation therapy for breast cancer, but a thin disposable paper brassiere may be safe to be used.

Does Thermoplastic Mask Alleivates Skin Sparing Effect of Photons in Head and Neck Cancer Patients: A Pilot study

Introduction: Head and Neck tumors are mainly treated with concurrent chemoradiation. Treatment delivery with Megavoltage beam has the advantage of skin sparing effect but still skin reactions have been a major side effect since 2D era. Initially these reactions were due to the delivery with bilateral opposed portals but with advent of IMRT/ VMAT, it has been possible to escalate the tumor dose with the need of strict immobilization with thermoplastic mask. This thermoplastic mask may have a bolus effect and can result in increase in surface dose resulting in skin reactions. The aim of this study was to evaluate if any bolus effect of thermoplastic mask exists. Materials and Methods: A total of 15 patients of histologically proven carcinoma oropharynx and hypopharynx were taken. Patients were scanned for planning CT with thermoplastic mask. Another scan was taken in the same position but without thermoplastic mask. Same contouring and planning were done on both the scans. Plans were made and ascertained that all OAR’s and target volumes should get similar doses. Skin contoured on both the scans was evaluated for the dose received. Results: Mean dose received by skin in patients with thermoplastic mask was 48.15 GY while Mean dose received by skin in patients without thermoplastic mask was 43.18 GY. A paired t-test was applied on the dataset which revealed a statistically significant difference between the skin doses with and without mask with a p value of < 0.05. Conclusion: Increase in skin dose can be attributed of the bolus effect of thermoplastic mask. This bolus effect should be considered once high dose to skin is observed during planning or patient develops skin reaction.