Medical Mask Wearing During Treatment for Patients Undergoing Radiotherapy in COVID-19 Pandemic - An Experience of Protocol Setup and Dosimetric Evaluation for Particle/Proton Beam Therapy.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has caused extreme challenges for the healthcare system. Medical masks have been proven to effectively block disease transmission. Radiotherapeutic departments are at unique risk for disease exposure with the repeated daily treatment schedule. A protocol of mask wearing during daily treatment was established, and the effect of wearing medical masks on dosimetry during proton beam therapy (PBT) was validated. METHODS: A department protocol of medical mask wearing was initiated after the COVID-19 pandemic. Medical masks that were made under standardized specification and regulation were obtained for analyses. The physical and dosimetric characteristics of these medical masks were measured by different proton energies using commercialized measurement tools. RESULTS: Patients and staff were able to adopt the protocol on a weekly basis, and no adverse events were reported. The average physical thickness of a single piece of medical mask was 0.5 mm with a water equivalent thickness (WET) of 0.1 mm. CONCLUSION: Our study revealed that mask wearing for patients undergoing daily radiotherapy is feasible and can provide basic protection for patients and staff. The impact of mask wearing on dosimetry was only 0.1 mm in WET, which has no impact on clinical PBT treatment. A medical mask-wearing policy can be applied safely without dosimetric concerns and should be considered as a standard practice for PBT centers during the COVID-19 pandemic.

The feasibility of anterior 180° 99m Tc-sestamibi parathyroid SPECT/CT.

OBJECTIVE: For 99mTc-sestamibi parathyroid single photon emission computed tomography/computed tomography (SPECT/CT), the traditional full-arc 360° acquisition technique has been suggested but not the theoretically low tissue-attenuated anterior 180° method. We aimed to compare the diagnostic performances and target-to-background ratios of anterior 180° and 360° SPECT/CT imaging. METHODS: Ninety-nine patients who underwent 99mTc-sestamibi scintigraphy and received a surgical-pathological diagnosis of parathyroid adenoma or hyperplasia were enrolled. The SPECT/CT reconstructed images with anterior 180° and full-arc 360° data were interpreted by two physicians using a scoring scale, and the lesions were semi-quantified using target-to-background ratios for both image sets. RESULTS: In total, 113 abnormal parathyroid lesions were identified on the SPECT/CT images. The agreements of interpretation between the two image sets and readers were very good (κ value: 0.83-1.00). The accuracies of summative interpretation for the anterior 180° and full-arc 360° SPECT/CT were 83.04% and 82.46%, respectively. The target-to-background ratios were significantly higher for the anterior 180° than the full-arc 360° images (P < 0.01). CONCLUSIONS: The anterior 180° SPECT/CT technique, a time-saving method, can provide satisfactory diagnostic performance and superior lesion contrast compared with the full-arc 360° SPECT/CT technique in 99mTc-sestamibi parathyroid imaging.

Relationships among patient characteristics, irradiation treatment planning parameters, and treatment toxicity of acute radiation dermatitis after breast hybrid intensity modulation radiation therapy.

To evaluate the relationships among patient characteristics, irradiation treatment planning parameters, and treatment toxicity of acute radiation dermatitis (RD) after breast hybrid intensity modulation radiation therapy (IMRT). The study cohort consisted of 95 breast cancer patients treated with hybrid IMRT. RD grade ≥2 (2+) toxicity was defined as clinically significant. Patient characteristics and the irradiation treatment planning parameters were used as the initial candidate factors. Prognostic factors were identified using the least absolute shrinkage and selection operator (LASSO)-based normal tissue complication probability (NTCP) model. A univariate cut-off dose NTCP model was developed to find the dose-volume limitation. Fifty-two (54.7%) of ninety-five patients experienced acute RD grade 2+ toxicity. The volume of skin receiving a dose >35 Gy (V35) was the most significant dosimetric predictor associated with RD grade 2+ toxicity. The NTCP model parameters for V35Gy were TV50 = 85.7 mL and γ50 = 0.77, where TV50 was defined as the volume corresponding to a 50% incidence of complications, and γ50 was the normalized slope of the volume-response curve. Additional potential predictive patient characteristics were energy and surgery, but the results were not statistically significant. To ensure a better quality of life and compliance for breast hybrid IMRT patients, the skin volume receiving a dose >35 Gy should be limited to <85.7 mL to keep the incidence of RD grade 2+ toxicities below 50%. To avoid RD toxicity, the volume of skin receiving a dose >35 Gy should follow sparing tolerance and the inherent patient characteristics should be considered.