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Purpose/objective(s): Low-dose radiotherapy (LD-RT) is a well-established treatment for multiple human inflammatory conditions. Whole-lung LD-RT may be effective in COVID-19-related pneumonia.Materials/methods: Patients hospitalized with COVID-19-related pneumonia receiving supportive care, glucocorticosteroids, and/or remdesivir were administered LD-RT treatment of 0.5 or 1.5 Gy to the bilateral lungs on a prospective, combined phase I/II, multi-site, single-institution trial. Patients were followed for 28 days or until discharge and compared to controls blindly matched by age, comorbidity, duration of symptoms, and disease severity. Eligible patients were confirmed by SARS-CoV-2 positive PCR, unable to wean from oxygen at enrollment, and had radiographic consolidations. Patients were enrolled into 5 cohorts stratified by treatment variables and severity of illness: LD-RT alone vs. LD-RT with concurrent drug therapies, non-intubated vs. intubated status, and low (1.5 Gy) vs. lower (0.5 Gy) radiation dose. Qualitative aims were to establish safety and explore efficacy. Quantitative endpoints were continuous, categorical, and time-to-event, and included clinical recovery, intubation, radiographic changes, and biomarker responses. Intubation endpoints are reported for all cohorts using the log-rank test and Kaplan-Meier method.Results: Outcomes of 80 patients were available for analysis at study closure. In total, 40 of 70 planned patients (57% trial enrollment) received whole-lung LD-RT between April 24 and December 7, 2020 and were compared to 40 matched controls. Cohorts 1&2: Ten non-intubated patients received 1.5 Gy without concurrent COVID-directed drug therapies (10 of 10 planned, 100% cohort enrollment) and were compared to matched controls. Intubation rates were 40% in controls compared to 10% following LD-RT (P = 0.11). Cohort 3: One intubated patient received 1.5 Gy (1 of 20 planned, 5% cohort enrollment). Cohort 4: Twenty separate non-intubated patients received 1.5 Gy with concurrent dexamethasone/remdesivir (20 of 20 planned, 100% cohort enrollment) and were compared to matched controls. Intubation rates were 32% in controls compared to 14% following LD-RT (P = 0.09). Cohort 5: Nine patients received 0.5 Gy with concurrent drug therapies (9 of 20 planned, 45% cohort enrollment) and were compared to matched controls. Zero controls required intubation compared to 11% following LD-RT (P = 0.32). Among all non-intubated patients and matched controls combined (n = 78), mechanical ventilation was required in 28% of controls compared to 12% following LD-RT (reduced 57%, P = 0.05). The trial was prematurely closed due to observed reproducibility of efficacy. A randomized trial is now ongoing.Conclusion: In the first, prospective, phase I/II trial of radiotherapy for COVID-19-related pneumonia, a single treatment of whole-lung LD-RT reduced intubation rates by 57% compared to controls in patients receiving supportive care with or without drug therapies (P = 0.05). [ABSTRACT FROM AUTHOR]

Purpose: Retrograde urethrography is a standard method to identify the prostatic apex during planning for prostate cancer radiotherapy. This is an invasive and uncomfortable procedure. With modern three-dimensional computed tomography planning, we explored whether retrograde urethrography was still necessary to accurately identify the prostatic apex., Methods and Materials: Fifteen patients underwent computed tomography simulation with and without bladder, urethral, and rectal contrast. The prostatic base and apex were identified on both scans, using contrast and anatomy, respectively. The anatomic location of the prostatic apex as defined by these methods was confirmed in another 57 patients with postbrachytherapy imaging., Results: The prostatic base and apex were within a mean of 3.8 mm between the two scans. In every case, the beak of the retrograde urethrogram abutted the line drawn parallel to, and bisecting, the pubic bone on the lateral films. With these anatomic relationships defined, in the postbrachytherapy patients, the distance from the prostatic apex to the point at which the urethra traversed the pelvic floor was an average of 11.7 mm. On lateral films, we found that the urethra exited the pelvis an average of 16.6 mm below the posterior-most fusion of the pubic symphysis. On axial images, this occurred at a mean separation of the ischia of about 25 mm., Conclusion: With a knowledge of the anatomic relationships and modern three-dimensional computed tomography planning equipment, the prostatic apex can be easily and consistently identified, obviating the need to subject patients to retrograde urethrography.

A more precise radiation therapy technique to treat unilateral optic nerve sheath meningioma is presented. It uses an immobilization device to align the ipsilateral optic nerve with a vertical axis and employs three small half-beam blocked fields to deliver radiation to a small conformal volume, thereby reducing the dose to the optic chiasm and the contralateral optic nerve. Three patients were successfully treated with this technique, and a fourth patient with optic nerve glioma was also treated in a similar fashion and was included in this study. The new technique irradiates a much smaller volume of tissue to high dose levels: 58 cm3 is irradiated to the 80% isodose level and only 18 cm3 to the 95% level. In contrast, the opposed lateral technique irradiates 171 and 73 cm3 to these levels, respectively. Thus, a considerable reduction in the volume of normal tissue irradiated was accomplished. Doses to the pituitary and contralateral optic nerve were 4% of the treatment dose for the new technique, whereas these doses were 40% and 100% for opposed laterals and 10% and 3% for wedged pair, respectively. The average setup error for this technique was very small, 50% of the setups measured were less than 1 mm off, and 92.5% were less than 3 mm off. However, for the conventional setups without a mask, only 21% of the setups were less than 1 mm off and 55% less than 3 mm off. We recommend this technique for localized unilateral optic nerve sheath meningioma and other optic nerve lesions that may require radiation therapy.