Dose simulations of an early 20th century kilovoltage pneumonia radiotherapy technique performed with a modern fluoroscope.

Autor: Roa D; Department of Radiation Oncology, University of California, Irvine Health, Orange, CA 92868, USA. Electronic address: droa@uci.edu., Moyses H; Department of Radiation Oncology, University of California, Irvine Health, Orange, CA 92868, USA., Leon S; Department of Radiology, University of Florida, Gainesville, FL 32610, USA., Hamrick B; Environmental Health and Safety, University of California, Irvine Health, Orange, CA 92868, USA., Sarria GR; Department of Radiation Oncology, University Hospital Bonn, University of Bonn, Bonn, Germany., Li B; Department of Radiation Oncology, University of California, San Francisco, CA 94115, USA., Tajima T; Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA., Necas A; TAE Technologies, Foothill Ranch, CA 92610, USA., Guzman C; Facultad de Ciencias Naturales y Matematica, Universidad Nacional Federico Villarreal, Lima, Peru., Paucar O; Facultad de Ingenieria Electrica y Electronica, Universidad Nacional de Ingenieria, Lima, Peru., Gonzales A; Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru., Challco R; Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru., Montoya M; Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru., Arqque Z; Facultad de Ciencias, Universidad Nacional de Ingenieria, Lima, Peru., Gonzales A; Clinica Aliada contra el Cancer, Lima, Peru., Hernandez J; HRS Oncology International, Las Vegas, NV 89119, USA., Drake J; Ziehm Imaging, Orlando, FL 32822, USA., Villane R; Ziehm Imaging, Orlando, FL 32822, USA., Lea J; GE Healthcare, Salt Lake Ciry, UT 84116, USA.
Jazyk: angličtina
Zdroj: Medical dosimetry : official journal of the American Association of Medical Dosimetrists [Med Dosim] 2021 Spring; Vol. 46 (1), pp. 74-79. Date of Electronic Publication: 2020 Sep 18.
DOI: 10.1016/j.meddos.2020.08.002
Abstrakt: To simulate an early 20th century viral pneumonia radiotherapy treatment using modern fluoroscopy and evaluated it according to current dose guidelines. Monte Carlo was used to assess the dose distribution on an anthropomorphic phantom. Critical organs were: skin, breasts, esophagus, ribs, vertebrae, heart, thymus, and spinal cord. A 100 kV p beam with 3 mm Al HVL, 25 × 25 cm 2 posterior-anterior (PA) field and 50 cm source-to-surface distance were simulated. Simulations had a resolution of 0.4 × 0.4 × 0.06 cm 3 and a 6% uncertainty. Hundred percent dose was normalized to the skin surface and results were displayed in axial, coronal, and sagittal planes. Dose volume histograms were generated in MATLAB for further analysis. Prescription doses of 0.3, 0.5, and 1.0 Gy were applied to the 15% isodose for organ-dose comparison to current tolerances and potential risk of detriment. Ninety-five and ninety-seven percent of the right and left lung volumes, respectively, were well-covered by the 15% isodose line. For the 0.3, 0.5, and 1.0 Gy prescriptions, the maximum skin doses were 2.9, 4.8, and 9.6 Gy compared to a 2.0 Gy transient erythema dose threshold; left/right lung maximum doses were 1.44/1.46, 2.4/2.4, and 4.8/4.9 Gy compared to a 6.5 Gy pneumonitis and 30 Gy fibrosis thresholds; maximum heart doses were 0.5, 0.9, and 1.8 Gy compared to the 0.5 Gy ICRP-recommendation; maximum spinal cord doses were 1.4, 2.3, and 4.6 Gy compared to 7.0 Gy single fraction dose threshold. Maximum doses to other critical organs were below modern dose thresholds. A 100 kV p PA field could deliver a 0.3 Gy or 0.5 Gy dose without risk of complications. However, a 1.0 Gy dose treatment could be problematic. Critical organ doses could be further reduced if more than one treatment field is used.
(Copyright © 2020 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE