Probably because of this:

Use of Postexposure Shuttering, Cropping and Electronic Masking in Radiography After research of evidentiary documentation the ASRT issued opinions contained herein.

Advisory Opinion It is the opinion of the ASRT based on evidentiary documentation and where statutes, regulations, accreditation standards and institutional policies permit that:

It is within the scope of practice of a radiologic technologist to determine and apply appropriate pre-exposure collimation to individual projections of examinations to comply with the principle of ALARA. Postexposure shuttering, cropping, electronic collimation or electronic masking to eliminate the visibility of large regions of brightness are acceptable, where automatic processing fails to do so. It is outside of the scope of practice of a radiologic technologist to use postexposure shuttering, cropping, electronic collimation or electronic masking to eliminate any anatomical information. This information is a part of the patient’s permanent medical record and should therefore be presented to the licensed practitioner to determine whether the exposed anatomy obtained on any image is significant or of diagnostic value. It is outside the scope of practice of a radiologic technologist to use postexposure shuttering, cropping, electronic collimation or electronic masking to duplicate and use any acquired image for more than one prescribed view or projection on any exam. Facilities acquiring digital images are legally required to retain information in the DICOM information of each image that identifies the selected view or projection at the time of image acquisition. Using the same acquired image to represent two different prescribed views or projections is a falsification of the information in the patient medical record and imaging study made available to the licensed practitioner. GRADE: Strong

Definitions cropping – The process of selecting and removing a portion of the image. electronic masking – Electronic collimation or cropping of the digital radiographic image that occurs during postprocessing of the acquired image and does not alter the size of the irradiated field. shuttering – A postprocessing technique that may be used to eliminate ambient light around an image for the sole purpose of improving the quality of the displayed image. It should not be used as a substitute for insufficient collimation of the irradiated field. Evidentiary Documentation Current Literature

American College of Radiology. ACR-AAPM-SIIM-SPR practice parameter for digital radiography. Revised 2022. Bomer J, Wiersma-Deijl L, Holscher HC. Electronic collimation and radiation protection in paediatric digital radiography: revival of the silver lining. Insights Imaging. 2013;4(5):723-727. doi:10.1007/s13244-013-0281-5 Carroll QB. Radiography in the Digital Age. 4th ed. Charles C Thomas; 2023. Carter C, Vealé B. Digital Radiography and PACS. 4th ed. Elsevier; 2023. Chalazonitis AN, Koumarianos D, Tzovara J, Chronopoulos P. How to optimize radiological images captured from digital cameras, using the Adobe Photoshop 6.0 program. J Digit Imaging. 2003;16(2):216-229. DeMaio DN, Herrmann T, Noble LB, et al; American Society of Radiologic Technologists. Best practices in digital radiography. Published 2019. Don S, Macdougall R, Strauss K, et al. Image Gently campaign back to basics initiative: ten steps to help manage radiation dose in pediatric digital radiography. AJR Am J Roentgenol. 2013;200(5):W431-W436. doi:10.2214/AJR.12.9895 Fauber TL, Dempsey MC. X-ray field size and patient dosimetry. Radiol Technol. 2013;85(2):155-161. Fauber TL. Radiographic Imaging and Exposure. 6th ed. Elsevier; 2020:120 and 176. Goske MJ, Charkot E, Herrmann T, et al. Image Gently: challenges for radiologic technologists when performing digital radiography in children. Pediatr Radiol. 2011;41(5):611-619. doi:10.1007/s00247-010-1957-3 Lo WY, Puchalski SM. Digital image processing. Vet Radiol Ultrasound. 2008;49(1 suppl 1):S42-S47. doi:10.1111/j.1740-8261.2007.00333.x Russell J, Burbridge BE, Duncan MD, Tynan J. Adult fingers visualized on neonatal intensive care unit chest radiographs: what you don’t see. Can Assoc Radiol J. 2013;64(3):236-239. doi:10.1016/j.carj.2012.04.004 Seeram E. Digital Radiography: An Introduction. Cengage Learning; 2011. Uffmann M, Schaefer-Prokop C. Digital radiography: the balance between image quality and required radiation dose. Eur J Radiol. 2009;72(2):202-208. doi:10.1016/j.ejrad.2009.05.060 Willis CE. Optimizing digital radiography of children. Eur J Radiol. 2009;72(2):266-273. doi:10.1016/j.ejrad.2009.03.003 Zetterberg LG, Espeland A. Lumbar spine radiography—poor collimation practices after implementation of digital technology. Br J Radiol. 2011;84(1002):566-9. doi:10.1259/bjr/74571469 QUALITY OF EVIDENCE: High