In Vivo Verification of Electron Beam Energy by Patient Exit Dose and Optical Density of Portal Films

Abstract

Measurements of the exit dose and evaluations of the optical density of portal films can be used to verify and document the energy of electron beams during radiotherapy.

Dose Delivery Accuracy of Therapeutic Photon and Electron Beams at Low Monitor Unit Settings

“…Dose estimation uncertainty of ± 2% is necessary to deliver a uniform target dose within ± 5% for better tumor control [6,7,10,12,21,26,27,30]. Dosimetric studies involving TLD phosphors for radiation protection, film dosimetry at low level of radiation dose, nuclear medicine dosimetry, estimation of low -doses and few other research applications related to environmental dosimetry require few monitor unit (MU) settings of photon and electron beams in a linear accelerator.…”

Portal Verification of High-Energy Electron Beams Using their Photon Contamination by Film-Cassette Systems

“…In our department direct verification of electron and abutted photon portals was introduced into clinical routine for irradiations of head-and-neck cancer and breast cancer. The same technique is also used to document the applied nominal electron energy [9]. In general, the EC film with the EC-L Fast or Regular cassette is used because of its higher quality compared to all other combinations.…”

Portal Verification Using the KODAK ACR 2000 RT Storage Phosphor Plate System and EC® Films

“…The exposure dose for an image (in monitor units) was set to 11-15 mGy (EC-L Regular ® cassette) or to 8-12 mGy (EC-L Fast ® cassette) in the film plane [12,13]. These dose values yielded to a gross optical density of 0.8-1.6.…”

“…Screen-film systems [10,24,27,36,38], the digital luminescence radiography [3,7,14,20,32,33,39], or electronic portal imaging devices [2, 6, 8-10, 17, 19, 21, 27, 29, 30, 34, 35] are used for the imaging of photon portals. Verification images of electron portals can also be generated using their photon contamination [4,12,13,15,22,24,37,39].…”

“…Regarding the image quality, the KODAK ACR 2000 RT was compared to EC ® film in combination with the EC-L ® cassette (Eastman Kodak Corp., Rochester, MN, USA). This screen-film combination showed the highest image quality for high-energy photon irradiation [11,13,16,18,31]. This comparison using patient images is complemented by phantom investigations and the imaging of the room lasers at the storage screens.…”