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Title: Reference dosimetry during diagnostic CT examination using XR-QA radiochromic film model

Abstract

Purpose: The authors applied 2D reference dosimetry protocol for dose measurements using XR-QA radiochromic film model during diagnostic computed tomography (CT) examinations carried out on patients and humanoid Rando phantom. Methods: Response of XR-QA model GAFCHROMIC film reference dosimetry system was calibrated in terms of Air-Kerma in air. Four most commonly used CT protocols were selected on their CT scanner (GE Lightspeed VCT 64), covering three anatomical sites (head, chest, and abdomen). For each protocol, 25 patients ongoing planned diagnostic CT examination were recruited. Surface dose was measured using four or eight film strips taped on patients' skin and on Rando phantom. Film pieces were scanned prior to and after irradiation using Epson Expression 10000XL document scanner. Optical reflectance of the unexposed film piece was subtracted from exposed one to obtain final net reflectance change, which is subsequently converted to dose using previously established calibration curves. Results: The authors' measurements show that body skin dose variation has a sinusoidal pattern along the scanning axis due to the helical movement of the x-ray tube, and a comb pattern for head dose measurements due to its axial movement. Results show that the mean skin dose at anterior position for patients is (51more » {+-} 6) mGy, (29 {+-} 11) mGy, (45 {+-} 13) mGy and (38 {+-} 20) mGy for head, abdomen, angio Abdomen, and chest and abdomen protocol (UP position), respectively. The obtained experimental dose length products (DLP) show higher values than CT based DLP taken from the scanner console for body protocols, but lower values for the head protocol. Internal dose measurements inside the phantom's head indicate nonuniformity of dose distribution within scanned volume. Conclusions: In this work, the authors applied an Air-Kerma in air based radiochromic film reference dosimetry protocol for in vivo skin dose measurements. In this work, they employed green channel extracted from the scanned RGB image for dose measurements in the range from 0 to 200 mGy. Measured skin doses and corresponding DLPs were higher than DLPs provided by the CT scanner manufacturer as they were measured on patients' skin.« less

Authors:
; ; ; ;  [1];  [2];  [2];  [2]
  1. Institut de Genie Biomedical, Universite de Montreal, Montreal, Quebec H3C 3J7 (Canada)
  2. (Canada)
Publication Date:
OSTI Identifier:
22098616
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 38; Journal Issue: 9; Other Information: (c) 2011 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ABDOMEN; CALIBRATION; CHEST; COMPUTERIZED TOMOGRAPHY; FILM DOSIMETRY; HEAD; IMAGE SCANNERS; IMAGES; IN VIVO; IRRADIATION; KERMA; OPTICAL EQUIPMENT; PATIENTS; PHANTOMS; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; SKIN; X-RAY TUBES

Citation Formats

Boivin, Jonathan, Tomic, Nada, Fadlallah, Bassam, DeBlois, Francois, Devic, Slobodan, Medical Physics Unit, McGill University, Montral, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, 3755 chemin de la Cote-Sainte-Catherine, Montreal, Quebec H3T 1E2, Department of Biomedical Engineering, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2, and Medical Physics Unit, McGill University, Montreal, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2. Reference dosimetry during diagnostic CT examination using XR-QA radiochromic film model. United States: N. p., 2011. Web. doi:10.1118/1.3622607.
Boivin, Jonathan, Tomic, Nada, Fadlallah, Bassam, DeBlois, Francois, Devic, Slobodan, Medical Physics Unit, McGill University, Montral, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, 3755 chemin de la Cote-Sainte-Catherine, Montreal, Quebec H3T 1E2, Department of Biomedical Engineering, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2, & Medical Physics Unit, McGill University, Montreal, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2. Reference dosimetry during diagnostic CT examination using XR-QA radiochromic film model. United States. doi:10.1118/1.3622607.
Boivin, Jonathan, Tomic, Nada, Fadlallah, Bassam, DeBlois, Francois, Devic, Slobodan, Medical Physics Unit, McGill University, Montral, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, 3755 chemin de la Cote-Sainte-Catherine, Montreal, Quebec H3T 1E2, Department of Biomedical Engineering, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2, and Medical Physics Unit, McGill University, Montreal, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2. Thu . "Reference dosimetry during diagnostic CT examination using XR-QA radiochromic film model". United States. doi:10.1118/1.3622607.
@article{osti_22098616,
title = {Reference dosimetry during diagnostic CT examination using XR-QA radiochromic film model},
author = {Boivin, Jonathan and Tomic, Nada and Fadlallah, Bassam and DeBlois, Francois and Devic, Slobodan and Medical Physics Unit, McGill University, Montral, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, 3755 chemin de la Cote-Sainte-Catherine, Montreal, Quebec H3T 1E2 and Department of Biomedical Engineering, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2 and Medical Physics Unit, McGill University, Montreal, Quebec H3G 1A4, Canada and Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2},
abstractNote = {Purpose: The authors applied 2D reference dosimetry protocol for dose measurements using XR-QA radiochromic film model during diagnostic computed tomography (CT) examinations carried out on patients and humanoid Rando phantom. Methods: Response of XR-QA model GAFCHROMIC film reference dosimetry system was calibrated in terms of Air-Kerma in air. Four most commonly used CT protocols were selected on their CT scanner (GE Lightspeed VCT 64), covering three anatomical sites (head, chest, and abdomen). For each protocol, 25 patients ongoing planned diagnostic CT examination were recruited. Surface dose was measured using four or eight film strips taped on patients' skin and on Rando phantom. Film pieces were scanned prior to and after irradiation using Epson Expression 10000XL document scanner. Optical reflectance of the unexposed film piece was subtracted from exposed one to obtain final net reflectance change, which is subsequently converted to dose using previously established calibration curves. Results: The authors' measurements show that body skin dose variation has a sinusoidal pattern along the scanning axis due to the helical movement of the x-ray tube, and a comb pattern for head dose measurements due to its axial movement. Results show that the mean skin dose at anterior position for patients is (51 {+-} 6) mGy, (29 {+-} 11) mGy, (45 {+-} 13) mGy and (38 {+-} 20) mGy for head, abdomen, angio Abdomen, and chest and abdomen protocol (UP position), respectively. The obtained experimental dose length products (DLP) show higher values than CT based DLP taken from the scanner console for body protocols, but lower values for the head protocol. Internal dose measurements inside the phantom's head indicate nonuniformity of dose distribution within scanned volume. Conclusions: In this work, the authors applied an Air-Kerma in air based radiochromic film reference dosimetry protocol for in vivo skin dose measurements. In this work, they employed green channel extracted from the scanned RGB image for dose measurements in the range from 0 to 200 mGy. Measured skin doses and corresponding DLPs were higher than DLPs provided by the CT scanner manufacturer as they were measured on patients' skin.},
doi = {10.1118/1.3622607},
journal = {Medical Physics},
issn = {0094-2405},
number = 9,
volume = 38,
place = {United States},
year = {2011},
month = {9}
}