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Title: SU-E-T-612: Photonuclear Activation of Prosthetic Hips in Radiotherapy

Abstract

Purpose: To measure the neutron induced activation of a prosthetic hip when exposed to an 18 MV radiotherapy linac beam to assess the potential dose to patients. Methods: A prosthetic hip (Thackray, UK) was placed in a water phantom and irradiated (both in-field and out-of-field) with an 18 MV linac beam. Gamma spectroscopy was used to identify the radioisotopes produced. Following the in-field irradiation where the induced activity is higher, high sensitivity lithium fluoride Thermoluminescence Dosimeters (TLD-100H) (Harshaw, USA) were placed on the surface to measure the dose which would be deposited to nearby tissue resulting from the induced radioactivity. Results: The radioisotopes produced in the hip prosthesis have been identified as {sup 5{sup 2}}V, {sup 5{sup 3}}Fe, and {sup 56}Mn which have half-lives of 3.74, 8.51 and minutes respectively. The 378 and 511 keV characteristic peaks of {sup 5{sup 3}}Fe do not appear in the spectra collected from hips irradiated in the out-of-field region. This isotope is produced by photonuclear interactions within the hip itself. {sup 52}V and {sup 56}Mn appear in spectra collected from hips irradiated either within the photon beam or in the nearby out-of-field region, implying that they are produced by incident neutron radiation produced inmore » components of the linear accelerator.The integrated dose which would be deposited in the tissue immediately surrounding the hip after four hours (1.5 half-lives of the longest lived product) was measured as approximately 100 µGy, following a 10,000 MU irradiation of the prosthesis. A highly accurate measurement of the dose is challenging because of the irregular shape of the prosthesis. Conclusion: The cumulative dose measured at the surface of the hip is 0.0001% of the in-field dose, and is therefore negligible compared with the doses the patient receives as a consequence of their treatment.« less

Authors:
; ;  [1]; ; ;  [2];  [3]
  1. RMIT University, Melbourne, VIC (Australia)
  2. William Buckland Radiotherapy Centre, Melbourne, VIC (Australia)
  3. Peter MacCallum Cancer Instit., Melbourne (Australia)
Publication Date:
OSTI Identifier:
22538122
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; 61 RADIATION PROTECTION AND DOSIMETRY; DOSIMETRY; GAMMA SPECTROSCOPY; GY RANGE; IRON 53; IRRADIATION; KEV RANGE 100-1000; LINEAR ACCELERATORS; LITHIUM FLUORIDES; MANGANESE 56; PATIENTS; PHOTON BEAMS; PHOTONUCLEAR REACTIONS; RADIATION DOSES; RADIATION PROTECTION; RADIOTHERAPY; THERMOLUMINESCENT DOSEMETERS; VANADIUM 52

Citation Formats

Keehan, S, Taylor, M, Franich, R, Smith, R, Millar, J, Esser, M, and Kron, T. SU-E-T-612: Photonuclear Activation of Prosthetic Hips in Radiotherapy. United States: N. p., 2015. Web. doi:10.1118/1.4924975.
Keehan, S, Taylor, M, Franich, R, Smith, R, Millar, J, Esser, M, & Kron, T. SU-E-T-612: Photonuclear Activation of Prosthetic Hips in Radiotherapy. United States. doi:10.1118/1.4924975.
Keehan, S, Taylor, M, Franich, R, Smith, R, Millar, J, Esser, M, and Kron, T. Mon . "SU-E-T-612: Photonuclear Activation of Prosthetic Hips in Radiotherapy". United States. doi:10.1118/1.4924975.
@article{osti_22538122,
title = {SU-E-T-612: Photonuclear Activation of Prosthetic Hips in Radiotherapy},
author = {Keehan, S and Taylor, M and Franich, R and Smith, R and Millar, J and Esser, M and Kron, T},
abstractNote = {Purpose: To measure the neutron induced activation of a prosthetic hip when exposed to an 18 MV radiotherapy linac beam to assess the potential dose to patients. Methods: A prosthetic hip (Thackray, UK) was placed in a water phantom and irradiated (both in-field and out-of-field) with an 18 MV linac beam. Gamma spectroscopy was used to identify the radioisotopes produced. Following the in-field irradiation where the induced activity is higher, high sensitivity lithium fluoride Thermoluminescence Dosimeters (TLD-100H) (Harshaw, USA) were placed on the surface to measure the dose which would be deposited to nearby tissue resulting from the induced radioactivity. Results: The radioisotopes produced in the hip prosthesis have been identified as {sup 5{sup 2}}V, {sup 5{sup 3}}Fe, and {sup 56}Mn which have half-lives of 3.74, 8.51 and minutes respectively. The 378 and 511 keV characteristic peaks of {sup 5{sup 3}}Fe do not appear in the spectra collected from hips irradiated in the out-of-field region. This isotope is produced by photonuclear interactions within the hip itself. {sup 52}V and {sup 56}Mn appear in spectra collected from hips irradiated either within the photon beam or in the nearby out-of-field region, implying that they are produced by incident neutron radiation produced in components of the linear accelerator.The integrated dose which would be deposited in the tissue immediately surrounding the hip after four hours (1.5 half-lives of the longest lived product) was measured as approximately 100 µGy, following a 10,000 MU irradiation of the prosthesis. A highly accurate measurement of the dose is challenging because of the irregular shape of the prosthesis. Conclusion: The cumulative dose measured at the surface of the hip is 0.0001% of the in-field dose, and is therefore negligible compared with the doses the patient receives as a consequence of their treatment.},
doi = {10.1118/1.4924975},
journal = {Medical Physics},
number = 6,
volume = 42,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}