Highlights
- •The surface dose was determined from the air kerma and HVL measured by a semiconductor detector.
- •A semiconductor detector was calibrated using the air kerma measured by an ionization chamber.
- •The Monte Carlo method was used to obtain the ratio of surface dose (Dw,z = 0) to air kerma (Kair).
- •Dw,z = 0 /Kair determined with a semiconductor detector agreed with Monte Carlo-calculated values.
Abstract
Purpose
To determine the surface dose of a water phantom using a semiconductor detector for
diagnostic kilovoltage x-ray beams.
Methods
An AGMS-DM+ semiconductor detector was calibrated in terms of air kerma measured with
an ionization chamber. Air kerma was measured for 20 x-ray beams with tube voltages
of 50–140 kVp and a half-value layer (HVL) of 2.2–9.7 mm Al for given quality index
(QI) values of 0.4, 0.5, and 0.6, and converted to the surface dose. Finally, the
air kerma and HVL measured by the AGMS-DM+ detector were expressed as a ratio of the
surface dose for 10 × 10 and 20 × 20 cm2 fields. The ratio of both was represented as a function of HVL for the given QI values
and verified by comparing it with that calculated using the Monte Carlo method.
Results
The air kerma calibration factor, CF, for the AGMS-DM+ detector ranged from 0.986
to 1.016 (0.9% in k = 1). The CF values were almost independent of the x-ray fluence spectra for the
given QI values. The ratio of the surface dose to the air kerma determined by the
PTW 30,013 chamber and the AGMS-DM+ detector was less than 1.8% for the values calculated
using the Monte Carlo method, and showed a good correlation with the HVL for the given
QI values.
Conclusion
It is possible to determine the surface dose of a water phantom from the air kerma
and HVL measured by a semiconductor detector for given QI values.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Physica Medica: European Journal of Medical PhysicsAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
Andreo P, Burns DT, Hohlfeld K, Huq MS, Tatsuaki K, Laitano F, et al. International Atomic Energy Agency (IAEA). Absorbed dose determination in external beam radiotherapy: An International Code of Practice for dosimetry based on standards of absorbed dose to water. IAEA Technical Reports Series no. 398. Vienna: IAEA; 2000.
- AAPM protocol for 40–300 kV x-ray beam dosimetry in radiotherapy and radiobiology.Med Phys. 2001; 28: 868-893https://doi.org/10.1118/1.1374247
Grimbergen TWM, Aalbers AHL, Mijnheer BJ, Seuntjens J, Thierens H, Van Dam J, et al. Nederlandse Commissie voor Stralingsdosimetrie (NCS). Dosimetry for low and medium energy X-rays: A code of practice in radiotherapy and radiobiology. NCS Report 10. Delft: NCS; 1997. doi: 10.25030/ncs-010.
- The IPEMB code of practice for the determination of absorbed dose for x-rays below 300 kV generating potential (0.035 mm Al-4 mm Cu HVL; 10–300 kV generating potential).Phys Med Biol. 1996;41:2605–25.; https://doi.org/10.1088/0031-9155/41/12/002
- International Atomic Energy Agency Dosimetry in Radiology: An International Code of Practice, Technical Reports Series no 457.IAEA, Vienna2007
- An evaluation of semiconductor detector and ionization chamber detectors for diagnostic x-ray dosimetry measurements.Phys Med Biol. 2007; 52: 4465-4480https://doi.org/10.1088/0031-9155/52/15
- Avoidance of radiation injuries from medical interventional procedures, ICRP Publication 85.ICRP. 2000; https://doi.org/10.1016/S0146-6453(01)00004-5
- Backscatter factors and mass energy-absorption coefficient ratios for diagnostic radiology dosimetry.Phys Med Biol. 2011; 56: 7179-7204https://doi.org/10.1088/0031-9155/56/22/012
- Evaluation of the MOSkin dosimeter for diagnostic X-ray CT beams.Phys Med. 2019; 60: 150-155https://doi.org/10.1016/j.ejmp.2019.03.030
- A comparison of entrance skin dose delivered by clinical angiographic c-arms using the real-time dosimeter: the MOSkin.Australas Phys Eng Sci Med. 2016; 39: 423-430https://doi.org/10.1007/s13246-016-0435-0
Kurosawa T, Takata N. Estimation of electron-loss and photon-scattering corrections for parallel-plate free-air chambers. J. Nucl. Sci. Technol. 2005;42:1077–80.doi:10.1080/18811248.2005.9711060.
ICRP 1990. Recommendations of International Commissioning on Radiological Protection. ICRP Report 60, Annals of the ICRP, Volume 21 No. 1-3.
- Accurate condensed history Monte Carlo simulation of electron transport. I. EGSnrc, the new EGS4 version.Med Phys. 2000; 27: 485-498https://doi.org/10.1118/1.598917
I. Kawrakow D.W.O. Rogers F. Tessier E. Mainegra-Hing B.R.B. Walters The EGSnrc code system: Monte Carlo simulation of electron and photon transport National Research Council of Canada Report 2020 PIRS–701.
Kawrakow I, Mainegra‐Hing E, Tessier F. EGSnrc C++ class library. National Research Council of Canada Report 2019; No. PIRS–898.
- Photon Cross Section Database, NIST Standard Reference Database.NIST, PML, Radiat Phys Div. 2010; https://doi.org/10.18434/T48G6X
- Calculation of x-ray spectra emerging from an x-ray tube. Part I. Electron penetration characteristics in x-ray targets.Med Phys. 2007; 34: 2164-2174https://doi.org/10.1118/1.2734725
- Calculation of x-ray spectra emerging from an x-ray tube. Part II. X-ray production and filtration in x-ray targets.Med Phys. 2007; 34: 2175-2186https://doi.org/10.1118/1.734726
- SpekCalc: A program to calculate photon spectra from tungsten anode x-ray tubes.Phys Med Biol. 2009; 54: N433-N438https://doi.org/10.1088/0031-9155/54/19/N01
- Determination of backscatter factors based on the quality index for diagnostic kilovoltage x-ray beams.Phys Med. 2020; 77: 48-53https://doi.org/10.1016/j.ejmp.2020.07.032
- Calculation of backscatter factors for diagnostic radiology using Monte Carlo methods Phys.Med Biol. 1998; 43: 2237-2250https://doi.org/10.1088/0031-9155/43/0/017
- Dependence of the photon backscatter factor for water on source-to-phantom irradiation field size.Phys Med Biol. 1990; 35: 1233-1245https://doi.org/10.1088/0031-9155/35/9/004
- Key data for ionizing-radiation dosimetry: measurement standards and applications ICRU Report 90.International Commission on Radiation Units and Measurements), (Bethesda, MD2014
Article info
Publication history
Published online: May 12, 2021
Accepted:
April 11,
2021
Received in revised form:
March 24,
2021
Received:
December 1,
2020
Identification
Copyright
© 2021 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
