Comments on “Calculated response and wall correction factors for ionization chambers exposed to <sup>6</sup>
                        <sup>0</sup>
Co gamma-rays”

McEwan, A.C.; Smyth, Vere

doi:10.1118/1.595607

Cited by 19 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Bond et a / (1978) and Nath and Schulz (1981) have simulated the response of ion chambers and determined wall correction factors for "CO y-rays in air which are in common use today in the majority of national and international recommended procedures for dosimetry. McEwan andSmyth (1983, 1984) and Rogers el ol (1985) have found, however, important discrepancies between their results and those of Nath and Schulz (1981) for the simulation of chamber response, attributable to defects in the Monte Carlo code of the latter authors, whereas differences in the calculated correction factors (which are ratios of responses) were within statistical uncertainties. Simulations of ion chambers including the effect of the central electrode at the energy of '"CO y-rays have been reported by Smyth and McEwan (1984) and Rogers et a!…”

Section: With Permission)mentioning

confidence: 94%

Monte Carlo techniques in medical radiation physics

1991

View full text Add to dashboard Cite

primer for health physicists Hcollh Phyr. 4 8 717-33 Udale M 1988 A Monte Carlo investigation of surface doses for broad electron beams Phya. Mcd. Bial. 33 939-54 Waihel E and Grosswendt B 1983 Spatial energy dissipation profiles, W values, backscatter coefficients, and ranges for low-energy electrons in methane Nucl. Instrum. Methods A 2 1 1 487-98 Webb S 1979 The ahsorbed dose in the vicinity of an interface between two media irradiated by a 6oCo source E d. J. Radio(. 5 2 962-7 Webb S and Fox R A 1979 The dose in water s u r r o n n d h ooint isotrooic ~amma-rav emitters B r i f .-.. I J. Rodiol. 52 482-4-1980 Verification bv Monte Carlo methods of a ~o w e r law tissue-air ratio alaorithm for inhom-geneily corrections in photon beam dose calculation P h y s M i d. Bid. 25 225-40

show abstract

Section: With Permission)mentioning

confidence: 94%

Monte Carlo techniques in medical radiation physics

1991

View full text Add to dashboard Cite

show abstract

“…Energy dependence: Ion chambers typically exhibit favorably small energy dependence, but the energy dependence is highly dependent on the materials of the chamber, particularly the central electrode. [188][189][190] Farmer chambers and scanning chambers constructed of low-atomic number (Z ≤ 13) materials show a nearly flat energy response, either over-or under-responding, but typically by less than 5% down to effective energies of 40 keV (compared to 60 Co). However, microchambers containing high-Z collecting electrodes show a dramatic overresponse that typically exceeds 50% at energies around 100 keV (and increases at lower energies).…”

Section: A2 Ion Chambersmentioning

confidence: 99%

AAPM TG158: Measurement and calculation of doses outside the treated volume from external‐beam radiation therapy

et al. 2017

View full text Add to dashboard Cite

The introduction of advanced techniques and technology in radiotherapy has greatly improved our ability to deliver highly conformal tumor doses while minimizing the dose to adjacent organs at risk. Despite these tremendous improvements, there remains a general concern about doses to normal tissues that are not the target of the radiation treatment; any "nontarget" radiation should be minimized as it offers no therapeutic benefit. As patients live longer after treatment, there is increased opportunity for late effects including second cancers and cardiac toxicity to manifest. Complicating the management of these issues, there are unique challenges with measuring, calculating, reducing, and reporting nontarget doses that many medical physicists may have limited experience with. Treatment planning systems become dramatically inaccurate outside the treatment field, necessitating a measurement or some other means of assessing the dose. However, measurements are challenging because outside the treatment field, the radiation energy spectrum, dose rate, and general shape of the dose distribution (particularly the percent depth dose) are very different and often require special consideration. Neutron dosimetry is also particularly challenging, and common errors in methodology can easily manifest as errors of several orders of magnitude. Task Group 158 was, therefore, formed to provide guidance for physicists in terms of assessing and managing nontarget doses. In particular, the report: (a) highlights major concerns with nontarget radiation; (b) provides a rough estimate of doses associated with different treatment approaches in clinical practice; (c) discusses the uses of dosimeters for measuring photon, electron, and neutron doses; (d) discusses the use of calculation techniques for dosimetric evaluations; (e) highlights techniques that may be considered for reducing nontarget doses; (f) discusses dose reporting; and (g) makes recommendations for both clinical and research practice.

show abstract

“…The quantity, p, is defined to be the ratio of absorbed dose to collision kerma. It has been used (AAPM 1983, McEwan and Smyth 1984, Schulz and Loevinger 1984, NACP 1980, 1981 to correct for the difference between collision kerma and dose in the wall of an ion chamber. The dose per unit collision kerma can be calculated for a parallel beam of monoenergetic primary photons interacting inside a water phantom directly from the energy deposition kernels.…”

Section: ~= C C ~P ( I J ) and P ( I J ) F ~L (9)mentioning

confidence: 99%

Generation of photon energy deposition kernels using the EGS Monte Carlo code

Mackie¹,

Bielajew²,

Rogers³

et al. 1988

Phys. Med. Biol.

231

201

View full text Add to dashboard Cite

The EGS Monte Carlo code was used to generate photon energy deposition kernels which describe the energy deposited by charged particles set in motion by primary, first scattered, second scattered, multiple scattered and bremsstrahlung plus annihilation photons. These were calculated for a water medium irradiated with monoenergetic photons with energies in the range 0.1-50 MeV. In addition to the primary energy deposition kernels, primary charged particle transport was further characterised by computing the effective centre of the voxels, and the effective penetration depth, effective radius and effective lateral distance travelled by these particles. The dose per unit collision kerma for parallel monoenergetic primary photons beta' was calculated. Additional applications of the energy deposition kernels are discussed.

show abstract

Comments on “Calculated response and wall correction factors for ionization chambers exposed to ⁶ ⁰ Co gamma-rays”

Cited by 19 publications

References 0 publications

Monte Carlo techniques in medical radiation physics

Monte Carlo techniques in medical radiation physics

AAPM TG158: Measurement and calculation of doses outside the treated volume from external‐beam radiation therapy

Generation of photon energy deposition kernels using the EGS Monte Carlo code

Contact Info

Product

Resources

About

Comments on “Calculated response and wall correction factors for ionization chambers exposed to 6 0 Co gamma-rays”

Cited by 19 publications

References 0 publications

Monte Carlo techniques in medical radiation physics

Monte Carlo techniques in medical radiation physics

AAPM TG158: Measurement and calculation of doses outside the treated volume from external‐beam radiation therapy

Generation of photon energy deposition kernels using the EGS Monte Carlo code

Contact Info

Product

Resources

About

Comments on “Calculated response and wall correction factors for ionization chambers exposed to ⁶ ⁰ Co gamma-rays”