Dosimetry of a low-kV intra-operative X-ray source using basic analytical beam models
- 1 September 2002
- journal article
- research article
- Published by Springer Science and Business Media LLC in Australasian Physics & Engineering Sciences in Medicine
- Vol. 25 (3), 119-123
- https://doi.org/10.1007/bf03178772
Abstract
The low energy (30–50 kVp) beams from an intra-operative X-ray source are modelled using a basic analytical model considering just primary beam attenuation and absorption. Spatial dosimetry at such low energies is difficult due to the rapid changes in dose-rate from the radiation source. The purpose of the model was to determine the variation with distance in water of coefficients required for beam dosimetry and to validate beam measurements performed in water of high-gradient dose distributions. The model predicts a change in mean mass-energy absorption coefficient of up to 3 % over the range of clinically-relevant distances in water. Distance-dose distributions (variation in dose with distance in water) for the X-ray source were calculated with the model and found to be in agreement with measurement (at clinically-relevant distances), to within a spatial distance comparable to the dimensions and positional accuracy of the ionization chamber used, and comparable to the expected dosimetric anisotropy of the radiation source. Measured and calculated distance-doses begin to diverge at relatively large distances from the radiation source, which is where dose-rates are so low that detector signal levels are comparable with noise.Keywords
This publication has 13 references indexed in Scilit:
- Air kerma calibration factors and chamber correction values for PTW soft x-ray, NACP and Roos ionization chambers at very low x-ray energiesPhysics in Medicine & Biology, 2001
- 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)Physics in Medicine & Biology, 1996
- A new miniature x‐ray device for interstitial radiosurgery: DosimetryMedical Physics, 1996
- A new miniature x‐ray source for interstitial radiosurgery: Device descriptionMedical Physics, 1996
- Sector Resection With or Without Postoperative Radiotherapy for Stage I Breast Cancer: Five-Year Results of a Randomized TrialJNCI Journal of the National Cancer Institute, 1994
- Conservative surgery for the management of invasive and noninvasive carcinoma of the breast: NSABP trialsWorld Journal of Surgery, 1994
- Radiotherapy after Breast-Preserving Surgery in Women with Localized Cancer of the BreastNew England Journal of Medicine, 1993
- Correction factors for a cylindrical ionization chamber used in medium-energy X-ray beamsPhysics in Medicine & Biology, 1993
- Eight-Year Results of a Randomized Clinical Trial Comparing Total Mastectomy and Lumpectomy with or without Irradiation in the Treatment of Breast CancerNew England Journal of Medicine, 1989
- Ten-year results of a randomized trial comparing a conservative treatment to mastectomy in early breast cancerRadiotherapy and Oncology, 1989