PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 10721321

Dose response characteristics and basic dose distribution data for a polymerization-based dosemeter gel evaluated using MR.

P Haraldsson·S A Bäck·P Magnusson·L E Olsson
View original source ↗Export metadata ↓

Abstract

A safe and reproducible mixing procedure for the manufacture of a polymerization-based dosemeter gel evaluated using MRI (PoMRI) is presented. The dose response, obtained by irradiating gel-filled vials with absorbed doses in the interval 0-20 Gy and evaluated with respect to 1/T2, was found to be linear in the interval 0-8 Gy, with a sensitivity of 0.211 s-1Gy-1 (r2 = 0.998) at 1.5 T. Evaluation of the same set of vials with respect to 1/T1 gave a sensitivity of 0.018 s-1Gy-1 (r2 = 0.960). PoMRI and diode data were compared for standard photon and electron treatment beams. A deviation of less than 3% was found between the two methods for central depth dose curves as well as dose profiles (2 mm for electrons in the steep dose gradient regions). The importance of the method used for background correction for the reliability of the results was also evaluated. Barex (with a wall thickness of 1.5 mm) was investigated for use as phantom material and found to be favourable compared with glass. The results obtained in this study show that PoMRI has excellent potential as a 3D detector.

Explore related subjects

Dose-Response Relationship, RadiationGelsMagnetic Resonance ImagingPhantoms, ImagingPolymersRadiometryRadiotherapy DosageReproducibility of ResultsSensitivity and SpecificityJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P Haraldsson, S A Bäck, P Magnusson, L E Olsson. 2000. Dose response characteristics and basic dose distribution data for a polymerization-based dosemeter gel evaluated using MR.. https://doi.org/10.1259/bjr.73.865.10721321

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2001

A technique for inguinal node boost using photon fields defined by asymmetric collimator jaws.

A technique is described for treating inguinal nodes when using radiotherapy in the control of pelvic malignancies. A posterior photon field treats the pelvis. A wider anterior photon field treats pelvis and inguinal nodes. An anterior photon boost to nodes is delivered using asymmetric collimator jaws moved across center line. Advantages of this technique include simplicity of setup and treatment (a single isocenter is retained, and no transmission block is needed), minimal dose inhomogeneity, reduced dose to femoral necks reducing the risk of femoral fracture, low risk of nodal underdose, and elimination of dosimetric difficulties inherent in electron beam boosts.

Dose-Response Relationship, Radiation↗
PubMed2001

A comparison of multileaf collimator with conformal blocks for the boost phase of dose-escalated conformal prostate radiotherapy.

A multileaf collimator (MLC) is compared with conformal blocks for delivering the boost phase of dose-escalated conformal prostate radiotherapy. When using conformal blocks, the volume of rectum irradiated to 90% (V90) is lower (1.4+/-1.3%, 1 SD) for a three-field plan with gantry angles 0 degree, 90 degrees, 270 degrees than for a six-field plan with gantry angles 50 degrees, 90 degrees, 130 degrees, 230 degrees, 270 degrees, 310 degrees (2.1 +/- 1.3%, P = 0.002). However, when using an MLC in which the leaves and wedge are oriented at right angles, V90 is higher (4.7 +/- 3.0%) for a three-field plan than for a six-field plan (2.7 +/- 1.6%, P=0.05). The larger increase in V90 for the three-field plan when changing from conformal blocks to MLC is mainly due to the limitation imposed upon the MLC orientation by the use of wedges.

Dose-Response Relationship, Radiation↗
PubMed2001

Comparison of the risks of cancer incidence and mortality following radiation therapy for benign and malignant disease with the cancer risks observed in the Japanese A-bomb survivors.

PURPOSES: To compare the radiation-associated relative risks of cancer incidence and mortality in groups exposed to ionizing radiation in the course of treatment for a variety of malignant and non-malignant conditions with those in the Japanese A-bomb survivor cancer incidence and mortality data. MATERIALS AND METHODS: Comparison of the excess relative risk coefficients derived from published information for each study with the excess relative risk coefficient in comparable (age at exposure, time since exposure, sex) matched subsets of the Japanese A-bomb survivor cancer incidence and mortality data. RESULTS: Sixty-five studies of persons who have received appreciable doses of ionizing radiation in the course of treatment and for whom there is adequate ascertainment of cancer incidence or mortality are identified, from which 116 cancer-site-specific estimates of excess relative risk are derived. Relative risks tend to be lower in the medical series than in the Japanese A-bomb survivors. The most marked discrepancies between the relative risks in the medical series and in the A-bomb survivors are for leukaemia, where 12 of the 17 medical studies have significantly lower relative risks than those observed in the Japanese data. However, the ratio between the relative risks in the medical studies and in the Japanese data tends to diminish with increasing average or maximal therapy dose. This is observed for all cancer sites and is particularly marked for leukaemia. After taking account of cell sterilization and dose fractionation the apparent differences between the relative risks for leukaemia in the Japanese A-bomb survivors and in the medical series largely disappear. This suggests that cell sterilization largely accounts for the discrepancy between the relative risks in the Japanese data and the medical studies. Other factors, such as the differences in underlying cancer risks between the Japanese A-bomb survivors and the medical series, and dose-fractionation effects, may also contribute. CONCLUSIONS: The relative risks of cancer in studies of persons exposed to appreciable doses of ionizing radiation in the course of treatment for a variety of malignant and non-malignant conditions are generally less than those in comparable subsets of the Japanese A-bomb survivor cancer incidence and mortality data. Cell sterilization effects can largely explain the discrepancy between the Japanese and the medical series.

Dose-Response Relationship, Radiation↗