The low energy X-ray response of the LiF:Mg:Cu:P thermoluminescent dosemeter: a comparison with LiF:Mg:Ti

LiF:Mg:Cu:P thermoluminescent dosemeters (TLD) can be used for the same X-ray dosimetry applications as LiF:Mg:Ti, with each type having the disadvantage of a response dependent on energy, particularly at low energies. Measurements were made of the response per unit air kerma of LiF:Mg:Cu:P and LiF:Mg:Ti to nine quasi-monoenergetic X-ray beams with mean energies from 12 keV to 208 keV. Each measurement was normalized to the value produced by 6 MV X-rays. LiF:Mg:Cu:P was found to under-respond to a majority of these radiations whereas LiF:Mg:Ti over-responded to a majority. Their smallest relative measured response was produced by the lowest energy beam, and the maximum measured relative response of 1.15+/-0.07 and 1.21+/-0.07 for LiF:Mg:Cu:P and LiF:Mg:Ti, respectively, occurred at 33 keV. Energy response coefficients were derived from these measurements to estimate the error introduced by using either type of TLD to measure the dose from an X-ray spectrum different to that used for its absolute response calibration. It was calculated that if the response of either type of TLD was calibrated at 100 kVp, then an error of no more than +/-2% would be introduced into measurements of tube output at potentials of 50-130 kVp. LiF:Mg:Cu:P was found to introduce a larger error (up to 30%) into the measurement of body exit dose than LiF:Mg:Ti at tube potentials of 40-150 kVp, if its absolute response was calibrated using the corresponding body entrance beam. The method should allow this type of error to be estimated in other dosimetry applications for either type of TLD.     

Case report: gastric schwannoma: MRI findings

MRI features are described in a case of gastric schwannoma. A large, discretely marginated, multilobular mass was seen adjacent to the gastric antrum with the epicentre of the mass in the gastrocolic ligament. The overall signal pattern was low on T(1) weighted images and moderate to markedly elevated on T(2) weighted images. Post-gadolinium sequences demonstrate slow but fairly uniform enhancement throughout the mass.     

Case report: retrocaval ureter: MR appearances

We present a case of retrocaval ureter and its MR appearances. This is the first case in reported literature. The findings on i.v. urography are correlated with the MRI findings. So far CT has been the procedure of choice to confirm the diagnosis of retrocaval ureter. However, we believe MRI is likely to replace CT in the diagnosis of retrocaval ureter.     

局限型胸膜间皮瘤1例报告

胸膜间皮瘤是一种起源于胸膜间皮细胞与纤维细胞的一X线检查:右肺中野近肺门旁8 cm×7 cm类圆形阴影,密度较高且较均匀,边缘光滑清晰。X线诊断:右肺占位,建议做进一步检查(图1)。CT检查:纵隔窗示右肺下叶背段近后胸壁处可见团块状软组织密度影,大小为8.5 cm×5 cm×7 cm,病灶内可见条行气体密度影,纵隔结构居中。大血管走行分布正常,纵隔内未见肿大淋巴结影。双侧胸腔未见积液征象。肺窗示右肺下叶背段病灶呈致密改变,与周围组织分界清晰(图2,3)。初步诊断:右肺下叶病灶考虑球形肺炎,建议抗炎治疗2周后复查。图1右肺中野近肺门旁8 cm×7 c…