Effect of Pelvic Bone Marrow Sparing Intensity Modulated Radiation Therapy on Acute Hematologic Toxicity in Rectal Cancer Patients Undergoing Chemo-Radiotherapy.

BACKGROUND: While chemo-radiotherapy improves local control in patients with locally advanced rectal cancer, it can also increase acute hematological toxicity (HT), which leads to poor outcomes. Patients receiving bone marrow radiation have been shown to develop acute HT. However, the safety and efficacy of bone marrow sparing is undetermined. The aim of our study was to explore the feasible dosimetric constraints for pelvic bone marrow (PBM) that can be widely used in rectal cancer patients undergoing chemo-radiotherapy. METHODS: 112 rectal cancer patients were selected and divided into the PBM sparing IMRT group (60 cases) and the non-PBM sparing IMRT group (52 cases). All patients underwent pelvic radiotherapy with concurrent capecitabine-based chemotherapy. The PBM dosimetric constraints in the PBM sparing IMRT group were set to:V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%. An independent sample t test was applied for the dose-volume parameters, and Chi-squared analysis was applied for clinical parameters and adverse events. RESULTS: The radiation dose to PBM (V5~V45, Dmean, P<0.05), PBM sub-regions (V10~V35, Dmean, P<0.05) and both femoral heads (V5~V40, Dmean, P<0.05) decreased significantly in the PBM sparing IMRT group compared with that of the non-PBM sparing IMRT group (P<0.05). There was no significant difference in any dose-volume parameters of the bladder and small bowel in either groups, and none in the planning target volume (PTV) dose homogeneity and conformity (P>0.05). For acute HT observation, the incidence of grade 3 acute HT (χ2 = 7.094, P=0.008) was significantly reduced in patients treated with PBM sparing IMRT compared with patients treated with non-PBM sparing IMRT. There was no statistical difference in the incidence of vomiting, diarrhea, fatigue, anorexia, nausea, hand-foot syndrome, cystitis, perianal pain and perianal dermatitis in patients of both groups (P >0.05). CONCLUSIONS: Applying PBM dosimetric constraints (V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%) can significantly reduce the radiation dose to PBM. The patients treated with PBM sparing IMRT had a lower incidence of acute HT compared with those treated with non-PBM sparing IMRT. Applying the PBM dosimetric constraints proposed by our study can benefits the patients with rectal cancer undergoing capecitabine-based chemo-radiotherapy.

A comprehensive and clinical-oriented evaluation criteria based on DVH information and gamma passing rates analysis for IMRT plan 3D verification.

PURPOSE: To accomplish the 3D dose verification to IMRT plan by incorporating DVH information and gamma passing rates (GPs) (DVH_GPs) so as to better correlate the patient-specific quality assurance (QA) results with clinically relevant metrics. MATERIALS AND METHODS: DVH_GPs analysis was performed to specific structures of 51 intensity-modulated radiotherapy (IMRT) treatment plans (17 plans each for oropharyngeal neoplasm, esophageal neoplasm, and cervical neoplasm) with Delta4 3D dose verification system. Based on the DVH action levels of 5% and GPs action levels of 90% (3%/2 mm), the evaluation results of DVH_GPs analysis were categorized into four regions as follows: the true positive (TP) (%DE> 5%, GPs < 90%), the false positive (FP) (%DE ≤ 5%, GPs < 90%), the false negative (FN) (%DE> 5%, GPs ≥ 90%), and the true negative (TN) (%DE ≤ 5%, GPs ≥ 90%). Considering the actual situation, the final patient-specific QA determination was made based on the DVH_GPs evaluation results. In order to exclude the impact of Delta4 phantom on the DVH_GPs evaluation results, 5 cm phantom shift verification was carried out to structures with abnormal results (femoral heads, lung, heart). RESULTS: In DVH_GPs evaluation, 58 cases with FN, 5 cases with FP, and 2 cases with TP were observed. After the phantom shift verification, the extremely abnormal FN of both lung (%DE = 21.52%±8.20%) and heart (%DE = 19.76%) in the oropharyngeal neoplasm plans and of the bilateral formal heads (%DE = 26.41%±13.45%) in cervical neoplasm plans disappeared dramatically. DVH_GPs analysis was performed to all evaluation results in combination with clinical treatment criteria. Finally, only one TP case from the oropharyngeal neoplasm plans and one FN case from the esophageal neoplasm plans did not meet the treatment requirements, so they needed to be replanned. CONCLUSION: The proposed DVH_GPs evaluation method first make up the deficiency of conventional gamma analysis regarding intensity information and space information. Moreover, it improves the correlation between the patient-specific QA results and clinically relevant metrics. Finally, it can distinguish the TP, TN, FP, and FN in the evaluation results. They are affected by many factors such as the action levels of DVH and GPs, the feature of the specific structure, the QA device, etc. Therefore, medical physicist should make final patient-specific QA decision not only by taking into account the information of DVH and GPs, but also the practical situation.

Microstructured-core photonic-crystal fiber for ultra-sensitive refractive index sensing.

We propose a novel photonic crystal fiber refractive index sensor which is based on the selectively resonant coupling between a conventional solid core and a microstructured core. The introduced microstructured core is realized by filling the air-holes in the core with low index analyte. We show that a detection limit (DL) of 2.02×10⁻6 refractive index unit (RIU) and a sensitivity of 8500 nm/RIU can be achieved for analyte with refractive index of 1.33.

[Study on spectroscopic properties of Eu and Tb mixed solid complexes with a diamide ligand].

In the present work, Eu(NO3)3 and Tb(NO3)3 complexes with a diamide ligand 1,6-bis[(2'-benzylaminoformyl)phenoxyl]hexane (L) were prepared in the solution of chloroform and ethyl acetate. Their mixed complexes with different molar ratio also synthesized by coprecipitation. Eu and Tb complexes were mixed with different molar ratio, mechanically ground, and a series of mixed solid complexes were obtained. These mixed complexes were characterized by elemental analysis, UV-Vis, IR and XPS spectra. The analytical data were obtained by a Vario EL CHN and indicated that Eu and Tb complexes formed a 2:3 metal-to-ligand stoichiometries 2RE(NO3)3 x 3L x 4H2O. Their IR spectra were recorded on a Bruke FTS66V/S spectrophotometer. The results indicate that all complexes have similar IR spectra, of which the characteristic bands have similar shifts, suggesting that they have a similar coordination structure. UV-Vis spectra were recorded on a Hitachi U-3010 spectrophotometer and showed that under the influence of the mixed ions, the absorbance of the mixed complexes is not identical with that of the pure complexes. XPS spectra were analyzed on a PHI-5702 X-ray photoelectron spectroscope (XPS) operating with monochromatic Mg K alpha irradiation at pass energy of 29.4 eV. The binding energies of O (1s), Eu (3d) and Tb (4d) in the two kinds of mixed complexes were changed compared with Eu-L and Tb-L complexes. This indicates that these two synthetic methods were not a simple physical mixing process, but there was some chemical effect between the mixed Eu-L and Tb-L complexes. The fluorescence spectra of the mixed complexes were obtained on a Hitachi F-4500 spectrophotometer at room temperature. The excitation and emission slit widths was 1.0 nm. It was concluded from the excitation spectra that the best excitation wavelengths for Eu and Tb complexes are 396 and 320 nm respectively. For the convenience of comparing the fluorescence intensities with each other, the excitation wavelengths were set to 320 nm. For the mixed complexes prepared by coprecipitation, the peak positions of the 5 D4-->7 F6 and 5 D4-->7 F5 transitions were not changed. The peak at 590 nm was assigned to the 5D0-->7 F1 and 5 D4-->7 F4 transitions. Its position is dependent on the content of Eu and Tb complexes. When the content of Eu complex is large, this peak is near to the position of the 5 D0-->7 F1 transition, but when the content of Tb complex is large, it is near to the position of the 5 D4-->7 F4 transition. The peak at 620 nm is a combined peak of the 5 D0-->7 F2 and 5 D4-->7 F3 transitions. It has a similar change with the peak at 590 nm. The change of these peak positions could indicate that there was interaction between Eu and Tb complexes. The fluorescence intensities of the mixed solid complexes were changed obviously as compared with the pure Eu and Tb complexes. The fluorescence intensities of their 5 D4-->7 F6 and 5 D4-->7 F5 transitions were lower than those of the Tb complex as well as the theoretical values calculated by the molar ratio of Tb complex, and decreased with the increase in the content of Eu complex, which shows that the fluorescence intensities of terbium ions were quenched by europium ions. The fluorescence intensities of the two combined peaks at 590 and 620 nm are higher than that of Eu complex but lower than that Tb complex and they increased with the increase in the content of Tb complex, which indicates that the fluorescence intensities of Eu3+ were sensitized by Tb3+. In the mixed complexes prepared by grinding, the fluorescence intensities of Eu3+ were also sensitized by Tb3+ and the fluorescence intensities of Tb3+ are also quenched by Eu3+. Under the excitation of UV light, the mixed complexes resulted by coprecipitation exhibit different fluorescence color.

Synthesis and luminescent properties of lanthanide complexes with a novel multipodal ligand.

Solid complexes of lanthanide nitrates, picrates and perchlorates with a novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2'-benzylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Eu and Tb complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level T(1) of this ligand matches better to the lowest resonance energy level of Tb(III) than to Eu(III) ion. The influence of the counter anion on the luminescent intensity was also discussed.