Comparison of photon versus electron for tumor bed boost radiotherapy post-breast conserving surgery.

INTRODUCTION: The standard treatment (photon or electron) for tumor bed boost in breast cancer has not yet been clearly established. The aim of this work was to compare photon vs. electron for tumor bed boost radiotherapy post breast-conserving surgery and whole-breast irradiation concerning different dosimetric parameters. METHODS: This study included 51 patients who underwent conservative surgery and adjuvant radiotherapy. Of these, 28 patients had right-sided and 23 patients had a left-sided tumors. All patients in this study were treated with photon and then re-planned with electron plans. RESULTS: Both techniques electron and photon plans provided acceptable results while there was a better performance of the latter in terms of target coverage with statistical significance (p < 0.05). The global and maximum dose was significantly higher with electron compared to photon. Homogeneity index (HI) and conformity index (CI) and conformity number (CN) were better in photon plans, especially in deep-seated tumors. The quality of electron plans differed between patients according to depth, irregular shapes, and location of the tumor bed boost. The results of organs at risk (OARs) for ipsilateral lung and heart showed that photon plans were better than electron plans (p < 0.05), especially at a low dose (V2Gy and V1Gy) for ipsilateral lung. For contralateral breast, both photon and electron had nearly comparable results, where the dose delivered to the contralateral breast for both techniques was close to zero. Interestingly, the number of monitor units (MU) was reduced in electron compared to photon by 15.94% (p < 0.001). CONCLUSIONS: This study recommends the use of photon in treatment of tumor bed boost in conservative breast cancer and then electron as a second line when the former is not available.

Spectroscopic and Photo-Physical Properties of Near-IR Laser Dye in Novel Benign Green Solvents.

IR-792 as near IR (NIR) laser dye was dissolved with different concentrations in two types of ionic liquids (ILs) of different anion and cation, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIM TFSI) & 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4), as the benign green solvent and in methanol (MeOH) as a standard solvent. The behavior of fluorescence of IR-792 dye was studied. The fluorescence of IR-792 dissolved in the ILs was heavily compared to organic solvent. Some photo-physical parameters of IR-792 were calculated. Mainly, IR-792 had a very low quantum yield of fluorescence with high intersystem crossing rate & fluorescence lifetime in picosecond range. Optical absorption and behavior of fluorescence for the rigorously the purified imidazolium ILs in the neat condition and effect of IR-792 on their fluorescence have been examined. The emission behavior of IR-792 in green solvents was independent upon the wavelength of excitation, while the emission behavior of green solvents dependent upon the wavelength of excitation whether in pure state or with NIR laser dye. At most, the intensity of fluorescence of ILs is dependent upon dye concentration.