Ultrafast two dimensional infrared (2D-IR) vibrational echo spectroscopy has emerged as a powerful method for the study of molecular dynamics under thermal equilibrium conditions occurring on ultrafast time scales. Here, we describe experimental details of 2D-IR vibrational echo spectroscopy including the experimental setup, pulse sequence, heterodyne detection, and extraction of the mainly absorptive part of the 2D-IR spectrum. As an experimental example, the measurements of the hydrogen bond dynamics of neat water and water in a high concentration of NaBr solution are presented and compared. The experiments are performed on OD stretching vibration of dilute HOD in H2O to eliminate contributions from vibrational excitation transport. A new experimental observable for extracting dynamical information that yields the frequency-frequency correlation function is presented. The observable is the inverse of the center line slope (CLS) of the 2D spectrum, which varies from a maximum of 1 to 0 as spectral diffusion proceeds. The CLS is the inverse of the slope of the line that connects the maxima of the peaks of a series of cuts through the 2D spectrum that are parallel to the frequency axis associated with the first radiation field-matter interaction. Comparisons of the dynamics obtained from the data on water and the concentrated NaBr solutions show that the hydrogen bond dynamics of water around ions are much slower than in bulk water.

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Purpose: The dose‐related effects of patient setup errors on biophysical indices were evaluated for conventional wedge (CW) and field‐in‐field (FIF) whole breast irradiation techniques. Methods: The treatment plans for 10 patients receiving whole left breast irradiation were retrospectively selected. Radiobiological and physical effects caused by dose variations were evaluated by shifting the isocenters and gantry angles of the treatment plans. Dose‐volume histograms of the planning target volume (PTV), heart, and lungs were generated, and conformity index (CI), homogeneity index (HI), tumor control probability (TCP), and normal tissue complication probability (NTCP) were determined. Results: For “isocenter shift plan” with posterior direction, the D95 of the PTV decreased by approximately 15% and the TCP of the PTV decreased by approximately 50% for the FIF technique and by 40% for the CW; however, the NTCPs of the lungs and heart increased by about 13% and 1%, respectively, for both techniques. Increasing the gantry angle decreased the TCPs of the PTV by 24.4% (CW) and by 34% (FIF). The NTCPs for the two techniques differed by only 3%. In case of CW, the CIs and HIs were much higher than that of the FIF in all cases. It had a significant difference between two techniques (p<0.01). According to our results, however, the FIF had more sensitive response by set up errors rather than CW in bio‐physical aspects. Conclusions: The radiobiological‐based analysis can detect significant dosimetric errors then, can provide a practical patient quality assurance method to guide the radiobiological and physical effects.

Purpose: The main purpose of this study is to investigate the optimum oblique‐beam arrangement for bilateral metallic prosthesis prostate cancer treatment in pencil beam scanning (PBS) proton therapy. Methods: A computed tomography dataset of bilateral metallic prosthesis prostate cancer case was selected for this retrospective study. A total of four beams (rightanterior‐ oblique [RAO], left‐anterior‐oblique [LAO], left‐posterior‐oblique [LPO], and right‐posterior‐oblique [RPO]) were selected for treatment planning. PBS plans were generated using multi‐field‐optimization technique for a total dose of 79.2 Gy[RBE] to be delivered in 44 fractions. Specifically, five different PBS plans were generated based on 2.5% ± 2 mm range uncertainty using five different beam arrangements (i)LAO+RAO+LPO+RPO, (ii)LAO+RAO, (iii)LPO+RPO, (iv)RAO+LPO, and (v)LAO+RPO. Each PBS plan was optimized by applying identical dose‐volume constraints to the PTV, rectum, and bladder. Treatment plans were then compared based on the dose‐volume histograms results. Results: The PTV coverage was found to be greater than 99% in all five plans. The homogeneity index (HI) was found to be almost identical (range, 0.03–0.04). The PTV mean dose was found to be comparable (range, 81.0–81.1 Gy[RBE]). For the rectum, the lowest mean dose (8.0 Gy[RBE]) and highest mean dose (31.1 Gy[RBE]) were found in RAO+LAO plan and LPO+RPO plan, respectively. LAO+RAO plan produced the most favorable dosimetric results of the rectum in the medium‐dose region (V50) and high‐dose region (V70). For the bladder, the lowest (5.0 Gy[RBE]) and highest mean dose (10.3 Gy[RBE]) were found in LPO+RPO plan and RAO+LAO plan, respectively. Other dosimetric results (V50 and V70) of the bladder were slightly better in LPO+RPO plan than in other plans. Conclusion: Dosimetric findings from this study suggest that two anterior‐oblique proton beams arrangement (LAO+RAO) is a more favorable option with the possibility of reducing rectal dose significantly while maintaining comparable target coverage and acceptable bladder dose.

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Single-field IMPT delivered higher dose to rectum, bladder, prostate, and CTV than any other technique. But two-file IMPT delivered most homogenous and consistent dose to prostate and CTV with much lower dose to rectum and bladder compare to DSPT and SFUD. With same respect two-field SFUD delivery produced better dose coverage to prostate and CTV compare to DSPT. The two-field IMPT with conjunction of daily cone beam CT can be considered a better dose delivery technique.

Purpose: To analysis delivered dose on target using gafchromic films for evaluating accuracy of target margin size obtained from cone beam computed tomography (CBCT) during lung stereotactic body radiation therapy (SBRT) Methods: The phantom consists of measurement part and driving part. The motor of Quasar motion phantom (Modus Medical Devices Inc, London, ON, Canada) was used for driving part and we developed measurement part which consist of cork cylindrical body and acrylic target with radiochromic film inserted into central and both ends of acrylic target. In this study lung SBRT cases through both four dimensional computed tomography (4DCT) and CBCT were selected. Target contouring including margin based on 4DCT is defined with a 1 cm margin around gross tumor volume (GTV) in all directions except for inferior direction. The moving range in inferior direction was larger than other directions thus, including 2 cm margin. In case of CBCT, the margin means blurring of target on CBCT images. This study was compared margin size determined through 4DCT and that of based on CBCT and we also evaluated dose profile and the length of margin in superior‐inferior direction on CBCT compared with 4DCT. Results: The length of target including margin was 2.48 cm (based on CBCT) and 2.66 cm (based on 4DCT), respectively in superior‐inferior direction. The difference of delivered dose on target between two margins was only within 1%. Conclusions: This study has shown the feasibility of determining target margin using CBCT for delivering more accurate prescription dose to lung cancer.

Purpose: The purpose of this study is to identify whether the change of MV CBCT intensity can improve intensity based registration accuracy using predefined modification level and filtering process. Methods: To obtain modification level, images of the cheese phantom and the deformable lung phantom which was intentionally created in the laboratory to imitate the changes of the breathing period was acquired from both kilovoltage CT (kV CT), megavoltage cone‐beam CT (MV CBCT). From the cheese phantom images, the modification level of MV CBCT was defined from the relationship between Hounsfield Units (HUs) of kV CT and MV CBCT images. ‘Gaussian smoothing filter’ was added to reduce the noise of the MV CBCT images. The intensity of MV CBCT image was changed to the intensity of the kV CT image to make the two images have the same intensity range as if they were obtained from the same modality. And then deformable registration was applied. Results: The vector differences from the result were 2.23, 1.39mm with/without modification of intensity of MV CBCT images, respectively. Conclusions: Our method has quantitatively improved the accuracy of deformable registration and could be a useful solution to improve the image registration accuracy.