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The present study evaluated the short-term characteristics (<3 days) of a hydrogel spacer from the time of injection during stereotactic body radiation therapy (SBRT) for prostate cancer. Fifteen patients treated with SBRT via the CyberKnife system (36.25 Gy/5 fractions) were enrolled in this retrospective study. Two magnetic resonance (MR) images were obtained with a hydrogel spacer: one on a computed tomography (CT) simulation day (MR pretreatment [MR pre ]) and the other on the last treatment day (MR posttreatment [MR post]). Two medical physicists contoured the hydrogel spacer on each MR image. The changes of the shapes and the volume for the hydrogel spacer between 2 MR images were evaluated. The median period between hydrogel spacer injection and CT simulation was 1 day (range, 1-9 days). The median period between CT simulation and the last treatment was 17 days (range, 14-25 days). Regarding the volume change of the hydrogel spacer, the 2 observers observed significant differences between the volumes of the hydrogel spacer on the MR pre and MR post. However, the average volume difference between them was less than 1 cm3. The average dice similarity coefficient between the MR pre and MR post to compare the shape was more than 0.83. In addition, no clear correlation was confirmed between the volume change and the period from hydrogel spacer injection to CT simulation. A single day is an acceptable interval between hydrogel spacer injection and treatment planning for SBRT for prostate cancer. [ABSTRACT FROM AUTHOR]

Abstract: The YBaCo4O7+d (Y-114) phase has recently attracted interests as a potential oxygen storage material due to its oxygen intake/release capability at 200–400°C. Nevertheless, thermal instability of Y-114 has been an obstacle for future applications, since this compound immediately starts to decompose when the sample is heated at 700–800°C in oxygen-rich atmosphere. Here we demonstrate that Al-for-Co substitution in Y-114 drastically enhances the thermal stability. Substituting only 10at.% of aluminum for cobalt in Y-114 essentially suppresses the decomposition reaction seen at 700–800°C, while well retaining its remarkable oxygen intake/release capability at 200–400°C. It is also revealed that the addition of aluminum effectively reduces the particle size. The Al-substituted Y-114 products exhibit superior oxygen intake/release response to the Al-free products upon switching the atmosphere between O2 and N2. [ABSTRACT FROM AUTHOR]

Abstract: Background and purpose: The aim of this study was to define the effects of voluntary anal contraction on prostate motion in an experimental setting. Materials and methods: Thirty-eight patients (median age, 76years) with prostate cancer underwent thin-slice computed tomography (CT) in the vicinity of the prostate before and after active anal contraction. Three-dimensional displacement of the pelvis and prostate was measured. Results: Mean (±standard deviation, SD) overall displacement of the prostate due to anal contraction was 0.3±1.4mm to the right, 9.3±7.8mm to the anterior, and 5±4mm to the cranial direction. Mean displacement of the pelvis was 0.5±1.8mm to the right, 4.1±7.1mm to the anterior, and 1±3mm to the cranial direction. Mean displacement of the prostate relative to the pelvis was 0.1±1.1mm to the left, 5.2±3.3mm to the anterior, and 4±4mm to the cranial direction. Conclusions: Voluntary anal contraction within an experimental setting induces large prostate and bone motion, mainly in the anterior and cranial directions. The frequency and magnitude of actual anal contractions during radiotherapy for prostate cancer need to be determined. [Copyright &y& Elsevier]

We have developed a novel irradiation technique for lung cancer that combines a linear accelerator and CT scanner with patient-controlled breath-hold and radiation beam switching. We applied this technique to stereotactic three-dimensional (3D) conformal radiotherapy for stage I non-small cell lung cancer (NSCLC) and evaluated the primary therapeutic outcomes. A total of 35 patients with stage I (15 IA, 20 IB) primary NSCLC (20 adeno, 13 squamous cell, and 2 others) were treated with this technique. Patients ranged from 65 to 92 years old (median, 78 years). Twenty-three (66%) patients were medically inoperable due to mainly chronic pulmonary disease or high age. Three-dimensional treatment plans were made using 10 different non-coplanar dynamic arcs. The total dose of 60 Gy was delivered in 10 fractions (over 5–8 days) at the minimum dose point in the planning target volume (PTV) using a 6 MV X-ray. After adjusting the isocenter of the PTV to the planned position by a unit comprising CT and linear accelerator, irradiation was performed under patient-controlled breath-hold and radiation beam switching. All patients completed the treatment course without complaint. Complete response (CR) and partial response (PR) rates were 8/35 (23%) and 25/35 (71%), respectively. Pulmonary complications of National Cancer Institute-Common Toxicity Criteria grade >2 were noted in three (9%) patients. During follow-up (range, 6–30 months; median, 13 months), two (6%) patients developed local progression and five (14%) developed distant or regional lymph node metastases. Two-year overall survival rates for total patients and medically operable patients were 58 and 83%, respectively. In conclusion, this new irradiation technique, utilizing patient-controlled radiation beam switching under self-breath-hold after precise alignment of the isocenter, allows safe high-dose stereotactic radiotherapy with sufficient margins around the CTV and reduced treatment times. Based on the initial results, excellent local control with minimal complications is expected for stage I NSCLC. [Copyright &y& Elsevier]

: PurposeTo introduce and assess a new irradiation technique for lung cancer that utilizes a linear accelerator and computed tomography (CT) scanner combination, along with a novel switching mechanism, which enables patients to synchronize the duration of irradiation with self-breath-holding without respiratory monitoring devices.: Methods and materialsA newly developed treatment unit, a linear accelerator combined with a CT scanner (CT-linac), was used for irradiation. A novel switching mechanism, connected directly to the console of the linear accelerator, enabled the patient to control the radiation beam to correspond with the duration of self-breath-holding during a session determined by a radiation technologist. Twenty patients with lung cancer were enrolled in this study. All patients were instructed in the technique of breath-holding during the inspiration phase using visualization of respiratory motion through fluoroscopy as a teaching aid. CT scans under patients’ self-breath-holding were repeated three times, and differences in tumor position on CT images were measured. The reproducibility of tumor position was visually evaluated on electronic portal images (EPI).: ResultsMean maximum differences in tumor position under patients’ self-breath-holding were 2.2 mm in the cranial-caudal direction, 1.4 mm in the anterior-posterior direction, and 1.3 mm in the right-left direction. Switching of the radiation beam was delayed less than 0.1 s behind patient switching. EPIs were used to determine that reproducibility of tumor position was satisfactorily accurate.: ConclusionThe reproducibility of tumor position, during patient self-breath-holding synchronized with patient-initiated radiation and without a respiratory monitoring device, was sufficiently accurate. This novel irradiation technique for lung tumors using a combination CT-linac offers reduced PTV, sufficient reproducibility, and decreased duration of treatment. [Copyright &y& Elsevier]

The purpose of this study was to measure the motion of the chest surface during breath-holding treatment for lung cancer using deformable image registration (DIR). Forty non–small-cell lung cancer patients treated with breath-holding stereotactic body radiation therapy were retrospectively examined. First, intensity-based DIR between 2 breath-holding computed tomography (CT) images was performed. Subsequently, deformation vector field (DVF) for all dimensions (left-right, anterior-posterior, and superior-inferior) was calculated from the result. For the analysis of chest surface, the DVF value of the only chest surface area was extracted after the chest surface was divided into 12 regions of interest (ROI) based on anatomy. Additionally, for the analysis of the correlation with the internal tumor motion, the median value of DVF for each surface ROI and the motion of the center of gravity of the tumor volume were used. It was possible to calculate the motion of chest surface without any outliers for all patients. For the average of 12 surface ROIs, the motion of 3D chest surface was within 2 mm (30 cases), 3 mm (8 cases), and 4 mm (2 cases). There was no correlation between the motion of the chest surface and that of the tumor for all 12 surface ROIs. We proposed a technique to evaluate the surface motion using DIR between multiple CT images. It could be a useful tool to calculate the motion of chest surface. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the robustness of 3-dimensional conformal technique with MLC position control into the planning target volume (PTV) in stereotactic body radiotherapy for lung cancer. Two techniques using fixed beams were compared; one technique involved setting the MLC position outside the PTV and was referred to as Plan "O." Another technique involved setting the MLC position inside the PTV and was referred to as Plan "I." Two tumor motions were simulated: (1) tumor motion on the internal target volume (ITV) boundary and (2) tumor motion on the PTV boundary. Ten-phase CT images that captured the tumor in respiratory motion were generated for 2 simulations. Then, 4-dimensional (4D) treatment planning was performed by using deformable image registration. The gross tumor volume (GTV) dose changes between the 4D accumulated dose and treatment planning dose were evaluated for Plan "O" and Plan "I," respectively. For the simulation of tumor motion on the ITV boundary, the changes in GTV D50% were −0.10 ± 0.31% and −0.22 ± 0.26% (p < 0.05) for Plan "O" and Plan "I," respectively. In the same manner, for the simulation of tumor motion on the PTV boundary, the changes in GTV D50% were −3.37 ± 2.16% and −3.68 ± 1.71% (p < 0.05). Our result suggested that the dose change would be negligible in a clinical situation where the tumor moves within the ITV margin for both techniques, while Plan "O" showed better robustness. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To investigate prognostic and risk factors for recurrence after stereotactic body radiation therapy (SBRT) in patients with stage I non-small cell lung carcinoma (NSCLC), focusing on dual time point [18]F-fluorodeoxyglucose positron emission tomography (FDG PET). Materials and methods: We prospectively evaluated 57 patients with stage I NSCLC (45 T1N0M0 and 12 T2N0M0) who had undergone pretreatment FDG-PET/CT and were subsequently treated with SBRT. All patients received a whole-body PET/CT scan at 60min and a whole-lung at 120min after the injection. The maximum standardized uptake value (SUV) and retention index (RI) of the lesions were calculated. Local recurrence, regional lymph node metastasis, distant metastasis, and the recurrence pattern were evaluated. Cox proportional hazard regression analyses were performed to evaluate prognostic factors or risk factors of recurrence. Results: During the median follow-up period of 27months, local recurrence, regional lymph node metastasis, and distant metastasis were seen in 17 (30%), 12 (21%), and 17 (30%) of the 57 patients, respectively. The 3-year overall survival rate was 63.4%. SUVmax did not affect any recurrence, DFS, OS, or CSS. RI significantly predicted higher distant metastasis (HR 47.546, p =0.026). In contrast, RI tended to predict lower local recurrence (HR 0.175, p =0.246) and regional lymph node metastasis (HR 0.109, p =0.115). Conclusions: SUVmax at staging FDG-PET does not predict any recurrence, DFS, OS or CSS. In contrast, higher RI predicts higher distant metastasis and tended to predict lower local or regional lymph node metastasis. [Copyright &y& Elsevier]

Docetaxel is a novel, potentially highly beneficial drug for the treatment of lung cancer, and has shown remarkable radio-sensitizing effects in vitro. In the present study, we evaluated whether weekly docetaxel (20 mg/m2) and conventionally fractionated radiotherapy with the two-dimensional (2D) technique could be tolerated and effective in the treatment of locally advanced non-small-cell lung cancer (NSCLC). Thirty-two stage III (IIIA:13, IIIB:19) NSCLC patients were treated with weekly administration of docetaxel (20 mg/m2) on days 1, 8, 15, 22, 29 and 36 in addition to concurrent radiation therapy. The total tumor dose was 60–66 Gy given with a 2D technique in 6–7 weeks. Complete response was observed in 9/32 (28%) patients and partial response in 20/32 (63%). Three (9%) patients died of chemoradiation-induced pneumonitis after completion of therapy. In total, grade >3 toxicities included pneumonitis (47%) and esophagitis (16%). The median overall survival duration was 12 months. The dimensions of the radiotherapy port were larger in patients who produced severe (grade >3) chemoradiation pneumonitis than in patients who did not (P<0.05). The median survival time was 12.4 months and 2-year overall survival were 35%. The survival was better in patients whose first radiotherapy port dimensions were less than 150 cm2 compared to patients whose first radiation port dimensions were ≧150 cm2 (P<0.05). In conclusion, concurrent weekly administration of docetaxel (20 mg/m2) with 2D radiotherapy for NSCLC, had good local response, but survival rate was not completely satisfactory due to chemoradiation pneumonitis, which was the principal toxicity that adversely affected prognosis in elderly patients whose radiotherapy port was large. [Copyright &y& Elsevier]

Purpose: To improve reproducibility in stereotactic irradiation (STI) without using noninvasive immobilization devices or body frames, we have developed an integrated computed tomography (CT)-linac irradiation system connecting CT scanner and linac via a common treatment couch.Methods and Materials: This system consists of a linac, a CT scanner, and a common treatment couch. The linac and the CT gantry are positioned on opposite ends of the couch so that, by rotating the treatment couch, linac radiotherapy or CT scanning can be performed. The rotational axis of the linac gantry is coaxial with that of the CT gantry, and the position of the linac isocenter on the couch matches the origin of the coordinate system for CT scanning when the couch is rotated 180 degrees toward the CT side. Instead of the couch moving into the gantry, as in conventional CT, in this case the table is fixed and scanning is accomplished by moving the gantry. We evaluated the rotational accuracy of the common couch and the scan-position accuracy of the self-moving gantry CT.Results: The positional accuracy of the common couch was 0.20, 0.18, and 0.39 mm in the lateral, longitudinal, and vertical directions, respectively. The scan-position accuracy of the CT gantry was less than 0.4 mm in the lateral, longitudinal, and vertical directions.Conclusion: This irradiation system has a high accuracy and is useful for noninvasive STI and for verification of the position of a target in three-dimensional conformal radiotherapy. [ABSTRACT FROM AUTHOR]