Three cases of Acanthamoeba keratitis diagnosed and treated in the early stage

Acanthamoeba keratitis (AK) is a severe infectious corneal ulcer that usually occurs in contact lens wearers. Although the number of AK cases in Japan has been increasing, many of these cases are diagnosed in the early stage and are treated adequately. This is probably because of the increased availability of various diagnostic techniques and the ever-increasing knowledge about AK among ophthalmologists. In this article, we described 3 cases of AK that were diagnosed and treated in the early stages of the disease, and we discuss why 1 of the cases had a less favorable prognosis than the other 2 cases, which had excellent prognoses, from an etiological point of view

肺腫瘍と留置マーカー間の日内および日間の位置誤差の検討

京都大学0048新制・課程博士博士(医学)甲第18452号医博第3907号新制||医||1004(附属図書館)31330京都大学大学院医学研究科医学専攻(主査)教授 伊達 洋至, 教授 武田 俊一, 教授 富樫 かおり学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Prediction of clinical outcome after stereotactic body radiotherapy for non-small cell lung cancer using diffusion-weighted MRI and (18)F-FDG PET.

To evaluate the use of diffusion-weighted magnetic resonance imaging (DW-MRI) and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for predicting disease progression (DP) among patients with non-small cell lung carcinoma (NSCLC) treated with stereotactic body radiotherapy (SBRT)

Intra- and interfractional variations in geometric arrangement between lung tumours and implanted markers.

[Purpose]To quantify the intra- and interfractional variations between lung tumours and implanted markers.[Materials and methods]Gold markers were implanted transbronchially around a lung tumour in fifteen patients. They underwent four-dimensional computed tomography scans twice, and the centroids of the tumour and markers were determined. Intrafractional variations were defined as the residual tumour motions relative to the markers due to respiration from the end-exhale phase. Interfractional variations were defined as the residual setup errors after correction for the position of the implanted markers in end-exhale phase images.[Results]The intrafractional variations differed between patients. The root mean squares of standard deviations for each phase were 0.6, 0.9, and 1.5 mm in the right–left, anterior–posterior, and superior–inferior directions, respectively. The maximum difference in intrafractional variation among 10 phases was correlated with the amplitude of tumour motion in all directions and the tumour-marker distance in the anterior–posterior and superior–inferior directions. The interfractional variations were within 2.5 mm.[Conclusions]The intrafractional variations differed according to the amount of tumour motion and the tumour-marker distance. Additionally, interfractional variations of up to 2.5 mm were observed. Thus, a corresponding margin should be considered during implanted marker-based beam delivery to account for these variations

The impact of abdominal compression on outcome in patients treated with stereotactic body radiotherapy for primary lung cancer.

The aim of this study was to evaluate the impact of abdominal compression (AC) on outcome in patients treated with stereotactic body radiotherapy (SBRT) for primary lung cancer. We retrospectively reviewed data for 47 patients with histologically proven non-small cell lung cancer and lung tumour motion ≥ 8 mm treated with SBRT. Setup error was corrected based on bony structure. The differences in overall survival (OS), local control (LC) and disease-free survival (DFS) were evaluated to compare patients treated with AC (n = 22) and without AC (n = 25). The median follow-up was 42.6 months (range, 1.4-94.6 months). The differences in the 3-year OS, LC and DFS rate between the two groups were not statistically significant (P = 0.909, 0.209 and 0.639, respectively). However, the largest difference was observed in the LC rate, which was 82.5% (95% CI, 54.9-94.0%) for patients treated without AC and 65.4% (95% CI, 40.2-82.0%) for those treated with AC. After stratifying the patients into prognostic groups based on sex and T-stage, the LC difference increased in the group with an unfavourable prognosis. The present study suggests that AC might be associated with a worse LC rate after SBRT using a bony-structure-based set-up

Dose-volume metrics associated with radiation pneumonitis after stereotactic body radiation therapy for lung cancer.

[Purpose]To identify dose–volume factors associated with radiation pneumonitis (RP) after stereotactic body radiation therapy (SBRT) for lung cancer. [Methods and Materials]This study analyzed 74 patients who underwent SBRT for primary lung cancer. The prescribed dose for SBRT was uniformly 48 Gy in four fractions at the isocenter. RP was graded according to the Common Terminology Criteria for Adverse Events (CTCAE) v.3. Symptomatic RP was defined as grade 2 or worse. Optimal cut-offs dividing the patient population into two subgroups based on the incidence of symptomatic RP were sought using the following dose–volume metrics: PTV volume (ml), mean lung dose (Gy), and V5, V10, V15, V20, V25, V30, V35, and V40 (%) of both lungs excluding the PTV. [Results]With a median follow-up duration of 31.4 months, symptomatic RP was observed in 15 patients (20.3%), including 1 patient with grade 3. Optimal cut-offs for pulmonary dose–volume metrics were V25 and V20. These two factors were highly correlated with each other, and V25 was more significant. Symptomatic RP was observed in 14.8% of the patients with V25 <4.2%, and the rate was 46.2% in the remainder (p = 0.019). PTV volume was another significant factor. The symptomatic RP rate was significantly lower in the group with PTV <37.7 ml compared with the larger PTV group (11.1% vs. 34.5%, p = 0.020). The patients were divided into three subgroups (patients with PTV <37.7 ml; patients with, PTV ≥37.7 ml and V25 <4.2%; and patients with PTV ≥37.7 ml and V25 ≥4.2%); the incidence of RP grade 2 or worse was 11.1%, 23.5%, and 50.0%, respectively (p = 0.013). [Conclusions]Lung V25 and PTV volume were significant factors associated with RP after SBRT

Optimization of a newly defined target volume in fiducial marker-based dynamic tumor-tracking radiotherapy

Background and purpose: To optimize the selection of fiducial markers used to determine the “internal target volume for tracking” (ITVtracking) for fiducial marker-based dynamic tumor-tracking (DTT) radiotherapy for lung tumors, with four-dimensional 320-row area-detector computed tomography (320-ADCT). Materials and methods: Ten patients with early-stage non-small cell lung carcinomas or metastatic lung tumors were enrolled. After implanting 4 or 5 fiducial markers around the lung tumor, all patients underwent 320-ADCT to determine the coordinates of the tumors and markers. The coordinate origin of each phase CT dataset was translated so that the marker-derived coordinate centers coincided. The ITVtracking was then defined by compositing the gross tumor volumes from all four-dimensional CT phases. We compared the ITVtracking with the typical ITV used in motion-encompassing method. We also compared the following 5 scenarios in selection of fiducial markers to define the coordinate center: a) the closest marker to the tumor, b) the closest two makers, c) the centroid of the all markers, d) the farthest two markers, and e) the farthest marker. Results: The scenario b was the best in 5 patients. The difference of the ITVtracking between the best scenario and b was less than 20% in the other 5 patients. The scenario c was the best in 4 patients. The ITVtracking was smaller than the typical ITV. Conclusion: ITVtracking was reasonable target in DTT radiotherapy. Proper ITVtracking might be created with choosing those midway between the two markers closest to the tumor or in the centroid of the markers

Intrafractional tracking accuracy in infrared marker-based hybrid dynamic tumour-tracking irradiation with a gimballed linac.

[Purpose]To verify the intrafractional tracking accuracy in infrared (IR) marker-based hybrid dynamic tumour tracking irradiation ("IR Tracking") with the Vero4DRT. [Materials and methods]The gimballed X-ray head tracks a moving target by predicting its future position from displacements of IR markers in real-time. Ten lung cancer patients who underwent IR Tracking were enrolled. The 95th percentiles of intrafractional mechanical (iE^[95]_M), prediction (iE^[95]_P), and overall targeting errors (iE^[95]_T ) were calculated from orthogonal fluoroscopy images acquired during tracking irradiation and from the synchronously acquired log files. [Results]Averaged intrafractional errors were (left–right, cranio-caudal [CC], anterior–posterior [AP]) = (0.1 mm, 0.4 mm, 0.1 mm) for iE^[95]_M, (1.2 mm, 2.7 mm, 2.1 mm) for iE^[95]_P , and (1.3 mm, 2.4 mm, 1.4 mm) for iE^[95]_T. By correcting systematic prediction errors in the previous field, the iE^[95]_P was reduced significantly, by an average of 0.4 mm in the CC (p < 0.05) and by 0.3 mm in the AP (p < 0.01) directions. [Conclusions]Prediction errors were the primary cause of overall targeting errors, whereas mechanical errors were negligible. Furthermore, improvement of the prediction accuracy could be achieved by correcting systematic prediction errors in the previous field

Evaluation of dynamic tumour tracking radiotherapy with real-time monitoring for lung tumours using a gimbal mounted linac.

[Purpose]To evaluate feasibility and acute toxicities after dynamic tumour tracking (DTT) irradiation with real-time monitoring for lung tumours using a gimbal mounted linac. [Materials and methods]Spherical gold markers were placed around the tumour using a bronchoscope prior to treatment planning. Prescription dose at the isocentre was 56 Gy in 4 fractions for T2a lung cancer and metastatic tumour, and 48 Gy in 4 fractions for the others. Dose-volume metrics were compared between DTT and conventional static irradiation using in-house developed software. [Results]Of twenty-two patients enrolled, DTT radiotherapy was successfully performed for 16 patients, except 4 patients who coughed out the gold markers, one who showed spontaneous tumour regression, and one where the abdominal wall motion did not correlate with the tumour motion. Dose covering 95% volume of GTV was not different between the two techniques, while normal lung volume receiving 20 Gy or more was reduced by 20%. A mean treatment time per fraction was 36 min using DTT. With a median follow-up period of 13.2 months, no severe toxicity grade 3 or worse was observed. [Conclusions]DTT radiotherapy using a gimbal mounted linac was clinically feasible for lung treatment without any severe acute toxicity

Differences in the dose-volume metrics with heterogeneity correction status and its influence on local control in stereotactic body radiation therapy for lung cancer

The purpose of this study is to evaluate the dose-volume metrics under different heterogeneity corrections and the factors associated with local recurrence (LR) after stereotactic body radiation therapy (SBRT) for non-small-cell lung cancer (NSCLC). Eighty-three patients who underwent SBRT for pathologically proven stage I NSCLC were reviewed retrospectively. The prescribed dose was 48 Gy in four fractions at the isocenter (IC) under heterogeneity correction with the Batho power law (BPL). The clinical plans were recalculated with Eclipse (Varian) for the same monitor units under the BPL and anisotropic analytical algorithm (AAA) and with no heterogeneity correction (NC). The dose at the IC, dose that covers 95% of the volume (D95), minimum dose (Min), and mean dose (Mean) of the planning target volume (PTV) were compared under each algorithm and between patients with local lesion control (LC) and LR. The IC doses under NC were significantly lower than those under the BPL and AAA. Under the BPL, the mean PTV D95, Min and Mean were 8.0, 9.4 and 7.4% higher than those under the AAA, and 9.6, 9.2 and 4.6% higher than those under NC, respectively. Under the AAA, all dose-volumetric parameters were significantly lower in T1a patients than in those with T1b and T2a. With a median follow-up of 35.9 months, LR occurred in 18 patients. Between the LC and LR groups, no significant differences were observed for any of the metrics. Even after stratification according to T-stage, no significant difference was observed between LC and LR