Yoshiki Norihisa

Kansai Medical University, Moriguchi, Ōsaka, Japan

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Publications (39)70.6 Total impact

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    ABSTRACT: There are few reports of the outcomes of external beam radiotherapy in Asian males with localized prostate cancer. The aim of this study is to evaluate the long-term outcomes of external beam irradiation using three-dimensional two-dynamic conformal arc therapy, combined with neoadjuvant hormonal therapy, in patients with T1c-T2N0M0 prostate cancer. Between March 2003 and August 2007, 150 Japanese patients with T1c-T2N0M0 prostate cancer were definitively treated with three-dimensional two-dynamic conformal arc therapy. The median age, pretreatment prostate-specific antigen values and neoadjuvant hormonal therapy period were 73 years, 9.4 ng/ml and 6 months, respectively. In principle, 74 Gy was delivered to the planning target volume, although the total dose was reduced to 70 Gy in patients with unfavorable risk factors, such as severe diabetes mellitus or anticoagulant therapy. No adjuvant hormonal therapy was given to any patient. Salvage hormonal therapy was started when the prostate-specific antigen value exceeded 4 ng/ml in a monotonically increasing manner. The median follow-up period was 79 months. Salvage hormonal therapy was initiated in 10 patients and the median prostate-specific antigen value at the initiation was 4.7 ng/ml. The 5-year Kaplan-Meier estimates of the biochemical relapse-free survival rate, the salvage hormonal therapy -free rate and the overall survival rate were 83.3% (95% confidence interval = 77.1-89.6%), 94.3% (95% confidence interval = 90.4-98.1%) and 96.3% (95% confidence interval = 93.1-99.5%), respectively. The 5-year cumulative incidence rates of developing more than Grade 2 late rectal and urinary toxicities were 5.5 and 2.9%, respectively. Three-dimensional two-dynamic conformal arc therapy, with up to 74 Gy, in patients with T1c-T2N0M0 prostate cancer with neoadjuvant hormonal therapy was well tolerated and achieved good biochemical control and survival outcomes.
    Japanese Journal of Clinical Oncology 12/2013; · 1.90 Impact Factor
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    ABSTRACT: Pathological diagnosis fails in some pulmonary tumors, although they may be highly suspected to be primary lung cancer. We studied the outcome of stereotactic body radiotherapy for a clinically diagnosed primary stage I lung cancer without pathological confirmation. The current study included 37 patients (39 lesions) treated with stereotactic body radiotherapy who were clinically diagnosed with primary stage I lung cancer between August 1998 and April 2009 at our hospital. Pulmonary tumors were highly suspected to be malignant from physical and imaging examinations. Biopsies were performed for 62 % of patients, although malignancy was not pathologically confirmed. In the other 38 % of patients, a biopsy was not feasible. Median age of the patients was 77 years. Median tumor diameter was 20 mm. A total median dose of 48 Gy was prescribed to the isocenter in four fractions. Median follow-up period was 39 months. The 3-year overall survival, local control, and regional-distant control were 74.2, 94.0, and 68.6 %, respectively. In patients with tumors ≤20 mm, overall survival and regional-distant control were significantly higher than in patients with tumors >20 mm (p ≤ 0.001), whereas no significant difference was observed regarding local control. No grade 3-5 adverse events possibly, probably, or definitely related to the treatment were observed. Stereotactic body radiotherapy is safe and effective for a clinically diagnosed primary stage I lung cancer when pathological diagnosis is difficult even with repeat biopsies, or a biopsy is not feasible for reasons of the patient's health condition or wishes.
    International Journal of Clinical Oncology 11/2013; · 1.41 Impact Factor
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    ABSTRACT: We report the case of a 41-year-old man with a late recurrence of nonseminomatous germ cell tumor, which was successfully treated with intensity-modulated radiation therapy. For the residual retrocrural tumor invading the 11th and 12th thoracic vertebrae with an abnormal level of tumor marker (α-fetoprotein: 23.2 ng/ml) after salvage chemotherapy, chemotherapy could not be continued due to its neurotoxicity, and surgery could not be performed due to the location. In this situation, intensity-modulated radiation therapy achieved a complete response of tumor marker. The patient remained in complete clinical remission after 3 years. The efficacy of radiotherapy, especially intensity-modulated radiation therapy, for a nonseminomatous germ cell tumor is discussed.
    Japanese Journal of Clinical Oncology 07/2013; · 1.90 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the interfractional prostate motion of patients immobilized in the prone position using a thermoplastic shell. A total of 24 patients with prostate calcifications detectable using a kilo-voltage X-ray image-guidance system (ExacTrac X-ray system) were examined. Daily displacements of the calcification within the prostate relative to pelvic bony structures were calculated by the ExacTrac X-ray system. The average displacement and standard deviation (SD) in each of the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were calculated for each patient. Based on the results of interfractional prostate motion, we also calculated planning target volume (PTV) margins using the van Herk formula and examined the validity of the PTV margin of our institute (a 9-mm margin everywhere except posteriorly, where a 6-mm margin was applied). In total, 899 data measurements from 24 patients were obtained. The average prostate displacements ± SD relative to bony structures were 2.8 ± 3.3, -2.0 ± 2.0 and 0.2 ± 0.4 mm, in the SI, AP and LR directions, respectively. The required PTV margins were 9.7, 6.1 and 1.4 mm in the SI, AP and LR directions, respectively. The clinical target volumes of 21 patients (87.5%) were located within the PTV for 90% or more of all treatment sessions. Interfractional prostate motion in the prone position with a thermoplastic shell was equivalent to that reported for the supine position. The PTV margin of our institute is considered appropriate for alignment, based on bony structures.
    Journal of Radiation Research 07/2013; · 1.45 Impact Factor
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    ABSTRACT: OBJECTIVES: Salvage radiotherapy is the only curative treatment for patients with prostate cancer showing biochemical progression after radical prostatectomy. In this study, we evaluated the clinicopathological parameters that influence the outcome of salvage radiotherapy. METHODS: Medical records of 49 patients who underwent salvage radiotherapy after radical prostatectomy from 1997 to 2008 at the Graduate School of Medicine, Kyoto University, were retrospectively reviewed. Radiotherapy was carried out with 66 Gy on the prostatic bed. RESULTS: Biochemical progression-free survival after salvage radiotherapy at 2, 5 and 7 years was 51.0%, 42.2% and 42.2%, respectively. Significant parameters predicting biochemical progression after salvage radiotherapy by Cox regression analysis were prostatectomy Gleason score sum ≥8 (hazard ratio 0.08; 95% confidence interval 0.03-0.22; P = 0.001), prostate-specific antigen nadir after radical prostatectomy ≥0.04 ng/mL (hazard ratio 0.30; 95% confidence interval 0.13-0.69; P = 0.005) and negative surgical margin (hazard ratio 0.28; 95% confidence interval 0.12-0.70; P = 0.006). When the patients were subgrouped by these risk factors, the 5-year progression-free survival rates after salvage radiotherapy were 77.8%, 50.0% and 6.7% in patients with 0, 1 and ≥2 predictors, respectively. CONCLUSION: In order to discriminate favorable candidates for salvage radiotherapy, Gleason score of prostatectomy, prostate-specific antigen nadir after prostatectomy and positive surgical margin represent independent predictors. Thus, progression-free survival might be more precisely predicted according to the presence/absence of these risk factors. The significance of this risk classification should be confirmed by large prospective studies.
    International Journal of Urology 01/2013; · 1.73 Impact Factor
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    ABSTRACT: Fifty-three patients with biochemical relapse (BCR) after receiving external beam radiotherapy (EBRT) against locally advanced prostate cancer (stage III : International Union Against Cancer [UICC] 6th edition) between September 1997 and January 2006 at our institution, who were treated with salvage hormonal therapy (HTx), were followed for a mean period of 75.5 months. There was progression to castrationresistant prostate cancer (CRPC) during the follow-up period in 17 patients (32.0%). The median time to CRPC after initial HTx was 17 months. Univariate analysis revealed that time to BCR after EBRT was significantly associated with progression to CRPC (p=0.022), while PSA-doubling time just before salvage HTx was marginally associated with irradiation dose (p=0. 088, p=0.128 respectively). Multivariate analysis showed that time to BCR after EBRT was the only significant predictor of progression to CRPC (p= 0.035, Hazard ratio ; 0.252, 95% confidence interval ; 0.070-0.905) conclusion, time to BCR after EBRT might be a good predictor for the efficiency of salvage HTx after EBRT against locally advanced prostate cancer.
    Hinyokika kiyo. Acta urologica Japonica 11/2012; 58(11):599-603.
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    ABSTRACT: 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.
    Journal of Radiation Research 09/2012; · 1.45 Impact Factor
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    ABSTRACT: Heterogeneity correction algorithms can have a large impact on the dose distributions of stereotactic body radiation therapy (SBRT) for lung tumors. Treatment plans of 20 patients who underwent SBRT for lung tumors with the prescribed dose of 48 Gy in four fractions at the isocenter were reviewed retrospectively and recalculated with different heterogeneity correction algorithms: the pencil beam convolution algorithm with a Batho power-law correction (BPL) in Eclipse, the radiological path length algorithm (RPL), and the X-ray Voxel Monte Carlo algorithm (XVMC) in iPlan. The doses at the periphery (minimum dose and D95) of the planning target volume (PTV) were compared using the same monitor units among the three heterogeneity correction algorithms, and the monitor units were compared between two methods of dose prescription, that is, an isocenter dose prescription (IC prescription) and dose-volume based prescription (D95 prescription). Mean values of the dose at the periphery of the PTV were significantly lower with XVMC than with BPL using the same monitor units (P < 0.001). In addition, under IC prescription using BPL, RPL and XVMC, the ratios of mean values of monitor units were 1, 0.959 and 0.986, respectively. Under D95 prescription, they were 1, 0.937 and 1.088, respectively. These observations indicated that the application of XVMC under D95 prescription results in an increase in the actually delivered dose by 8.8% on average compared with the application of BPL. The appropriateness of switching heterogeneity correction algorithms and dose prescription methods should be carefully validated from a clinical viewpoint.
    Journal of Radiation Research 07/2012; 53(5):777-84. · 1.45 Impact Factor
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    ABSTRACT: To identify dose-volume factors associated with radiation pneumonitis (RP) after stereotactic body radiation therapy (SBRT) for lung cancer. 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. 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). Lung V25 and PTV volume were significant factors associated with RP after SBRT.
    International journal of radiation oncology, biology, physics 03/2012; 83(4):e545-9. · 4.59 Impact Factor
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    ABSTRACT: Long-term outcomes remain unknown after stereotactic body radiation therapy (SBRT). We observed a few patients who developed disease progression late, at 5 years or more, after SBRT. In this report, we describe the characteristics of those patients with late recurrence after SBRT. We retrospectively reviewed patients who underwent SBRT for non-small cell lung cancer with histological confirmation between January 1999 and December 2005 at our institution. During this period, 48 Gy of SBRT in four fractions at the isocenter was prescribed for all patients. In total, 66 patients were eligible. With a median follow-up period of 35.9 months, the 5-year overall survival and disease-free survival rates were 44.6% (95% confidence interval, 33.5-59.5%) and 33.8% (95% confidence interval, 23.6-48.4%), respectively. Of the patients, 16 survived without disease progression for 5 years or more after SBRT. Of these, four patients developed late recurrence at 76, 101, 108, and 109 months after SBRT. Three of the patients were females with adenocarcinomas; the other was a male with squamous cell carcinoma. The initial sites of recurrence were local in two patients, distant in one, and simultaneously local and distant in one. A total of two patients with local recurrence alone were still alive at 138 months after SBRT. The rate of late recurrence was not negligible in long-term survivors after SBRT. Our experiences indicate that long-term follow-up is needed after SBRT for non-small cell lung cancer.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 02/2012; 7(2):453-6. · 4.55 Impact Factor
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    ABSTRACT: BACKGROUND: The outcomes of three-dimensional conformal radiation therapy (3D-CRT) combined with neoadjuvant hormonal therapy (NAHT) in Japanese patients with T1c-T2N0M0 prostate cancer, with initiation of salvage hormonal therapy (SHT) at a relatively early phase, were analyzed. METHODS: Fifty-nine Japanese patients with T1c-T2N0M0 prostate cancer who received radical 3D-CRT between January 1999 and January 2003 were evaluated. The median age, initial prostate-specific antigen (PSA) level, and duration of NAHT were: 72 years, 9.4 ng/ml, and 6 months, respectively. Seventy Gy was given in 35 fractions confined to the prostate ± seminal vesicles. AHT was not administered after 3D-CRT in any patients. RESULTS: The median follow-up period was 89 months. The median PSA value at the time of initiation of SHT was 4.7 ng/ml (range 0.1-21.6 ng/ml). The overall, disease-specific, PSA failure-free (based on the Phoenix definition), and SHT-free survival rates at 8 years were 82.8% (95% confidence interval [CI] 72.4-93.2), 100%, 62.4% (47.1-77.8), and 82.6% (71.3-94.0), respectively. Only one patient developed grade 3 late toxicity. CONCLUSIONS: The PSA control rates in our series of Japanese patients with stage T1c-T2N0M0 prostate cancer treated with the standard dose of 3D-CRT combined with NAHT seemed at least comparable to those reported from Western countries; as well, the patients had excellent outcomes. The present outcomes can be used as basic data for evaluating the impact of dose escalation with intensity-modulated radiation therapy for Japanese patients with prostate cancer in the future.
    International Journal of Clinical Oncology 10/2011; · 1.41 Impact Factor
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    ABSTRACT: Intensity-modulated radiation therapy (IMRT) has been employed as a precision radiation therapy with higher conformity to the target. Although clinical outcomes have been reported for many investigations, detailed treatment planning results have not been mentioned to date. The aim of this study was to evaluate the dose specifications of our IMRT treatment plans for locally advanced prostate cancer. Seventy-seven clinically applied IMRT plans treated between September 2003 and December 2005, in which patients were irradiated with 78 Gy in the prone position, were retrospectively analyzed. Dosimetric data output from dose volume histograms were evaluated in detail. The mean dose ± standard deviation, homogeneity index, and conformity index to the planning target volume (PTV) were 78.3 ± 0.7 Gy (100.4 ± 0.9%), 13.7 ± 3.0, and 0.83 ± 0.04, respectively. For the clinical target volume, the mean dose was 80.3 ± 0.7 Gy (102.9 ± 0.9%).The V40, V60, and V70 Gy of the rectal wall were 58.3 ± 2.8, 29.6 ± 2.7, and 15.2 ± 3.0%, respectively. Planning difficulties were encountered in patients whose bowels were displaced downward, as constraints imposed by the bowel position altered the dose index of the PTV. In many cases, additional bowel optimization parameters were required to satisfy constraints for organs at risk. However, major deviation could be avoided by inverse planning with computer optimization. IMRT allowed the creation of acceptable and practical treatment plans for locally advanced prostate cancer. Reports regarding detailed dosimetric evaluations are mandatory for interpreting clinical outcomes in the future.
    International Journal of Clinical Oncology 09/2011; 17(5):505-11. · 1.41 Impact Factor
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    ABSTRACT: To develop a consensus-based guideline to define clinical target volume for primary disease (clinical target volume primary) in external beam radiotherapy for intact uterine cervical cancer. The working subgroup of the JCOG Radiation Therapy Study Group began developing a guideline for primary clinical target volume in November 2009. The group consisted of 10 radiation oncologists and 2 gynecologic oncologists. The process started with comparing the contouring on computed tomographic images of actual cervical cancer cases among the members. This was followed by a comprehensive literature review that included primary research articles and textbooks as well as information on surgical procedures. Extensive discussion occurred in face-to-face meetings (three occasions) and frequent e-mail communications until a consensus was reached. The working subgroup reached a consensus on the definition for the clinical target volume primary. The clinical target volume primary consists of the gross tumor volume, uterine cervix, uterine corpus, parametrium, vagina and ovaries. Definitions for these component structures were determined. Anatomical boundaries in all directions were defined for the parametrium. Examples delineating these boundaries were prepared for the posterior border of the parametrium for various clinical situations (i.e. central tumor bulk, degree of parametrial involvement). A consensus-based guideline defining the clinical target volume primary was developed for external beam radiotherapy for intact uterine cervical cancer. This guideline will serve as a template for radiotherapy protocols in future clinical trials. It may also be used in actual clinical practice in the setting of highly precise external beam radiotherapy, including intensity-modulated radiotherapy.
    Japanese Journal of Clinical Oncology 09/2011; 41(9):1119-26. · 1.90 Impact Factor
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    ABSTRACT: To investigate the factors that influence clinical outcomes after stereotactic body radiotherapy (SBRT) for non-small-cell lung cancer (NSCLC). A total of 101 consecutive patients who underwent SBRT with 48 Gy in 4 fractions for histologically confirmed Stage I NSCLC were enrolled in this study. Factors including age, maximal tumor diameter, sex, performance status, operability, histology, and overall treatment time were evaluated with regard to local progression (LP), disease progression (DP), and overall survival (OS) using the Cox proportional hazards model. Prognostic models were built with recursive partitioning analysis. Three-year OS was 58.6% with a median follow-up of 31.4 months. Cumulative incidence rates of LP and DP were 13.2% and 40.8% at 3 years, respectively. Multivariate analysis demonstrated that tumor diameter was a significant factor in all endpoints of LP, DP, and OS. Other significant factors were age in DP and sex in OS. Recursive partitioning analysis indicated a condition for good prognosis (Class I) as follows: female or T1a (tumor diameter ≤20 mm). When the remaining male patients with T1b-2a (>20 mm) were defined as Class II, 3-year LP, DP, and OS were 6.8%, 23.6%, and 69.9% in recursive partitioning analysis Class I, respectively, whereas these values were 19.9%, 58.3%, and 47.1% in Class II. The differences between the classes were statistically significant. Tumor diameter and sex were the most significant factors in SBRT for NSCLC. T1a or female patients had good prognosis.
    International journal of radiation oncology, biology, physics 03/2011; 79(4):1104-11. · 4.59 Impact Factor
  • Fuel and Energy Abstracts 01/2011; 81(2).
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    ABSTRACT: The outcomes of three-dimensional conformal radiation therapy (3D-CRT) combined with neoadjuvant hormonal therapy (NAHT) in Japanese patients with locally advanced prostate cancer who initiated salvage hormonal therapy (SHT) at a relatively early phase were evaluated. Between April 1998 and April 2003, 70 Japanese patients with T3N0M0 prostate cancer who received radical 3D-CRT treatment were evaluated. The median age, initial prostate-specific antigen (PSA) level, and duration of NAHT were 73 years old, 26.3 ng/ml, and 4 months, respectively. Seventy grays were given in 35 fractions that were confined to the prostate and seminal vesicles. Adjuvant hormonal therapy was not administered after 3D-CRT in any of the cases. The median follow-up period was 64.9 months. The median PSA value at the time of initiation of SHT was 5.0 ng/ml (range 0.1-21.6 ng/ml). Overall, disease-specific, PSA failure-free (based on the Phoenix definition) and SHT-free survival rates at 5 years were 90.3% (95% CI 86.5-94.0), 96.5% (94.0-98.9), 60.5% (48.2-72.7), and 63.5% (57.2-69.8), respectively. Therefore, two-thirds of the patients were still hormone-free at 5 years. PSA control rates in our series of Japanese patients with stage T3N0M0 prostate cancer treated with the standard dose of 3D-CRT combined with NAHT seemed higher than expected. This approach involving 3D-CRT combined with NAHT with the initiation of SHT at PSA values of around 5 ng/ml may be one option for Japanese patients with locally advanced prostate cancer, although further prospective study is required to confirm the validity.
    International Journal of Clinical Oncology 12/2010; 15(6):571-7. · 1.41 Impact Factor
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    ABSTRACT: The purpose was to characterize (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) findings after stereotactic body radiation therapy (SBRT) for lung cancer. This was a retrospective review of 32 FDG-PET scans from 23 patients who underwent SBRT for lung cancer and who showed no evidence of local recurrence. The FDG uptake by lesions was assessed visually using a 3-point scale (0, none or faint; 1, mild; or 2, moderate to intense), and the demarcation (ill- or well-defined) was evaluated. For semi-quantitative analysis, the maximum standardized uptake value (SUVmax) was calculated. Grade 2 intensity was observed in 70%, 33%, 30%, and 0% of PET scans performed <6, 6-12, 12-24, and >24 months, respectively, after SBRT; well-defined demarcation was observed in 80%, 33%, 40%, and 17%, respectively, and the respective means of the SUVmax were 4.9, 2.6, 3.0, and 2.3. The SUVmax was significantly higher for scans performed at <6 months than at 6-12 or >24 months. FDG uptake tended to be intense and well-defined at early times after SBRT, especially within 6 months, and was faint and ill-defined at later periods. Moderate to intense FDG uptake observed soon after SBRT does not always indicate a residual tumour.
    Radiotherapy and Oncology 11/2010; 97(2):200-4. · 4.52 Impact Factor
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    ABSTRACT: Prostate motion and rectal sparing are important treatment strategy issues in external-beam radiotherapy for localized prostate cancer. To address these issues, we prospectively investigated the feasibility of using a double-balloon rectal catheter. The rectal catheter has inner and outer balloons that wedge the anus between them. Computed tomography (CT) examinations with and without the catheter were conducted in seven patients with localized prostate cancer treated by external-beam radiotherapy. The rectal wall sparing effect was evaluated using virtual three-dimensional conformal radiotherapy plans in each arm. To evaluate interfractional prostate motion, each patient underwent a series of four CT examinations consisting of a planning CT followed by three additional series of CT with and without a catheter during the course of radiotherapy. Virtual plans demonstrated the reduction of the dose to the rectum by expanding the posterior wall to lie outside the high- to intermediate-dose area when a catheter was applied. Interfractional prostate motion in the anteroposterior direction was effectively reduced by catheter usage; the mean ± standard deviation (SD) of the displacement was 1.3 ± 0.9 mm with a catheter as compared to 2.8 ± 1.8 mm without a catheter (P = 0.014), and the maximum displacement was successfully suppressed to 3 mm with a catheter compared to 6 mm without a catheter. Systematic and random components were also reduced with the catheter. These results suggest the feasibility and clinical applicability of the double-balloon rectal catheter.
    International Journal of Clinical Oncology 10/2010; 16(1):50-6. · 1.41 Impact Factor
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    ABSTRACT: The aim of this study was to investigate the impact of multileaf collimator width (MLC-W) on intraprostatic dose painting plans for prostate cancer.Prostate cancer maps based on the histopathological findings were superimposed onto simulation CT images. Clinical target volume (CTV) 1 was defined as the prostate and the base of the seminal vesicles, and CTV2 was defined as the dominant intraprostatic lesions. Planning target volume (PTV) 1 and PTV2 were delineated by adding 5 mm margins to CTV1 and CTV2, respectively. For each case, two dose painting plans were created to deliver 74 Gy to PTV1 and 84 Gy to PTV2 with dynamic multileaf collimator technique using two different MLCs: m3 (MLC-W: 3mm) and Millennium (5 mm). Plans were evaluated by comparing the conformation number (CN), a quantity that defines the degree of conformality.The CNs for plans using the m3 and Millennium were 0.68 and 0.67 for PTV1 and 0.59 and 0.58 for PTV2, respectively. The CNs tended to be higher for a thinner leaf width (p < 0.05).Dosimetric advantages associated with smaller leaves were observed. However, differences between 3 mm and 5 mm leaf width were relatively small, which suggested that 5 mm leaf width would be acceptable in dose painting plans for prostate cancer.
    Journal of Applied Clinical Medical Physics 01/2010; 11(4):3193. · 0.96 Impact Factor
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    ABSTRACT: To investigate the interfraction variations in volume, motion range, and position of the gross tumor volume (GTV) in hypofractionated stereotactic body radiotherapy (SBRT) for lung cancer using four-dimensional computed tomography. Four-dimensional computed tomography scans were acquired for 8 patients once at treatment planning and twice during the SBRT period using a stereotactic body frame. The image registration was performed to correct setup errors for clinical four-dimensional computed tomography. The interfraction variations in volume, motion range, and position of GTV were computed at end-inhalation (EI) and end-exhalation (EE). The random variations in the GTV were 0.59 cm(3) at EI and 0.53 cm(3) at EE, and the systematic variations were 3.04 cm(3) at EI and 3.21 cm(3) at EE. No significant variations in GTV were found during the SBRT sessions (p = .301 at EI and p = .081 at EE). The random variations in GTV motion range for the upper lobe in the craniocaudal direction were within 1.0 mm and for the lower lobe was 3.4 mm. The interfraction variations in the GTV centroid position in the anteroposterior and craniocaudal directions were mostly larger than in the right-left direction; however, no significant displacement was observed among the sessions in any direction. For patients undergoing hypofractionated SBRT, interfraction variations in GTV, motion range, and position mainly remained small. An additional approach is needed to assess the margin size.
    International journal of radiation oncology, biology, physics 11/2009; 75(2):543-8. · 4.59 Impact Factor

Publication Stats

538 Citations
70.60 Total Impact Points

Institutions

  • 2013
    • Kansai Medical University
      • Department of Urology
      Moriguchi, Ōsaka, Japan
  • 2005–2013
    • Kyoto University
      • • Department of Radiation Oncology and Image-Applied Therapy
      • • Graduate School of Medicine / Faculty of Medicine
      Kioto, Kyōto, Japan
  • 2011
    • University of the Ryukyus
      • Department of Radiology
      Okinawa, Okinawa-ken, Japan
  • 2010
    • Niigata University
      • Division of Radiation Oncology
      Niahi-niigata, Niigata, Japan