Biomedical subjects

Shigeyuki Murayama

Publications and source records attributed to Shigeyuki Murayama.

6 recordsLinked to original sources

PubMed2006

Frequency and characteristics of docetaxel-induced radiation recall phenomenon.

PURPOSE: The aim of this study was to investigate the frequency and characteristics of a docetaxel-induced radiation recall phenomenon. METHODS AND MATERIALS: Past histories of radiotherapy and radiation recall phenomenon (RRP) were analyzed in 461 patients who were administered docetaxel at our hospital between September 2002 and November 2005. RESULTS: Of the 461 patients, 171 underwent radiotherapy before starting docetaxel. RRP was noted in 3 patients (1.8%). The 3 cases show that RRP tends to develop in patients treated with lower-energy photon beams of < or =6 MV and in patients with marked acute phase reactions during radiotherapy. CONCLUSIONS: The incidence of RRP induced by docetaxel was 1.8%, making it a comparatively rare condition. However, docetaxel is increasingly being used for patients with head and neck tumors, and caution regarding development of RRP is warranted after use of docetaxel after high-dose radiotherapy with photon beams of < or =6 MV.

Adult↗

PubMed2005

Evaluation of anatomy-based dwell position and inverse optimization in high-dose-rate brachytherapy of prostate cancer: a dosimetric comparison to a conventional cylindrical dwell position, geometric optimization, and dose-point optimization.

BACKGROUND AND PURPOSE: To compare treatment planning methods in high-dose-rate (HDR) brachytherapy of prostate cancer. In particular, to assess quantitatively the dosimetric superiority, if any, of the anatomy-based dwell position (ABDP) and inverse optimization (IO) over the conventional cylindrical dwell position (CDP), geometric optimization (GO), and dose-point optimization (DO) in terms of the determination of dwell positions and dwell times. PATIENTS AND METHODS: Between September 2002 and April 2003, 10 cases of treatment-planning CT images were taken for external radiotherapy for prostate cancer. Treatment planning computer software and the CT data were used to create hypothetical HDR brachytherapy applicator needles, which were properly implanted in the prostate. Six different plans including IO with ABDP (IO(ABDP)), IO with CDP (IO(CDP)), GO with ABDP (GO(ABDP)), GO with CDP (GO(CDP)), DO with ABDP (DO(ABDP)), and DO with CDP (DO(CDP)) were made for each case, that is, 60 plans in total. All plans were normalized so that the D(95) should be equal to 100% of the prescribed dose. Dose-volume histograms from all 60 plans were analyzed, and multiple implant quality indices, including CI, EI, DNR, %V(R 75), %V(B 75), and %V(U 150) for each plan, were extracted and compared. Then, the best settings for IO(ABDP) regarding dwell position and dose limit were sought for. RESULTS: ABDP showed a statistically significantly lower EI (P<0.001), %V(R 75) (P=0.002), and %V(B 75) (P=0.015) than CDP. IO showed a statistically significantly lower %V(U 150) than GO (P=0.009), or than DO (P<0.001). Given a definition that a figure exceeding three-fold of the minimum figure of the index is clinically unacceptable, only in IO(ABDP) all index figures were clinically acceptable, while in the other five plans at least one index figure was unacceptable. CONCLUSIONS: In the CT-based treatment planning for prostate HDR brachytherapy, ABDP is useful to achieve a high conformity, which leads to a reduction of the doses to the bladder, rectum, and surrounding normal tissue. IO is useful to lower the urethral dose without sacrificing conformity. IO(ABDP) is recommended on the basis of the current study. However, this conclusion has been drawn from the idealized hypothetical settings, and some possibility remains that this conclusion is not always applicable to the real implants.

Brachytherapy↗

PubMed2005

Patient positioning method based on binary image correlation between two edge images for proton-beam radiation therapy.

A new technique based on normalized binary image correlation between two edge images has been proposed for positioning proton-beam radiotherapy patients. A Canny edge detector was used to extract two edge images from a reference x-ray image and a test x-ray image of a patient before positioning. While translating and rotating the edged test image, the absolute value of the normalized binary image correlation between the two edge images is iteratively maximized. Each time before rotation, dilation is applied to the edged test image to avoid a steep reduction of the image correlation. To evaluate robustness of the proposed method, a simulation has been carried out using 240 simulated edged head front-view images extracted from a reference image by varying parameters of the Canny algorithm with a given range of rotation angles and translation amounts in x and y directions. It was shown that resulting registration errors have an accuracy of one pixel in x and y directions and zero degrees in rotation, even when the number of edge pixels significantly differs between the edged reference image and the edged simulation image. Subsequently, positioning experiments using several sets of head, lung, and hip data have been performed. We have observed that the differences of translation and rotation between manual positioning and the proposed method were within one pixel in translation and one degree in rotation. From the results of the validation study, it can be concluded that a significant reduction in workload for the physicians and technicians can be achieved with this method.

Algorithms↗

PubMed2005

[Initial clinical experience of proton therapy at Shizuoka Cancer Center].

PURPOSE: To present the initial experience and preliminary clinical results of patients treated mainly with proton irradiation at the newly developed proton therapy facility at Shizuoka Cancer Center. MATERIALS AND METHODS: We reviewed 125 patients who underwent proton therapy between July 2003 and December 2004. Of these 125 patients, 11 had head and neck malignancies, 15 non-small cell lung cancers, 22 hepatocellular carcinomas, 62 prostate cancers, and 15 other malignant tumors. RESULTS: Most patients experienced Grade 0-1 acute morbidities (NCI-CTC) in skin or mucosa, while a temporary Grade 2-3 reaction was observed in a high dose area. Response rates were 73% for H & N malignancies, 100% for NSCLC, and 77% for HCC. PSA evaluation for patients with prostate cancer revealed a high rate of complete response. CONCLUSION: The efficacy and safety of proton therapy at Shizuoka Cancer Center was demonstrated for patients with early-stage cancer or locally advanced disease.

Adolescent↗

PubMed2003

Small-field radiotherapy in combination with concomitant chemotherapy for locally advanced pancreatic carcinoma.

PURPOSE: To evaluate the effectiveness of small-field radiotherapy in combination with concomitant 5-fluorouracil (5FU) or cisplatin for locally advanced pancreatic carcinoma. MATERIALS AND METHODS: From November 1993 to January 1999, 53 patients underwent continuous 5FU infusion at 200mg/m2 (27 patients) or a 30-min cisplatin infusion at 5mg/m2/day (26 patients) just prior to each irradiation. The radiation field was limited to cover the primary and the paraaortic regions at celiac and supramesenteric axis levels. A total dose of 50.4Gy in 28 sessions was given in 5.6 weeks. RESULTS: Median and 1-year survival rates were 10.2 months and 35.2%, respectively. Local failure occurred in 19 patients (36%) and liver metastases in 16 patients (30%). All local recurrences occurred only within the radiation field. CONCLUSIONS: Median survival rates were comparable to other studies. Because local failure occurred only within the radiation field, the use of relatively small-field radiotherapy may be justified in the treatment of locally advanced pancreatic carcinoma in addition to concurrent administration of either 5FU or cisplatin.

Antineoplastic Agents↗

PubMed2003

[High-dose-rate interstitial brachytherapy using inverse planning for locally advanced cervical cancer].

A 56-year-old woman with bulky cervical cancer was treated with high-dose-rate interstitial brachytherapy combined with external beam irradiation and chemotherapy. Inverse planning (IP) was used in the treatment planning for brachytherapy. Source dwell positions were selected automatically, once the required information had been input, for example, to prohibit dwelling inside the organs at risk (OARs) and to permit dwelling inside the planning target volume with a 2-mm inner margin. IP was compared with conventional geometrical optimization (GO) and dose point optimization (DO). The dwell positions of 3 plannings (IP, GOIP, and DOIP) were the same as IP, while in the other 2 plannings (GOConv and DOConv) dwell positions had the same length in all the applicators without concern for anatomy. D90 was equalized in all plannings as 100% prescription dose, and so the coverage index was always 90%. There was no definite tendency in dose non-uniformity ratio in the 5 plannings. As for sparing OARs such as the bladder, urethra, and rectum, IP showed the best % V75. The calculation time of the computer was fast enough. This is the first report in Japan on the clinical use of IP in interstitial brachytherapy, and it implies the usefulness of IP.

Brachytherapy↗