Hydrogel spacer shrinkage during external-beam radiation therapy following low-dose-rate brachytherapy for high-risk prostate cancer: a case series.

BACKGROUND: Few studies have assessed hydrogel spacer shrinkage during external-beam radiation therapy following brachytherapy for localized high-risk prostate cancer. This case presentation evaluated the changes in hydrogel spacer appearance by magnetic resonance imaging during external-beam radiation therapy after brachytherapy for prostate cancer and analyzed the effect of this shrinkage on the dose distribution in four cases. CASE PRESENTATION: In all cases, we implanted 125I sources using a modified peripheral loading pattern for seed placement. The prescribed dose for each implant was 110 Gy. After delivering the sources, a hydrogel spacer was injected. All cases underwent external-beam radiation therapy approximately 1-2 months after brachytherapy. The prescribed dose of external-beam radiation therapy was 45 Gy in 1.8-Gy fractions. Magnetic resonance imaging was performed for evaluation on the day following seed implantation (baseline), at external-beam radiation therapy planning, and during external-beam radiation therapy. The median hydrogel spacer volume was 16.2 (range 10.9-17.7) cc at baseline, 14.4 (range, 9.4-16.1) cc at external-beam radiation therapy planning, and 7.1 (range, 2.0-11.4) cc during external-beam radiation therapy. The hydrogel spacer volume during external-beam radiation therapy was significantly lower than that at external-beam radiation therapy planning. The rectum V60-80 (rectal volume receiving at least 60-80% of the prescribed dose of external-beam radiation therapy) during external-beam radiation therapy was significantly higher than that at external-beam radiation therapy planning. CONCLUSIONS: The potential reduction in hydrogel spacer size during external-beam radiation therapy following brachytherapy can lead to unexpected irradiation to the rectum. This case presentation would be helpful for similar cases.

A single institution experience of the treatment of pancreatic ductal carcinoma: The demand and the role of radiation therapy.

We aimed to demonstrate a single institution experience of treatment of pancreatic ductal carcinoma and to identify the role of radiation therapy. We assessed all patients who were diagnosed with pancreatic ductal carcinoma from January 2011 to December 2017. A total of 342 patients were enrolled. Thirteen, 131, 36, and 162 patients had stage I, II, III, and IV disease, respectively (UICC TNM, 7th edition). Among the patients with stages I-III disease, 94 underwent surgery, and the median overall survival (OS) was 33 months. Of patients with stages I-III disease who were not suitable for surgery, 58 patients received chemotherapy, and the median OS was 12 months. Among them, 17 patients received chemoradiotherapy added on chemotherapy and their OS was significantly better than that of patients who received chemotherapy alone. Of patients with stage IV disease, 111 received chemotherapy, and the median OS was 6 months. This study evaluated the demand, role, and outcome of each treatment modality and demonstrated a single institution experience of treatment of pancreatic ductal carcinoma. The demand and role of radiation therapy remained small; however, radiation therapy might have some importance as a local treatment.

Comparison of clinical outcome between computed tomography-based image-guided brachytherapy and two-dimensional-based brachytherapy for cervical cancer.

This study aimed to analyze the clinical results of radiotherapy for cervical cancer using two-dimensional (2D) intracavitary brachytherapy (ICBT) and computed tomography (CT)-based image-guided brachytherapy (IGBT) at our institution. Patients with stage IB-IVA cervical cancer who received ICBT between April 2008 and April 2014 were included in this study. In total 58 patients were assessed. The first 38 patients received ICBT with the 2D treatment plan (the 2D group), and the remaining 20 patients received CT-based IGBT (the IGBT group). The dose of point A tended to be lower in the IGBT group (mean value, 60.6 Gy vs. 62.5 Gy; p = .07), though the minimum dose to the 90% (D90) of the clinical target volume (CTV) was equivalent in both groups (mean value, 66.0 Gy vs. 66.2 Gy; p = .91). The rectum minimum dose to 2 cc (D2cc) was significantly lower in the IGBT group than in the 2D group (mean value, 61.2 Gy vs. 69.1 Gy; p = .001). With a median follow-up time of 60 months, the 5-year local control rates (LCRs) of the IGBT group and 2D group were 100% and 83%, respectively (p = .12). The 5-year incidence of rectal complications in the IGBT group and the 2D group were 11% and 29%, respectively (p = .26). Our study showed favorable LCR and preferred incidence of rectal complications in patients treated with CT-based IGBT.

Radiation myelitis after durvalumab administration following chemoradiotherapy for locally advanced non-small cell lung cancer: an illustrative case report and review of the literature.

A 69-year-old man with stage IIIB lung adenocarcinoma received durvalumab following chemoradiotherapy. The prescribed dose was 50 Gy in 2 Gy fractions, and the maximum spinal cord dose was 40 Gy. After three cycles of durvalumab, he experienced bladder and rectal disturbance, muscle weakness in the lower limbs, and sensory loss in the lower body. Magnetic resonance imaging revealed T2 signal hyperintensity involving the thoracic spinal cord. As the thoracic spinal cord with T2 signal hyperintensity matched with the irradiated site, the patient was diagnosed with radiation myelitis. This case report shows the clinical and radiographic features of a case of locally advanced non-small cell lung cancer that demonstrated radiation myelitis following durvalumab administration. The time of onset was very early and the influence of durvalumab was suspected as the cause of myelitis.

Treatment outcomes according to the macroscopic tumor type in locally advanced esophageal squamous cell carcinoma treated by chemoradiotherapy.

PURPOSE: To identify predictive factors for local control of locally advanced esophageal cancer by chemoradiotherapy, the relationship between clinical features, including macroscopic tumor type, and treatment outcome was analyzed in 83 patients. MATERIALS AND METHODS: Macroscopic tumor type was defined by endoscopy as follows: type 1: protruding type; type 2: ulcerative and localized type; type 3: ulcerative and infiltrative type; type 4: diffusely infiltrative type; and type 5: unclassifiable type. We analyzed the overall survival, cause-specific survival, local progression-free rate, and predictive factors for locally advanced esophageal cancer after chemoradiotherapy. RESULTS: The median follow-up period at the time of evaluation was 59 months among survivors. The 5-year overall survival, cause-specific survival, and local progression-free rates for type 1 and other types were 37.0% and 23.3% (P = 0.4255), 71.8% and 30.3% (P = 0.0325), and 100% and 63.3% (P = 0.0246), respectively. Macroscopic tumor type (type 1) was the most significant predictive factor of cause-specific survival and local progression-free rates. CONCLUSIONS: Macroscopic tumor type 1 was the significant favorable predictive factor for local control. The study results suggested that the macroscopic tumor type was useful in predicting tumor responses.

Clinical features of prostate-specific antigen bounce after 125I brachytherapy for prostate cancer.

The aim of this study was to analyse the clinical features of prostate-specific antigen (PSA) bounce and the difference between biochemical failure and large-magnitude PSA bounce. The cases of 352 patients with prostate cancer who underwent brachytherapy were analysed. PSA bounce was defined as an increase in PSA of ≥0.2 ng/ml above an initial PSA nadir, with subsequent decline to or below that initial nadir without treatment. PSA bounce +2 was defined as an increase in PSA of ≥2.0 ng/ml above the nadir with subsequent decline to or below that initial nadir without treatment. We analysed the rates, time to onset, and predictive factors for PSA bounce and PSA bounce +2. The median follow-up period at the time of evaluation was 82 months. One hundred and seventeen patients had PSA bounce; of them, 10 had PSA bounce +2. Biochemical failure occurred in 29 patients. The median times to onset of PSA bounce, PSA bounce +2, and biochemical failure were 20, 17.5 and 51 months, respectively. Younger age at implant and larger prostate volume were significant predictive factors for PSA bounce. Age was a significant factor for PSA bounce +2, and PSA bounce +2 patients were significantly younger than biochemical failure patients. The maximum duration from the date of PSA bounce +2 to the date when PSA level decreased was 12 months. Age at implant, time to onset, and 1-year follow-up after an increase in PSA level of ≥2 ng/ml above nadir level are useful for distinguishing between biochemical failure and PSA bounce +2.

[Two Case Reports of Chemotherapy-Induced Radiation Myositis].

Radiation recall is regarded as an acute inflammatory reaction that is triggered by cytotoxic agents within a previously irradiated area, and the most common site is the skin. Gemcitabine-related radiation recall is rare, and most reported cases involving gemcitabine occur in the muscle, unlike those of other chemotherapeutic agents. Here, we report 2 cases of chemotherapy- induced radiation myositis. Combination chemotherapy with gemcitabine and S-1 was performed in both patients after radiation therapy. The irradiation dose to the muscle was quite low compared to the muscle tolerance dose in both cases. To the best of our knowledge, there are no reports on radiation recall with S-1. Therefore, it is unclear whether S-1 is related to myositis in these cases. Although radiation recall with gemcitabine is rare and uncommon, it has the potential to occur in any organ in forms such as myositis or central nervous system necrosis, and careful observation is required for patients who received chemotherapy that includes gemcitabine after radiation therapy.

Clinical outcomes of concurrent chemoradiotherapy with volumetric modulated arc therapy in patients with locally advanced nasopharyngeal carcinoma.

PURPOSE: The purpose of this study was to analyze the clinical results of concurrent chemoradiotherapy (CCRT) with volumetric modulated arc therapy (VMAT) for nasopharyngeal carcinoma (NPC) patients. MATERIALS AND METHODS: Patients with stage II-IVB NPC who received CCRT with VMAT between 2010 and 2014 were included in this study. The planned dose was 70 Gy in 35 fractions. RESULTS: Twenty patients aged between 28 and 85 years (median 60 years) were assessed. With a median follow-up time of 47 months, the 3-year overall survival and progression-free survival rates were 85 and 65%, respectively. The 3-year local, regional and distant control rates were 78, 88 and 79%, respectively. At 0, 3, 6 and 12 months from CCRT, 19, 6, 3, and 1 patients had grade 2 dry mouth, respectively. No cases of grade 3 or worse dry mouth were observed. The severity of dry mouth was downgraded from grade 2 to grade 0 or 1 significantly earlier in younger patients (<70 years, p = 0.02) or patients in whom the mean dose to one parotid gland was lower (<26 Gy, p = 0.04). CONCLUSIONS: Our clinical results regarding CCRT with VMAT for NPC patients showed favorable survival rates while maintaining organ function.

Relationship between sentinel lymph nodes and postoperative tangential fields in early breast cancer, evaluated using SPECT/CT.

Single-photon emission computed tomography/computed tomography (SPECT/CT) demonstrates the precise location of the sentinel lymph nodes (SLNs) in patients with breast cancer. We evaluated the relationship between SLNs and postoperative tangential fields by using SPECT/CT images. Subjects included 72 patients with early breast cancer who underwent SPECT/CT of the SLNs and received whole-breast irradiation with tangential fields after partial mastectomy. The SLN locations evaluated by using SPECT/CT images were entered into the treatment-planning CT image with a 5-mm-diameter sphere. A 15-mm-diameter sphere including the 5-mm treatment margin around the SLNs was defined as PTV-SLN. The PTV-SLN doses with tangential irradiation were evaluated and expressed as the percentage of the prescribed dose. In 69 patients, SLNs were detected by using SPECT/CT; 68 SLNs were located at axillary lymph node Level I, and one was located at Level II. A total of 62 SLNs (90%) were determined to be located inside the tangential fields on the digitally reconstructed radiography (DRR) images. The median doses of SLN center, mean PTV-SLN dose, and PTV-SLN D95 (the minimum dose delivered to 95% of the volume) were 94.1% (range, 15.3-101.9%), 93.7% (range, 29.3-104.0%) and 84.8% (range, 6.8-99.8%). The D95 for the SLNs with treatment margins were ≤90% of the prescribed doses in more than half of the cases. Modification of the individual treatment fields seemed to be necessary to ensure coverage of the SLNs in whole-breast irradiation.

Time-adjusted internal target volume: a novel approach focusing on heterogeneity of tumor motion based on 4-dimensional computed tomography imaging for radiation therapy planning of lung cancer.

PURPOSE: To consider nonuniform tumor motion within the internal target volume (ITV) by defining time-adjusted ITV (TTV), a volume designed to include heterogeneity of tumor existence on the basis of 4-dimensional computed tomography (4D-CT). METHODS AND MATERIALS: We evaluated 30 lung cancer patients. Breath-hold CT (BH-CT) and free-breathing 4D-CT scans were acquired for each patient. The tumors were manually delineated using a lung CT window setting (window, 1600 HU; level, -300 HU). Tumor in BH-CT images was defined as gross tumor volume (GTV), and the sum of tumors in 4D-CT images was defined as ITV-4D. The TTV images were generated from the 4D-CT datasets, and the tumor existence probability within ITV-4D was calculated. We calculated the TTV80 value, which is the percentage of the volume with a tumor existence probability that exceeded 80% on ITV-4D. Several factors that affected the TTV80 value, such as the ITV-4D/GTV ratio or tumor centroid deviation, were evaluated. RESULTS: Time-adjusted ITV images were acquired for all patients, and tumor respiratory motion heterogeneity was visualized. The median (range) ITV-4D/GTV ratio and median tumor centroid deviation were 1.6 (1.0-4.1) and 6.3 mm (0.1-30.3 mm), respectively. The median TTV80 value was 43.3% (2.9-98.7%). Strong correlations were observed between the TTV80 value and the ITV-4D/GTV ratio (R=-0.71) and tumor centroid deviation (R=-0.72). The TTV images revealed the tumor motion pattern features within ITV. CONCLUSIONS: The TTV images reflected nonuniform tumor motion, and they revealed the tumor motion pattern features, suggesting that the TTV concept may facilitate various aspects of radiation therapy planning of lung cancer while incorporating respiratory motion in the future.

An unusual unilocular mesothelial cyst of the pleura: a case report.

A 79-year-old woman was found to have an abnormal shadow on chest radiography. Computed tomography demonstrated a pleural mass. The F-18 fluorodeoxyglucose positron emission tomography (FDG PET) was performed to determine whether the pleural mass was benign or malignant. The histologic examination of the resected mass showed a unilocular mesothelial cyst of the pleura. The FDG PET findings of a mesothelial cyst of the pleura have not yet been previously reported. The FDG PET findings of a mesothelial cyst in the pleura reflected the microscopic findings of the resected mass. The FDG PET findings, therefore, seem to be useful in the diagnosis of mesothelial cysts.

Computed tomography-based three-dimensional dosimetry of intracavitary brachytherapy for cervical cancer.

PURPOSE: The aim of this study was to show the results of computed tomography (CT)-based dosimetry of intracavitary brachytherapy for cervical cancer. MATERIALS AND METHODS: A total of 20 patients with cervical cancer underwent intracavitary brachytherapy with external beam radiation therapy. The prescribed dose of brachytherapy was 6 Gy per fraction to point A. In every fraction a CT scan was performed after applicator insertion and three-dimensional (3D) dosimetry was done. The tumor dose was evaluated using D90 (the minimum dose delivered to 90% of the volume), and the doses of risk organs were evaluated using D2cc (the minimum dose in the most irradiated 2 cm3 of the volume). RESULTS: The mean D90 for the clinical target volume (CTV) was 7.0 Gy (range 4.8-9.8 Gy). There was a negative correlation between the volume and the D90 for the CTV. The mean D2cc doses for the rectum and bladder were 6.0 Gy (range 3.9-9.0 Gy) and 6.5 Gy 5 Gy 2.9-9.0 Gy), respectively. CONCLUSION: CT-based 3D dosimetry of intracavitary brachytherapy for cervical cancer was useful for evaluating the doses of the CTV and the organs at risk. In cases with a large CTV, CTV D90 was often lower than the point A dose, and modulation of the prescribed dose might have to be considered.

Results of a preliminary study using hypofractionated involved-field radiation therapy and concurrent carboplatin/paclitaxel in the treatment of locally advanced non-small-cell lung cancer.

BACKGROUND: We aimed to evaluate the feasibility and efficacy of hypofractionated involved-field radiation therapy (IFRT) omitting elective nodal irradiation (ENI) with concurrent chemotherapy for locally advanced non-small-cell lung cancer (NSCLC). METHODS: Between July 2004 and July 2006, ten patients with locally advanced NSCLC were included in this study. One had stage IIIA and 9 had stage IIIB disease. The treatment consisted of IFRT in fractions of 2.5 Gy and weekly carboplatin (CBDCA)/paclitaxel (PTX). Hypofractionated IFRT with a median total dose of 65 Gy with median percent total lung volume exceeding 20 Gy (V20) of 20.2%, and a median of five courses of chemotherapy with weekly CBDCA (area under the curve, 1.5-2.0)/PTX (30-35 mg/m(2)) were given to all patients. RESULTS: The median survival time and the 1-, 2-, and 3-year overall survival rates were 29.5 months and 90.0%, 58.3%, and 43.8%, respectively. No elective nodal failure was encountered during the median follow up of 18.2 months. No acute or late toxicities of grade 3 or worse were observed. No in-field recurrence occurred in the group with a total dose of 67.5 Gy or more, but there was such recurrence in 83.3% of those in the group with less than 67.5 Gy. CONCLUSION: Hypofractionated IFRT with weekly CBDCA/PTX was a feasible treatment regimen. Hypofractionated IFRT with a total dose of 67.5 Gy or more could be a promising modality to improve the treatment results in patients with locally advanced NSCLC.

[Treatment results of concurrent chemoradiotherapy with CDDP or CDGP plus 5-FU for carcinoma of the oropharynx and hypopharynx].

Twenty-eight patients with oropharyngeal or hypopharyngeal carcinoma received concurrent chemoradiotherapy with CDDP or CDGP plus 5-FU between January 2001 and April 2006. The numbers of patients according to clinical stage were stage II:2; stage III:5; stage IVa:19 ; and stage IVb:2. Total radiation dose was 60-73.8 Gy (median 66 Gy) and overall treatment time was 41-57 days (median 47 days). Two courses of 5-FU 700 mg/m(2) on days 1-5 and CDDP or CDGP 70 mg/m(2) on day 4 were administered concurrently with radiotherapy. Median follow-up period was 26 months (range, 8-64 months). The incidences of grade 3 or greater acute toxicity were leukopenia 29%, anemia 21%, thrombocytopenia 7%, pharyngeal mucositis 43% and nausea 14%. No severe late toxicity was observed. Treatment responses of primary lesions were CR in 24 patients (86%) and PR in 4 patients (14%). The two-year local control rate was 87% and the 2-year overall survival rate was 72%. Concurrent chemoradiotherapy with CDDP or CDGP plus 5-FU seemed to be effective for advanced carcinomas of the oropharynx and hypopharynx.

Phase I study of docetaxel (TXT) and 5-fluorouracil (5-FU) with concurrent radiotherapy in patients with advanced esophageal cancer.

UNLABELLED: This phase I study was designed to determine the maximum-tolerated dose (MTD) of docetaxel (TXT) and toxicities of combining weekly administration of TXT and continuous infusion of 5-fluorouracil (5-FU) with concomitant radiotherapy for advanced esophageal cancer. PATIENTS AND METHODS: Patients received TXT by i.v. infusion over 1 h on days 1, 8, 22 and 29. They were also given 5-FU 250 mg/m2/day by continuous infusion for 24 h on days 1-5, 8-12, 15-19, 22-26, 29-33, 36-40 and 43-45. Fractionated radiotherapy was performed on days 1-5, 8-12, 15-19, 22-26, 29-33, 36-40 and 43-45, and a total dose of 60 to 66 Gy was delivered. The starting dose level (Level 1) of TXT was set at 7.5 mg/m2. Dose escalation was conducted in increments of 25 mg/m2, until the dose reached Level 4 (15 mg/m2). At least three patients were enrolled at each level. RESULTS: Seven patients (median age, 64 years) were enrolled. Six patients had stage III (T4NIMO) and one had stage IVb (T4N1M1b) esophageal cancer; six had squamous cell carcinoma and one had carcinosarcoma. No patient had received prior chemotherapy or radiotherapy, and two patients had undergone esophageal bypass surgery using a whole stomach tube without resection of primary or metastatic lesions. In the 7patients, the regimen was well-tolerated, with esophagitis as the most common toxicity (grade 3: n=1; grade 4: n=3). In general, hematological toxicity was mild. Dose-limiting toxicity (DLT) was observed at Level 2 (TXT 10 mg/m2) when three patients developed grade 4 esophagitis and this dose was deemed the MTD for this regimen. In the 7 assessable patients, the overall clinical response rate was 85.7%. CONCLUSION: The MTD of TXT in this regimen was 10 mg/m2 and the recommended dose of TXT was 7.5 mg/m2. Although esophagitis was the dose-limiting and the most frequent toxicity, the regimen was safe and well-tolerated, and demonstrated the possibility of good efficacy in patients with advanced esophageal cancer.

Treatment results of adjuvant radiotherapy and salvage radiotherapy after radical prostatectomy for prostate cancer.

BACKGROUND: The indications for and the efficacy of radiation therapy after radical operation for patients with prostate cancer are not clear. We analyzed the treatment results of adjuvant radiotherapy and salvage radiotherapy after radical prostatectomy. METHODS: Between September 1997 and November 2004, 57 patients received adjuvant radiotherapy or salvage radiotherapy after radical prostatectomy. Fifteen patients received radiation therapy because of positive margins and/or extracapsular invasion in surgical specimens (adjuvant group). Forty-two patients received radiation therapy because of rising prostate-specific antigen (PSA) during follow-up (salvage group). Radiation therapy was delivered to the fossa of the prostate +/- seminal vesicles by a three-dimensional (3-D) conformal technique to a total dose of 60-66 Gy (median, 60 Gy). Biochemical control was defined as the maintenance of a PSA level of less than 0.2 ng/ml. RESULTS: The median follow-up period after radiation therapy was 33 months (range, 12-98 months). Three-year biochemical control rates were 87% for the adjuvant group and 61% for the salvage group. For patients in the salvage group treated without hormone therapy, the preradiation PSA value was the most significant factor for the biochemical control rate. The 3-year biochemical control rate was 93% in patients whose preradiation PSA was 0.5 ng/ml or less and 29% in patients whose preradiation PSA was more than 0.5 ng/ml. No severe adverse effects (equal to or more than grade 3) were seen in treated patients. CONCLUSION: Radiation therapy after radical prostatectomy seemed to be effective for adjuvant therapy and for salvage therapy in patients with a preradiation PSA of 0.5 ng/ml or less. Also, radiation to the fossa of the prostate +/- seminal vesicles, to a total dose of 60-66 Gy, using a three-dimensional (3-D) conformal technique, seemed to be safe.

CT appearance of radiation injury of the lung and clinical symptoms after stereotactic body radiation therapy (SBRT) for lung cancers: are patients with pulmonary emphysema also candidates for SBRT for lung cancers?

PURPOSE: The purpose of this study was to analyze the computed tomographic (CT) appearance of radiation injury to the lung and clinical symptoms after stereotactic body radiation therapy (SBRT) and evaluate the difference by the presence of pulmonary emphysema (PE) for small lung cancers. METHODS AND MATERIALS: In this analysis, 45 patients with 52 primary or metastatic lung cancers were enrolled. We evaluated the CT appearance of acute radiation pneumonitis (within 6 months) and radiation fibrosis (after 6 months) after SBRT. Clinical symptoms were evaluated by Common Terminology Criteria for Adverse Events, version 3.0. We also evaluated the relationship between CT appearance, clinical symptoms, and PE. RESULTS: CT appearance of acute radiation pneumonitis was classified as follows: (1) diffuse consolidation, 38.5%; (2) patchy consolidation and ground-glass opacities (GGO), 15.4%; (3) diffuse GGO, 11.5%; (4) patchy GGO, 2.0%; (5) no evidence of increasing density, 32.6%. CT appearance of radiation fibrosis was classified as follows: (1) modified conventional pattern, 61.5%; (2) mass-like pattern, 17.3%; (3) scar-like pattern, 21.2%. Patients who were diagnosed with more than Grade 2 pneumonitis showed significantly less no evidence of increased density pattern and scar-like pattern than any other pattern (p=0.0314, 0.0297, respectively). Significantly, most of these patients with no evidence of increased density pattern and scar-like pattern had PE (p=0.00038, 0.00044, respectively). CONCLUSION: Computed tomographic appearance after SBRT was classified into five patterns of acute radiation pneumonitis and three patterns of radiation fibrosis. Our results suggest that SBRT can be also safely performed even in patients with PE.

Reproducibility of organ position using voluntary breath-hold method with spirometer for extracranial stereotactic radiotherapy.

PURPOSE: To evaluate in healthy volunteers the reproducibility of organ position using a voluntary breath-hold method with a spirometer and the feasibility of this method for extracranial stereotactic radiotherapy in a clinical setting. METHODS AND MATERIALS: For this study, 5 healthy volunteers were enrolled. After training sessions, they held their breath at the end-inspiration and the end-expiration phase under spirometer-based monitoring. Computed tomography (CT) scans were performed twice at each respiratory phase, with a 10-min interval, on 2 separate days. The total number of CT scans was four at each respiratory phase. After CT volume data were transferred to a three-dimensional treatment-planning system, digitally reconstructed radiographs (DRRs) were calculated for anterior-posterior and left-right beams. Verification was performed with DRRs relative to the diaphragm position, bony landmarks, and the isocenter in each healthy volunteer at each respiratory phase. To evaluate intrafraction reproducibility, we measured the distance between diaphragm position and bony landmarks. To evaluate interfraction reproducibility, we measured the distance between diaphragm position and the isocenter. Reproducibility and setup error were defined as the average value of the differences between each DRR with regard to the first DRR. RESULTS: Intrafraction reproducibility of the caudal-cranial direction was 4.0 +/- 3.5 mm at the end-inspiration phase and 2.2 +/- 2.0 mm at the end-expiration phase. Interfraction reproducibility of the caudal-cranial direction was 5.1 +/- 4.8 mm at the end-inspiration phase and 2.1 +/- 1.8 mm at the end-expiration phase. The end-expiration phase was more stable than the end-inspiration phase. CONCLUSIONS: The voluntary breath-hold method with a spirometer is feasible, with relatively good reproducibility. We are encouraged about the use of this technique clinically for extracranial stereotactic radiotherapy.