Search PubMed⌕ Search

Biomedical subjects

Hiroki Shirato

Publications and source records attributed to Hiroki Shirato.

At least 19 recordsLinked to original sources
PubMed2006

A novel approach to advanced carcinoma of the tongue: cases successfully treated with combination of superselective intra-arterial chemotherapy and external/high-dose-rate interstitial radiotherapy.

OBJECTIVE: This study sought to evaluate the efficacy and safety of a novel treatment regimen, intra-arterial cisplatin infusion plus external/high-dose-rate radiotherapy. METHODS: Superselective intra-arterial infusion of cisplatin (100-120 mg) was performed concomitantly with external radiotherapy in four patients with locally advanced carcinoma of the tongue. A high-dose-rate brachytherapy boost was performed after combination therapy in all patients. Brachytherapy was performed after external radiotherapy, and the treatment schedule was twice daily, with a fraction of 600 cGy up to a total of 30-48 Gy. RESULTS: All patients completed the therapy as scheduled. There were no vascular or neurological complications. Grade III acute radiation mucositis developed in all patients but this did not necessitate a treatment break. With a mean follow-up period of 35 months, loco-regional control was obtained for all patients. CONCLUSIONS: The combination of weekly administration of intra-arterial cisplatin plus external/high-dose-rate radiotherapy seems effective for advanced carcinoma of the tongue.

Adenocarcinoma↗
PubMed2006

Dosimetric verification in participating institutions in a stereotactic body radiotherapy trial for stage I non-small cell lung cancer: Japan clinical oncology group trial (JCOG0403).

A multicentre phase II trial of stereotactic body radiotherapy for T1N0M0 non-small cell lung cancer was initiated in Japan as the Japan Clinical Oncology Group trial (JCOG0403). Before starting the trial, a decision was made to evaluate the treatment machine and treatment planning in participating institutions to minimize the variations of the prescription dose between the institutions. We visited the 16 participating institutions and examined the absolute dose at the centre of a simulated spherical tumour of 3.0 cm diameter in the lung using the radiation treatment planning systems in each institution. A lung phantom for stereotactic body radiotherapy (SBRT) was developed and used for the treatment planning and film dosimetry. In the JCOG radiotherapy study group, the no model-based calculation algorithm or the model-based calculation algorithm with a dose kernel unscaled for heterogeneities were selected for use in the initial SBRT trials started in 2004, and the model-based calculation algorithm with a dose kernel scaled for heterogeneities was selected for the coming trial. The findings of this study suggest that the clinical results of lung SBRT trials should be carefully evaluated in comparison with the actual dose given to patients.

Algorithms↗
PubMed2006

Stereotactic radiosurgery plus whole-brain radiation therapy vs stereotactic radiosurgery alone for treatment of brain metastases: a randomized controlled trial.

CONTEXT: In patients with brain metastases, it is unclear whether adding up-front whole-brain radiation therapy (WBRT) to stereotactic radiosurgery (SRS) has beneficial effects on mortality or neurologic function compared with SRS alone. OBJECTIVE: To determine if WBRT combined with SRS results in improvements in survival, brain tumor control, functional preservation rate, and frequency of neurologic death. DESIGN, SETTING, AND PATIENTS: Randomized controlled trial of 132 patients with 1 to 4 brain metastases, each less than 3 cm in diameter, enrolled at 11 hospitals in Japan between October 1999 and December 2003. INTERVENTIONS: Patients were randomly assigned to receive WBRT plus SRS (65 patients) or SRS alone (67 patients). MAIN OUTCOME MEASURES: The primary end point was overall survival; secondary end points were brain tumor recurrence, salvage brain treatment, functional preservation, toxic effects of radiation, and cause of death. RESULTS: The median survival time and the 1-year actuarial survival rate were 7.5 months and 38.5% (95% confidence interval, 26.7%-50.3%) in the WBRT + SRS group and 8.0 months and 28.4% (95% confidence interval, 17.6%-39.2%) for SRS alone (P = .42). The 12-month brain tumor recurrence rate was 46.8% in the WBRT + SRS group and 76.4% for SRS alone group (P<.001). Salvage brain treatment was less frequently required in the WBRT + SRS group (n = 10) than with SRS alone (n = 29) (P<.001). Death was attributed to neurologic causes in 22.8% of patients in the WBRT + SRS group and in 19.3% of those treated with SRS alone (P = .64). There were no significant differences in systemic and neurologic functional preservation and toxic effects of radiation. CONCLUSIONS: Compared with SRS alone, the use of WBRT plus SRS did not improve survival for patients with 1 to 4 brain metastases, but intracranial relapse occurred considerably more frequently in those who did not receive WBRT. Consequently, salvage treatment is frequently required when up-front WBRT is not used. TRIAL REGISTRATION: umin.ac.jp/ctr Identifier: C000000412.

Adult↗
PubMed2006

Uncertainty in treatment of head-and-neck tumors by use of intraoral mouthpiece and embedded fiducials.

PURPOSE: To reduce setup error and intrafractional movement in head-and-neck treatment, a real-time tumor tracking radiotherapy (RTRT) system was used with the aid of gold markers implanted in a mouthpiece. METHODS AND MATERIALS: Three 2-mm gold markers were implanted into a mouthpiece that had been custom made for each patient before the treatment planning process. Setup errors in the conventional immobilization system using the shell (manual setup) and in the RTRT system (RTRT setup) were compared. Eight patients with pharyngeal tumors were enrolled. RESULTS: The systematic setup errors were 1.8, 1.6, and 1.1 mm in the manual setup and 0.2, 0.3, and 0.3 mm in the RTRT setup in right-left, craniocaudal, and AP directions, respectively. Statistically significant differences were observed with respect to the variances in setup error (p <0.001). The systematic and random intrafractional errors were maintained within the ranges of 0.2-0.6 mm and 1.0-2.0 mm, respectively. The rotational systematic and random intrafractional errors were estimated to be 2.2-3.2 degrees and 1.5-1.6 degrees , respectively. CONCLUSIONS: The setup error and planning target volume margin can be significantly reduced using an RTRT system with a mouthpiece and three gold markers.

Adult↗
PubMed2006

Speed and amplitude of lung tumor motion precisely detected in four-dimensional setup and in real-time tumor-tracking radiotherapy.

BACKGROUND: To reduce the uncertainty of registration for lung tumors, we have developed a four-dimensional (4D) setup system using a real-time tumor-tracking radiotherapy system. METHODS AND MATERIALS: During treatment planning and daily setup in the treatment room, the trajectory of the internal fiducial marker was recorded for 1 to 2 min at the rate of 30 times per second by the real-time tumor-tracking radiotherapy system. To maximize gating efficiency, the patient's position on the treatment couch was adjusted using the 4D setup system with fine on-line remote control of the treatment couch. RESULTS: The trajectory of the marker detected in the 4D setup system was well visualized and used for daily setup. Various degrees of interfractional and intrafractional changes in the absolute amplitude and speed of the internal marker were detected. Readjustments were necessary during each treatment session, prompted by baseline shifting of the tumor position. CONCLUSION: The 4D setup system was shown to be useful for reducing the uncertainty of tumor motion and for increasing the efficiency of gated irradiation. Considering the interfractional and intrafractional changes in speed and amplitude detected in this study, intercepting radiotherapy is the safe and cost-effective method for 4D radiotherapy using real-time tracking technology.

Dose Fractionation, Radiation↗
PubMed2006

Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates.

It has been noted that some lung tumors exhibit large periodic motion due to respiration. To limit the amount of dose to healthy lung tissues, many clinics have begun gating radiotherapy treatment using externally placed surrogates. It has been observed by several institutions that the end-of-exhale (EOE) tumor position is more reproducible than other phases of the breathing cycle, so the gating window is often set there. From a treatment planning perspective, end-of-inhale (EOI) phase might be preferred for gating because the expanded lungs will further decrease the healthy tissue within the treatment field. We simulate gated treatment at the EOI phase, using a set of recently measured internal/external anatomy patient data. This paper attempts to answer three questions: (1) How much is the tumor residual motion when we use an external surrogate gating window at EOI? (2) How could we reduce the residual motion in the EOI gating window? (3) Is there a preference for amplitude- versus phase-based gating at EOI? We found that under free breathing conditions the residual motion of the tumors is much larger for EOI phase than for EOE phase. The mean values of residual motion at EOI were found to be 2.2 and 2.7 mm for amplitude- and phase-based gating, respectively, and, at EOE, 1.0 and 1.2 mm for amplitude- and phase-based gating, respectively. However, we note that the residual motion in the EOI gating window is correlated well with the reproducibility of the external surface position in the EOI phase. Using the results of a published breath-coaching study, we deduce that the residual motion of a lung tumor at EOI would approach that at EOE, with the same duty cycle (30%), under breath-coaching conditions. Additionally, we found that under these same conditions, phase-based gating approaches the same residual motion as amplitude-based gating, going from a 28% difference to 11%, for the patient with the largest difference between the two gating modalities. We conclude that it is feasible to achieve the same reproducibility of tumor location at EOI as at EOE if breath coaching is implemented, enabling us to reap the benefits of the dosimetric advantage of EOI gating.

Artifacts↗
PubMed2005

Spinal cord gliomas: A multi-institutional retrospective analysis.

PURPOSE: To determine the impact of postoperative radiation therapy (POXRT) on outcome in spinal cord gliomas. PATIENTS AND METHODS: Data from 242 patients were collected retrospectively from six institutions using a standardized data sheet. Pathology specimens, when available, were centrally reviewed. RESULTS: A total of 183 patients were analyzed: 82 received surgery alone as initial treatment, whereas 101 had surgery and POXRT. Demographic, diagnostic, and treatment factors were analyzed for impact on progression-free (PFS) and overall survival (OS). PFS in ependymoma patients was 74%, 60%, and 35% at 5, 10, 15 years, respectively, and was significantly influenced by treatment type, race, age, tumor grade, and type of surgery on univariate analysis, with age being the only significant factor on multivariate analysis (MVA) (p = 0.01). OS of ependymoma patients was 91%, 84%, and 75% at 5, 10, and 15 years, respectively, and was significantly influenced by both complete resection (p = 0.04) and age (p = 0.03) on MVA. In astrocytomas, PFS was 42%, 29%, and 15% at 5, 10, and 15 years, and was significantly influenced by POXRT in low- and intermediate-grade tumors on MVA (p = 0.02). OS at 5, 10, and 15 years was 59%, 53%, and 32%, respectively, and was significantly influenced by grade on MVA (p < 0.01). CONCLUSION: Postoperative radiation therapy reduced disease progression in low- and moderate-grade astrocytomas. In ependymomas, complete resection significantly influenced OS.

Adolescent↗
PubMed2005

Hypofractionated radiotherapy boost for dose escalation as a treatment option for high-grade spinal cord astrocytic tumor.

PURPOSE: To retrospectively analyze the outcome of post-operative radiotherapy for spinal cord glioma with the emphasis on the hypofractionated radiotherapy boost for dose escalation as a treatment option for high-grade spinal cord astrocytic tumors. MATERIALS AND METHODS: Forty-one patients with spinal cord glioma received post-operative radiotherapy between 1979 and 2003. The median age was 34 years (range, 10-66 years). Median follow-up was 49 months (range, 5-291 months). There were 12 low-grade astrocytic tumors, 11 high-grade astrocytic tumors, 16 low-grade ependymal tumors and 2 high-grade ependymal tumors. Among 11 patients with high-grade astrocytic tumors, 5 with anaplastic astrocytoma and 1 with glioblastoma received hypofractionated radiotherapy boost for dose escalation. The median total dose of the conventional radiotherapy was 45.5 Gy in 19 fractions (range, 30.0-60.0 Gy). The median normalized total dose (using daily dose of 2.0 Gy and an alpha/ per thousandbeta ratio of 2.0) of the hypofractionated radiotherapy boost was 131 Gy2 (range, 85-249). RESULTS: The Kaplan-Meier survival rates at 10 years from the date of the first surgery were 64% for the entire group, 47% for the astrocytic tumors and 84% for the ependymal tumors, respectively (P=0.009). Among 11 patients with high-grade astrocytic tumors, the actuarial survival rate at 10 years was 35%. The actuarial survival rates at 10 years were 67% for those who received hypofractionated radiotherapy boost for dose escalation, and 20% for those who did not (P=0.47). DISCUSSION: The results for ependymal tumors and low-grade astrocytic tumors were comparable to those reported in the literature. Hypofractionated radiotherapy boost for dose escalation may help to prolong the survival of patients with high-grade astrocytic tumors.

Adolescent↗
PubMed2005

The effect of tumor location and respiratory function on tumor movement estimated by real-time tracking radiotherapy (RTRT) system.

PURPOSE: The effects of tumor location and pulmonary function on the motion of fiducial markers near lung tumors were evaluated to deduce simple guidelines for determining the internal margin in radiotherapy without fiducial markers. METHODS AND MATERIALS: Pooled data collected by a real-time tumor-tracking radiotherapy system on 42 markers in 39 patients were analyzed. The pulmonary functions of all patients were assessed before radiotherapy. Using chest X-ray film, the position of the marker was expressed relative to the geometry of the unilateral lung. Posterior location meant the area of the posterior half of the lung in a lateral chest X-ray film, and caudal location meant the caudal half of the chest X-ray film; these categories were determined by measuring the distance between the marker and anatomic landmarks, including the apex, costophrenic angle, midline of spinal canal, lateral, anterior, and posterior boundary of the lung. RESULTS: Before the radiotherapy, 18 patients had obstructive respiratory dysfunction (ratio of forced expiratory volume in 1 s to forced vital capacity [FEV1.0/FVC] <70), 5 patients had constrictive dysfunction (percent vital capacity [%VC] <80), and 3 had mixed dysfunction. Means of FEV1.0/FVC and %VC were 97.0% and 66.5%, respectively. Median tumor movements in the x (left-right), y (anteroposterior), and z (craniocaudal) directions were 1.1 mm, 2.3 mm, and 5.4 mm, respectively. There was no significant correlation between respiratory function and magnitude of marker movement in any direction. Median marker movement in the z direction was 2.6 mm for the cranial location and 11.8 mm for the caudal location, respectively (p < 0.001). Median movement in the z direction was 11.8 mm for posterior location and 3.4 mm for anterior location, respectively (p < 0.01). CONCLUSIONS: Simple measurement of the relative location on plain chest X-ray film was related, but respiratory function test was not related, to the craniocaudal amplitude of the motion of the fiducial marker near lung tumors.

Adult↗
PubMed2005

Insertion and fixation of fiducial markers for setup and tracking of lung tumors in radiotherapy.

PURPOSE: Internal 1.5-mm fiducial markers were used in real-time tumor-tracking radiotherapy (RT) for lung cancer. The fixation rate of the markers using the bronchial insertion technique, reliability of the setup using markers around the target volume, dislocation of the markers after real-time tumor-tracking RT, and long-term toxicity of marker insertion were investigated. METHODS AND MATERIALS: Between July 2000 and April 2004, 154 gold markers were inserted into 57 patients with peripheral lung cancer. The distances between the implanted markers in 198 measurements in 71 set-ups in 11 patients were measured using two sets of orthogonal diagnostic X-ray images of the real-time tumor-tracking RT system. The distance between the markers and the chest wall was also measured in a transaxial CT image on 186 occasions in 48 patients during treatment planning and during follow-up. The median treatment time was 6 days (range, 4-14 days). RESULTS: In 115 (75%) of the 154 inserted markers, the gold marker was detected throughout the treatment period. In 122 markers detected at CT planning, 115 (94%) were detected until the end of treatment. The variation in the distances between the implanted markers was within +/-2 mm in 95% and +/-1 mm in 80% during treatment. The variation in the distances between the implanted markers was >2 mm in at least one direction in 9% of the setups for which reexamination with a CT scan was indicated. The fixation rate in the left upper lobe was lower than in the other lobes. A statistically significant relationship was found between a shorter distance between the markers and the chest wall and the fixation rate, suggesting that the markers in the smaller bronchial lumens fixed better than those in the larger lumens. A learning curve among the endoscopists was suggested in the fixation rate. The distance between the markers and the chest wall changed significantly within a median of 44 days (range, 16-181 days) after treatment. CONCLUSION: The fixation of markers into the bronchial tree was useful for the setup for peripheral lung cancer and had an accuracy of +/-2 mm during the 1-2-week treatment period. The relationship between the markers and tumor can change significantly after 2 weeks, suggesting that adaptive four-dimensional RT is required.

Adult↗
PubMed2005

Residual motion of lung tumours in gated radiotherapy with external respiratory surrogates.

Due to respiration, many tumours in the thorax and abdomen may move as much as 3 cm peak-to-peak during radiation treatment. To mitigate motion-induced irradiation of normal lung tissue, clinics have employed external markers to gate the treatment beam. This technique assumes that the correlation between the external surface and the internal tumour position remains constant inter-fractionally and intra-fractionally. In this work, a study has been performed to assess the validity of this correlation assumption for external surface based gated radiotherapy, by measuring the residual tumour motion within a gating window. Eight lung patients with implanted fiducial markers were studied at the NTT Hospital in Sapporo, Japan. Synchronized internal marker positions and external abdominal surface positions were measured during the entire course of treatment. Stereoscopic imaging was used to find the internal markers in four dimensions. The data were used retrospectively to assess conventional external surrogate respiratory-gated treatment. Both amplitude- and phase-based gating methods were investigated. For each method, three gating windows were investigated, each giving 40%, 30% and 20% duty cycle, respectively. The residual motion of the internal marker within these six gating windows was calculated. The beam-to-beam variation and day-to-day variation in the residual motion were calculated for both gating modalities. We found that the residual motion (95th percentile) was between 0.7 and 5.8 mm, 0.8 and 6.0 mm, and 0.9 and 6.2 mm for 20%, 30% and 40% duty cycle windows, respectively. Five of the eight patients showed less residual motion with amplitude-based gating than with phase-based gating. Large fluctuations (>300%) were seen in the residual motion between some beams. Overall, the mean beam-to-beam variation was 37% and 42% from the previous treatment beam for amplitude- and phase-based gating, respectively. The day-to-day variation was 29% and 34% from the previous day for amplitude- and phase-based gating, respectively. Although gating reduced the total tumour motion, the residual motion behaved unpredictably. Residual motion during treatment could exceed that which might have been considered in the treatment plan. Treatment margins that account for motion should be individualized and daily imaging should be performed to ensure that the residual motion is not exceeding the planned motion on a given day.

Dose-Response Relationship, Radiation↗
PubMed2005

Comparison of imaging modalities for the accurate delineation of arteriovenous malformation, with reference to stereotactic radiosurgery.

PURPOSE: To investigate the discrepancy between the arteriovenous malformations seen on magnetic resonance angiography (MRA) and on stereotactic digital subtracted angiography (DSA). METHODS AND MATERIALS: The target volume on stereotactic DSA (V(DSA)) and the target volume on MRA (V(MRA)) were separately delineated in 28 intracranial arteriovenous malformations. The coordinates of the center and the outer edges of V(DSA) and V(MRA) were calculated and used for the analyses. RESULTS: The standard deviations (mean value) of the displacement of centers of V(MRA) from V(DSA) were 2.67 mm (-1.82 mm) in the left-right direction, 3.23 mm (-0.08 mm) in the anterior-posterior direction, and 2.16 mm (0.91 mm) in the craniocaudal direction. V(MRA) covered less than 80% of V(DSA) in any dimensions in 9 cases (32%), although no significant difference was seen in the target volume between each method, with a mean value of 11.9 cc for V(DSA) and 12.3 cc for V(MRA) (p = 0.948). CONCLUSION: The shift of centers between each modality is not negligible. Considering no significant difference between V(DSA) and V(MRA), but inadequate coverage of the V(DSA) by V(MRA), it is reasonable to consider that the target on MRA might include the feeding artery and draining vein and possibly miss a portion of the nidus.

Adolescent↗
PubMed2005

Real-time monitoring of a digestive tract marker to reduce adverse effects of moving organs at risk (OAR) in radiotherapy for thoracic and abdominal tumors.

PURPOSE: To evaluate the feasibility of real-time monitoring of a fiducial marker in/near the digestive tract and to analyze the motion of organs at risk to determine a reasonable internal margin. METHODS AND MATERIALS: We developed two methods to insert a fiducial marker into/near the digestive tract adjacent to the target volume. One method involves an intraoperative insertion technique, and the other involves endoscopic insertion into the submucosal layer of the normal digestive tract. A fluoroscopic real-time tumor-tracking radiotherapy system was used to monitor the marker. RESULTS: Fourteen markers (2 in the mediastinum and 12 in the abdomen) were implanted intraoperatively in 14 patients with no apparent migration. Seventeen of 20 markers (13/14 in the esophagus, 1/2 in the stomach, and 3/4 in the duodenum) in 18 patients were implanted using endoscopy without dropping. No symptomatic adverse effects related to insertion were observed. The mean/standard deviation of the range of motion of the esophagus was 3.5/1.8, 8.3/3.8, and 4.0/2.6 mm for lateral, craniocaudal and anteroposterior directions, respectively, in patients with intrafractional tumor motion less than 1.0 cm. CONCLUSION: Both intraoperative and endoscopic insertions of a fiducial marker into/near the digestive tract for monitoring of organs at risk were feasible. The margin for internal motion can be individualized using this system.

Abdominal Neoplasms↗
PubMed2005

Rapid superselective high-dose cisplatin infusion with concomitant radiotherapy for advanced head and neck cancer.

PURPOSE: The purpose of this study was to evaluate the efficacy of rapid superselective high-dose cisplatin infusion with concomitant radiotherapy for previously untreated patients with advanced head and neck cancer. METHODS: Forty-three patients for whom surgery was contraindicated or who rejected radical surgery were given superselective intra-arterial infusions of cisplatin (100-120 mg/m2/week) with simultaneous intravenous infusion of thiosulfate to neutralize cisplatin toxicity and conventional extra-beam radiotherapy (65 Gy/26 f/6.5 weeks). RESULTS: Thirty-nine patients had stage IV disease, and the remaining four had stage III disease. During the median follow-up period of 21 months, the 3-year locoregional progression-free rates of all patients (n = 43) and patients with unresectable disease (n = 24) were 68.9% and 56.4%, respectively. In addition, the 3-year overall survival of all patients and patients with unresectable disease was 54.0% and 39.6%, respectively. Thirty-five patients (81.4%) experienced nonhematologic grade III to IV toxicity, including mucositis (n = 16), nausea/vomiting (n = 8), and neurologic signs (n = 2). No patient died as a result of treatment toxicity. There are 29 surviving patients without evidence of disease, all of whom are able to have oral intake without feeding-tube support. CONCLUSIONS: We confirmed the efficacy of superselective arterial infusion and concomitant radiotherapy, which can concentrate the attack of supradose cisplatin on locoregional disease. Even patients with unresectable disease can be cured. Further studies are needed to establish the indications, long-term outcome, and possible late side effects of this treatment.

Adult↗
PubMed2005

[Highly quality-controlled radiation therapy].

Advanced radiation therapy for intracranial disease has focused on set-up accuracy for the past 15 years. However, quality control in the prescribed dose is actually as important as the tumor set-up in radiation therapy. Because of the complexity of the three-dimensional radiation treatment planning system in recent years, the highly quality-controlled prescription of the dose has now been reappraised as the mainstream to improve the treatment outcome of radiation therapy for intracranial disease. The Japanese Committee for Quality Control of Radiation Therapy has developed fundamental requirements such as a QC committee in each hospital, a medical physicist, dosimetrists (QC members), and an external audit.

Antineoplastic Agents, Alkylating↗
PubMed2004

Tracking errors in a prototype real-time tumour tracking system.

In motion-compensated radiation therapy, radio-opaque markers can be implanted in or near a tumour and tracked in real-time using fluoroscopic imaging. Tracking these implanted markers gives highly accurate position information, except when tracking fails due to poor or ambiguous imaging conditions. This study investigates methods for automatic detection of tracking errors, and assesses the frequency and impact of tracking errors on treatments using the prototype real-time tumour tracking system. We investigated four indicators for automatic detection of tracking errors, and found that the distance between corresponding rays was most effective. We also found that tracking errors cause a loss of gating efficiency of between 7.6 and 10.2%. The incidence of treatment beam delivery during tracking errors was estimated at between 0.8% and 1.25%.

Algorithms↗
PubMed2004

A finite state model for respiratory motion analysis in image guided radiation therapy.

Effective image guided radiation treatment of a moving tumour requires adequate information on respiratory motion characteristics. For margin expansion, beam tracking and respiratory gating, the tumour motion must be quantified for pretreatment planning and monitored on-line. We propose a finite state model for respiratory motion analysis that captures our natural understanding of breathing stages. In this model, a regular breathing cycle is represented by three line segments, exhale, end-of-exhale and inhale, while abnormal breathing is represented by an irregular breathing state. In addition, we describe an on-line implementation of this model in one dimension. We found this model can accurately characterize a wide variety of patient breathing patterns. This model was used to describe the respiratory motion for 23 patients with peak-to-peak motion greater than 7 mm. The average root mean square error over all patients was less than 1 mm and no patient has an error worse than 1.5 mm. Our model provides a convenient tool to quantify respiratory motion characteristics, such as patterns of frequency changes and amplitude changes, and can be applied to internal or external motion, including internal tumour position, abdominal surface, diaphragm, spirometry and other surrogates.

Algorithms↗