ABSTRACT: Respiratory gating radiotherapy is used to irradiate a local area and to reduce normal tissue toxicity. There are certain methods for the detection of tumor motions, for example, using internal markers or an external respiration signal. However, because some of these respiratory monitoring systems require special or expensive equipment, respiratory monitoring can usually be performed only in limited facilities. In this study, the feasibility of using an acceleration sensor for respiratory monitoring was evaluated. The respiratory motion was represented by means of a platform and measured five times with the iPod touch® at 3, 4 and 5 s periods of five breathing cycles. For these three periods of the reference waveform, the absolute means ± standard deviation (SD) of displacement were 0.45 ± 0.34 mm, 0.33 ± 0.24 mm and 0.31 ± 0.23 mm, respectively. On the other hand, the corresponding absolute means ± SD for the periods were 0.04 ± 0.09 s, 0.04 ± 0.02 s and 0.06 ± 0.04 s. The accuracy of respiratory monitoring using the acceleration sensor was satisfactory in terms of the absolute means ± SD. Using the iPod touch® for respiratory monitoring does not need special equipment and makes respiratory monitoring easier. For these reasons, this system is a viable alternative to other respiratory monitoring systems.
Physics in Medicine and Biology 09/2011; 56(19):6279-89. · 2.83 Impact Factor
ABSTRACT: To develop an infrastructure for the integrated Monte Carlo verification system (MCVS) to verify the accuracy of conventional dose calculations, which often fail to accurately predict dose distributions, mainly due to inhomogeneities in the patient's anatomy, for example, in lung and bone.
The MCVS consists of the graphical user interface (GUI) based on a computational environment for radiotherapy research (CERR) with MATLAB language. The MCVS GUI acts as an interface between the MCVS and a commercial treatment planning system to import the treatment plan, create MC input files, and analyze MC output dose files. The MCVS consists of the EGSnrc MC codes, which include EGSnrc/BEAMnrc to simulate the treatment head and EGSnrc/DOSXYZnrc to calculate the dose distributions in the patient/phantom. In order to improve computation time without approximations, an in-house cluster system was constructed.
The phase-space data of a 6-MV photon beam from a Varian Clinac unit was developed and used to establish several benchmarks under homogeneous conditions. The MC results agreed with the ionization chamber measurements to within 1%. The MCVS GUI could import and display the radiotherapy treatment plan created by the MC method and various treatment planning systems, such as RTOG and DICOM-RT formats. Dose distributions could be analyzed by using dose profiles and dose volume histograms and compared on the same platform. With the cluster system, calculation time was improved in line with the increase in the number of central processing units (CPUs) at a computation efficiency of more than 98%.
Development of the MCVS was successful for performing MC simulations and analyzing dose distributions.
International journal of radiation oncology, biology, physics 11/2009; 75(2):571-9. · 4.59 Impact Factor
ABSTRACT: The Japan Patterns of Care Study (JPCS) conducted two national surveys to identify changes associated with the treatment process of care for patients undergoing breast-conserving therapy (BCT). Between the two national surveys, the Japanese Breast Cancer Society published its treatment guideline for BCT.
The first survey collected data on 865 patients treated between 1995 and 1997 (JPCS-1), and the second on 746 patients treated between1999 and 2001 (JPCS-2) by extramural audits.
There was a shift to an older age distribution in JPCS-2 compared with JPCS-1. In JPCS-2, the average patient age was 53.9 compared with 51.5 in JPCS-1 (P < 0.001). There was a reduction in the extent of breast surgery and the proportion of the patients who received quadrantectomy was 57.0% in JPCS-1 and 30.3% in JPCS-2 (P < 0.001). In JPCS-2, a cast or shell for immobilization was used at a significantly higher rate of 52.9% compared with 32.6% for JPCS-1 (P < 0.001). The rate of boost irradiation was increased in JPCS-2, especially for patients with a positive surgical margin; it was significantly increased to 83.5% in JPCS-2 compared with 53.9% in JPCS-1 (P < 0.001).
The second survey revealed a rapid change in the trend of the treatment of BCT in Japan and represented high compliance of the treatment guideline for BCT published by the Japanese Breast Cancer Society (JBCS) in 1999.
Japanese Journal of Clinical Oncology 11/2007; 37(10):737-43. · 1.78 Impact Factor