J Appl Clin Med Phys
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J Appl Clin Med Phys · Apr 2007
Simplifying intensity-modulated radiotherapy plans with fewer beam angles for the treatment of oropharyngeal carcinoma.
The first aim of the present study was to investigate the feasibility of using fewer beam angles to improve delivery efficiency for the treatment of oropharyngeal cancer (OPC) with inverse-planned intensity-modulated radiation therapy (IP-IMRT). A secondary aim was to evaluate whether the simplified IP-IMRT plans could reduce the indirect radiation dose. The treatment plans for 5 consecutive OPC patients previously treated with a forward-planned IMRT (FP-IMRT) technique were selected as benchmarks for this study. ⋯ As compared with the complex IP-IMRT plans, the simple IP-IMRT plans significantly reduced the mean treatment time (maximum probability for four pairwise comparisons: p = 0.0003). In conclusion, our study demonstrates that, as compared with complex IP-IMRT, simple IP-IMRT can significantly improve treatment delivery efficiency while maintaining similar target coverage and sparing of critical structures. However, the improved efficiency does not significantly reduce the total number of MUs nor the indirect radiation dose.
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J Appl Clin Med Phys · Jan 2006
An investigation of the potential of rapid prototyping technology for image guided surgery.
Image-guided surgery can be broken down into two broad categories: frame-based guidance and frameless guidance. In order to reduce both the invasive nature of stereotactic guidance and the cost in equipment and time, we have developed a new guidance technique based on rapid prototyping (RP) technology. This new system first builds a computer model of the patient anatomy and then fabricates a physical reference frame that provides a precise and unique fit to the patient anatomy. ⋯ The results show that the RP technology can replicate an object from CT scans with submillimeter resolution. The fabricated reference frames, when positioned on the surface of the phantom and used to guide a surgical probe, can position the probe tip with an accuracy of 1.7 mm at the probe tip. These results demonstrate that the RP technology can be used for the fabrication of customized positioning frames for use in image-guided surgery.
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J Appl Clin Med Phys · Jan 2005
Errors in radiation oncology: a study in pathways and dosimetric impact.
As complexity for treating patients increases, so does the risk of error. Some publications have suggested that record and verify (R&V) systems may contribute in propagating errors. Direct data transfer has the potential to eliminate most, but not all, errors. ⋯ As R&V systems become more automated, more accurate and efficient data transfer will occur. This will require further analysis. Finally, we have begun examining potential intensity-modulated radiation therapy (IMRT) errors according to the same criteria.
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J Appl Clin Med Phys · Jan 2004
Clinical TrialStereotactic IMRT for prostate cancer: dosimetric impact of multileaf collimator leaf width in the treatment of prostate cancer with IMRT.
The focus of this work is the dosimetric impact of multileaf collimator (MLC) leaf width on the treatment of prostate cancer with intensity-modulated radiation therapy (IMRT). Ten patients with prostate cancer were planned for IMRT delivery using two different MLC leaf widths--4mm and 10mm--representing the Radionics micro-multileaf collimator (mMLC) and Siemens MLC, respectively. Treatment planning was performed on the XKnifeRT2 treatment-planning system (Radionics, Burlington, MA). ⋯ The target dose inhomogeneity was improved in the mMLC plans by an average of 29%. In the high-dose range, there was no significant difference in the dose deposited in the "hottest" 1 cm3 of the rectum between the two plans for all cases (p > 0.78). In conclusion, the use of the mMLC for IMRT of the prostate resulted in significant improvement in the DVH parameters of the prostate and critical organs, which may improve the therapeutic ratio.
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J Appl Clin Med Phys · Jan 2004
Clinical TrialStereotactic IMRT for prostate cancer: setup accuracy of a new stereotactic body localization system.
The purpose of this work is to prospectively assess the setup accuracy that can be achieved with a stereotactic body localizer (SBL) in immobilizing patients for stereotactic intensity-modulated radiotherapy (IMRT) for prostate cancer. By quantifying this important factor and target mobility in the SBL, we expect to provide a guideline for selecting planning target volume margins for stereotactic treatment planning. We analyzed data from 40 computed tomography (CT) studies (with slice thickness of 3 mm) involving 10 patients with prostate cancer. ⋯ The mean target mobility relative to the bony landmarks was 2.22 +/- 3.45 mm, 0.17 +/- 1.11 mm, and 0.11 +/- 2.69 mm in the AP, LAT, and SI directions, respectively. In conclusion, the body immobilization system has the ability to immobilize prostate cancer patients with satisfactory setup accuracy for fractionated extracranial stereotactic radiotherapy. A rigid frame system serves as a reliable alignment reference in terms of repositioning patients into the planning position, while skin-based reference showed larger deviations in repositioning patients.