Simple technique to visualize random set-up displacements using a commercially available radiotherapy planning system.

Hiromichi Ishiyama; Masashi Kitano; Yuzuru Niibe; Mineko Uemae; Kazushige Hayakawa

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PubMed · 15940071

Simple technique to visualize random set-up displacements using a commercially available radiotherapy planning system.

Hiromichi Ishiyama·Masashi Kitano·Yuzuru Niibe·Mineko Uemae·Kazushige Hayakawa

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Abstract

PURPOSE: To visualize random set-up displacements in isodose distribution images, we introduce a simple technique using a commercially available radiotherapy planning system (RTP). MATERIALS AND METHODS: A distribution of set-up displacement is known to be compatible with that of a Gaussian distribution. Based on that assumption, 41 intentionally misaligned beams with 1-mm intervals were planned in the respective weights according to Gaussian distribution. "Modified" isodose distributions were then visualized using a commercially available RTP. In the next step, only two beams misaligned with one standard deviation (SD) of the Gaussian distribution were used in place of 41 beams, as a large number of beams increases the workload and is unsuitable for clinical use. Differences between the two versions of isodose distribution images were assessed visually. RESULTS: In modified dose distribution images, the edge of distribution was dull compared to normal images. These images show that the larger SD of set-up displacement dulls the edge of dose distribution. Images from two beams were not significantly different to those from 41 beams. CONCLUSION: Using this technique, the impact of random set-up displacements was effectively reflected in isodose distribution images.

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Humans Male Phantoms, Imaging Prostatic Neoplasms Radiotherapy Dosage Radiotherapy Planning, Computer-Assisted Journal Article Research Support, Non-U.S. Gov't

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Hiromichi Ishiyama, Masashi Kitano, Yuzuru Niibe, Mineko Uemae, Kazushige Hayakawa. 2005. Simple technique to visualize random set-up displacements using a commercially available radiotherapy planning system.. https://pubmed.ncbi.nlm.nih.gov/15940071/

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