Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2013 Jul 21;58(14):4921-32.
doi: 10.1088/0031-9155/58/14/4921. Epub 2013 Jun 25.

Reduction of prostate intrafractional motion from shortening the treatment time

Jin Sheng Li  1 , Mu-Han Lin, Mark K Buyyounouski, Eric M Horwitz, Chang-Ming Ma
Affiliations

Reduction of prostate intrafractional motion from shortening the treatment time

Jin Sheng Li et al. Phys Med Biol. .

Abstract

This study aims to quantify the reduction of the intrafractional motion when the prostate intensity modulated radiation therapy (IMRT) treatment time is shortened. Prostate intrafractional motion data recorded by the Calypso system for 105 patients was analyzed. Statistical distributions of the prostate displacements for the regular IMRT treatment and the first 1, 2, 3 and 5 min of the treatment were calculated and used for treatment margin estimation for all the selected patients. The treatment margins estimated for the first 1, 2, 3 and 5 min were compared with those for the regular IMRT treatment to quantify the reduction of the motion. If the treatment can be completed within 5 (3) min, the standard deviation of the prostate displacement could be reduced by up to 45% and the required treatment margins could be reduced to 1.2 (1.1), 0.9 (0.8), 2.2 (1.9), 1.9 (1.5), 1.9 (1.7) and 2.8 (2.4) mm from 1.5, 1.1, 2.8, 3.0, 2.4 and 3.9 mm in the left, right, superior, inferior, anterior and posterior directions, respectively. The same work was also performed for 19 of the 105 patients who exhibited the largest motion with 30% of their treatment time having 3D motion more than 3 mm. For this group of patients, the required margins change to 1.4 (1.2), 0.8 (0.8), 1.8 (1.6), 2.3 (1.8), 1.7 (1.5) and 3.4 (2.8) mm from 1.9, 1.2, 1.7, 3.7, 1.6 and 4.9 mm in the six directions when the treatment time is reduced to 5 (3) min. The intrafractional motion effects on prostate treatment are significantly smaller and the required margins can be therefore reduced when the treatment is shortened.

PubMed Disclaimer

Conflict of interest statement

Conflict of Interest: We declare that we don't have any conflict of interest with any party.

Figures

Figure 1
Figure 1
Histogram of the treatment time distribution for regular IMRT.
Figure 2
Figure 2
Required treatment margin to cover the intrafractional motion for patient groups with different treatment time.
Figure 3
Figure 3
Comparison of margins calculated based on the intrafractional motion data of the regular IMRT and the first 5, 3, 2, 1 minute of treatment and the residual setup errors for the entire patient population.
Figure 4
Figure 4
Histogram of the percentage treatment time distribution with 3D motion > 3mm.
Figure 5
Figure 5
Comparison of margins calculated for the regular IMRT treatment between the small group of patient and the entire patient population.
Figure 6
Figure 6
Comparison margins calculated for the regular IMRT, the first 5 minutes and the first 3 minutes of the treatment for the small group of patient
See this image and copyright information in PMC

References

    1. Aubry JF, Beaulieu L, Girouard LM, Aubin S, Tremblay D, Laverdiere J, Vigneault E. Measurements of intrafraction motion and interfraction and intrafraction rotation of prostate by three-dimensional analysis of daily portal imaging with radiopaque markers. International journal of radiation oncology, biology, physics. 2004;60:30–9. - PubMed
    1. Balter JM, Sandler HM, Lam K, Bree RL, Lichter AS, ten Haken RK. Measurement of prostate movement over the course of routine radiotherapy using implanted markers. International journal of radiation oncology, biology, physics. 1995;31:113–8. - PubMed
    1. Balter JM, Wright JN, Newell LJ, Friemel B, Dimmer S, Cheng Y, Wong J, Vertatschitsch E, Mate TP. Accuracy of a wireless localization system for radiotherapy. International journal of radiation oncology, biology, physics. 2005;61:933–7. - PubMed
    1. Bittner N, Butler WM, Reed JL, Murray BC, Kurko BS, Wallner KE, Merrick GS. Electromagnetic tracking of intrafraction prostate displacement in patients externally immobilized in the prone position. International journal of radiation oncology, biology, physics. 2010;77:490–5. - PubMed
    1. Britton KR, Takai Y, Mitsuya M, Nemoto K, Ogawa Y, Yamada S. Evaluation of inter- and intrafraction organ motion during intensity modulated radiation therapy (IMRT) for localized prostate cancer measured by a newly developed on-board image-guided system. Radiat Med. 2005;23:14–24. - PubMed

Publication types