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The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer.

Sung W, Park JM, Choi CH, Ha SW, Ye SJ - Radiat Oncol J (2012)

Bottom Line: However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV.Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%.The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea. ; Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.

ABSTRACT

Purpose: To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients.

Materials and methods: Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose.

Results: Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The V(20 Gy) of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%.

Conclusion: In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

No MeSH data available.


Related in: MedlinePlus

Dose volume histogram (DVH) for bladder is shown. The solid lines indicate DVHs of intensity-modulated radiation therapy with 6-MV photon beams while dashed lines and dotted lines indicate DVHs of intensity-modulated radiation therapy with 10-MV and 15-MV, respectively. No clear differences among three types of plans are observed.
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Figure 3: Dose volume histogram (DVH) for bladder is shown. The solid lines indicate DVHs of intensity-modulated radiation therapy with 6-MV photon beams while dashed lines and dotted lines indicate DVHs of intensity-modulated radiation therapy with 10-MV and 15-MV, respectively. No clear differences among three types of plans are observed.

Mentions: The 6-MV beam achieved slightly less mean dose to bladder than 15-MV beam (2.9%) but showed no statistical improvement compared with 10-MV. For bladder, the volumes receiving ≥70, 66.6, 50, 40, and 20 Gy were smaller with 6-MV than others, however, the amount of increased volume were less than 3% on average. Mean DVH curve of bladder (Fig. 3) clearly shows that there are only negligible differences between three types of energy.


The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer.

Sung W, Park JM, Choi CH, Ha SW, Ye SJ - Radiat Oncol J (2012)

Dose volume histogram (DVH) for bladder is shown. The solid lines indicate DVHs of intensity-modulated radiation therapy with 6-MV photon beams while dashed lines and dotted lines indicate DVHs of intensity-modulated radiation therapy with 10-MV and 15-MV, respectively. No clear differences among three types of plans are observed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3475960&req=5

Figure 3: Dose volume histogram (DVH) for bladder is shown. The solid lines indicate DVHs of intensity-modulated radiation therapy with 6-MV photon beams while dashed lines and dotted lines indicate DVHs of intensity-modulated radiation therapy with 10-MV and 15-MV, respectively. No clear differences among three types of plans are observed.
Mentions: The 6-MV beam achieved slightly less mean dose to bladder than 15-MV beam (2.9%) but showed no statistical improvement compared with 10-MV. For bladder, the volumes receiving ≥70, 66.6, 50, 40, and 20 Gy were smaller with 6-MV than others, however, the amount of increased volume were less than 3% on average. Mean DVH curve of bladder (Fig. 3) clearly shows that there are only negligible differences between three types of energy.

Bottom Line: However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV.Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%.The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea. ; Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea.

ABSTRACT

Purpose: To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients.

Materials and methods: Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose.

Results: Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The V(20 Gy) of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%.

Conclusion: In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

No MeSH data available.


Related in: MedlinePlus