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Intensity-modulated radiation therapy using static ports of tomotherapy (TomoDirect): comparison with the TomoHelical mode.

Murai T, Shibamoto Y, Manabe Y, Murata R, Sugie C, Hayashi A, Ito H, Miyoshi Y - Radiat Oncol (2013)

Bottom Line: The purpose of this study was to evaluate the characteristics of TomoDirect plans compared to conventional TomoHelical plans.Treatment time did not differ significantly between the thoracic wall and lung plans.Prostate cancers should be treated with the TomoHelical mode.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan. taro8864@yahoo.co.jp

ABSTRACT

Purpose: With the new mode of Tomotherapy, irradiation can be delivered using static ports of the TomoDirect mode. The purpose of this study was to evaluate the characteristics of TomoDirect plans compared to conventional TomoHelical plans.

Methods: TomoDirect and TomoHelical plans were compared in 46 patients with a prostate, thoracic wall or lung tumor. The mean target dose was used as the prescription dose. The minimum coverage dose of 95% of the target (D95%), conformity index (CI), uniformity index (UI), dose distribution in organs at risk and treatment time were evaluated. For TomoDirect, 2 to 5 static ports were used depending on the tumor location.

Results: For the prostate target volume, TomoDirect plans could not reduce the rectal dose and required a longer treatment time than TomoHelical. For the thoracic wall target volume, the V5Gy of the lung or liver was lower in TomoDirect than in TomoHelical (p = 0.02). For the lung target volume, TomoDirect yielded higher CI (p = 0.009) but smaller V5Gy of the lung (p = 0.005) than TomoHelical. Treatment time did not differ significantly between the thoracic wall and lung plans.

Conclusion: Prostate cancers should be treated with the TomoHelical mode. Considering the risk of low-dose radiation to the lung, the TomoDirect mode could be an option for thoracic wall and lung tumors.

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Related in: MedlinePlus

Dose volume histograms of TomoHelical and TomoDirect plans for prostate target volume. (a) TomoHelical plan. (b) TomoDirect plan – Angles A. (c) TomoDirect plan – Angles B.
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Figure 3: Dose volume histograms of TomoHelical and TomoDirect plans for prostate target volume. (a) TomoHelical plan. (b) TomoDirect plan – Angles A. (c) TomoDirect plan – Angles B.

Mentions: A typical dose distribution and a typical dose volume histogram of the prostate plans are shown in Table 1, Figure 2 and Figure 3. Table 1 summarizes the treatment parameters, dose-volume parameters and treatment times of the two plans in 19 patients. D95%, CI and UI were almost equal. The dose distributions of the bladder were similar between TomoDirect (angles A) and TomoHelical plans; only V60 Gy and V70 Gy of the bladder in the TomoDirect plan using angles B were significantly higher than those in the TomoHelical plan. On the other hand, the V30, 40, 50, 60 and 70 Gy of the rectum in both of the TomoDirect plans were significantly higher than those in TomoHelical. Irrespective of the angles, TomoDirect plans could not satisfy the initial dose constraints. In TomoHelical plans, the rectal dose exceeded the prescribed dose (74.8 Gy) in 16 of 19 patients. In TomoDirect plans, the rectal dose exceeded 74.8 Gy in 14 patients for angles A and 17 patients for angles B. However, the rectal volumes receiving > 74.8 Gy were less than 1 cc in any of the cases. Beam-on times in both TomoDirect plans were longer than those in TomoHelical. No significant differences between these two TomoDirect plans were observed in the dose distribution of the bladder and rectum, CI, UI and beam-on time.


Intensity-modulated radiation therapy using static ports of tomotherapy (TomoDirect): comparison with the TomoHelical mode.

Murai T, Shibamoto Y, Manabe Y, Murata R, Sugie C, Hayashi A, Ito H, Miyoshi Y - Radiat Oncol (2013)

Dose volume histograms of TomoHelical and TomoDirect plans for prostate target volume. (a) TomoHelical plan. (b) TomoDirect plan – Angles A. (c) TomoDirect plan – Angles B.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643840&req=5

Figure 3: Dose volume histograms of TomoHelical and TomoDirect plans for prostate target volume. (a) TomoHelical plan. (b) TomoDirect plan – Angles A. (c) TomoDirect plan – Angles B.
Mentions: A typical dose distribution and a typical dose volume histogram of the prostate plans are shown in Table 1, Figure 2 and Figure 3. Table 1 summarizes the treatment parameters, dose-volume parameters and treatment times of the two plans in 19 patients. D95%, CI and UI were almost equal. The dose distributions of the bladder were similar between TomoDirect (angles A) and TomoHelical plans; only V60 Gy and V70 Gy of the bladder in the TomoDirect plan using angles B were significantly higher than those in the TomoHelical plan. On the other hand, the V30, 40, 50, 60 and 70 Gy of the rectum in both of the TomoDirect plans were significantly higher than those in TomoHelical. Irrespective of the angles, TomoDirect plans could not satisfy the initial dose constraints. In TomoHelical plans, the rectal dose exceeded the prescribed dose (74.8 Gy) in 16 of 19 patients. In TomoDirect plans, the rectal dose exceeded 74.8 Gy in 14 patients for angles A and 17 patients for angles B. However, the rectal volumes receiving > 74.8 Gy were less than 1 cc in any of the cases. Beam-on times in both TomoDirect plans were longer than those in TomoHelical. No significant differences between these two TomoDirect plans were observed in the dose distribution of the bladder and rectum, CI, UI and beam-on time.

Bottom Line: The purpose of this study was to evaluate the characteristics of TomoDirect plans compared to conventional TomoHelical plans.Treatment time did not differ significantly between the thoracic wall and lung plans.Prostate cancers should be treated with the TomoHelical mode.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan. taro8864@yahoo.co.jp

ABSTRACT

Purpose: With the new mode of Tomotherapy, irradiation can be delivered using static ports of the TomoDirect mode. The purpose of this study was to evaluate the characteristics of TomoDirect plans compared to conventional TomoHelical plans.

Methods: TomoDirect and TomoHelical plans were compared in 46 patients with a prostate, thoracic wall or lung tumor. The mean target dose was used as the prescription dose. The minimum coverage dose of 95% of the target (D95%), conformity index (CI), uniformity index (UI), dose distribution in organs at risk and treatment time were evaluated. For TomoDirect, 2 to 5 static ports were used depending on the tumor location.

Results: For the prostate target volume, TomoDirect plans could not reduce the rectal dose and required a longer treatment time than TomoHelical. For the thoracic wall target volume, the V5Gy of the lung or liver was lower in TomoDirect than in TomoHelical (p = 0.02). For the lung target volume, TomoDirect yielded higher CI (p = 0.009) but smaller V5Gy of the lung (p = 0.005) than TomoHelical. Treatment time did not differ significantly between the thoracic wall and lung plans.

Conclusion: Prostate cancers should be treated with the TomoHelical mode. Considering the risk of low-dose radiation to the lung, the TomoDirect mode could be an option for thoracic wall and lung tumors.

Show MeSH
Related in: MedlinePlus