Treatment of exceptionally large prostate cancer patients with low‐energy intensity‐modulated photons

Sun, Meina; Ma, Lijun

doi:10.1120/jacmp.v7i4.2263

Cited by 27 publications

(22 citation statements)

References 20 publications

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“…Previous studies have already showed that IMRT plan quality could be hardly affected by the choice of beam energy. 10,11,15 However, in those studies they employed only single photon energy per plan and analyzed mainly the high dose regions. In our study, we focused on the low dose regions for IMRT plans of multiple photon energies and showed that the volume irradiated less than 50% of prescribed dose could be reduced by the energy modulation.…”

Section: Discussionmentioning

confidence: 99%

“…In this situation, the use of fewer fields increases the potential of energy optimization in order to avoid dose in regions distant from the target volume (i.e., close to the skin surface). 10,11,15 Beam energy optimization could find its use in these situations.…”

Section: Discussionmentioning

confidence: 99%

“…This simulation was independent of the movable jaws. The thickness of mercury inside the energy modulator varied from 0 to 40 mm (0, 2, 4, 6,8,10,15,20,25,30,35, and 40 mm). The other simulations for different field sizes of 5 Â 5, 10 Â 10, and 20 Â 20 cm 2 were performed by using the phase space files on Plane A as an input.…”

Section: Iib2 Monte Carlo Simulations For Energy Modulatormentioning

confidence: 99%

“…1 Also, other studies showed that the use of a large number of beam portals in IMRT diminished the need to optimize the photon energy. 10,11,15 On the other hand, a study evaluated the advantage of using very high-energy photons (50 MV) over low-energy photons (6 MV) to treat lung cancers. 7 A number of independent studies mentioned that high-energy should not be excluded a priori, but its use must be carefully weighted to overcome problems in lateral disequilibrium and potential dose calculation inaccuracies.…”

Section: Introductionmentioning

confidence: 99%

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Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

et al. 2012

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Iib2 Monte Carlo Simulations For Energy Modulatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

et al. 2012

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“…An arrangement of 7 coplanar beams at gantry angles 0, 51, 102, 153, 207, 258, and 309 degrees with 6-MV photon energy was used for IMRT. (15)(16)(17)(18)(19)(20) The dose constraint to the PPO was 100% of the PPO covered by 95% of the prescribed dose (78 Gy). The dose constraints of organs at risk followed the dose guidelines designed by the Radiation Therapy Oncology Group (RTOG) for patients being treated for localized prostate cancer under RTOG protocol 0126.…”

Section: Imrt Techniquementioning

confidence: 99%

Comparison of intensity‐modulated radiotherapy and forward‐planning dynamic arc therapy techniques for prostate cancer

Metwaly

Awaad

El-Sayed

et al. 2008

J Applied Clin Med Phys

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We compare an inverse‐planning intensity‐modulated radiotherapy (IMRT) technique with three previously published forward‐planning dynamic arc therapy techniques and a newly implemented technique for treatment of prostate only. The three previously published dynamic arc techniques are dynamic arc therapy (DAT), two‐axis dynamic arc therapy (2A‐DAT), and modified dynamic arc therapy (M‐DAT). The newly implemented technique is the bilateral wedged dynamic arc (BW‐DAT). In all dynamic arcs, the multileaf collimator is moving during rotation to fit the prostate, except that, in 2A‐DAT, it is fitting two separate symmetrical rhombi including the prostate. The rectum is shielded during rotation only in the cases of M‐DAT and BW‐DAT.The results obtained indicate that the BW‐DAT, M‐DAT, and DAT techniques provide the intended dose coverage of the prescribed dose to the planning target volume (PTV)—that is, 95% of the PTV is covered by 100% of the dose. The maximum dose to a 3‐cm margin of healthy tissue that surrounds the PTV is lower by 2.5% in the case of IMRT than in both BW‐DAT and M‐DAT, but it is lower by 5.0% than that in both DAT and 2A‐DAT. The maximum dose to the rest of the healthy tissue in the case of BW‐DAT is 33.2Gy±2.2Gy. This dose covers percentage healthy body volumes of 8%±3.2% with IMRT, 4%±1.5% with DAT, and 6%±1.2% with both 2A‐DAT and M‐DAT. Also, this dose is much lower than the accepted maximum dose (52 Gy) to the femoral heads and necks according to Report 62 from the International Commission on Radiation Units and Measurements. Accordingly, it would be possible to neglect delineation of the femoral heads and necks as organs at risk in cases of BW‐DAT.Doses to 15%, 25%, 35%, and 50% (D15%, D25%, D35%, and D50%) of the rectum volume in the case of BW‐DAT were 43.5Gy±8.6Gy, 24.2Gy±8.7Gy, 13.2Gy±4.2Gy, and 5.7Gy±2.1Gy respectively. The D15% of rectum in the case of IMRT was lower than that in BW‐DAT, M‐DAT, 2A‐DAT, and DAT by 7.3%, 10.3%, 33.0%, and 17.6% of the prescribed dose (78 Gy in 39 fractions) respectively. The D25%, D35%, and D50% of the rectum volume in the cases of IMRT and DAT were comparable (with a maximum variation of 4.5%); they were similarly comparable in the cases of M‐DAT and BW‐DAT (with maximum variation of 1.5%). These same doses in BW‐DAT were lower than those in IMRT by 8.7%, 10.6%, and 6.2% respectively, but they were quite lower than those in 2A‐DAT, because the average variation was 41.6% (with a maximum of 44.0%).The D15%, D25%, D35%, and D50% of the bladder volume in the case of BW‐DAT were 33.2Gy±10.9Gy, 17.4Gy±7.9Gy, 6.5Gy±4.3Gy, and 4.2Gy±3.5Gy respectively. The D15% and D25% of the bladder in the cases of IMRT, M‐DAT, and BW‐DAT were comparable (with a maximum variation of 2.2% and 3.6% respectively), and the mean values of each dose were lower in DAT by 14.3% and 11.7% respectively. However, the values of D35% and D50% in the four techniques were comparable, with maximum variations of 5.1% and 2.7% respectively. The D15%, D25%, D35%, and D50% of the bladder in the ...

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Evaluating the influence of 6 MV and 15 MV photon beams on prostate intensity-modulated radiation therapy plans

El Gendy,

Attalla,

Elkerm

et al. 2016

Oncology and Translational Medicine

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ObjectiveWe aimed to determine the effects of low- and high-energy intensity-modulated radiation therapy (IMRT) photon beams on the target volume planning and on the critical organs in the case of prostate cancer.MethodsThirty plans were generated by using either 6 MV or 15 MV beams separately, and a combination of both 6 and 15 MV beams. All plans were generated by using suitable planning objectives and dose constraints, which were identical across the plans, except the beam energy. The plans were analyzed in terms of their target coverage, conformity, and homogeneity, regardless of the beam energy.ResultsThe mean percentage values of V70Gy for the rectal wall for the plans with 6 MV, 15 MV, and mixedenergy beams were 16.9%, 17.8%, and 16.4%, respectively, while the mean percentage values of V40Gy were 53.6%, 52.3%, and 50.4%. The mean dose values to the femoral heads for the 6 MV, 15 MV, and mixed-energy plans were 30.1 Gy, 25.5 Gy, and 25.4 Gy, respectively. The mean integral dose for the 6 MV plans was 10% larger than those for the 15 MV and mixed-energy plans.ConclusionThese preliminary results suggest that mixed-energy IMRT plans may be advantageous with respect to the dosimetric characteristics of low- and high-energy beams. Although the reduction of dose to the organs at risk may not be clinically relevant, in this study, IMRT plans using mixed-energy beams exhibited better OAR sparing and overall higher plan quality for deep-seated tumors.

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Treatment of exceptionally large prostate cancer patients with low‐energy intensity‐modulated photons

Cited by 27 publications

References 20 publications

Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

Comparison of intensity‐modulated radiotherapy and forward‐planning dynamic arc therapy techniques for prostate cancer

Evaluating the influence of 6 MV and 15 MV photon beams on prostate intensity-modulated radiation therapy plans

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