A fixed-jaw method to protect critical organs during intensity-modulated radiotherapy

Chen, Jiayun; Chen, Xinyuan; Huang, Manni; Dai, Jianrong

doi:10.1016/j.meddos.2014.05.006

Cited by 10 publications

(12 citation statements)

References 9 publications

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“…Our data showed that the FJT plans provided comparable target dose conformity, homogeneity, and coverage for the PTV50.4 and PTV60 to the SFT plans, although some parts of the PTV50.4 were covered by fewer beam directions in the FJT plans. This is consistent with the study of Chen et al, which might be ascribed to two reasons. First, each part of PTV50.4 has been covered by a sufficient number of beam directions (at least six beams).…”

Section: Discussionsupporting

confidence: 94%

“…Our data showed that the volumes of the body‐PTV50.4 and lung receiving low and intermediate doses were significantly reduced with the FJT, and the other OARs, including the heart and spinal cord PRV, were also better spared compared to the SFT. This improved protection for OARs is in agreement with the findings from previous studies, but it is worth noting that our study achieved a higher degree of lung sparing than the study of Wang et al In their study, the collimator jaws covered the entire target volume at each gantry angle for both the FJT and non‐FJT plan, and the reduction in the low‐dose volumes of the lung can only be ascribed to the leaf transmission reduction. In contrast, we shielded some parts of the PTV50.4 further away from the radiation source with the collimator jaws to further reduce the transmission in some beam directions in the FJT plan.…”

Section: Discussionsupporting

confidence: 92%

“…Therefore, great consideration should be given to minimizing the low‐dose exposure of the lung during IMRT planning. Recently, a fixed‐jaw technique (FJT) has been proposed to reduce MLC transmission in IMRT by properly adjusting and fixing the secondary collimator jaw positions during plan optimization, which has been demonstrated to be effective in limiting low doses spreading to normal tissues while maintaining the target coverage for gynecological cancer, breast cancer, lung cancer, and head and neck cancer . However, to the best of our knowledge, the application of FJT to the treatment of cervical and upper thoracic EC has not yet been reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Fixed‐jaw technique to improve IMRT plan quality for the treatment of cervical and upper thoracic esophageal cancer

Song

Liu

et al. 2019

J Applied Clin Med Phys

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The purpose of this study was to investigate the potential advantages of the fixed‐jaw technique (FJT) over the conventional split‐field technique (SFT) for cervical and upper thoracic esophageal cancer (EC) patients treated with intensity‐modulated radiotherapy. The SFT and FJT plans were generated for 15 patients with cervical and upper thoracic EC. Dosimetric parameters and delivery efficiency were compared. An area ratio (AR) of the jaw opening to multileaf collimator (MLC) aperture weighted by the number of monitor units (MUs) was defined to evaluate the impact of the transmission through the MLC on the dose gradient outside the PTV50.4, and the correlation between the gradient index (GI) and AR was analyzed. The FJT plans achieved a better GI and AR (P < 0.001). There was a positive correlation between the GI and AR in the FJT (r = 0.883, P < 0.001) and SFT plans (r = 0.836, P < 0.001), respectively. Moreover, the mean dose (Dmean), V5Gy–V40Gy for the lungs and the Dmean, V5Gy–V50Gy for the body‐PTV50.4 in the FJT plans were lower than those in the SFT plans (P < 0.05). The FJT plans demonstrated a reduction trend in the doses to the spinal cord PRV and heart, but only the difference in the heart Dmean reached statistical significance (P < 0.05). The FJT plans reduced the number of MUs and subfields by 5.5% and 17.9% and slightly shortened the delivery time by 0.23 min (P < 0.05). The gamma‐index passing rates were above 95% for both plans. The FJT combined with target splitting can provide superior organs at risk sparing and similar target coverage without compromising delivery efficiency and should be a preferred intensity‐modulated radiotherapy planning method for cervical and upper thoracic EC patients.

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Section: Discussionsupporting

confidence: 94%

Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Fixed‐jaw technique to improve IMRT plan quality for the treatment of cervical and upper thoracic esophageal cancer

Song

Liu

et al. 2019

J Applied Clin Med Phys

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“…Recently, a fixed collimator jaws technique (FJT) IMRT was developed where the collimator jaws were locked to a fixed position during optimization for large fields in order to circumvent the problems associated with split fields and to further spare the critical OARs [26, 27]. The collimator jaw positions in FJT IMRT could be adjusted depending on the PTV and OARs positions, sizes and shapes.…”

Section: Introductionmentioning

confidence: 99%

Intensity modulated radiotherapy with fixed collimator jaws for locoregional left-sided breast cancer irradiation

Wang

Yang

et al. 2017

Oncotarget

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The purpose of this study is to evaluate the intensity modulated radiotherapy (IMRT) with the fixed collimator jaws technique (FJT) for the left breast and regional lymph node. The targeted breast tissue and the lymph nodes, and the normal tissues were contoured for 16 left-sided breast cancer patients previously treated with radiotherapy after lumpectomy. For each patient, treatment plans using different planning techniques, i.e., volumetric modulated arc therapy (VMAT), tangential IMRT (tangential-IMRT), and IMRT with FJT (FJT-IMRT) were developed for dosimetric comparisons. A dose of 50Gy was prescribed to the planning target volume. The dose-volume histograms were generated, and the paired t-test was used to analyze the dose differences. FJT-IMRT had similar mean heart volume receiving 30Gy (V30 Gy) with tangential-IMRT (1.5% and 1.6%, p = 0.41), but inferior to the VMAT (0.8%, p < 0.001). In the average heart mean dose comparison, FJT-IMRT had the lowest value, and it was 0.6Gy lower than that for the VMAT plans (p < 0.01). A significant dose increase in the contralateral breast and lung was observed in VMAT plans. Compared with tangential-IMRT and VMAT plans, FJT-IMRT reduced the mean dose of thyroid, humeral head and cervical esophageal by 47.6% (p < 0.01) and 45.7% (p < 0.01), 74.3% (p = < 0.01) and 73% (p = < 0.01), and 26.7% (p = < 0.01) and 29.2% (p = < 0.01). In conclusion, compared with tangential-IMRT and VMAT, FJT-IMRT plan has the lowest thyroid, humeral head and cervical esophageal mean dose and it can be a reasonable treatment option for a certain subgroup of patients, such as young left-breast cancer patients and/or patients with previous thyroid disease.

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“…The following equations were used to calculate HI [26] and CI [27].

HI = (D_{2 %} - D_{98 %}) / D_{50 %}

where D 2% , D 98% and D 50% are the minimum absorbed doses covering 2%, 98% and 50% of the volume of the PTV.…”

Section: Methodsmentioning

confidence: 99%

Predictive parameters for selection of electronic tissue compensation radiotherapy in early-stage breast cancer patients after breast-conserving surgery

et al. 2016

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Electronic tissue compensation (eComp) is an external beam planning technique allowing user to manually generate dynamic beam fluence to produce more uniform or modulated dose distribution. In this study, we compared the effectiveness between conventional three-dimensional conformal radiotherapy (3DCRT) and eComp for whole breast irradiation. 3DCRT and eComp planning techniques were used to generate treatment plans for 60 whole breast patients, respectively. The planning goal was to cover 95% of the planning target volume (PTV) with 95% of the prescription dose while minimizing doses to lung, heart, and skin. Comparing to 3DCRT plans, on the average, eComp treatment planning process was about 7 minutes longer, but resulted in lower lung V20Gy, lower mean skin dose, with similar heart dose. The benefits were more pronounced for larger breast patients. Statistical analyses were performed between critical organ doses and patient anatomic features, i.e., central lung distance (CLD), maximal heart distance (MHD), maximal heart length (MHL) and breast separation (BS) to explore any correlations and planning method selection. It was found that to keep the lung V20Gy lower than 20% and mean skin dose lower than 85% of the prescription dose, eComp was the preferred method for patients with more than 2.3 cm CLD or larger than 22.5 cm BS. The study results may be useful in providing a handy criterion in clinical practice allowing us to easily choose between different planning techniques to satisfy the planning goal with minimal increase in complexity and cost.

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A fixed-jaw method to protect critical organs during intensity-modulated radiotherapy

Cited by 10 publications

References 9 publications

Fixed‐jaw technique to improve IMRT plan quality for the treatment of cervical and upper thoracic esophageal cancer

Fixed‐jaw technique to improve IMRT plan quality for the treatment of cervical and upper thoracic esophageal cancer

Intensity modulated radiotherapy with fixed collimator jaws for locoregional left-sided breast cancer irradiation

Predictive parameters for selection of electronic tissue compensation radiotherapy in early-stage breast cancer patients after breast-conserving surgery

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