A Dosimetric Study of Using Fixed-Jaw Volumetric Modulated Arc Therapy for the Treatment of Nasopharyngeal Carcinoma with Cervical Lymph Node Metastasis

Zhang, Wu-Zhe; Lu, Jie; Chen, Jianzhou; Zhai, Tian‐Tian; Huang, Bao-Tian; Li, Derui; Chen, Chuangzhen

doi:10.1371/journal.pone.0156675

Cited by 11 publications

(11 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Consequently, VMAT-HF showed reducing volume receiving a dose of less than 10 Gy for left-sided breast cancer, which is more challenging than the right-sided case due to heart dose sparing. Furthermore, the VMAT using a fixed-jaw (opening of 15 cm in the X direction), considering the limitation of maximum leaf span of the MLC, also showed parotid dose sparing (26). The dose was optimized using (A, C) a fully opened field size (VMAT-FF) to cover the planning target volume and (B, D) a half-beam technique (VMAT-HF).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the HF at the matching line could bring out dose reduction of the lung in breast treatment. Maintaining such dosimetric benefit and more effectively reducing doses to OAR, studies were expanded to employ intensity modulation using optimal segments from HF ( 26 , 53 , 54 ). Consequently, VMAT-HF showed reducing volume receiving a dose of less than 10 Gy for left-sided breast cancer, which is more challenging than the right-sided case due to heart dose sparing.…”

Section: Discussionmentioning

confidence: 99%

“…Because MLC leaves move in one direction as the collimator angle is fixed, if the OAR are located between the separated target volumes along the same direction with the MLC movement, suboptimal MLC segments can be created. When each discretized gantry angle has one MLC segment, the limit of a maximum MLC traveling distance and speed between control points can restrict full utilization of the optimization engine's capability to provide optimal MLC sequence (24)(25)(26). For example, while one side of the MLC conforms to half of the target contour, the other side cannot properly shield OAR or opens more than necessary outside of the planning target volume (PTV) to meet the prescribed dose.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effective Organs-at-Risk Dose Sparing in Volumetric Modulated Arc Therapy Using a Half-Beam Technique in Whole Pelvic Irradiation

et al. 2021

View full text Add to dashboard Cite

BackgroundAlthough there are some controversies regarding whole pelvic radiation therapy (WPRT) due to its gastrointestinal and hematologic toxicities, it is considered for patients with gynecological, rectal, and prostate cancer. To effectively spare organs-at-risk (OAR) doses using multi-leaf collimator (MLC)’s optimal segments, potential dosimetric benefits in volumetric modulated arc therapy (VMAT) using a half-beam technique (HF) were investigated for WPRT.MethodsWhile the size of a fully opened field (FF) was decided to entirely include a planning target volume in all beam’s eye view across arc angles, the HF was designed to use half the FF from the isocenter for dose optimization. The left or the right half of the FF was alternatively opened in VMAT-HF using a pair of arcs rotating clockwise and counterclockwise. Dosimetric benefits of VMAT-HF, presented with dose conformity, homogeneity, and dose–volume parameters in terms of modulation complex score, were compared to VMAT optimized using the FF (VMAT-FF). Consequent normal tissue complication probability (NTCP) by reducing the irradiated volumes was evaluated as well as dose–volume parameters with statistical analysis for OAR. Moreover, beam-on time and MLC position precision were analyzed with log files to assess plan deliverability and clinical applicability of VMAT-HF as compared to VMAT-FF.ResultsWhile VMAT-HF used 60%–70% less intensity modulation complexity than VMAT-FF, it showed superior dose conformity. The small intestine and colon in VMAT-HF showed a noticeable reduction in the irradiated volumes of up to 35% and 15%, respectively, at an intermediate dose of 20–45 Gy. The small intestine showed statistically significant dose sparing at the volumes that received a dose from 15 to 45 Gy. Such a dose reduction for the small intestine and colon in VMAT-HF presented a significant NTCP reduction from that in VMAT-FF. Without sacrificing the beam delivery efficiency, VMAT-HF achieved effective OAR dose reduction in dose–volume histograms.ConclusionsVMAT-HF led to deliver conformal doses with effective gastrointestinal-OAR dose sparing despite using less modulation complexity. The dose of VMAT-HF was delivered with the same beam-on time with VMAT-FF but precise MLC leaf motions. The VMAT-HF potentially can play a valuable role in reducing OAR toxicities associated with WPRT.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effective Organs-at-Risk Dose Sparing in Volumetric Modulated Arc Therapy Using a Half-Beam Technique in Whole Pelvic Irradiation

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The average Y direction jaw for all plans was 30.26 AE 0.98 cm. The X-direction jaw was fixed at 16 cm because of the maximum leaf span of the MLCs in Varian 10 The mean delivery MU in the VMAT plans was 676.60 AE 33.97. The lowest to highest average %OF/IN from VMAT plans for five patients were the contralateral ovary, uterus and ipsilateral ovary.…”

Section: Ovarian and Uterine Doses In Vmat Plans: Rando Phantommentioning

confidence: 99%

Estimated radiation doses to ovarian and uterine organs in breast cancer irradiation using radio‐photoluminescent glass dosimeters (RPLDs)

Oonsiri

Vannavijit

Wimolnoch

et al. 2020

J of Medical Radiation Sci

View full text Add to dashboard Cite

Introduction:The well-being of breast cancer patients is essential, especially fertility in patients of reproductive age. The objective of this study was to estimate the radiation doses to the ovaries and uterus for different treatment techniques of breast cancer irradiation using radio-photoluminescent glass dosimeters (RPLDs). Methods: A Farmer-type ionisation chamber (IBA FC-65G) and RPLDs were used to measure in-and out-of-field radiation doses in a solid water phantom. The field sizes were set to 10 9 10 cm 2 and 8 9 17 cm 2 with the central axis at out-of-field measurement distances of 30 or 50 cm. The Rando phantom's left breast was planned using four different techniques: two tangential standard fields with and without electronic tissue compensator (E-comp) techniques, intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). The radiation doses in the ipsilateral ovary, contralateral ovary and uterus were measured using RPLDs. Results: The percentage ratio of out of field to in field was affected by distance from the central axis to the point of measurement, in addition to the field sizes associated with collimator scatter. Advanced techniques such as IMRT and VMAT produced higher doses to the ovaries and uterus. The estimated results of the worst-case scenario for the ipsilateral ovary, contralateral ovary and uterus were 0.84% (42 cGy), 0.62% (31 cGy) and 0.76% (38 cGy), respectively, for a 5000 cGy prescription dose. Conclusion:The lowest to highest out-of-field radiation doses to the ovarian and uterine organs from breast irradiation were the two tangential field techniques, VMAT and IMRT. These advanced techniques yielded higher radiation leakage, which potentially contributed to the out-of-field radiation dose.

show abstract

“…And such neuro-cognitive dysfunction was later found out to be attributed to radiation damage on the hippocampus dentate gyrus caused by radiation treatment 4 . However, intensity modulated radiation therapy (IMRT) 5 , including Volumetric Modulated Arc Therapy (VMAT) 6 , 7 , has been widely used in NPC patients. And therapeutic plans can help to maximize the conformal radiation dose on the targets and minimize the dose on surrounding normal organs at risk (OAR).…”

Section: Introductionmentioning

confidence: 99%

The Hippocampus Sparing Volume Modulated Arc Therapy does not Influence Plan Quality on Locally Advanced Nasopharyngeal Carcinoma Patients

et al. 2017

Sci Rep

View full text Add to dashboard Cite

Irradiation on hippocampus would lead to neuro-cognitive dysfunction in locally advanced nasopharyneal carcinoma (LA-NPC) patients accepting radiotherapy. Our study here aimed to investigate if undergoing hippocampus sparing (HS) volume modulated arc therapy (VMAT) would influence the plan quality in LA NPC patients. We designed three kinds of radiotherapeutic plans for 11 LA NPC patients: conventional VMAT (C-VMAT), HS-VMAT and HS intensity modulated radiation therapy with dynamic multileaf collimator (HS-dMLC). And the dose distribution on targets and surrounding organs at risk (OAR) were carefully evaluated. We found out that the expected doses on hippocampus were significantly lowered in HS-VMAT (899 ± 378 cGy) and HS-dMLC (896 ± 321 cGy) as compared to C-VMAT (1518 ± 337 cGy, p < 0.05), but meaningless difference was presented on plan quality of targets (p > 0.05). Moreover, lower radiation doses on brain stem were observed in HS-VMAT plan in comparison with C-VMAT plan (p < 0.05). However, there were no statistically meaningful diversities in the doses received by other OARs among all plans. Here we concluded that HS-VMAT presented promising advantages on protecting hipppcampus and brain stem as compared to C-VMAT and HS-dMLC, but enthusiastically had no effects on plan quality in LA-NPC patients.

show abstract

A Dosimetric Study of Using Fixed-Jaw Volumetric Modulated Arc Therapy for the Treatment of Nasopharyngeal Carcinoma with Cervical Lymph Node Metastasis

Cited by 11 publications

References 12 publications

Effective Organs-at-Risk Dose Sparing in Volumetric Modulated Arc Therapy Using a Half-Beam Technique in Whole Pelvic Irradiation

Effective Organs-at-Risk Dose Sparing in Volumetric Modulated Arc Therapy Using a Half-Beam Technique in Whole Pelvic Irradiation

Estimated radiation doses to ovarian and uterine organs in breast cancer irradiation using radio‐photoluminescent glass dosimeters (RPLDs)

The Hippocampus Sparing Volume Modulated Arc Therapy does not Influence Plan Quality on Locally Advanced Nasopharyngeal Carcinoma Patients

Contact Info

Product

Resources

About