A pilot study of volumetric-modulated arc therapy for malignant pleural mesothelioma

Our plain-English summary of A pilot study of volumetric-modulated arc therapy for malignant pleural mesothelioma, by L. Runxiao, C. Yankun, W. Lan (Journal of Applied Clinical Medical Physics, 2016).

The study

• Authors: L. Runxiao, C. Yankun, W. Lan
• Journal: Journal of Applied Clinical Medical Physics
• Published: 2016;17(2):139-144
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is an extremely difficult disease to treat. This pilot study investigates the feasibility of using volumetric-modulated arc therapy (VMAT) for malignant pleural mesothelioma (MPM), and compares VMAT to static field intensity-modulated radiotherapy (IMRT) for five patients. To identify the best treatment technique for MPM, in five patients, we made a representative comparative analysis of two kinds of techniques for radiation therapy planning: IMRT and VMAT. The plans were created for an Elekta Synergy linear accelerator with 6 MV photons using Oncentra version 4.3 treatment planning system. Dose prescription was 50 Gy to the average of the planning target volume (PTV). PTV coverage and homogeneity, dose of organs at risk, numbers of segments, MUs, and delivery time were evaluated for all techniques. VMAT allowed better homogeneous and conformity indices compared with IMRT (HI = 0.17 vs. 0.12, CI = 0.64 vs. 0.77, respectively, p < 0.05). VMAT plan had a significantly shorter delivery time (326 s) compared with in IMRT plans (510 s), (p < 0.05). In the dose verification, an average of 93.16% of the detector points passed the 3%/3 mmγ criterion for VMAT plans, while in IMRT plans the dose verification was 95.12%.(p > 0.05).

In plain English

This pilot study, from the Fourth Hospital of Hebei Medical University in China, compared two ways of planning radiotherapy for malignant pleural mesothelioma in five patients: volumetric-modulated arc therapy (VMAT) and static-field intensity-modulated radiotherapy (IMRT). For each patient, both kinds of computer treatment plan were made to deliver 50 Gy in 25 fractions, and the plans were checked with a detector array. The study did not look at asbestos exposure or report how patients fared. In the article's results and tables, VMAT plans had a homogeneity index of 0.12 against 0.17 for IMRT and a conformity index of 0.77 against 0.64. These differences were reported as statistically significant; the abstract prints the same figures the other way round. Average delivery time was 326 seconds for VMAT and 510 seconds for IMRT. VMAT plans gave lower heart and lung doses on several measures, but a higher maximum spinal cord dose and a larger share of lung receiving more than 5 Gy. In the dose checks, an average of 93.16% of detector points passed for VMAT plans and 95.12% for IMRT plans, a difference not statistically significant. The authors concluded that VMAT is another promising radiotherapy option for this disease.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Pilot treatment-planning comparison study: VMAT and IMRT radiotherapy plans were both generated for each patient and compared. Plan accuracy was checked with a detector array. No patient outcomes were reported.
• Who was studied: Five patients with malignant pleural mesothelioma, Radiotherapy and Oncology Department, Fourth Hospital of Hebei Medical University, Shijiazhuang, China. The article gives no study dates and no patient characteristics.
• Exposure: No asbestos exposure was studied. What was compared was two radiotherapy planning techniques (VMAT and step-and-shoot IMRT), each planned to deliver a total of 50 Gy in 25 fractions to the planning target volume, using 6 MV photons on an Elekta Synergy linear accelerator.
• Main results:
  • Averaged over the five patients, the homogeneity index was 0.12 for VMAT plans and 0.17 for IMRT plans, and the conformity index was 0.77 for VMAT and 0.64 for IMRT. Both differences had p less than 0.05 (Table 2). The authors described these as significant improvements with VMAT.
  • The share of the target volume receiving 110% of the prescribed dose was 7.18 plus or minus 4.78% with VMAT and 21.98 plus or minus 4.56% with IMRT. The share receiving 105% was 55.65 plus or minus 3.91% with VMAT and 72.85 plus or minus 4.31% with IMRT. Both differences had p less than 0.05.
  • Average delivery time was 326 plus or minus 18 seconds for VMAT and 510 plus or minus 21 seconds for IMRT. Monitor units were 657 plus or minus 26 for VMAT and 829 plus or minus 33 for IMRT. Both differences had p less than 0.05. VMAT plans had more segments: 118 plus or minus 6, against 47 plus or minus 4 for IMRT.
  • Mean heart dose was 28.51 Gy with VMAT and 30.09 Gy with IMRT. The share of heart receiving more than 20 Gy was 59.33% with VMAT and 72.59% with IMRT. Mean whole-lung dose was 15.50 Gy with VMAT and 16.09 Gy with IMRT. All three differences had p less than 0.05.
  • Maximum spinal cord dose was higher with VMAT: 44.04 Gy, against 38.85 Gy with IMRT (p less than 0.05).
  • The share of lung receiving more than 5 Gy was lower with IMRT. For the whole lung it was 58.43% with IMRT and 65.19% with VMAT; for the contralateral lung, 44.21% with IMRT and 52.37% with VMAT.
  • In the dose verification, an average of 93.16% of detector points passed the 3% and 3 mm gamma criterion for VMAT plans and 95.12% for IMRT plans (p greater than 0.05).
• The authors' conclusion: The authors concluded that VMAT is another promising radiotherapy option for malignant pleural mesothelioma. They wrote that it allows reducing dose to most organs at risk without compromising target coverage, while keeping the shortest treatment time.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Intensity-Modulated Radiation Therapy (IMRT).

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