Comparing conformal, arc radiotherapy and helical tomotherapy in craniospinal irradiation planning

Abstract

Currently, radiotherapy treatment plan acceptance is based primarily on dosimetric performance measures. However, use of radiobiological analysis to assess benefit in terms of tumor control and harm in terms of injury to normal tissues can be advantageous. For pediatric craniospinal axis irradiation (CSI) patients, in particular, knowing the technique that will optimize the probabilities of benefit versus injury can lead to better long‐term outcomes. Twenty‐four CSI pediatric patients (median age 10) were retrospectively planned with three techniques: three‐dimensional conformal radiation therapy (3D CRT), volumetric‐modulated arc therapy (VMAT), and helical tomotherapy (HT). VMAT plans consisted of one superior and one inferior full arc, and tomotherapy plans were created using a 5.02 cm field width and helical pitch of 0.287. Each plan was normalized to 95% of target volume (whole brain and spinal cord) receiving prescription dose 23.4 Gy in 13 fractions. Using an in‐house MATLAB code and DVH data from each plan, the three techniques were evaluated based on biologically effective uniform dose (Dfalse¯false¯), the complication‐free tumor control probability (normalP+), and the width of the therapeutically beneficial range. Overall, 3D CRT and VMAT plans had similar values of Dfalse¯false¯ (24.1 and 24.2 Gy), while HT had a Dfalse¯false¯ slightly lower (23.6 Gy). The average values of the normalP+ index were 64.6, 67.4, and 56.6% for 3D CRT, VMAT, and HT plans, respectively, with the VMAT plans having a statistically significant increase in normalP+. Optimal values of Dfalse¯false¯ were 28.4, 33.0, and 31.9 Gy for 3D CRT, VMAT, and HT plans, respectively. Although normalP+ values that correspond to the initial dose prescription were lower for HT, after optimizing the Dfalse¯false¯ prescription level, the optimal normalP+ became 94.1, 99.5, and 99.6% for 3D CRT, VMAT, and HT, respectively, with the VMAT and HT plans having statistically significant increases in normalP+. If the optimal dose level is prescribed using a radiobiological evaluation method, as opposed to a purely dosimetric one, the two IMRT techniques, VMAT and HT, will yield largest overall benefit to CSI patients by maximizing tumor control and limiting normal tissue injury. Using VMAT or HT may provide these pediatric patients with better long‐term outcomes after radiotherapy.PACS number: 87.55.dk

Acute toxicity of craniospinal irradiation with volumetric‐modulated arc therapy in children with solid tumors

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Recurrence pattern and Survival analysis in patients undergoing radiotherapy IMRT technique for medulloblastoma

“…c .The interval time of surgery and radiotherapy is twelve weeks. 1 .M0 vs M2; 2 .M0 vs M3; 3 .M0 vs M2; 4 .M0 vs M3; 5 .None vs EP; 6 .None vs TMZ; 7 .None vs EP; 8 .None vs TMZ. Survival outcomes.…”

“…To our knowledge,IMRT, volumetric-modulated arc therapy (VMAT), Tomotherapy (TOMO) and other modern radiotherapy technologies are obviously better than 3D-CRT and conventional radiotherapy technologies in terms of dose distribution in the target volume and normal tissue protection [2][3][4].Previous study have shown that 3D-CRT avoiding failures related to radiotherapy uncertainties to some extent, but there are still 1/3 failures statement [5]. Previous study had shown the pattern of failure associated with medulloblastoma patients treated with proton radiation therapy was similar to the pattern of failure in patients treated with photon radiation therapy [6].Howerver, there are few reports about recurrence patterns after radiotherapy.…”

Universal field matching in craniospinal irradiation by a background‐dose gradient‐optimized method

“…In craniospinal irradiation the large target volume needs complex treatment planning. With the exception of helical tomotherapy treatments, it entails setting multiple isocenters and matching a large number of fields to obtain satisfactory plans . The field junction area is a critical region, because under‐dosage may compromise tumor control, while over‐dosage may increase the risk of serious radiation‐induced late effects, e.g.…”