Dosimetric Study on Dose Escalation in Internal Target of Pancreatic Cancer With Helical Tomotherapy

Zhu, Fuhai; Xia, Tingyi; Wu, Weizhang

doi:10.1016/j.ijrobp.2014.05.1161

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“…In the SIB mode, we applied high dose irradiation inside the target area and relatively low dose irradiation to the surrounding area, which not only restricted gastrointestinal toxicities, but also improved the local control of the tumor. Also, pathological studies and clinical observation revealed that different tumor areas may require different doses of radiation, which can be determined by the biological characteristics of solid tumor (21,22). Thus, dose escalation using HT in the SIB mode can also benefit the treatment of tumors in this regard.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric feasibility on hypofractionated intensity-modulated radiotherapy and simultaneous integrated boost for locally advanced unresectable pancreatic cancer with helical tomotherapy

Feng¹,

Meng²,

Zhu³

2021

J Gastrointest Oncol

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Background: This dosimetric study on locally advanced pancreatic cancer (LAPC) and the surrounding gastrointestinal organs at risk (OARs) aimed at exploring the potential of further improving the internal dose and reducing the fractionation number by concurrent hypofractionated simultaneous integrated boost (SIB) radiotherapy using helical tomotherapy (HT). Methods: We collected computed tomography positioning images from a LAPC study of 17 consecutive patients. Gross tumor volume (GTV)1, GTV2, and GTV3 were defined as the GTV minus a margin of 3, 6, and 9 mm from the external part in all directions, respectively. Under the same physical parameters and limited dose on normal organs, each case had 4 sets of SIB radiotherapy plans. Upon dose escalation, we statistically analyzed the difference of dosimetric parameters received by the OARs between group A [planning target volume (PTV)/GTV=50 Gy/70 Gy] and the other groups. According to the equivalent bioradiotherapy formula, we calculated the hypofractionated standard dose by converting the average tolerated dose of each OAR with the corresponding number of fractions. Then, we compared the dose and volume parameters of the gastrointestinal tract from the less-than-20-fraction modes with the corresponding gastrointestinal hypofractionated standard dose. Results: For dose escalation, although there were a few differences in the parameters of the OAR between group A and group D, all OAR doses of group D (PTV/GTV/GTV1/GTV2/GTV3= 50 Gy/70 Gy/80 Gy/90 Gy/100 Gy) were within the limited dose range. In the hypofractionated mode, there was a statistically significant difference between the gastrointestinal dose-volume parameters and the doselimiting reference standard when the fraction number was less than 14 or 15 for group A or D, respectively. Conclusions: The dose of the internal target can be increased to 100 Gy with 15 fractions in the hypofractionated SIB radiotherapy for LAPC with HT. The corresponding tolerance dose of OARs may also be acceptable.

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Section: Discussionmentioning

confidence: 99%