open access

Vol 25, No 3 (2020)
Original research articles
Published online: 2020-05-01
Submitted: 2019-09-30
Get Citation

A comparison of a moderately hypofractionated IMRT planning technique used in a randomised UK external beam radiotherapy trial with an in-house technique for localised prostate cancer

Ian Gleeson
DOI: 10.1016/j.rpor.2020.03.010
·
Rep Pract Oncol Radiother 2020;25(3):360-366.

open access

Vol 25, No 3 (2020)
Original research articles
Published online: 2020-05-01
Submitted: 2019-09-30

Abstract

Aim

To compare the radiotherapy technique used in a randomised trial with VMAT and an in-house technique for prostate cancer.

Background

Techniques are evolving with volumetric modulated arc therapy (VMAT) commonly used. The CHHiP trial used a 3 PTV forward planned IMRT technique (FP_CH). Our centre has adopted a simpler two PTV technique with locally calculated margins.

Materials and methods

25 patients treated with FP_CH to 60Gy in 20 fractions were re-planned with VMAT (VMAT_CH) and a two PTV protocol (VMAT_60/52 and VMAT_60/48). Target coverage, conformity index (CI), homogeneity index (HI), monitor units (MU) and dose to the rectum, bladder, hips and penile bulb were compared.

Results

PTV coverage was high for all techniques. VMAT_CH plans had better CI than FP_CH (p≤ 0.05). VMAT_60/52/48 plans had better CI than VMAT_CH. FP_CH had better HI and fewer MU than VMAT (p≤ 0.05). More favourable rectum doses were found for VMAT _CH than FP_CH (V48.6, V52.8, V57, p≤ 0.05) with less difference for bladder (p≥ 0.05). Comparing VMAT_CH to VMAT_60/52/48 showed little differences for the bladder and rectum but VMAT_CH had larger penile bulb doses (V40.8, V48.6, mean, D2, p≤ 0.05). Femoral head doses (V40.8) were similarly low for all techniques (p=≥ 0.05).

Conclusion

VMAT produced more conformal plans with smaller rectum doses compared to FP_CH albeit worse HI and more MU. VMAT_60/52 and VMAT_60/48 plans had similar rectal and bladder doses to VMAT_CH but better CI and penile bulb doses which may reduce toxicity.

Abstract

Aim

To compare the radiotherapy technique used in a randomised trial with VMAT and an in-house technique for prostate cancer.

Background

Techniques are evolving with volumetric modulated arc therapy (VMAT) commonly used. The CHHiP trial used a 3 PTV forward planned IMRT technique (FP_CH). Our centre has adopted a simpler two PTV technique with locally calculated margins.

Materials and methods

25 patients treated with FP_CH to 60Gy in 20 fractions were re-planned with VMAT (VMAT_CH) and a two PTV protocol (VMAT_60/52 and VMAT_60/48). Target coverage, conformity index (CI), homogeneity index (HI), monitor units (MU) and dose to the rectum, bladder, hips and penile bulb were compared.

Results

PTV coverage was high for all techniques. VMAT_CH plans had better CI than FP_CH (p≤ 0.05). VMAT_60/52/48 plans had better CI than VMAT_CH. FP_CH had better HI and fewer MU than VMAT (p≤ 0.05). More favourable rectum doses were found for VMAT _CH than FP_CH (V48.6, V52.8, V57, p≤ 0.05) with less difference for bladder (p≥ 0.05). Comparing VMAT_CH to VMAT_60/52/48 showed little differences for the bladder and rectum but VMAT_CH had larger penile bulb doses (V40.8, V48.6, mean, D2, p≤ 0.05). Femoral head doses (V40.8) were similarly low for all techniques (p=≥ 0.05).

Conclusion

VMAT produced more conformal plans with smaller rectum doses compared to FP_CH albeit worse HI and more MU. VMAT_60/52 and VMAT_60/48 plans had similar rectal and bladder doses to VMAT_CH but better CI and penile bulb doses which may reduce toxicity.

Get Citation

Keywords

Prostate cancer; Intensity modulated radiotherapy; Dosimetric comparison; Hypofractionation; Planning technique

About this article
Title

A comparison of a moderately hypofractionated IMRT planning technique used in a randomised UK external beam radiotherapy trial with an in-house technique for localised prostate cancer

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 3 (2020)

Pages

360-366

Published online

2020-05-01

DOI

10.1016/j.rpor.2020.03.010

Bibliographic record

Rep Pract Oncol Radiother 2020;25(3):360-366.

Keywords

Prostate cancer
Intensity modulated radiotherapy
Dosimetric comparison
Hypofractionation
Planning technique

Authors

Ian Gleeson

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