Impact of 99mTc-GSA SPECT Image-Guided Inverse Planning on Dose-Function Histogram Parameters for Stereotactic Body Radiation Therapy Planning for Patients With Hepatocellular Carcinoma: A Dosimetric Comparison Study

Ryo Toya; Tetsuo Saito; Yudai Kai; Shinya Shiraishi; Tomohiko Matsuyama; Takahiro Watakabe; Fumi Sakamoto; Noriko Tsuda; Yoshinobu Shimohigashi; Yasuyuki Yamashita; Natsuo Oya

doi:10.1177/1559325819832149

Impact of ^99mTc-GSA SPECT Image-Guided Inverse Planning on Dose-Function Histogram Parameters for Stereotactic Body Radiation Therapy Planning for Patients With Hepatocellular Carcinoma: A Dosimetric Comparison Study

Dose Response. 2019 Mar 4;17(1):1559325819832149. doi: 10.1177/1559325819832149. eCollection 2019 Jan-Mar.

Affiliations

¹ Department of Radiation Oncology, Kumamoto University Hospital, Kumamoto, Japan.
² Department of Radiological Technology, Kumamoto University Hospital, Kumamoto, Japan.
³ Department of Diagnostic Radiology, Kumamoto University Hospital, Kumamoto, Japan.

Abstract

Purpose: To evaluate the impact of ^99mTc-labeled diethylene triamine pentaacetate-galactosyl human serum albumin (^99mTc-GSA) single-photon emission computed tomography (SPECT) image-guided inverse planning on the dose-function histogram (DFH) parameters for stereotactic body radiation therapy planning in patients with hepatocellular carcinoma (HCC).

Methods: Eleven patients were enrolled in this study. The functional liver structure (FLS) was derived from SPECT thresholds of 60% to 80% of the maximum pixel value. Two treatment plans optimized without FLS (plan C) and with FLS (plan F) were designed for 50 Gy to the planning target volume (PTV). The DFH parameters were calculated as follows: Fx = (sum of the counts within the liver volume receiving a dose >x Gy/sum of the counts within the whole liver volume) × 100. Other parameters for the PTV included D₉₅, mean dose, conformity index (CI), and homogeneity index (HI).

Results: Compared with plan C, plan F significantly reduced DFH parameters of F₅ to F₄₀ (P < .05). There were no significant differences in the parameters of the PTV of D₉₅, mean dose, CI, and HI and organs at risks (stomach, duodenum, spinal cord, and kidneys) between plans C and F.

Conclusion: DFH analyses revealed that ^99mTc-GSA SPECT image-guided inverse planning provided dosimetric benefits related to sparing of liver function and may reduce hepatic toxicities.

Keywords: dose–function histogram; dose–volume histogram; hepatocellular carcinoma; molecular imaging; radiation-induced liver disease; stereotactic body radiation therapy.