Application of active bone marrow defined with single photon emission computed tomography to optimize the intensity modulated radiotherapy plan in cervical cancer after hysterectomy / 中华放射医学与防护杂志

ABSTRACT

Objective To explore the dosimetric characteristics of single photon emission computed tomography(SPECT)combined with bone marrow sparing intensity modulated radiotherapy in patients with cervical cancer.Methods Twenty patients with cervical cancer after hysterectomy were performed on 99Tc thiocolloid SPECT bone marrow imaging to determine the active bone marrow in the pelvis.SPECT image combined with the simulation CT was used as the primary planning data set.Two plans for bone marrow sparing modulated radiotherapy were generated according to the bone marrow volume defined by SPECT and outline of the pelvis(SPECT-IMRT planning and BMS-IMRT planning).Furthermore,the target section and the dosimetric distribution in organs at risk(bone marrow,small intestine,rectum and bladder)in the two plannings were compared.The prescribed dose to the PTV was 45 Gy.Results The volume of the bone marrow in SPECT-IMRT planning and BMS-IMRT planning was(238.15 ±36.82)and(1 100.61 ±109.92)cm3,respectively(t＝33.273,P＜0.05).The average bone marrow volume of SPECT-IMRT planning in high-dose radiation region(V30,V40and V45)was decreased by 6.9％,5.7％and 2.6％respectively compared with BMS-IMRT planning(t ＝3.540,3.4261,3.448,P＜0.05),but there was no statistical significant difference between the two plannings in the dose volume of low-dose radiation(V10and V20,P＞0.05).The PTV coverage rate and exposure dose of other organs at risk(small intestine,rectum and bladder)in the two plannings were not significantly different(P＞0.05).Conclusions SPECT bone marrow imaging could clearly show the range of active bone marrow on CT scan images.Compared with BMS-IMRT,SPECT-IMRT could further reduce the dose volume of high-dose radiation(V30,V40and V45).Yet the clinical significance of this advantage also needs to be confirmed by large-scale clinical studies.