Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 Apr 18;8(16):27529-27540.
doi: 10.18632/oncotarget.16770.

Clinical study of the time of repeated computed tomography and replanning for patients with nasopharyngeal carcinoma

Xiujuan Gai  1   2 , Yumei Wei  2 , Hengmin Tao  3   4 , Jian Zhu  5 , Baosheng Li  2
Affiliations

Clinical study of the time of repeated computed tomography and replanning for patients with nasopharyngeal carcinoma

Xiujuan Gai et al. Oncotarget. .

Abstract

Purpose: To study the necessity of repeat computed tomography (CT) scan and replanning and know a more accurate time using weekly kilovoltage cone beam computed tomography (kV-CBCT) scans for patients with nasopharyngeal carcinoma (NPC) during radiotherapy.

Methods and materials: Thirteen NPC patients treated with IMRT were enrolled into this prospective study. Weekly pretreatment kV-CBCT scans were performed on the 1st, 6th, 11st, 16th, 21st and 26th radiation time, respectively. Target delineations were contoured on all fractionated CBCT images, including the gross tumor volume of the primary nasopharyngeal tumor (GTVnx) and parotid glands. The volumes of GTVnx and parotid glands were calculated automatically using the Pinnacle3 8.0 system. Compared to the original GTVnx, the percentage of shrinking volume (ΔP) ≥ 50% was considered significantly.

Results: As the radiation proceeding, the GTVnx had a trend of shrinkage. Of all 13 patients, 11 cases (84.6%) had the volume shrinking ≥ 50% before the 21st radiation and 12 cases (92.3%) before the 26th radiation. And the parotid volume decreased significantly in the first four-week radiation, 6.45 ± 3.16cm3 (range, 3.06-13.9cm3) for the left parotid gland and 5.78 ± 2.39cm3 (range, 2.70-11.2cm3) for the right. Furthermore, only a little displacement occurred to bilateral parotid glands.

Conclusion: The replanning for NPC patients with IMRT is necessary, and the time between the 21st to 25th radiations is appropriate.

Keywords: cone beam computed tomography (CBCT); displacement; gross tumor volume (GTV); nasopharyngeal carcinoma (NPC); parotid gland.

PubMed Disclaimer

Conflict of interest statement

CONFLICTS OF INTEREST

The authors have no conflict of interest.

Figures

Figure 1
Figure 1. The contrast of the nasopharynx in the transverse section between the planning CT image and CBCT image before the first radiation from one patient
A. the planning CT B. CBCT before the first radiation.
Figure 2
Figure 2. The tendency of median volumetric changes of GTVnx between the fractionated volume and original volume
Figure 3
Figure 3. The variation tendency of mean percentage of shrinking volume for the fractionated volume compared to the original volume
Figure 4
Figure 4. CBCT images performed before the 1
st, 6th, 11st, 16th, 21st and 26th radiation time from one patient, corresponding to letter A, B, C, D, E, F. (In this level, the GTV and parotid glands were showed typically and clearly. The red outlines were GTV, and the yellow were parotids.)
Figure 5
Figure 5. The variation tendency of the bilateral parotid glands’ volume (cm3) on the fractionated CBCT
Figure 6
Figure 6. The variation trend of average mean doses (Dmean) delivered to bilateral parotid glands per fraction on the fractionated CBCT
See this image and copyright information in PMC

References

    1. Al-Sarraf M, LeBlanc M, Giri PG, Fu KK, Cooper J, Vuong T, Forastiere AA, Adams G, Sakr WA, Schuller DE, Ensley JF. Chemoradiotherapy versus radiotherapy in patients with advanced nasopharyngeal. Cancer: Phase III randomized Intergroup study 0099. J Clin Oncol. 1998;16:1310–1317. - PubMed
    1. Hunt MA, Zelefsky MJ, Wolden S, Chui CS, LoSasso T, Rosenzweig K, Chong L, Spirou SV, Fromme L, Lumley M, Amols HA, Ling CC, Leibel SA. Treatment planning and delivery of intensity-modulated radiation therapy for primary nasopharynx cancer. Int J Radiat Oncol Biol Phys. 2001;49:623–632. - PubMed
    1. Kam M, Chau RM, Suen J, Choi PH, Teo PM. Intensity-modulated radiotherapy in nasopharyngeal carcinoma: Dosimetric advantage over conventional plans and feasibility of dose escalation. Int J Radiat Oncol Biol Phys. 2003;56:145–157. - PubMed
    1. Lee N, Xia P, Quivey JM, Sultanem K, Poon I, Akazawa C, Akazawa P, Weinberg V, Fu KK. Intensity-modulated radiotherapy in the treatment of nasopharyngeal carcinoma: an update of the USCF experience. Int J Radiat Oncol Biol Phys. 2002;53:12–22. - PubMed
    1. Lin S, Pan J, Han L, Zhang X, Liao X, Lu JJ. Nasopharyngeal carcinoma treated with reduced-volume intensity-modulated therapy: report on the 3-years outcome of a prospective series. Int J Radiat Oncol Biol Phys. 2009;75:1071–1078. - PubMed

MeSH terms