Feasibility analysis of cone beam CT-based adaptive radiation therapy for prostate cancer

doi:10.3760/cma.j.cn371439-20260228-00097

Abstract

Abstract:

Objective To investigate the feasibility and clinical value of establishing individualized target volumes for prostate cancer based on cone beam CT （CBCT） and implementing offline adaptive radiation therapy （ART）. Methods A retrospective collection was performed on the planning CT and CBCT images of 28 patients with localized prostate cancer who received radiotherapy at Ezhou Central Hospital of Hubei Province，between October 2022 and December 2025. An initial radiotherapy plan （Plan_p） was designed based on the planning target volume （PTV_p） delineated on the planning CT images. Based on the daily CBCT images acquired in the 1st and 4th weeks of treatment，the clinical target volume （CTV） was delineated and superimposed to generate the individualized internal target volume，which was then expanded by the corresponding weekly mean setup errors to sequentially generate the ART plan target volumes for the 1st week （PTV_a） and the 4th week （PTV_b）. ART plans Plan_a and Plan_b were subsequently designed based on PTV_a and PTV_b，respectively. All three plans （Plan_p，Plan_a，and Plan_b） were calculated using identical optimization parameters for dose computation. The three groups of radiotherapy plans were compared in terms of target volume，prescribed dose coverage，and dosimetric parameters for both targets and organs at risk （OARs）. Results The target volumes of PTV_p，PTV_a，and PTV_b were （281.6±52.8），（224.6±46.2），and （194.2±58.2） cm³，respectively，with a statistically significant difference （F=4.78，P=0.013）. Pairwise comparisons all showed statistically significant differences （all P<0.05）. The prescribed dose coverage rates for PTV_p，PTV_a，and PTV_b were （97.4±2.1）%，（97.8±2.4）%，and （98.3±2.0）%，respectively，showing no statistically significant difference （F=0.55，P=0.582）. Regarding target dose hotspots，the D_2% values for Plan_p，Plan_a，and Plan_b were （74.1±1.2），（73.9±1.2），and （73.6±1.3） Gy，respectively，with a statistically significant difference （F=3.88，P=0.027），and pairwise comparisons all reached statistical significance （all P<0.05）. No statistically significant differences were observed in D_50%，D_98%，or D_mean across the three plans （all P>0.05）. The homogeneity index values for the three plans were 0.051±0.019，0.046±0.021，and 0.042±0.018，respectively，with a statistically significant difference （F=4.28，P=0.019），and all pairwise comparisons were statistically significant （all P<0.05）. The conformity index （CI） values were 0.847±0.032，0.845±0.037，and 0.864±0.032，respectively，with a statistically significant difference （F=3.58，P=0.035）； pairwise comparisons showed a statistically significant difference only between Plan_a and Plan_b （P<0.05）. In terms of OARs dose，the V₅₀，V₆₀，and V₇₀ of the rectum and bladder all showed statistically significant differences among the three plans （all P<0.05），and all pairwise comparisons were also statistically significant （all P<0.05）. Pelvic bone V₃₀ showed a statistically significant difference （F=3.85，P=0.027），pairwise comparisons showed that both Plan_a and Plan_b differed significantly from Plan_p （both P<0.05）； however，pelvic bone D_mean showed no statistically significant difference （F=2.85，P=0.066）. No statistically significant differences were found in D_mean or V₃₀ for either the left or right femoral heads （all P>0.05）. Conclusions Offline CBCT-based ART for prostate cancer can significantly reduce target volume，decrease hotspots within the target，improve dose homogeneity，and effectively reduce radiation doses to the rectum and bladder，all while maintaining prescribed dose coverage of the target.

Key words: Prostatic neoplasms, Cone-beam computed tomography, Radiotherapy, Radiotherapy dosage

Li Bao, Chen Yongzhong, Chen Jingsheng, Xu Liming, Jin Jun. Feasibility analysis of cone beam CT-based adaptive radiation therapy for prostate cancer[J]. Journal of International Oncology, 2026, 53(10): 615-622.

Figures/Tables 10

References 24

[1]	Sung H, Filho AM, Laversanne M, et al. Global cancer statistics 2024: GLOBOCAN estimates of incidence and mortality worldwide for 34 cancers in 186 countries[J]. CA Cancer J Clin, 2026, 76(4): e70090. DOI: 10.3322/caac.70090.
[2]	Abu-Hijlih R, Alzibdeh A, Abaza H, et al. Prostatectomy versus definitive radiation for localized prostate cancer: revisiting the debate at a tertiary cancer center[J]. Front Oncol, 2026, 16: 1756635. DOI: 10.3389/fonc.2026.1756635.
[3]	van As N, Griffin C, Tree A, et al. Phase 3 trial of stereotactic body radiotherapy in localized prostate cancer[J]. N Engl J Med, 2024, 391(15): 1413-1425. DOI: 10.1056/NEJMoa2403365.
[4]	赵鑫, 范学武, 田龙, 等. 三维超声在前列腺癌图像引导放疗中的应用与评价研究[J]. 国际肿瘤学杂志, 2024, 51(1): 43-49. DOI: 10.3760/cma.j.cn371439-20230418-00005.
[5]	赫捷, 陈万青, 李霓. 中国前列腺癌筛查与早诊早治指南(2022,北京)[J]. 中国肿瘤, 2022, 31(1): 1-30. DOI: 10.11735/j.issn.1004-0242.2022.01.A001.
[6]	Schaeffer EM, Srinivas S, Adra N, et al. Prostate cancer, version 4.2023, NCCN clinical practice guidelines in oncology[J]. J Natl Compr Canc Netw, 2023, 21(10): 1067-1096. DOI: 10.6004/jnccn.2023.0050.
[7]	Amin MB, Edge SB, Greene FL, et al. AJCC cancer staging manual[M]. 8th ed. New York: Springer, 2016: 589-628. DOI: 10.1007/978-3-319-40618-3.
[8]	Landberg T, Chavaudra J, Dobbs J, et al. Prescribing, recording and reporting photon beam therapy (supplement to ICRU Report 50): ICRU Report 62[M]. Bethesda: ICRU, 1999. DOI: 10.1093/jicru/os32.1.1.
[9]	Knopf AC, Boye D, Lomax A, et al. Adequate margin definition for scanned particle therapy in the incidence of intrafractional motion[J]. Phys Med Biol, 2013, 58(17): 6079-6094. DOI: 10.1088/0031-9155/58/17/6079.
[10]	Wang W, Wu Q, Yan D. Quantitative evaluation of cone-beam computed tomography in target volume definition for offline image-guided radiation therapy of prostate cancer[J]. Radiother Oncol, 2010, 94(1): 71-75. DOI: 10.1016/j.radonc.2009.10.005. pmid: 19897268
[11]	Eckl M, Alfakhori N, Willam M, et al. A cone-beam computed tomography based workflow for online adaptive ultra-hypofractionated radiotherapy of prostate cancer[J]. Phys Imaging Radiat Oncol, 2025, 36: 100869. DOI: 10.1016/j.phro.2025.100869.
[12]	Zhu LL, Bredfeldt JS, Hancox C, et al. CT online adaptive radiotherapy is associated with dosimetric and acute toxicity improvements in prostate cancer treatment[J]. Radiother Oncol, 2025, 213: 111207. DOI: 10.1016/j.radonc.2025.111207.
[13]	Christiansen RL, Dysager L, Hansen CR, et al. Online adaptive radiotherapy potentially reduces toxicity for high-risk prostate cancer treatment[J]. Radiother Oncol, 2022, 167: 165-171. DOI: 10.1016/j.radonc.2021.12.013.
[14]	Amjad A, Chen X, Hall WA, et al. Patient-specific deep learning auto-segmentation for MR-guided adaptive radiotherapy of prostate cancer[J]. Int J Radiat Oncol Biol Phys, 2023, 117(2): e638-e639. DOI: 10.1016/j.ijrobp.2023.06.2044.
[15]	Kim JY, Tawk B, Knoll M, et al. Clinical workflow of cone beam computer tomography-based daily online adaptive radiotherapy with offline magnetic resonance guidance: the modular adaptive radiotherapy system (MARS)[J]. Cancers (Basel), 2024, 16(6): 1210. DOI: 10.3390/cancers16061210.
[16]	Groot Koerkamp ML, Bol GH, Kroon PS, et al. Bringing online adaptive radiotherapy to a standard C-arm linac[J]. Phys Imaging Radiat Oncol, 2024, 31: 100597. DOI: 10.1016/j.phro.2024.100597.
[17]	Ferrara E, Beldì D, Yin J, et al. Adaptive strategy for external beam radiation therapy in prostate cancer: management of the geometrical uncertainties with robust optimization[J]. Pract Radiat Oncol, 2020, 10(6): e521-e528. DOI: 10.1016/j.prro.2020.05.006. pmid: 32464369
[18]	Posiewnik M, Piotrowski T. A review of cone-beam CT applications for adaptive radiotherapy of prostate cancer[J]. Phys Med, 2019, 59: 13-21. DOI: 10.1016/j.ejmp.2019.02.014. pmid: 30928061
[19]	Capone L, Cavallo F, Di Minico D, et al. Offline adaptive radiation therapy for prostate cancer: using daily CBCT and deformable image fusion for correct replanning[J]. J Biomed Pract, 2021, 5(1): 5937. DOI: 10.13135/2532-7925/5937.
[20]	Mansour IR, Johnstone CD, Malkov V, et al. Comparison of online adaptation strategies for magnetic resonance guided prostate radiation therapy[J]. Phys Imaging Radiat Oncol, 2025, 35: 100816. DOI: 10.1016/j.phro.2025.100816.
[21]	Malygina H, Auerbach H, Ries M, et al. Intra-adaptational changes in online adaptive radiotherapy: from the ideal to the real dose[J]. Strahlenther Onkol, 2025, 201(11): 1170-1184. DOI: 10.1007/s00066-025-02425-9. pmid: 40663147
[22]	赵永瑞, 高莹, 陈怡东, 等. 基于直线加速器的分次立体定向放疗对小体积脑转移瘤的有效性及安全性[J]. 国际肿瘤学杂志, 2023, 50(3): 138-143. DOI: 10.3760/cma.j.cn371439-20221214-00028.
[23]	Saito N, Schmitt D, Bangert M. Correlation between intrafractional motion and dosimetric changes for prostate IMRT: comparison of different adaptive strategies[J]. J Appl Clin Med Phys, 2018, 19(4): 87-97. DOI: 10.1002/acm2.12359. pmid: 29862644
[24]	Shan G, Hu W, Chen L, et al. Dosimetric evaluation of image-guided radiation therapy for prostate cancer[J]. Med Dosim, 2021, 46(2): 117-126. DOI: 10.1016/j.meddos.2020.09.007. pmid: 33020024

结构	剂量限值
PTV	①≤5%的PTV体积接受≥110%处方剂量；②PTV内最高剂量<115%处方剂量；③高剂量区应避开小肠、结肠、直肠；④PTV内最低剂量≥93%处方剂量
小肠	V₅₀<5%，D_max<52 Gy
直肠	V₅₀<60%，V₆₀<50%，V₇₀<25%
膀胱	V₅₀<60%，V₆₀<50%，V₇₀<30%
骨盆	V₃₀<30%，D_mean<20 Gy
左股骨头	V₃₀<20%，D_mean<30 Gy
右股骨头	V₃₀<20%，D_mean<30 Gy

参数	Plan_p	Plan_a	Plan_b	F值	P值
D_2%（Gy）	74.1±1.2	73.9±1.2^a	73.6±1.3^ab	3.88	0.027
D_50%（Gy）	71.9±1.0	71.8±1.0	71.7±1.1	0.05	0.951
D_98%（Gy）	70.2±0.7	70.3±0.6	70.3±0.7	0.31	0.735
D_mean（Gy）	71.9±0.9	71.9±1.0	71.8±1.0	0.03	0.971
HI	0.051±0.019	0.046±0.021^a	0.042±0.018^ab	4.28	0.019
CI	0.847±0.032	0.845±0.037	0.864±0.032^b	3.58	0.035

参数	Plan_p	Plan_a	Plan_b	F值	P值
直肠
V₅₀（%）	52.4±2.3	47.2±2.9^a	44.3±3.0^ab	4.65	0.013
V₆₀（%）	38.4±3.3	33.4±3.5^a	30.4±3.1^ab	4.42	0.017
V₇₀（%）	18.4±3.5	12.4±3.7^a	10.4±3.3^ab	4.28	0.019
膀胱
V₅₀（%）	54.6±2.1	50.1±3.0^a	45.2±3.2^ab	4.35	0.018
V₆₀（%）	43.8±3.4	36.4±3.7^a	32.4±3.1^ab	4.33	0.018
V₇₀（%）	21.8±3.6	15.4±3.9^a	11.4±3.3^ab	4.42	0.017
骨盆
D_mean（Gy）	12.3±1.0	11.2±0.9	10.7±1.1	2.85	0.066
V₃₀（%）	27.8±3.2	25.1±3.4^a	22.7±3.1^a	3.85	0.027
左股骨头
D_mean（Gy）	15.6±1.0	15.1±0.9	14.6±1.0	1.52	0.228
V₃₀（%）	16.0±1.8	15.1±1.7	14.5±1.6	1.48	0.237
右股骨头
D_mean（Gy）	15.1±1.0	15.6±1.0	14.6±0.9	1.55	0.222
V₃₀（%）	12.2±2.4	12.5±2.5	11.9±2.3	0.52	0.598
注：OAR为危及器官；Plan_p为基于CT的初始放疗计划；Plan_a为第1周ART计划；Plan_b为第4周ART计划；^a为与Plan_p比较，P<0.05；^b为与Plan_a比较，P<0.05；ART为自适应放疗