OL Oncology Letters 1792-1074 1792-1082 D.A. Spandidos 10.3892/ol.2019.10467 OL-0-0-10467 Articles Dosimetric comparison between three- and four-dimensional computerised tomography radiotherapy for breast cancer YanYanli 1 LuZhou 2 LiuZi 1 LuoWei 1 ShaoShuai 1 TanLi 1 MaXiaowei 1 LiuJiaxin 1 DrokowEmmanuel Kwateng 1 RenJuan 1 Department of Radiotherapy, Oncology Department, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China Department of Radiotherapy, Oncology Department, Xi'an Gaoxin Hospital, Xi'an, Shaanxi 710075, P.R. China Correspondence to: Professor Juan Ren, Department of Radiotherapy, Oncology Department, The First Affiliated Hospital of Xi'an Jiaotong University, 227 Yanta West Road, Xi'an, Shaanxi 710061, P.R. China, E-mail: 869491533@qq.com 08 2019 12 06 2019 18 2 1800 1814 17042018 12042019 Copyright: © Yan et al. 2019 This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

At present, methods of radiotherapy simulation for breast cancer based on four-dimensional computerised tomography (4D-CT) or three-dimensional CT (3D-CT) simulation remain controversial. In the present study, 7 patients with residual breast tissue received whole breast radiotherapy based on 3D-CT and 4D-CT simulation. For the 4D-CT plan, four types of CT images were produced, including images of the end of inspiration and the end of expiration, and images acquired by the maximal intensity projection (MIP) and average intensity projection (AIP). In the 3D-CT plan, the clinical target volume (CTV) and plan target volume (PTV) were marginally higher compared with the 4D-CT plan. In addition, the minimum point dose of the target volume (Dmin), the maximum point dose of the target volume (Dmax) and the mean point dose of the target volume (Dmean) of the CTV and PTV in the MIP and AIP plans were marginally higher compared with the 3D-CT plan. For the contralateral breast (C-B), volumes of the 4D-CT plan were markedly lower compared with the 3D-CT plan. Furthermore, Dmin, Dmax and Dmean of the 3D-CT plan were higher compared with the AIP and MIP plans. For the ipsilateral lungs (I-L), volumes of the 3D-CT and AIP plans were higher compared with the MIP plan. Furthermore, when breast lesions were on the left side, for the heart, the volume receiving no less than 40% of the prescription dose (V40) and the volume receiving no less than 30% of the prescription dose (V30) of the MIP and AIP plans were slightly lower compared with those of the 3D plan. In conclusion, 4D-CT radiotherapy based on the MIP and AIP plans provides a slightly smaller radiation area and slightly higher radiotherapy dosage of the CTV and PTV compared with 3D-CT radiotherapy for breast radiotherapy. Therefore, the MIP and AIP plans prevent C-B radiation exposure and improve sparing of the heart and I-L.

 three-dimensional computerised tomography four-dimensional computerised tomography maximal intensity projection average intensity projection breast cancer radiotherapy dosimetry Introduction

The extensive use of whole breast radiotherapy has rendered it a standard treatment for patients with early breast cancer undergoing breast-conserving surgery (1–4). Previous advancements of individualised treatment for breast cancer have facilitated the gradual application of whole breast radiotherapy to neoadjuvant radiotherapy (5,6) and palliative radiotherapy (7,8), which have enhanced opportunities for surgical intervention, and improved the survival time and quality of life of patients with breast cancer.

At present, radiotherapy techniques for breast cancer are typically based on three-dimensional computerised tomography (3D-CT) simulation. However, the 3D-CT plan overlooks the target volume and radiotherapy dosage bias induced by breathing movements. Reportedly, 3D-CT images depend on different respiration phases when the CT scan starts (9). Previous studies have established that the accuracy and efficiency of radiotherapy in the chest and abdomen can easily be reduced by motions of tumours and organs at risk (OAR) (10,11). To overcome these problems, a novel technological innovation, four-dimensional (4D)-CT radiotherapy technique, has emerged. Compared with conventional scanning, more accurate images of tumours and normal organs can be acquired by the 4D-CT process (11). At present, 4D-CT radiotherapy has been extensively applied in the treatment of lung cancer, liver cancer, oesophageal cancer, gastric cancer and kidney cancer; however, it has rarely been applied for breast cancer (11–19). For 4D-CT simulation, a breathing cycle is evenly divided into ten respiration phases and ten sets of CT images are acquired, respectively (10,11). Typically, the outline of targets and OAR on all ten sets of images is delineated by radiation oncologists, which increases the workload compared with 3D-CT radiotherapy (17,20,21). A number of composite methods have been used to decrease and optimise the work, including maximal intensity projection (MIP), average intensity projection (AIP), minimum intensity projection and two-extreme-phases fusion (21,22). While MIP and MIP-CT images are acquired by finding the maximum and minimum CT value along the slices at the same pixel location, AIP-CT images are acquired by averaging all CT values along the slices at the same pixel location (22,23). The two-extreme-phases fusion method involves delineating target outlines on CT images of the two extreme respiration phases (T00 for the end of inhalation and T50 for the end of exhalation) and then fusing them (21). Notably, MIP-CT images are effective for assessing the motion of the organ but not for determining the tumour boundary near the diaphragm and chest wall, which can be readily demonstrated by AIP-CT and MIP-CT images (22). For partial breast irradiation, previous studies have demonstrated that 4D-CT radiotherapy improves the target definition and decreases the radiation dose of OAR (18,19). Furthermore, certain previous studies have compared different composite methods for lung cancer and liver cancer (21,23–28); however, to the best of our knowledge, at present, there is no study that has been published in English for breast cancer.

Therefore, the present study aimed to compare the target volumes and the dosimetric difference between the 3D-CT and 4D-CT plans for whole breast radiotherapy to determine the more effective radiotherapy technique for breast cancer.

 Patients and methods <sec> <title>Patients and design

In the present study, seven female patients with breast cancer with residual breast tissue received whole breast radiotherapy based on 3D-CT and 4D-CT between March 2016 and April 2017 at The First Affiliated Hospital of Xi'an Jiaotong University (Xi'an, China). Inclusion criteria: i) Female patients were digonsed with breast cancer by pathology and and clinical examination; ii) patients were willing to accept and could tolerate breast radiotherapy; and iii) patients had no radiotherapeutic contraindication. Exclusion criteria: i) patients with metastatic or recurrent breast cancer; and ii) patients who had previously received chest radiotherapy. Table I summarises the characteristics of all patients. The present study was approved by The Ethics Committee of First Affiliated Hospital of Xi'an Jiaotong University (approval no. 2015-101). Written informed consent was obtained from all participants.

 CT simulation

All seven patients were fixed in position using thermoplastic sheets or breast brackets. Subsequently, 3D-CT or 4D-CT scans were received sequentially with free breathing in the supine position. For each patient, images were obtained using a Philips Big Bore CT-Simulator (Philips Medical Systems, Inc., Bothell, WA, USA) with 5-mm slice thickness and a scan range from the submentum to the subphrenic, including the heart, bilateral breasts and bilateral lungs. All CT images were then uploaded and reconstructed on the Monaco 5.11.01 radiation treatment planning system (TPS) (ELEKTA Co., Sweden).

In addition, the 4D-CT scan was acquired using the Cine model and supplemented by the real-time position management (RPM) system (Philips Co., Holland) during breathing. Notably, the scan time was >1 respiratory cycle. For each patient, the respiratory cycle was evenly divided into ten respiration phases by the RPM system. T00 was defined as the end of inhalation and T50 was defined as the end of exhalation. Furthermore, ten sets of 4D-CT images of the ten respiration phases were acquired, and the MIP-CT and AIP-CT images of each patient were fused and reconstructed.

 Targets and OAR delineation, and dose prescription

All acquired CT images were uploaded and rebuilt on the Monaco 5.11.01 TPS. Clinical doctors delineated the outlines of target areas and OAR, and medical physicists formulated radiotherapy plans. In addition, all delineations and the five types of plans (3D, T00, T50, MIP and AIP) were separately implemented for each patient by the same skilled doctor and medical physicist.

 Target delineation

The clinical target volume (CTV) consisted of the whole residual breast tissue. The upper and lower boundaries of the CTV indicated the edges of breast tissue, the inner boundary indicated the sternal line, and the outer boundary indicated the anterior axillary line. The anterior boundary was 5 mm below the skin surface and the posterior boundary was the ectopectoralis fascia. In addition, the plan target volume (PTV) was attained by adding 5-mm isotropic expansion of the CTV and the anterior boundary was refined 3 mm below the skin surface simultaneously.

 OAR delineation

In the present study, the delineation method of the contralateral breast (C-B) was similar to the aformentioned method of the CTV. The heart was delineated from the right atrium and the right ventricle to the cardiac apex, excluding the pulmonary trunk, ascending aorta and vena cava. In addition, the right and left lungs were delineated by the automatic function of the Monaco TPS and manual modification. Furthermore, the spinal cord and bilateral humeral heads were delineated on all layers of the CT scans.

 Plan evaluation

The present study used a dose volume histogram (DVH) to evaluate the quality of the radiation plan. For the CTV and PTV, Dx represents the minimum dose delivered to x% of the target volume and Vx represents the volume receiving no less than x% of the prescription dose (29,30). In addition, Dmin, Dmax and Dmean of the CTV and PTV represent the minimum, maximum and mean point dose of the target volume, respectively.

The conformity index (CI) and the homogeneity index (HI) of the PTV were automatically evaluated by the Monaco TPS to assess the PTV coverage rate. The CI indicates the ratio between the PTV and the irradiated volume at the prescription dose, and the HI implies the uniformity of the dose distribution in the target volume (31). The computational formulas of the CI and HI were as follows: CI=TV12/TV × VR1, where TV1 represents the volume of the target that received the prescription dose, TV represents the target volume and VR1 represents the total volume of the prescription isodose. Notably, values of CI closer to 1.0 represent a better dose conformity of the PTV. HI=Dmax/Dmin, where Dmax represents the maximum point dose and Dmin represents the minimum point dose of the target volume. Notably, values of HI closer to 1.0 indicate a plan with less heterogeneity. Definitions of Dx, Dmin, Dmax and Dmean for all OAR and Vx for the C-B are similar to definitions for the target volume. Other Vx represents the volume receiving no less than x Gray (Gy) (29,30).

 Dose prescription

Intensity-modulated radiotherapy (IMRT) plans were performed with 6-mV x-ray, and 5–9 coplanar and isocenter radiation treatment fields for five groups of each patient. Subsequently, a dose of 50 Gy in 25 fractions of 2 Gy was prescribed to the PTV. Notably, 95% of the target volume should be included by 95% of the prescribed dose (4,750 centigray, cGy) and not >5% should be encompassed by 105% of the prescribed dose (5,250 cGy). In the present study, the dose limits of OAR were as follows: For the ipsilateral lungs (I-L), V20<25% and Dmean<15Gy; for the bilateral lungs, V20<20%; and for the heart, V30<10% and V40<5%.

 Statistical analysis

The disease stage of patients was evaluated according to the 7th American Association of Cancer (AJCC) staging system (32). Dx, Vx, CI and HI were extracted using the Monaco system. All data were analysed using SPSS software (version 21.0; IBM Corp., Armonk, NY, USA) with a randomised block design. The Shapiro-Wilk test and Levene test were used to evaluate the normality and homogeneity of data. Data that are normaly distributed are expressed as mean ± standard deviation and presented as bar plots; all other data are expressed as median (interquartile range) and presented as box and whisker plots (Figs. 1–9). For each evaluation index, analysis of variance followed by a Least Significant Difference test were used when data satisfied normal distribution and homoscedasticity. Otherwise, a Friedman test and pairwise comparison were used. P<0.05 was considered to indicate a statistically significant difference.

 Results <sec> <title>Dosage comparison of the CTV and PTV between the 3D-CT plan and the 4D-CT plan

The present study compared the dosimetric characteristics between the 3D-CT radiotherapy plan and four different 4D-CT radiotherapy plans (AIP, MIP, T00 and T50) in the same order for the seven patients with residual breast tissue. For target dose parameters, no significant difference was observed in the CI and HI of the PTV between the 3D-CT and 4D-CT plans (Table II; Fig. 1). In addition, target volumes (including the total volume, V100, V95, V90 and V50) of the CTV and PTV of the 4D-CT plan were slightly lower compared with the 3D-CT plan (Table II; Figs. 2 and 3). Furthermore, Dmin, Dmax and Dmean of the CTV and PTV in the MIP and AIP plans were slightly higher compared with that of the 3D-CT plan (Table II; Figs. 2 and 3).

 Dosage comparison of OAR between the 3D-CT and 4D-CT plans

In the present study, the following comparisons of dose parameters of OAR were made. For the C-B (Table III; Fig. 4), the total volume of the 4D-CT plan was markedly lower compared with the 3D-CT plan. In addition, Dmin, Dmax and Dmean of the AIP plan were lower than those of 3D-CT and MIP plans. No marked differences were observed in dose parameters between the MIP and AIP plans. For the I-L (Table III; Fig. 5), volumes (including the total volume, V30, V20, and V10) of the T00 plan were the highest, followed by the 3D-CT and AIP plans, and the volumes of the T50 and MIP plans were the lowest. For the contralateral lungs (C-L) (Table III; Fig. 6), the total volumes of the MIP plan were markedly lower compared with that of the 3D-CT, AIP and T00 plans; however, the volume, of the T00 plan were higher compared with the T50 plan. For the I-L and C-L (Table III; Figs. 5 and 6), no statistical differences were observed in the dosage among the five plans. In addition, for the contralateral and ipsilateral humeral head (Table III; Fig. 7), no significant differences were observed in dose parameters between the 3D-CT and 4D-CT plans. For the heart (Table III; Figs. 8 and 9), regardless of whether breast lesions were in the right or left side, the volume of the MIP and AIP plans were slightly higher compared with that of the 3D-CT plan, with no significant difference in dose among the 3D-CT, MIP and AIP plans. When breast lesions were on the left side, for the heart, V40 and V30 of the MIP and AIP plans were slightly lower compared with those of the 3D-CT plan (Table III; Fig. 8).

 Discussion

Previous studies have established that radiotherapy based on 4D-CT simulation enhances the accuracy of dosage and determines the locations of tumour(s) and OAR in the chest and abdomen (9–26,33). Certain previous studies have compared the composite methods of 4D-CT radiotherapy for lung cancer and liver cancer (9,17,20,23–26,33); however, at present, to the best of our knowldege, there is no study that has been published in English, which has investigated the same for breast cancer. To the best of the our knowledge, the present study is the first to compare the target volume and dosimetric differences between the 3D-CT radiotherapy plan and four 4D-CT radiotherapy plans (T00, T50, MIP and AIP plans) for whole breast radiotherapy.

For dose parameters of targets, all target volumes (including the total volume, V100, V95, V90 and V50) of the CTV and PTV in the 3D-CT plan were slightly higher compared with four 4D-CT plans, with no difference between the T00 and T50 plans. For the C-B, the total volume in the 3D-CT plan was markedly higher compared with the 4D-CT plan. Therefore, it could be concluded that breast tissues exert little impact on the respiration movement, which suggests that the volume changes of the breasts should be ignored (34). In addition, differences in target volumes between the 3D-CT and 4D-CT plans were not due to respiration movement-caused displacement. In free breathing, partial target areas of the 3D-CT plan were scanned recurrently or missed due to uncertainty in the beginning time of the scan and the whole scan time was longer compared with the 4D-CT scan; therefore, 4D-CT images evaluated the location, size and shape of targets more precisely (35). However, Bedi et al (36) reported no significant differences in the left breast volume contoured on a 3D-CT scan (1,005±559 cm3), 4D-CT scan with full inspiration phase (1,019±563 cm3), 4D-CT scan with full expiration phase (1,023±573 cm3) and 4D-CT scan derived by AIP (1023±573 cm3). The difference between the two studies could be attributed to the following: i) Breast locations in western females are more easily affected by the respiration movement, as the breast size of western females is typically larger compared with Chinese females; and ii) all breast lesions in the previous study by Bedi et al (36) were in the left chest where the impact of the cardiac motion could not be ignored; however, in the present study, the number of lesions on the right side was greater than that on the left side (right-to-left ratio, 4:3)

Respiration movements not only affect displacements of target volumes but also exert a considerable impact on the radiation dose distribution (37–39). In the clinical setting, during the process of treatment, changes in the dose distribution caused by target bias in the 3D-CT plan cannot satisfy the treatment requirements, which may increase the risk of local recurrence. In the present study, Dmin, Dmax and Dmean of the CTV and PTV in the MIP and AIP plans were slightly higher compared with that of the 3D-CT plan. However, Dmin, Dmax and Dmean of the C-B in the 3D-CT and T00 plans were the highest and those of the AIP and MIP plans were the lowest. In addition, no marked difference was observed in dose parameters between the MIP and AIP plans, indicating that the dose distribution of the MIP and AIP plans is better compared with that of the 3D-CT plan. In addition, this suggests that the MIP and AIP plans can prevent and decrease radiation exposure to normal breast. In the present study, no marked differences were observed in the CI and HI between the 3D-CT and four 4D-CT plans. As the target volumes in the five groups were similar, all plans were achieved by IMRT with the same pattern. Reportedly, the IMRT technique achieved improved CI and HI compared with 3D conformal radiotherapy, and increased OAR sparing and decreased the late effects, which enhanced the quality of life of the patients (31,40,41).

Previous studies have compared different composite methods for lung cancer and liver cancer (21,23–28). Zhao et al (27) reported that lung volumes of the AIP plan were close to the 3D-CT volume in lung cancer and that of the MIP plan was smaller compared with the AIP plan by 11.4±2.3%. In addition, the DVH of the MIP plan revealed that the MIP plan was less sensitive to breathing movements (27). However, Simon et al (28) reported that the internal target volume of the MIP plan was closer to the actual volume compared with that of the AIP plan. Similarly, a previous study determined that the GTV of the MIP plan was markedly higher compared with that of the AIP plan for stereotactic body radiotherapy planning in lung cancer (20). The differences in the aforementioned studies may have resulted from different evaluated standard and research methods. MIP images are acquired by finding the maximum CT value of images from all respiratory phases. A previous study reported that MIP images include the motion and position extent of a lung tumour as the density of a tumour was higher compared with that of the surrounding normal lung tissue (42). However, Mohatt et al (25) reported that in clinical lung tumour cases with displacements ranging between 0.1 and 2.2 cm, the MIP plan typically underestimated target volumes and resulted in a PTV ratio of 0.95±0.15. When tumours were located close to the chest wall, MIP images were more easily affected by the surrounding structures with high or equal density, including the cartilage tissues and muscles, compared with AIP images (22,27). Park et al (43) reported that the MIP plan was markedly different from the ten-phase fusion plan when breathing was irregular or a tumour was close to similar-density tissues. However, in the present study, no marked dosimetric difference was observed between the MIP and AIP plans, which could be attributed to the fact that breast tissue movements are less sensitive to breathing; therefore, the impact of MIP images caused by surrounding structures was low.

In addition to improving the sparing of the C-B, another objective of breast radiotherapy is to decrease the irradiation dose and volume of the heart and bilateral lungs. In the present study, for the I-L, marked differences were identified in volumes (including the total volume, V30, V20, V10 and V5) among the five plans (3D-CT, T00, T50, MIP and AIP). Additionally, volumes of the T00 plan were the highest, followed by the 3D-CT and AIP plans, and those of the T50 and MIP plans were the lowest. For the C-L, total volumes of the MIP plan were markedly lower compared with those of the 3D-CT, AIP and T00 plans, and total volumes of the T00 plan were higher compared with those of the T50 plan. Whether in the I-L or C-L, no statistical difference of dosage was observed among the five plans, indicating that in free breathing, although no apparent breast displacements occurred between the two extreme respiratory phases, the sufficiently apparent difference of bilateral lungs volumes resulting from thoracic movements were easily observed. Total volumes of the lungs in the MIP plan were easily affected by the surrounding structures with high or equal density (22,27), which induced smaller volumes in the MIP plan compared with others and then induced the smallest V30, V20, V10 and V5. Therefore, the present study could not completely establish that the MIP plan is superior to the others. For the heart, dosimetric parameters of plans are affected not only by respiratory movements but also by their own rhythm. In the present study, whether breast lesions were in the right or left side, heart volumes of the MIP and AIP plans were slightly higher compared with that of the 3D-CT plan, with no marked differences in dose among the 3D-CT, MIP and AIP plans. However, for hearts of patients with lesions in the left breast, V40 and V30 of the MIP and AIP plans were slightly lower compared with that of the 3D-CT plan. These results indicated that the MIP and AIP plans may improve sparing of the heart, particualy lesions in the left side, and the I-L. However, Bedi et al (36) reported that dosimetric results for the heart and the I-L exhibited no statistically significant differences between the 3D-CT and 4D-CT plans for patients with left-sided breast cancer, and that improved sparing of the heart and the lungs could only be attained by decreasing the posterior margins of the breast target volumes. For contralateral and ipsilateral humeral heads, no marked differences were observed in dose parameters between the 3D-CT and 4D-CT plans as humeral heads were far away from the targets and could not be affected by therapy plans.

In conclusion, for whole breast radiotherapy of breast cancer with residual tissues (including postoperative radiotherapy, neoadjuvant radiotherapy and palliative radiotherapy), 4D-CT radiotherapy techniques based on the MIP and AIP plans provide a slightly smaller radiation area and slightly higher radiotherapy dosage of the CTV and PTV compared with 3D-CT radiotherapy. For the C-B, the dose distribution in the MIP and AIP plans is better compared with the 3D-CT plan; therefore, MIP and AIP plans prevent and reduce radiation exposure to normal breast. The MIP and AIP plans also improve sparing of the heart (particularly breast lesions in the left side) and the I-L. Furthermore, the dosimetric differences between the MIP and AIP plans are not significant. Therefore, these plans are worth considering for whole breast radiotherapy.

 Acknowledgements

Not applicable.

 Funding

The present study was supported by the National Natural Science Foundations of China (grant nos. 81772793/H1621, 31201060/C0709, 30973175/C1701 and 81172490/H1621), Programme for New Century Excellent Talents in University (grant no. NCET-12-0440), Scientific and Technological Research Foundation of Shaanxi Province (grant no. 2012K13-01-06), Research Foundation of Health Department of Shaanxi Province (grant no. 2010D41), Qing Nian Jiao Shi Gen Zong Ji Hua of Xi'an Jiaotong University (‘The Fundamental Research Funds for the Central Universities’ awarded to to JR) and the Clinical Research Award of the First Affiliated Hospital of Xi'an Jiaotong University (grant no. XJTU1AHCR2014-041).

 Availability of data and materials

All data generated or analysed during the present study are included in this published article.

 Authors' contributions

YY delineated the target area, performed the data analysis and drafted the manuscript. ZLu, ZLi and WL participated in the experiments, and performed the radiation plan and reviewing. SS, LT, XM, JL and ED participated in data collection and reviewed the manuscript. JR participated in experimental design, experimental operation, helped to draft the manuscript and approved the final version of the manuscript to be published.

 Ethics approval and consent to participate

The present study was approved by the Ethics Committee of First Affiliated Hospital of Xi'an Jiaotong University (Xi'an, China; approval no. 2015-101). Written informed consent was obtained from all participants.

 Patient consent for publication

Not applicable.

 Competing interests

The authors declare that they have no competing interests.

 References KunklerIHWilliamsLJJackWJCameronDADixonJMPRIME II investigatorsBreast-conserving surgery with or without irradiation in women aged 65 years or older with early breast cancer (PRIME II): A randomised controlled trialLancet Oncol16266273201510.1016/S1470-2045(14)71221-525637340 ChanTYTanPWTangJIIntensity-modulated radiation therapy for early-stage breast cancer: Is it ready for prime time?Breast Cancer (Dove Med Press)9177183201728360536 KellerLMSopkaDMLiTKlaytonTLiJAndersonPRBleicherRJSigurdsonERFreedmanGMFive-year results of whole breast intensity modulated radiation therapy for the treatment of early stage breast cancer: The fox chase cancer center experienceInt J Radiat Oncol84881887201210.1016/j.ijrobp.2012.01.069 CastanedaSAStrasserJUpdates in the treatment of breast cancer with radiotherapySurg Oncol Clin N Am26371382201710.1016/j.soc.2017.01.01328576177 PoleszczukJLuddyKChenLLeeJKHarrisonLBCzernieckiBJSolimanHEnderlingHNeoadjuvant radiotherapy of early-stage breast cancer and long-term disease-free survivalBreast Cancer Res1975201710.1186/s13058-017-0870-128666457 CoelhoRCDa SilvaFDMLDo CarmoIMLBonaccorsiBVFaroniLDNeoadjuvant radiotherapy in locally advanced breast cancer refractory to chemotherapy-a single institution experience in BrazilAnn Oncol263031201510.1093/annonc/mdv519.55 MaherMCampanaFMosseriVDreyfusHVilcoqJRGautierCAsselainBFourquetABreast-cancer in elderly women: A retrospective analysis of combined treatment with tamoxifen and once-weekly irradiationInt J Radiat Oncol Biol Phys31783789199510.1016/0360-3016(94)00564-87860389 FakieNAdvanced breast cancer: A retrospective review comparing two palliative radiotherapy protocols used at Groote Schuur Hospital between 2010 and 2013University of Cape Town2016 WuGLianJShenDImproving image-guided radiation therapy of lung cancer by reconstructing 4D-CT from a single free-breathing 3D-CT on the treatment dayMed Phys3976947709201210.1118/1.476822623231317 TanZLiuCZhouYShenWPreliminary comparison of the registration effect of 4D-CBCT and 3D-CBCT in image-guided radiotherapy of stage IA non-small-cell lung cancerJ Radiat Res58854861201710.1093/jrr/rrx04028992047 LowD4D imaging and 4D radiation therapy: A new era of therapy design and deliveryFront Radiat Ther Oncol4399117201110.1159/00032241021625150 WangJZLiJBQiHPLiYKWangYZhangYJWangWEffect of contrast enhancement in delineating GTV and constructing IGTV of thoracic oesophageal cancer based on 4D-CT scansRadiother Oncol119172178201610.1016/j.radonc.2016.02.03126987472 LiFLiJXingJZhangYFanTXuMShangDLiuTSongJAnalysis of the advantage of individual PTVs defined on axial 3D CT and 4D CT images for liver cancerJ Appl Clin Med Phys134017201210.1120/jacmp.v13i6.401723149795 HuangTCHsiaoCYChienCRLiangJAShihTCZhangGGIMRT treatment plans and functional planning with functional lung imaging from 4D-CT for thoracic cancer patientsRadiat Oncol83201310.1186/1748-717X-8-323281734 HoangJKReimanRENguyenGBJanuzisNChinBBLowryCYoshizumiTTLifetime attributable risk of cancer from radiation exposure during parathyroid imaging: Comparison of 4D CT and parathyroid scintigraphyAJR Am J Roentgenol204W579W585201510.2214/AJR.14.1327825905965 DingYLiJWangWWangSFanTXuMShaoQMaZDisplacement of the lumpectomy cavity defined by surgical clips and seroma based on 4D-CT scan for external-beam partial breast irradiation after breast-conserving surgery: A comparative studyBr J Radiol8620130416201310.1259/bjr.2013041623995875 ZhangSLinSYuHZhangHZhangGHanPApplication of AIP and MIP CT on individual GTV delineation for tumor moving with respirationInternational conference on biomedical engineering and biotechnology7367392012 ParkCKPritzJZhangGGForsterKMHarrisEEValidating fiducial markers for image-guided radiation therapy for accelerated partial breast irradiation in early-stage breast cancerInt J Radiat Oncol Biol Phys82e425e431201210.1016/j.ijrobp.2011.07.02722284037 WangSLiJWangWZhangYLiFFanTShangDA study on the displacements of the clips in surgical cavity for external-beam partial breast irradiation after breast-conserving surgery based on 4DCTJ Radiat Res53433438201210.1269/jrr.1113122739012 BradleyJDNofalANEl NaqaIMLuWLiuJHubenschmidtJLowDADrzymalaREKhullarDComparison of helical, maximum intensity projection (MIP), and averaged intensity (AI) 4D CT imaging for stereotactic body radiation therapy (SBRT) planning in lung cancerRadiother Oncol81264268200610.1016/j.radonc.2006.10.00917113668 EzhilMVedamSBalterPChoiBMirkovicDStarkschallGChangJYDetermination of patient-specific internal gross tumor volumes for lung cancer using four-dimensional computed tomographyRadiat Oncol44200910.1186/1748-717X-4-419173738 PanTSunXLuoDImprovement of the cine-CT based 4D-CT imagingMed Phys3444994503200710.1118/1.279422518072515 LeeSYLimSMaSYYuJGross tumor volume dependency on phase sorting methods of four-dimensional computed tomography images for lung cancerRadiat Oncol J35274280201710.3857/roj.2017.0044429037025 HanCHSampathSSchultheisssTEWongJYCVariations of target volume definition and daily target volume localization in stereotactic body radiotherapy for early-stage non-small cell lung cancer patients under abdominal compressionMed Dosim42116121201710.1016/j.meddos.2017.01.00828433482 MohattDJKeimJMGreeneMCPatel-YadavAGomezJAMalhotraHKAn investigation into the range dependence of target delineation strategies for stereotactic lung radiotherapyRadiat Oncol12166201710.1186/s13014-017-0907-829100548 KhamfongkhrueaCThongsawadSTannanontaCChamchodSComparison of CT images with average intensity projection, free breathing, and mid-ventilation for dose calculation in lung cancerJ Appl Clin Med Phys182636201710.1002/acm2.1203728300381 ZhaoLSandisonGAFarrJBHsiWCLiXADosimetric impact of intrafraction motion for compensator-based proton therapy of lung cancerPhys Med Biol5333433364200810.1088/0031-9155/53/12/01918523345 SimonLGiraudPServoisVRosenwaldJCInitial evaluation of a four-dimensional computed tomography system, using a programmable motorJ Appl Clin Med Phys75065200610.1120/jacmp.v7i4.230117533356 DeseynePSpeleersBDe NeveWBouteBPaelinckLVan HoofTVan de VeldeJVan GrevelingAMontenCPostGWhole breast and regional nodal irradiation in prone versus supine position in left sided breast cancerRadiat Oncol1289201710.1186/s13014-017-0828-628549483 YinLWuHGongJGengJHJiangFShiAHYuRLiYHHanSKXuBZhuGYVolumetric-modulated arc therapy vs. c-IMRT in esophageal cancer: A treatment planning comparisonWorld J Gastroenterol1852665275201223066322 SalimiMAbiKSTNedaieHAHassaniHGharaatiHSameiMShahiRZareiHAssessment and comparison of homogeneity and conformity indexes in step-and-shoot and compensator-based intensity modulated radiation therapy (IMRT) and Three-dimensional conformal radiation therapy (3D CRT) in prostate cancerJ Med Signals Sens7102107201728553583 LeeJHEubankWBMankoffDABreast CancerNuclear OncologyStraussHMarianiGVolterraniDLarsonSSpringerNew York, NY363382201310.1007/978-0-387-48894-3_12 XingJLiJBZhangYJLiFXFanTYXuMShangDPHanJJComparison of three methods to delineate internal gross target volume of the primary hepatocarcinoma based on four-dimensional CT simulation imagesZhonghua Zhong Liu Za Zhi341221282012(In Chinese)22780930 RichterASweeneyRBaierKFlentjeMGuckenbergerMEffect of breathing motion in radiotherapy of breast cancer: 4D dose calculation and motion tracking via EPIDStrahlenther Onkol185425430200910.1007/s00066-009-1980-119714303 PerssonGFNygaardDEMunck Af RosenschöldPRichter VogeliusIJosipovicMSpechtLKorremanSSArtifacts in conventional computed tomography (CT) and free breathing four-dimensional CT induce uncertainty in gross tumor volume determinationInt J Radiat Oncol Biol Phys8015731580201110.1016/j.ijrobp.2010.10.03621163584 BediCKronTWillisDHubbardPMilnerAChuaBComparison of radiotherapy treatment plans for left-sided breast cancer patients based on three- and four-dimensional computed tomography imagingClin Oncol (R Coll Radiol)23601607201110.1016/j.clon.2011.04.00421549580 FrazierRCViciniFASharpeMBYanDFayadJBaglanKLKestinLLRemouchampsVMMartinezAAWongJWImpact of breathing motion on whole breast radiotherapy: A dosimetric analysis using active breathing controlInt J Radiat Oncol Biol Phys5810411047200410.1016/j.ijrobp.2003.07.00515001243 DingMSLiJSDengJFourkalEMaCMDose correlation for thoracic motion in radiation therapy of breast cancerMed Phys3025202529200310.1118/1.160374414528974 YueNJLiXBeriwalSHeronDESontagMRHuqMSThe intrafraction motion induced dosimetric impacts in breast 3D radiation treatment: A 4DCT based studyMed Phys3427892800200710.1118/1.273981517821986 LuxtonGHancockSLBoyerALDosimetry and radiobiologic model comparison of IMRT and 3D conformal radiotherapy in treatment of carcinoma of the prostateInt J Radiat Oncol59267284200410.1016/j.ijrobp.2004.01.024 FisherJScottCStevensRMarconiBChampionLFreedmanGMAsrariFPilepichMVGagnonJDWongGRandomized phase III study comparing Best Supportive Care to Biafine as a prophylactic agent for radiation-induced skin toxicity for women undergoing breast irradiation: Radiation therapy oncology group (RTOG) 97–13Int J Radiat Oncol4813071310200010.1016/S0360-3016(00)00782-3 CaiJReadPWShengKThe effect of respiratory motion variability and tumor size on the accuracy of average intensity projection from four-dimensional computed tomography: An investigation based on dynamic MRIMed Phys3549744981200810.1118/1.298224519070231 ParkKHuangLGagneHPapiezLDo Maximum Intensity Projection Images Truly Capture Tumor Motion?Int J Radiat Oncol Biol Phys73618625200910.1016/j.ijrobp.2008.10.00819147026

CI and HI values for the 3D computerised tomography and four-dimensional computerised tomography plans in 7 patients. (A) CI values. (B) HI values. The horizontal axis represents the five different plans and the vertical axis represents the median values of the CI and HI. CI, conformity index; HI, homogeneity index; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; 3D, three-dimensional; Gy, gray.

Parameters of the CTV between the 3D and four-dimensional computerised tomography plans in seven patients. (A) CTV–Volume. (B) CTV–V100. (C) CTV–V95. (D) CTV–V90. (E) CTV–V50. (F) CTV-D95. (G) CTV-D90. (H) CTV-D50. (I) CTV-D5. (J) CTV-Dmin. (K) CTV-Dmax. (L) CTV-Dmean. The horizontal axis represents five different plans and the vertical axis represents the mean or median dose size. CTV, clinical target volume; 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx, the volume receiving no less than x% of the prescription dose; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Parameters of the PTV between the 3D and four-dimensional computerised tomography plans in seven patients. (A) PTV–Volume. (B) PTV–V100. (C) PTV–V95. (D) PTV–V90. (E) PTV–V50. (F) PTV-D95. (G) PTV-D90. (H) PTV-D50. (I) PTV-D5. (J) PTV-Dmin. (K) PTV-Dmax. (L) PTV-Dmean. The horizontal axis represents the five different plans and the vertical axis represents the mean or median dose size. PTV, plan target volume; 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx, the volume receiving no less than x% of the prescription dose; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Parameters of the contralateral breast between the 3D and four-dimensional computerised tomography plans in seven patients. (A) Contralateral Breast-Volume. (B) Contralateral Breast-D95. (C) Contralateral Breast-D90. (D) Contralateral Breast-D50. (E) Contralateral Breast-Dmin. (F) Contralateral Breast-Dmax. (G) Contralateral Breast-Dmean. The horizontal axis represents the five different plans and the vertical axis represents the mean or median dose size. 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx, the volume receiving no less than x% of the prescription dose; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Parameters of the ipsilateral lungs between the 3D and four-dimensional computerised tomography plans in seven patients. (A) Ipsilateral Lungs-Volume. (B) Ipsilateral Lungs-V30. (C) Ipsilateral Lungs-V20. (D) Ipsilateral Lungs-V10. (E) Ipsilateral Lungs-V5. (F) Ipsilateral Lungs-Dmin. (G) Ipsilateral Lungs-Dmax. (H) Ipsilateral Lungs-Dmean. The horizontal axis represents the five different plans and the vertical axis represents the mean or median dose size. 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx represents the volume receiving no less than x Gy; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Parameters of the contralateral lungs between the 3D and four-dimensional computerised tomography plans in seven patients. (A) Contralateral Lungs-Volume. (B) Contralateral Lungs-V20. (C) Contralateral Lungs-V10. (D) Contralateral Lungs-V5. (E) Contralateral Lungs-Dmin. (F) Contralateral Lungs-Dmax. (G) Contralateral Lungs-Dmean. The horizontal axis represents the five different plans and the vertical axis represents the mean or median dose size. 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx, represents the volume receiving no less than x Gy; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Parameters of the contralateral and ipsilateral humeral head between the 3D and four-dimensional computerised tomography plans in seven patients. (A) Contralateral Humeral Head-Volume. (B) Contralateral Humeral Head-Dmin. (C) Contralateral Humeral Head-Dmax. (D) Contralateral Humeral Head-Dmean. (E) Ipsilateral Humeral Head-Volume. (F) Ipsilateral Humeral Head-Dmin. (G) Ipsilateral Humeral Head-Dmax. (H) Ipsilateral Humeral Head-Dmean. The horizontal axis represents the five different plans and the vertical axis represents the mean or median dose size. 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx represents the volume receiving no less than x Gy; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Parameters of the heart (breast lesions in the left) between the 3D and four-dimensional computerised tomography plans in seven patients. (A) Heart (lesions in the left breast)-Volume. (B) Heart (lesions in the left breast)-V40. (C) Heart (lesions in the left breast)-V30. (D) Heart (lesions in the left breast)-Dmin. (E) Heart (lesions in the left breast)-Dmax. (F) Heart (lesions in the left breast)-Dmean. The horizontal axis represents the five different plans and the vertical axis represents the mean or median dose size. 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx, represents the volume receiving no less than x Gy; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Parameters of the heart (breast lesions in the right) between the 3D and four-dimensional computerised tomography plans in seven patients. (A) Heart (lesions in the right breast)-Volume. (B) Heart (lesions in the right breast)-Dmin. (C) Heart (lesions in the right breast)-Dmax. (D) Heart (lesions in the right breast)-Dmean. The horizontal axis represents the five different plans and the vertical axis represents the mean or median dose size. 3D, three-dimensional; AIP, average intensity projection; MIP, maximal intensity projection; T00, end of inhalation; T50, end of exhalation; Dx, the minimum dose delivered to x% of the target volume; Vx, represents the volume receiving no less than x Gy; Dmax, maximum point dose; Dmin, minimum point dose of the target volume; Dmean, mean point dose of the target volume; Gy, gray.

Characteristics of the patients (n=7).

Characteristic Median (range) n
Age, years 50.57 (39–76)
Disease stage
  Ia 2
  IIa 3
  IIb 1
  IV 1
Radiotherapy location
  Right breast 4
  Left breast 3
Type of radiotherapy
  Postoperative 4
  Neoadjuvant 2
  Palliative 1
Surgical treatment
  Yes 5
  No 2
Plan target volume, cm3 757.702 (500.37–1,063.08)

Comparisons of the CTV and PTV between the 3D-CT plan and 4D-CT plans.

A, Comparisons of the CTV between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 524.034±128.999 509.609±132.411 504.793±121.959 507.669±125.227 492.642±131.491
V100, cm3 513.763±123.248 502.839±130.326 508.235±142.437 501.892±123.518 487.116±129.799
V95, cm3 523.997±128.984 470.608±79.413 504.319±121.564 507.525±125.144 500.237±120.540
V90, cm3 524.033±128.998 509.376±132.225 504.566±121.769 507.623±125.200 500.334±120.610
V50, cm3 524.034±128.999 509.610±132.409 504.793±121.959 507.669±125.227 500.357±120.627
D95, cGy 5,053.800 (22.900) 5,046.400±18.634 5,050.343±28.339 5,051.371±24.420 5,063.600 (359.900)
D90, cGy 5,061.614±19.707 5,072.657±14.535 5,075.471±22.474 5,076.157±21.694 5,075.214±12.667
D50, cGy 5,157.857±13.989 5,168.357±20.056 5,171.300±15.592 5,170.800±16.469 5,170.100 (30.800)
D5, cGy 5,283.629±16.116 5,309.086±42.371 5,301.171±29.122 5,299.757±19.366 5,294.3 (41.800)
Dmin, cGy 4,580.300 (398.200) 4,813.900 (295.200) 4,881.100 (79.400) 4,755.500 (211.500) 4,848.700 (169.700)
Dmax, cGy 5,529.571±35.763 5,561.643±49.271 5,566.429±60.886 5,543.700±54.525 5,554.171±58.020
Dmean, cGy 5,157.986±14.612 5,173.371±19.373 5,170.900 (43.700) 5,172.243±16.606 5,171.700 (6.800)
B, Comparisons of the PTV between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 776.249±166.189 763.390±171.117 754.455±162.964 758.134±173.683 736.284±185.678
V100, cm3 703.954 (703.954) 710.172 (147.870) 722.857±152.885 732.503±161.832 706.833±172.300
V95, cm3 771.304±165.881 758.704±170.350 747.790±161.510 754.069±173.358 730.658±184.550
V90, cm3 776.115±166.052 762.838±170.593 753.770±162.274 757.892±173.439 735.909±185.307
V50, cm3 776.249±166.189 763.390±171.117 754.455±162.964 758.134±173.683 736.284±185.678
D95, cGy 5,022.000 (28.600) 5,048.700 (37.300) 5,035.400 (46.100) 5,058.100 (38.700) 5,038.200 (43.2000)
D90, cGy 5,050.300 (26.600) 5,058.400 (32.800) 5,061.200 (36.700) 5,084.400 (36.900) 5,065.000 (35.100)
D50, cGy 5,151.614±19.883 5,176.000 (41.500) 5,165.229±21.177 5,166.171±21.292 5,169.214±18.955
D5, cGy 5,286.186±17.435 5,312.900±37.372 5,305.486±28.646 5,304.314±21.177 5,302.400 (21.400)
Dmin, cGy 3,902.786±553.158 3,999.829±570.432 4,139.871±612.871 4,043.829±445.634 3,898.843±583.582
Dmax, cGy 5,580.943±32.960 5,602.914±42.095 5,596.357±41.632 5,628.786±74.522 5,608.300±56.299
Dmean, cGy 5,149.371±23.292 5,165.586±23.352 5,162.686±26.861 5,165.514±25.106 5,167.086±21.546
CI 0.840 (0.080) 0.840 (0.050) 0.840 (0.060) 0.840 (0.050) 0.830 (0.040)
HI 1.050 (0) 1.050 (0.020) 1.050 (0.010) 1.050 (0) 1.050 (0.030)

Data that are normaly distributed are expressed as mean ± standard and all other data are expressed as median (interquartile range). 3D-CT, three-dimensional computed tomography; 4D-CT, four-dimensional computed tomography; AIP, average intensity projection; CI, conformity index; CTV, clinical target volume; Dmax, maximum point dose of the target volume; Dmean, mean point dose of the target volume; Dmin, minimum point dose of the target volume; Dx, minimum dose delivered to x% of the target volume; Vx, the volume receiving no less than x% of the prescription dose; HI, homogeneity index; PTV, plan target volume; cGy, centigray.

Comparison of organs at risk between the 3D-CT plan and 4D-CT plans.

A, Comparison of contralateral breast between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 443.632±125.842bcde 412.736±123.953a 420.366±119.146a 415.838±122.482a 405.546±122.296a
V100, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V95, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V90, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V50, cm3 0.051 (2.025) 0 (1.492) 0 (2.918) 1.079±1.355 0 (1.174)
D95, cGy 235.100±85.804 222.943±60.973 218.500±78.801 256 (127.100) 249.943±109.144
D90, cGy 268.471±88.399 259.257±65.953 252.157±86.770 270.857±69.291 292.329±118.998
D50, cGy 468.743±110.044 464.371±107.091 453.971±143.022 499.000±123.028 514.757±193.549
Dmin, cGy 130.000±60.833 118.757±28.180 125.257±50.198 137.414±44.952 145.243±72.691
Dmax, cGy 3,095.100±1,134.238 2,985.429±1,126.133 3,097.929±1,097.616 3,169.829±1,202.651 2,606.800±1,223.300
Dmean, cGy 552.814±160.896 548.000±135.008 552.214±153.072 585.171±153.823 576.814±224.615
B, Comparison of contralateral lungs between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 1,277.545±299.910c 1,282.555±316.948c 1,160.681±303.191abd 1,292.970±305.323c 1,192.409±315.200
V30, cm3 0 (0.028) 0 (0.114) 0 (0) 0 (0.029) 0 (0.046)
V20, cm3 0.033 (8.205) 0.430 (10.358) 0 (3.852) 0.767 (10.545) 0.023 (8.181)
V10, cm3 104.212±94.178 100.521±74.605 80.887±71.878 99.002±79.668 120.292±124.364
V5, cm3 571.566±215.984 547.182±223.574 467.601±261.863 591.245±291.803 533.447±282.082
Dmin, cGy 70.314±47.183 58.886±29.400 61.743±33.861 54.614±32.909 62.186±33.771
Dmax, cGy 2,411.371±926.260 2,475.143±861.417 2,098.871±796.763 2,340.914±815.578 2,291.971±923.247
Dmean, cGy 506.500 (48.600) 506.786±69.115 478.943±114.060 498.743±89.702 522.500±137.952
C, Comparison of ipsilateral lungs between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 1,293.366±296.783cde 1,283.719±304.658cde 1,184.856±269.076abd 1,373.630±315.333abce 1,207.775±273.286abd
V30, cm3 221.643±38.121cde 228.896±46.964ce 203.222±40.910abd 238.280±43.928ace 205.054±43.384abd
V20, cm3 314.498±66.481cde 316.125±62.331ce 286.039±62.517abd 334.568±65.860ace 289.286±60.105abd
V10, cm3 486.178±117.650ce 473.562±111.914 436.175±101.303ad 506.874±103.594ce 446.127±86.055ad
V5, cm3 729.099±165.369c 642.457 (174.459)e 587.799 (125.114)ad 673.485 (119.525)ce 591.269 (101.470)bd
Dmin, cGy 82.371±51.204 79.386±47.893 84.300±49.682 68.314±50.053 81.357±54.990
Dmax, cGy 5,284.614±76.128 5,283.543±62.539 5,315.743±120.179 5,305.214±79.738 5,288.486±53.484
Dmean, cGy 1,281.600 (211.200) 1,267.300 (63.000) 1,275.700 (74.700) 1,259.200 (143.300) 1,275.400 (150.300)
D, Comparison of contralateral humeral head between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 28.462±10.357 25.734±10.141 26.783±11.037 25.989±10.215 26.011±9.347
V30, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V20, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V10, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V5, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
Dmin, cGy 22.800 (81.300) 43.671±25.406 35.971±20.888 46.786±33.600 33.071±23.574
Dmax, cGy 84.3 (251.200) 217.500±146.926 194.157±170.316 214.600±181.153 248.014±171.875
Dmean, cGy 44.300 (212.500) 117.957±96.788 87.600 (75.500) 69.200 (171.700) 139.329±112.214
E, Comparison of Ipsilateral humeral head between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 26.099±12.287 19.600 (21.870) 26.470±13.640 25.693±12.298 25.506±12.668
V30, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V20, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V10, cm3 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
V5, cm3 0 (4.104) 0 (10.989) 0 (0.103) 0 (1.498) 0 (4.481)
Dmin, cGy 66.3 (72.900) 52.000 (145.500) 57.900 (56.300) 57.700 (77.200) 68.000 (77.500)
Dmax, cGy 190.500 (873.600) 408.200 (1230.20) 363.300 (385.700) 217.800 (690.300) 420.800 (752.200)
Dmean, cGy 108.300 (253.000) 113.100 (562.100) 98.800 (96.400) 95.400 (170.100) 113.400 (285.000)
F, Comparison of Heart (lesions in the left breast) between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 536.802±57.042 552.668±111.836 597.627±144.324 550.867±100.890 574.107±117.065
V40, cm3 24.698±9.714 16.812±3.546 21.360±3.066 19.028±3.066 16.127±6.813
V30, cm3 53.045±21.852 43.779±2.348 45.758±5.379 43.508±4.896 42.364±9.319
Dmin, cGy 167.767±36.235 168.533±17.404 154.933±49.980 145.667±47.388 171.067±31.825
Dmax, cGy 5,171.133±97.184 5,135.067±129.853 5,262.267±80.123 5,246.333±109.470 5094.500±109.390
Dmean, cGy 1,049.933±249.937 929.733±62.684 966.733±76.793 953.200±70.634 975.767±59.327
G, Comparison of Heart (lesions in the right breast) between the 3D-CT plan and 4D-CT plans
4D-CT
Dose parameters 3D-CT AIP MIP T00 T50
Volume, cm3 579.013 (297.004) 655.683±111.829 606.943 (197.833) 633.784±104.173 576.575 (207.698)
V40, cm3 0 (0.040) 0 (0) 0 (0) 0 (0) 0.051(0.281)
V30, cm3 1.557±1.801 1.382±2.078 1.151±1.623 2.452±3.116 2.120±1.993
Dmin, cGy 155.825±72.060 163.850±44.906 163.925±71.999 153.350±39.108 160.125±72.390
VDmax, cGy 3,350.775±758.403 3,313.925±541.515 3,262.275±808.223 3,658.650±588.156 3,764.050±865.463
Dmean, cGy 839.850±83.354 809.775±92.947 745.275±169.622 809.375±44.920 852.950±128.064

P<0.05 vs. 3D-CT plan

P<0.05 vs. AIP plan

P<0.05 vs. MIP plan

P<0.05 vs. T00 plan

P<0.05 vs. T50 plan. Data that are normaly distributed are expressed as mean ± standard and all other data are expressed as median (interquartile range). 3D-CT, three-dimensional computed tomography; 4D-CT, four-dimensional computed tomography; AIP, average intensity projection; CI, conformity index; CTV, clinical target volume; Dmax, maximum point dose of the target volume; Dmean, mean point dose of the target volume; Dmin, minimum point dose of the target volume; Dx, minimum dose delivered to x% of the target volume; Vx, the volume receiving no less than x Gy; cGy, centigray; Gy, gray.