Imaging in Adaptive Radiotherapy for Cervical Cancers

Introduction

The essay aims to discuss and critically analyze the role of imaging in adaptive radiotherapy for cervical cancers. Over recent years, imaging has had a significant role in adaptive radiotherapy. First, these ranges from volume delineation and localization besides a treatment plan (Ria et al., 2017). Second, it aids optimization of the plan prior to treatment, thus minimizing toxicity while maximizing adaptive radiotherapy. At the same time Spencer (2020), notes that Magnetic Resonance Imaging (MRI) and Cone Beam Computer Tomography (CBCT), imaging modalities, have been proven to provide information that is enormously valuable for planning ART to the cervix, as well as aiding to avoid organs at risk, though the enormous cost around these technologies has always been taken into consideration, for this reason we don’t have these them in each and every one of the radiotherapy departments across the UK. Third, CBCT can discriminate, identify and pinpoint with accuracy the PTV (planning target volume) allocated for treatment. Fourth, through imaging, the accuracy of radiotherapy is made possible (McNair & Buijs, 2019) this implies that it’ll be considered to have an essential role in ART of the cervix. Fifth, the authors also note that imaging in radiotherapy has dramatically influenced and reflected the advances of technology.

Discussion

Imaging is ultimately significant for women who have a cervical malignancy. According to Haldorsen et al. (2019), imaging is essential to the primary diagnostic workups in tumors arising from the cervix. Cecelia's findings agree with this as she states that imaging assists greatly in cervical treatment (2019). According to McNair & Buijs (2019), integrating CBCT into radiotherapy for cervical cancer planning has seen a dramatic upsurge with notable success and improved patient outcomes. Similarly, Spencer (2020) notes that many clinical interventions for cancer through radiotherapy have adopted imaging as the preliminary approach; consequently, the contribution of imaging to adaptive radiotherapy is evident from form the application in various studies and healthcare settings. During radiation treatment of tumors of the cervix, the cervical anatomy and surrounding organs such as bladder tends to change. Adaptive radiotherapy (ART) delivers accurate and precise radiation during such diversities (Kupelian & Sonke, 2016) . ART, as defined by Kupelian & Sonke (2016), is the radiation therapy where treatment is adapted to cover for possible anatomical changes of tumors as well as surrounding organs. This definition is similar to that by Hunt et al. (2018). It thus incorporates deviations in planned, delivered use and anatomy of the same. Hunt’s work implies that the cervical tumour will possibly shrink in size after two weeks of treatment, therefore highlights the need for plan optimization. According to Hunt et al. (2018), adaptive radiotherapy monitors the variations of the malignancy as well as the movement/activity of organs at risk surrounding the cervix. Besides, the authors add that the procedure's importance is to capture the actual dose delivered to the target and the adjacent critical organs at risk on the course of radiotherapy. Similarly, Cecilia (2019) note that image guidance's quality of radiation delivery has influenced the accuracy of procedures. They support their argument that organ motion such as bladder and rectum as well as neoplasm shrinkage occur throughout the delivery of radiotherapy to the cervix (Kupelian & Sonke, 2016). These authors expose the significance of imaging in radiotherapy for cervical cancer. The imaging procedure helps distinguish uterine cervical carcinoma from the normal uterine cervix besides differentiating metastatic nodes from benign nodes. This specific patient group requires imaging for diagnosis and treatment of the condition via adaptive radiotherapy (Kupelian & Sonke, 2016). To better assess the tumor extent and metastatic disease, Haldorsen et al. Recommend diagnostic imaging during the primary diagnostic workups (2019). Also, diagnostic imaging is ultimately instrumental for pretreatment; what’s more adequate immobilization devices will be selected, this step is very important as it will aid repetition and reproducibility during the adaptive radiotherapy treatment of the pelvis area, aiding the patient hold still in the desired position and this way guiding optimal treatment strategy. Following on from Haldorsen et al. (2019) it is important to take into consideration that planning of the treatment will begin in CT (computer tomography) where the first image is obtained with the aim of developing a plan. The title suggest a tumor arising from the cervix, this tell us that it will be an early stage, such as T1N0M0, which could mean the course of radiotherapy will be administered over the course of several weeks hence the importance of immobilization devices for accurate reproduction and duplication of the first time position adopted during the CT procedure. As already mentioned in the discussions above, Bourgioti et al. identify cross-sectional imaging as the most desired imaging modality required for adaptive radiotherapy (2016). Besides, CBCT is the preferred imaging modality for cervical cancer in the UK due to its high contrast resolution (Bourgioti et al., 2016). Similarly, Haldorsen et al. (2019) note that CBCT accurately values for determining the tumour morphology. In patients with cervical cancer, sparing bladder, rectum, and small bowel is a challenge since all organs at risk (OAR) in the pelvic area change their shape and positions daily as a result of variations in filling (Spencer, 2020). However, with the implementation of CBCT during ART, observing the organs’ internal variations of patients during each treatment fraction has been made a possibility (Rodgers et al., 2020). CBCT has enabled a reduction in toxicity and better target coverage due to re-adaptations to cater to the tumour shrinkage and changes in OAR morphology and topography. The OAR is inclusive of the uterus that can move rectum and the bladder that undergoes filling and emptying changing its morphology. National Radiotherapy Implementation Group Report (NRIG) and Society of Radiographers have recommended the integration of CBCT in the UK, and CBCT is available in radiotherapy departments across the UK. Duffton et al. (2020), argues that CBCT has an adequate role in the treatment of cervical cancer where bladder filling is a dominant factor of shape changes and a critical step to reduce bladder exposure when its size is increased, displacing itself as well as organs at risk away from the field of the radiation. According to Mason et al. (2019), the use of CBCT encounters barriers. First, it requires an additional radiation dose and has low soft-tissue contrast due to scattering and reconstruction artifacts. Soft tissues are thus not viewed properly. CBCT imaging noise is detrimental. CBCT has increased scan time; consequently, Mason et al. (2019), argues that motion artifact is present. In another study, scan volume by CBCT shows to be insufficient. Kamburoğlu (2015), advocates that the use of CBCT adds extra time. Besides, Mason et al. argue that the scattered radiation contributes to increased noise of the image, thus reducing the contrast of the cone-beam system (2019). Patient movements cause image degradation. CBCT is also costly relative to other cheaper imaging modalities. CBCT has a limited field of view (Kamburoğlu, 2015). The higher the radiation exposure in CBCT the more future side effects the patients might experience, CBCT adheres to ALARP/A, as low as reasonably practicable/achievable principle that aims at ensuring minimal radiation and as advocated by the IRMER, Ionising Radiation for Medical Exposures Regulations (Kamburoğlu, 2015). Reducing unnecessary exposure is an important role and part of safe practices of the Operators as well as practitioners.

Conclusion

Cervical cancer is one of the conditions affecting women in the UK. Due to the dangerous implications, evidence-based intervention is essential to the management of the state of the cervix. Adaptive radiotherapy is one of the best interventions for the treatment. This paper has critically discussed the role of imaging in adaptive radiotherapy in cervical cancer. For instance, the essay has noted that imaging helps distinguish the activity of organs that surround the cervix as well as accurately exposing the PTV (planning target volume). Also, the essay has identified the best imaging modality for adaptive radiotherapy, which is CBCT. Strengths, limitations of this imaging modality have been discussed, and its availability in radiotherapy departments across the UK (Saunders et al., 2016). The paper has detailed the role that imaging plays in adaptive radiotherapy for cervical cancer patients in a broad context. In conclusion, imaging in adaptive radiotherapy has a severe and indispensable part when delivering ART to the cervix.

Dig deeper into Identifying Target Groups, and Addressing Critical Health Needs with our selection of articles.

Reference

Bourgioti, C., Chatoupis, K., & Moulopoulos, L. A. (2016). Current imaging strategies for the evaluation of uterine cervical cancer. World journal of radiology, 8(4), 342–354. https://doi.org/10.4329/wjr.v8.i4.342

Cecelia H. B. (2019) What is the role of imaging studies in the workup of cervical cancer? Virginia Gynecologic Oncology https://www.medscape.com/

determine management and predict an outcome.

Duffton, A., Li, W., & Forde, E. (2020). The pivotal role of the therapeutic radiographer/radiation therapist in image-guided radiotherapy research and development. Clinical Oncology.

Haldorsen, I. S., Lura, N., Blaakær, J., Fischerova, D., & Werner, H. (2019). What Is the Role of Imaging at Primary Diagnostic Work-Up in Uterine Cervical Cancer?. Current oncology reports, 21(9), 77. https://doi.org/10.1007/s11912-019-0824-0

Hunt, A., Hansen, V. N., Oelfke, U., Nill, S., & Hafeez, S. (2018). Adaptive radiotherapy enabled by MRI guidance. Clinical Oncology, 30(11), 711-719.

Kamburoğlu, K. (2015). Use of dentomaxillofacial cone-beam computed tomography. World journal of radiology, 7(6), 128–130. https://doi.org/10.4329/wjr.v7.i6.128

Kupelian, P., & Sonke, J. J. (2016). Magnetic resonance-guided adaptive radiotherapy: a solution to the future. In Seminars in radiation oncology (Vol. 24, No. 3, pp. 227-232).

Mason, S. A., White, I. M., O'Shea, T., McNair, H. A., Alexander, S., Kalaitzaki, E., Bamber, J. C., Harris, E. J., & Lalondrelle, S. (2019). Combined Ultrasound and Cone Beam CT

Improve Target Segmentation for Image-Guided Radiation Therapy in Uterine Cervix Cancer. International Journal of radiation oncology, biology, physics, 104(3), 685–693. https://doi.org/10.1016/j.ijrobp.2019.03.003

McNair, H., & Buijs, M. (2019). Image guided radiotherapy moving towards real time adaptive radiotherapy; global positioning system for radiotherapy?. Technical innovations & patient support in radiation oncology, 12, 1–2. https://doi.org/10.1016/j.tipsro.2019.10.006

Rai, R., Kumar, S., Batumalai, V., Elwadia, D., Ohanessian, L., Juresic, E., Cassapi, L., Vinod, S. K., Holloway, L., Keall, P. J., & Liney, G. P. (2017). The integration of MRI in radiation therapy: a collaboration of radiographers and radiation therapists. Journal of medical radiation sciences, 64(1), 61–68. https://doi.org/10.1002/jmrs.225

Rodgers, J., Hales, R., Whiteside, L., Parker, J., McHugh, L., Cree, A., ... & Eccles, C. L. (2020). Comparison of radiographer interobserver image registration variability using cone-beam CT and MR for cervix radiotherapy. The British Journal of radiology, 93(1112), 20200169.

Spencer, J. A. (2020). Magnetic resonance imaging of the pelvis: Better techniques can help

Tan, L. T., de Leeuw PhD, A., Remi Nout, M. D., Simon Duke, M. B. B. S., Lars Fokdal, M. D., Alina Sturdza, M. D., ... & Jürgenliemk-Schulz, I. (2019, July). Image-guided adaptive radiotherapy in cervical cancer. In Seminars in Radiation Oncology (Vol. 29, No. 3, pp. 284-298). WB Saunders.

WB Saunders. McPartlin, A. J., Li, X. A., Kershaw, L. E., Heide, U., Kerkmeijer, L., Lawton, C., ... & Vesprini, D. (2016). MRI-guided prostate adaptive radiotherapy–a systematic review. Radiotherapy and Oncology, 119(3), 371-380.