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Introduction: Radiotherapy is the use of ionizing radiation for treatment of diseases, mostly malignant and non-malignant. Its goal is to deliver maximum radiation dose to tumour cells while minimizing dose to the surrounding normal cells. Studies have shown that patients who underwent radiotherapy usually receive highest scattered radiation dose to organs closest to the treatment sites due to inevitable exposure and making them susceptible to cancer induction. This study aims at quantify scattered radiation dose to closest critical organs during external beam radiotherapy of the head & neck, breast, and cervix at the University College Hospital, Ibadan, Nigeria.
Materials and Methods: Seventy-nine patients living with cancer in the region of head & neck, breast or cervix, who gave permission to participate were considered. The closest critical organs of interest are the eye lens, thyroid and femur head respectively. Thermoluminescence dosimeters (TLDs) were used to measure scattered radiation dose to these reference organs during radiation therapy of the target organs. After each treatment session, the exposed TLDs were taken to the designated Research Laboratory for processing with manual TLD reader system, HARSHAW, model 3500.
Results: The mean scattered radiation doses to reference organs during the treatment of head & neck, breast and cervical cancer cases were 110 ±77 cGy (Eye lens), 211 ± 83 cGy (Thyroid), and 319 ±103 cGy (Femur head) respectively.
Conclusion: In all, Femur head received the highest (87% of prescribed dose to target organ) scattered radiation dose followed by thyroid (54%) and the eye lens (32%) from their respective target organ.
Brenner DJ et al. Cancer risks attributable to low doses of ionizing radiation: Assessing what we really know. Proc. Natl. Acad. Sci. 2003;100:13761–13766.
Travis LB, Ng AK, Allan JM et al. Second malignant neoplasms and cardiovascular disease following radiotherapy. Jour. Natl Cancer. 2012;104:357 – 370.
Chaturvedi AK, Engels EA, Gilbert ES, et al. Second cancers among 104,760 survivors of cervical cancer: Evaluation of long-term risk. Jour. Natl Cancer Inst. 2007;99:1634-1643.
Taylor ML, Kron T. Consideration of the radiation dose delivered away from the treatment field to patients in radiotherapy. Jour. Med. Phys. 2011;36(2):59–71.
Miljanic S, Bordy J, D’Errico F, Harrison R, Olko P. Out-of-field dose measurements in radiotherapy- An overview of activity of EURADOS Working Group 9: Radiation protection in medicine. Elsevier, Radiation Measurements. 2014;71:270-275.
Elumelu-Kupoluyi TN, Akinlade BI, Abdus-Salam AA, Adenipekun AA. Measurement of scattered radiation dose to the eyes, breasts and gonads of patients during external beam radiation therapy. Cancer Biology. 2011;1(2):10-16.
Ciraj-Bjelac O, Rehani MM, Sim KH, Liew HB, Vano E, Kleiman NJ. Risk for radiation-induced cataract for staff in interventional cardiology: Is there reason for concern? Catheter Cardio Interv. 2010; 76:826–834.
Followill D, Geis P, Boyer A. Estimates of whole-body dose equivalent produced by beam intensity modulated conformal therapy. Int. J. Radiat. Oncol. Biol. Phys. 1997;38:667–672.
Hall EJ, Wuu CS. Radiation-induced second cancers: The impact of 3D-CRT and IMRT. Int. Jour. Radiat. Oncol. Biol. Phys. 2003;56:83–89.
Kry SF, Salehpour M, Followill DS, Stovall M, Kuban DA, White RA, Rosen I. The calculated risk of fatal secondary malignancies from intensity-modulated radiation therapy. Int. J. Radiat. Oncol. Biol. Phys. 2005;62:1195–1203.
Harvey EB, Brinton LA. Second cancer following cancer of the breast in Connecticut. Journal of the National Cancer Institute Monographs. 1985;68:99-112.
Visneswaran N, Williams MD. Epidemiological trends in head and neck cancer and aids in diagnosis. Oral Maxillofac Surg Clin North Am. 2014; 26:123-141.
Ntekim A, Nufu FT, Campbell OB. Breast cancer in young women in Ibadan, Nigeria, Afr. Health Sci. 2009;9(4):242-246.
Akinfenwa AT, Monsur TA. Burden of cervical cancer in Northern Nigeria. Trop J Obstet. Gynaecol. 2018;35:25-29.
Dorr W, Herrmann T. Second primary tumors after radiotherapy for malignancies, treatment-related parameters. Strahlenther. Onkol. 2002;178: 357–362.
Boice JD Jr, Engholm G, Kleinerman RA. et al. Radiation dose and second cancer risk in patients treated for cancer of the cervix. Radiat. Res. 1998; 116:50-55.
Boice JD, Harvey EB, Blettner M, Stovall M, Flannery JT. Cancer in the contralateral breast after radiotherapy for breast cancer. N. Engl. J. Med. 1992;326:781-785.
Miah FK., Ahmed MF, Begum Z, Alam B, Chowdhury Q. Dose Distribution Over Different Parts of Cancer Patients during Radiotherapy Treatment in Bangladesh. Radiat. Prot. Dosim. 1998;77:199–203.
Ogundare FO, Ademola JA. Scattered doses to different parts of cancer patients during radiotherapy treatment in Nigeria, Radiation Protection Dosimetry. 2002; 102(1):71-74.
Tubiana M. The 2007 Marie Curie prize: the linear no threshold relationship and advances in our understanding of carcinogenesis. Int. J. low Radiat. 2008; 5:173-204.