Submit Manuscript | http://medcraveonline.com Background In the past few decades, CT has been widely used in all kinds of diagnostic procedures and proved clinically efective. 1 The very past decade has also seen the dramatic increase in the applications of CBCT in the radiotherapeutic management of cancers. 2 Although implemented diferently in the clinic, the radiation dose from both CT and CBCT scans has been a great concern among the clinicians and the general public, particularly to the children, as they are far more susceptible than the adults to radiation-induced late efects such as growth retardation and second malignancies. 1,3 While CT Dose Index (CTDI) has been widely used in categorizing radiation doses from CT and CBCT scanners, it is a scanner-dependent index and not directly related to the organ dose in the patient being scanned. 4 On the other hand, modern radiotherapy treatment planning systems (TPS) do not ofer CT/CBCT dose calculation capability. Although the Monte Carlo algorithm can be used to simulate the radiation dose from CT/CBCT scans, it is very time-consuming and usually requires Monte Carlo expertise. Hence, it would be highly desirable to have an easy-to-use tool that can be used to estimate the radiation dose from an imaging procedure performed on an individual anatomy. Development of an iphone app As the Apple iPhone is highly popular around the world, an iPhone app designed for such a purpose would be ideal to maximize its accessibility to the general public as well as medical practitioners. In October 2011, the CT Gently app project was initiated in collaboration with Komatsu Business Service Co. in Tokyo, Japan. The app was developed with Apple Xcode 4.2.1 toolkits with all the functionalities running on an Apple iPhone platform. The whole project was fnished by June 2013 and the CT Gently app was released to the public for free downloads via Apple iTunes at https://itunes.apple.com/us/app/ ct-gently/id654734773?mt=8. The philosophy for the interface design is two-folds: simplicity and efciency. As shown in Figure 1, after the user inputs one’s gender, age, weight, corresponding circumference at three anatomic sites (i.e., head, chest and abdomen) and given mAs and kVp values, CT Gently can generate comparative results both quantitatively and graphically on the organ doses and the associated cancer risks between the reference and the optimized settings for a CT or CBCT scan. It also allows the user to switch the units for weight and length between the international standard and the English system. In addition, a Question & Answer (Q&A) page can be accessed for simple explanations on the basic terms and concepts such as CT, CBCT, mAs, kVp, organ dose and relative risk etc. Organ dose estimation Based on Monte Carlo modeling of the CT and CBCT scans and particle transport simulation in human anatomy of various dimensions, the radiation doses to the various organs-at-risk (OARs) at the head, the chest and the abdomen regions can be obtained for a specifc scan of given mAs and kVp values. 5‒12 In addition, personalized estimation of organ dose has been made possible based on some early cohort studies investigating the correlations between the organ dose and one’s weight, circumference, scan mAs and kVp. 9‒12 Finally, to facilitate the calculation of organ dose, these correlations between the organ dose and the scan settings as well as anthropometric parameters have been formulated and implemented in CT Gently. Figure 1 Screen shots of the CT Gently app running in the CT mode (left and middle panels) and CBCT mode (right panel), respectively. Specifcally, a head CT scan is shown on the left with the mean radiation dose to the brain tissue and relative cancer risk calculated for the reference and optimized settings, respectively. Similarly, a chest CT scan and an abdominal CBCT scan are illustrated in the middle and right with lung tissue and red bone marrow as the critical structures, respectively. Screen shots of the CT Gently app running in the CT mode (left and middle panels) and CBCT mode (right panel), respectively. Specifcally, a head CT scan is shown on the left with the mean radiation dose to the brain tissue and relative cancer risk calculated for the reference and optimized settings, respectively. Similarly, a chest CT scan and an abdominal CBCT scan are illustrated in the middle and right with lung tissue and red bone marrow as the critical structures, respectively. J Cancer Prev Curr Res. 2014;1(1):4‒6. 4 ©2014 Deng et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestrited use, distribution, and build upon your work non-commercially. CT gently: a mobile tool for CT/CBCT dose and cancer risk estimation Volume 1 Issue 1 - 2014 Jun Deng, 1 Huajun Zhang, 2 Hai Qi 2 1 Department of Therapeutic Radiology,Yale University, USA 2 Komatsu Business Service Co., Chiyoda-ku, Japan Correspondence: Jun Deng, Department of Therapeutic Radiology of Yale University School of Medicine,Yale University, Yale-New Haven Hospital, New Haven, CT, USA, Email Received: April 23, 2014 | Published: May 16, 2014 Abstract Computed tomography (CT) and cone-beam computed tomography (CBCT) scans have been widely used in the radiotherapy of cancers worldwide. Yet, so far there has been no efcient way available to estimate the organ dose and cancer risk originated from those imaging studies. To address this issue, we have recently developed an iPhone app called CT Gently that can be used to estimate organ doses and associated cancer risk from CT and CBCT scans based on individual anatomy and scan mode. In addition, the CT Gently app can be used to generate optimized mAs and kVp settings for personalized low-dose CT and CBCT scans. Journal of Cancer Prevention & Current Research Short Communication Open Access