Radiotherapy Room Research Articles

An initial study on common concrete, titanium dioxide and tungsten dioxide for shielding of a standard external photon beam radiotherapy room

High-energy ionizing radiations have several applications including the treatment of various types of cancer. Advanced techniques such as IMRT (Intensity Modulated Radiation Therapy) and VMAT (Volumetric Modulated Arc Therapy) using high-energy photon beams have been largely used for radiation therapy of cancer. An important issue in radiotherapy is the evaluation of the shielding of the walls of the facility room housing a linear accelerator that produces high-energy photon beams. In this study we performed an estimation of the thicknesses of a standard radiotherapy room considering three different materials: common concrete, titanium dioxide (TiO2) and tungsten dioxide (WO2). It is assumed that patients are treated with photon beams of energies varying from 4 to 30 MeV and considering two types of treatments, only conventional and conventional plus IMRT and VMAT treatment. Results have shown an overall growth of thicknesses with energy, workload, area and type of treatment. At 1,000 Gy/week and 30 MeV photon energy the primary barrier thickness using concrete as the shielding material showed to be substantially higher as compared to TiO2 (143%) and WO2 (1,360%). Results have also indicated an overall linear increasing of volumes with the area used to construct the facility room.

Gamma rays and neutrons attenuation performance of a developed lead borate glass for radiotherapy room.

The development of radiation therapy necessitated a continuous R&D for radiotherapy rooms' glass windows to reach the highest levels of protection for the staff of the radiotherapy facility. Therefore, in this article, a novel type of lead borate glass depending on parallel augmenting of lead and boron was produced to be used as gamma-rays and fast and thermal neutrons barriers in radiotherapy rooms. Neutrons and gamma rays' attenuation parameters, fast neutrons removal cross section ${\varSigma}_R$, thermal neutron total cross section ${\sigma}_T$, mass attenuation coefficient $\sigma$, linear attenuation coefficient μ, half-value layer, mean free path, effective atomic number Zeff, effective electron density Neff, and buildup factor for energy absorption (energy absorption buildup factor) and exposure (exposure buildup factor) were studied extensively. Three tools, Phy-X/PSD, EpiXS and XCOM computer programs and the standard mixture rules were utilized to estimate the attenuation parameters. The improvement caused by the augmentation of lead and boron in both gamma rays and neutrons attenuation was evident from the obtained results. The glass containing the highest lead and boron concentration PbB5, 40Pb-50B, which is the most efficient attenuator for gamma rays and both thermal and fast neutrons was recommended to be a distinguished choice as a shield in a radiotherapy room.

MLEM Neutron Spectra Unfolding in a Radiotherapy Bunker Using Bonner Sphere Spectrometer

High-energy radiotherapy treatments of a medical Linear Accelerator (LinAc) generate secondary neutrons that can produce health damage on the human body as the induction of secondary cancers. The energy spectrum of these neutrons must be determined to estimate the extra dose received by patients inside a radiotherapy room during radiotherapy treatment. To quantify the neutron production, a Ludlum Bonner sphere spectrometer (BSS) is used for measurement at different points of a LinAc bunker at the Hospital Universitari i Politècnic La Fe de València. With the neutron measured data and a set of response detector curves obtained by Monte Carlo simulations with MCNP6.1.1, the Maximum Likelihood Expectation Maximization unfolding method is used to unfold the energy neutron spectrum. Unfolded neutron spectra at different locations were compared to those obtained by Monte Carlo simulation of the same setup, showing the same energetic behavior. The fluence rate decreases with source distance, and the shape changes from a fast neutron peak in the nearest LinAc head location to a prominent thermal neutron peak in the bunker maze region. Moreover, the neutron ambient equivalent dose was obtained from the unfolded spectra and compared to Berthold detector measurements, being consistent.

Radiotherapy Infrastructure Shielding Calculations: software development for shielding calculations in a linear accelerator radiotherapy room.

This work aimed to develop and validate software that calculates the shielding thickness required for a radiotherapy room with a linear accelerator utilising geometric and dosimetric data. The software "Radiotherapy Infrastructure Shielding Calculations" (RISC) was developed using MATLAB programming. It does not require the installation of the MATLAB platform, and the user only needs to download and install the application, which displays a graphical user interface (GUI). The GUI includes empty cells to insert numerical values for several parameters to calculate the proper shielding thickness. The GUI comprises two main interfaces, one for the primary and one for the secondary barrier calculation. The interface of the primary barrier is divided into four tabs: (a) primary radiation, (b) patient scattered and leakage radiation, (c) IMRT techniques and (d) the shielding cost calculations. The interface of the secondary barrier includes three tabs: (a) patient scattered and leakage radiation, (b) IMRT techniques and (c) the shielding cost calculations. Each tab consists of two sections: one for input and one for output of the necessary data. The RISC is based on the methods and formulae of the NCRP 151 and calculates the primary and secondary barrier thickness for ordinary concrete with a density of 2.35g/cm3 and the cost for a radiotherapy room with a linear accelerator that performs conventional or IMRT techniques. Calculations can be performed for photon energies of 4, 6, 10, 15, 18, 20, 25 and 30 MV of a dual-energy linear accelerator, while instantaneous dose rate (IDR) calculations are also performed. The RISC has been validated using all comparative examples of NCRP 151 and the calculations from shielding reports of the Varian IX linear accelerator at Methodist Hospital of Willowbrook and Elekta Infinity at the University Hospital of Patras. The RISC is accompanied by two text files: (a) "Terminology," extensively describing all parameters, and (b) "User's Manual," providing useful instructions to the user. The RISC is user-friendly, simple, fast and precise, providing accurate shielding calculations and quickly and easily reproducing different shielding scenarios for a radiotherapy room with a linear accelerator. Additionally, it could be used during the educational process of shielding calculations by graduate students or trainee medical physicists. As a future work, the RISC will be updated with new features such as skyshine radiation, door shielding, and other types of machines and shielding materials.

Modification of 3D Printable Polymer Filaments for Radiation Shielding Applications

There is a growing need to develop lead-free shielding materials that are safe, low weight, durable, environmentally friendly, chemically and mechanically stable and customizable for specific applications. Fused deposition modeling (FDM), an additive manufacturing technique based on the extrusion of a thermoplastic filament into a 3D printed object one layer at a time, could be employed well in applications involving ionizing radiation due to its relatively low cost, design flexibility and high manufacturing precision. This study aimed at developing 3D printing composites that contain Titanium dioxide as a filler agent for shielding in a medical radiation environment. First, the effect of low-dose ionizing radiation (up to 15 Gy) on the mechanical properties of common 3D printing polymers, ABS, ULTRAT, PLA, NYLON, ASA and PETG, was investigated. Since ABS experienced the lowest variation in its ultimate tensile strength (±5%) and Young's modulus (-5%/+11%), it was chosen as a matrix for a new extruded 3D filament containing TiO2 at 1 wt.%, 3 wt.%, and 5 wt.%. With the incorporation of TiO2 at different filler contents, the UTS of the ABS composites varied between 24.1 MPa and 28.4 MPa, with the highest value recorded for 3 wt.% TiO2. Young's modulus values were dependent on both the TiO2 concentration and on the irradiation dose. In addition, the ABS/TiO2 composites with a higher filler content (3 wt.% and 5 wt.%) maintained their attenuation ability even after exposure to a radiation dose of 100 Gy as opposed to pure ABS, which exhibited a ~2.5% reduction in its mass attenuation coefficient after exposure to the same dose of radiation. The pilot investigation performed demonstrated that the newly developed ABS/TiO2 composite containing 5 wt.% of filler can be successfully employed to shield electronic devices operating in a radiotherapy room.

Pilot study of aerosols visualized and evaluated in a radiotherapy room.

Health care institutions provide prevention strategies for coronavirus disease 2019 and non-infectious disease care. We investigated the characteristics of patient contamination in a radiotherapy room by examining the trajectory and number of airborne particles in the air when talking and coughing occurred and clarified the actual state of contamination in this closed space. Aerosols were visualized and evaluated in the vertical height and head-to-tail width directions when the participant was lying on the radiotherapy tabletop. Aerosol reach was significantly greater for loud voice and coughing both at vertical height and the head-to-tail width direction. The size and number of particles around the radiotherapy tabletop were also visualized and evaluated in the radiotherapy room. The radiotherapy staff who were in the presence of the participant sometimes had many particles adhering to their facial area; particle adhesion to the staff was dominated by small size particles. Particle adherence to the irradiation device surface near the ceiling had particles larger than 1mm. Tabletop particles tended to have a wider size range, including bigger sizes and a larger count compared to the surrounding floor. The 0.7-m radius distance from the participant's mouth tended to be highly contaminated, and the smaller the particle size, the farther it reached. The capacity to estimate areas prone to contamination can be used to predict infection of other patients and medical staff in a radiotherapy room.

Evaluation of neutron spectra and different fluences inside a radiotherapy room with a modified simple geometry of LINAC head

The photoneutron spectra and ambient dose equivalent were determined in a radiotherapy room with a 15 MV linear accelerator using Monte Carlo simulation. A modified simple geometry of the accelerator’s head was modeled by different simulations. Then, by putting it in a radiotherapy room, the photoneutron spectra at different distances from the isocenter and in the maze were determined. The source term spectrum is due to evaporation, and knock-on neutrons. In the presence of the walls, as the distance from isocenter is increased, evaporation and knock-on neutrons are reduced; however, epithermal and thermal neutrons tend to remain constant. The walls also play an influential role in increasing the photoneutron ambient dose equivalent. Subsequently, by placing this modified accelerator’s head in the radiotherapy room, the coefficients of scattered and thermal fluences were also estimated.

An estimation of cost of concrete shielding in a radiotherapy room housing a clinical linear accelerator that produces high-energy photons – Part II

High-energy photons produced by large medical linear accelerators are widely used in medicine for the treatment of various types of malignant tumors. In the last decades the use of photon beams in radiation therapy was improved due to the arising of advanced technologies and techniques of treatment such as IMRT (intensity modulated radiation therapy), VMAT (volumetric modulated arc therapy), IGRT (image guided radiotherapy) and SBRT (stereotactic body radiation therapy). However, we should guarantee that the use of these procedures does not increase the radiation doses in the vicinities of the radiotherapy room above the permissible level. In this work we carry out an estimation of cost of concrete shielding for a standard radiotherapy room and for photon energies ranging from 4 to 30 MeV (megaelectron volts), and always considering the constraint of the allowed level of radiation in the vicinity of the room. Results have indicated that total cost of concrete increases about 22-25% when photon energies increase from the minimum to the maximum values analyzed. Results also indicated an overall linear increasing of cost with the area of the treatment room and may support some of the guidelines of radiation protection.

An estimation of cost of concrete shielding in a radiotherapy room housing a clinical linear accelerator that produces high-energy photons

Ionizing radiations have an important role in medicine in the treatment of various types of cancer. In particular high-energy photon beams associated with advanced techniques such as IMRT (intensity modulated radiation therapy) and VMAT (volumetric modulated arc therapy) have been largely used in external beam radiotherapy. However, the use of these techniques requires a special attention to the shielding of the walls of the facility room housing a linear accelerator that produces high-energy photon beams. In this study we performed an estimation of cost of concrete shielding to a radiotherapy room where patients are treated with photon beams of energies from 4 to 30 MeV (mega-electron volts) based on simple assumptions. Results have shown that total cost of concrete increases about 19% when photon energies increase from 4 to 30 MeV for conventional therapy and about 23% when modern techniques are included. Results have also indicated a linear increasing of costs with the area of the facility room.

Manual on the proper use of meta-[211At] astato-benzylguanidine ([211At] MABG) injections in clinical trials for targeted alpha therapy (1st edition)

In this manuscript, we present the guideline for use of meta-[211At] astatobenzylguanidine ([211At] MABG), a newly introduced alpha emitting radiopharmaceutical to the up-coming World’s first clinical trial for targeted alpha therapy (TAT) at Fukushima Medical University in Japan, focusing on radiation safety issues in Japan. This guideline was prepared based on a study supported by the Ministry of Health, Labour, and Welfare, and approved by the Japanese Society of Nuclear Medicine on Oct. 5th, 2021. The study showed that patients receiving [211At] MABG do not need to be admitted to a radiotherapy room and that TAT using [211At] MABG is possible on an outpatient basis. The radiation exposure from the patient is within the safety standards of the ICRP and IAEA recommendations for the general public and caregivers or patient’s family members. In this guideline, the following contents are also included: precautions for patients and their families, safety management associated with the use of [211At] MABG, education and training, and disposal of medical radioactive contaminants. TAT using [211At] MABG in Japan should be carried out according to this guideline. Although this guideline is based on the medical environment and laws and regulations in Japan, the issues for radiation protection and evaluation methodology presented in this guideline are useful and internationally acceptable as well.

Comparison of backscattered photons from various thicknesses of ordinary and baryte concretes using FLUKA code for energies 0.25–20 MeV

With the advancement of medical technology and increased radiation technologies, the main material in radiation building construction is concrete, either ordinary or, more recently, heavy-weight concrete called baryte concrete (BaSO4). Numerous studies were performed on calculating and measuring linear attenuation coefficients μ (cm−1) for ordinary and baryte concrete, but few for backscattered photons and reflection coefficients. As a result, determining the photon reflection coefficient and backscattered photon data for ordinary and baryte concrete has become more commonplace. The ability to provide precise reflection coefficient data has consequences in various fields, including radiation protection, industry, and radiotherapy room design. As a result, the purpose of this study is to determine photon reflection coefficients for different thicknesses of ordinary and baryte concrete. This new information might be applied to various uses, such as saving money and space by enhancing the design of mazes used in radiation facilities. The FLUKA Monte Carlo code was used to calculate photon reflection coefficients with different energies and for varying thicknesses of ordinary and baryte concrete to investigate the impact of concrete wall thicknesses. The reflection coefficient as a function of various energies has been tabulated and figured to study the dose reduction factor compared to ordinary concrete. Recent research reveals that baryte concrete with a high density is beneficial as a shield for constructing radiation facilities to minimise the backscattered photon exposure in the incident energy range below 2 MeV. This new data has been presented in many applications, such as improving the mazes used for radiotherapy rooms; reducing cost and space requirements. In addition, the Monte Carlo method enables calculating the energy distribution of reflected photons, and these were shown for a range of angles.

Anesthesia Services for Children's Radiotherapy During Pandemic COVID-19 in 2020: Experience from East Indonesia

Background: The global COVID-19 pandemic has significantly strained the healthcare sector, with overwhelmed health services in affected countries worldwide. Despite the need to sustain vital oncology treatments, particularly for children, radiotherapy practitioners are unsure how to treat during the pandemic. At the same time, several anesthesia procedures may increasingly expose anesthesia providers to COVID-19. The challenging services for handling oncology cases in children at Dr. Soetomo Hospital during the COVID-19 pandemic can be carried out properly with various adjustments. Objective: The purpose of this study was to describe how the radiotherapy center in East Indonesia responds to the challenge in this pandemic era.Method: During 2020, we gathered information by using administrative datasets on the number of patients, the types of anesthesia services provided, and undesired events in the radiotherapy room. We use descriptive statistics to describe what is going on in our data.Result: The total number of patients who underwent radiotherapy was 12, with 188 sessions, and uncooperative children received midazolam and propofol during the procedure. The result showed that there was no untoward incident in 2020.Conclusion: Therefore, it indicates that we provided relatively safe sedation services for children's radiotherapy.

Monte Carlo simulation of photons backscattering from various thicknesses of lead layered over concrete for energies 0.25\u201320\xa0MeV using FLUKA code

There is an increased interest in determining the photon reflection coefficient for layered systems consisting of lead (Pb) and concrete. The generation of accurate reflection coefficient data has implications for many fields, especially radiation protection, industry, and radiotherapy room design. Therefore, this study aims to calculate the reflection coefficients of photons for various lead thicknesses covering the concrete. This new data for lead, layered over concrete, supports various applications, such as an improved design of the mazes used for radiotherapy rooms, which helps to reduce cost and space requirements. The FLUKA Monte Carlo code was used to calculate photon reflection coefficients for a concrete wall with different energies. The reflection coefficient was also calculated for a concrete wall covered by varying thicknesses of lead to study the effect of lining this metal on the concrete wall. The concrete's reflection coefficient data were compared to internationally published data and showed that Monte Carlo calculations differed significantly from some of the extrapolated data. The absorbed dose of backscattered photons for various thicknesses of lead covering the ordinary concrete has been tabulated as a function of the reflection angle. Also, the reflection coefficient as a function of the Pb thicknesses covering the ordinary concrete has been figured to study the dose reduction factor. The generation of accurate data for reflection coefficients is vital for many fields, especially for radiation protection and radiotherapy room design. The new data have been presented for lead layered over concrete in various applications, such as an improvement in the design of the mazes used for radiotherapy rooms, thereby reducing the cost and space requirements. In addition, the Monte Carlo method enables calculating the energy distribution of reflected photons, and these were shown for a range of angles.

Manual on the proper use of sodium astatide ([211At]NaAt) injections in clinical trials for targeted alpha therapy (1st edition)

We present the guideline for use of [211At] sodium astatide (NaAt) for targeted alpha therapy in clinical trials on the basis of radiation safety issues in Japan. This guideline was prepared by a study supported by the Ministry of Health, Labour, and Welfare, and approved by the Japanese Society of Nuclear Medicine on 8th Feb, 2021. The study showed that patients receiving [211At]NaAt do not need to be admitted to a radiotherapy room and outpatient treatment is possible. The radiation exposure from the patient is within the safety standards of the ICRP and IAEA recommendations for the general public and caregivers. Precautions for patients and their families, safety management associated with the use of [211At]NaAt, education and training, and disposal of medical radioactive contaminants are also included in this guideline. Treatment using [211At]NaAt in Japan should be carried out according to this guideline. Although this guideline is applied in Japan, the issues for radiation protection and evaluation methodology shown here are considered internationally useful as well.

Study of the Effectiveness of Radiation Retaining Materials for the Entrance of LINAC 6 MV Radiotherapy Room

LINAC radiotherapy devices can produce scattering radiation and leak radiation from the gantry. The doses of scattering radiation result from the scattering radiations from the wall (HST) and the patient (HPS). Gantry leak radiation is gantry leak radiation through the labyrinth hall (HLS) and the one that goes directly to the entrance (HLT). These four components play a role in producing radiation doses at the entrance. The scattering radiation in the LINAC 6 MV radiotherapy installation can spread in all directions. Therefore, there is a need for a special review to examine the scattering radiation to the entrance of the room. The constituent of the radiation retaining wall also influences the reflection coefficient of the wall (α). Therefore, it is important to pay attention to the α value in evaluating the radiation dose at the labyrinth entrance. Radiation protection efforts for radiation workers and the community around the radiotherapy room need to be considered by creating a radiation barrier that can minimize the radiation received. With that in mind, the purpose of this study is to examine several possible materials for radiation shielding, especially at the entrance of the radiotherapy room. Materials used for the entrance are lead (Pb), borated polyethylene (BPE), aluminum (Al), and iron (Fe) with a thickness of 6 mm, respectively. The variation of the reflected angle used in the calculation of HST, HLS, and HPS values starts from an angle of 50° to 80°. The result showed that the most effective material for reducing the amount of radiation is lead with effectiveness of 86.79%.

Novel design of radiotherapy room suggestion - three-band maze

The objective of this study was to analyze the dependence of the neutron dose from the geometry of the second band of the maze using dosimetric measurements of neutrons and Monte Carlo simulations, and based on those results to design a novel radiotherapy room layout. Measurements of the neutron dose at a two-band maze therapy room were performed for a 15 MeV photon beam only. Monte Carlo simulations were performed using the GEANT4 toolkit. In order to obtain the geometry dependence, we were changing the second band angle while we kept the length, height, and width the same as in reality. Results show that the highest calculated dose was obtained for the 60? angle of the second maze. It is 17 % higher than for standard 0? angle. For 30? it was 30 % smaller and for 90? was 10% smaller. Although the lowest dose was obtained for 30? band angle with calculations, it is not very practical for clinical use. Clinically the most interesting would be the 90? angle which is practically a short three-band maze, which could be promising from the perspective of neutron radiation protection since it could offer a compact constructional solution, and better optimization of the available space.

Measurement of Neutron Contamination at Different Points in the Radiotherapy Room

Radyoterapi, kanser tedavisinde kullanılan en önemli tedavi yöntemlerinden birisidir. Ancak, radyoterapide yüksek enerjili foton ve elektron demetlerinin kullanımı sırasında (>7 MV) lineer hızlandırıcı kafasında bulunan ağır metallerden kaynaklı nötron kirliliği oluşmaktadır. Bu durum, hedef hacimde ve çevresindeki diğer organlarda nötron kirliliğinden kaynaklı doz belirsizliğine neden olmakta ve ikincil kanser riski oluşturmaktadır. Bu çalışmada, 18 MV foton enerjisinde, Elekta Synergy lineer hızlandırıcıda Thermo Scientific Rad Eye NL marka nötron dedektörü ile alan açıklığının ve eşmerkeze olan uzaklığın nötron doz hızına olan etkisi incelenmiştir. Ayrıca, alan açıklığının nötron doz hızı üzerindeki etkisi eşmerkezde, eşmerkezden farklı uzaklıklarda, radyoterapi odası kapısının içi ve dışında, konsol odasında ölçümler alınarak araştırılmıştır. Radyoterapide, 18 MV enerjili fotonların neden olduğu nötron kirliliğinden kaynaklı doz belirsizliğinin ikincil kanser riskini artırabileceği öngörülmüştür. Bu nedenle, radyoterapide istenmeyen fotonötron dozunun dikkate alınmasının çok önemli olduğu sonucuna varılmıştır.

Shielding implications on secondary radiation doses in prostate cancer treatment

AbstractMedical linear accelerators (linacs) require a physical structure designed to provide adequate structural support which ensures the safety of patients, operators and the general public. During a radiotherapy session, healthy tissues are exposed to radiation, even with these safety guarantees. This unwanted exposure may increase the likelihood of developing secondary cancer. This work uses the MCNP-5 code to computationally simulate a conformational 3D radiotherapy protocol for prostate cancer. Also, it investigates the potential effects of radiotherapy room shielding composition on equivalent and effective doses in the patient’s body. A computational model of an actual room was developed considering a Varian Trilogy linac operating at 10 MeV. This model enabled dose calculations for an anthropomorphic phantom called REX to be performed. This phantom has sufficient details of all relevant organs and tissues needed to estimate the effective dose of the patient. The treatment protocol modeled in this study came from the database of patients treated by the Brazilian National Cancer Institute (Inca). For this protocol, the total dose to be applied to the patient is equally distributed over the four gantry inclination angles (0°, 90°, 180° and 270°). The simulated results suggested that the equivalent dose on different organs and tissues has been increased by concrete shielding. Regarding the effective dose due to the presence of additional shielding (steel or lead), the simulation suggests that such variations can be considered small. Overall the results allowed quantifying the specific contribution of concrete, lead, and steel as part of shielding on the equivalent and effective doses in the patient.

Application of the phase-space distribution approach of Monte Carlo for radiation contamination dose estimation from the (n,γ), (γ,n) nuclear reactions and linac leakage photons in the megavoltage radiotherapy facility.

The aim of this study was to characterize the radiation contamination inside and outside the megavoltage radiotherapy room. Radiation contamination components in the 18MV linac room are the secondary neutron, prompt gamma ray, electron and linac leakage radiation. An 18MV linac modeled in a typical bunker employing the MCNPX code of Monte Carlo. For fast calculation, phase-space distribution (PSD) file modeling was applied and the calculations were conducted for the radiation contamination components dose and spectra at 6 locations inside and outside the bunker. The results showed that the difference of measured and calculated percent depth-dose (PDD) and photo beam-profile (PBP) datasets were lower than acceptable values. At isocenter, the obtained photon dose and neutron fluence were 2.4×10-14 Gy/initial e° and 2.22×10-8 n°/cm2, respectively. Then, neutron apparent source strength (QN) value was found as 1.34×1012 n°/Gy X at isocenter and the model verified to photon and neutron calculations. A surface at 2cm below the flattening filter was modeled as phase-space (PS) file for PDD and PBP calculations. Then by use of a spherical cell in the center of the linac target as a PS surface, contaminant radiations dose, fluence and spectra were estimated at 6 locations in a considerably short time, using the registered history of all particles and photons in the 13GB PSD file as primary source in the second step. Designing the PSD file in MC modeling helps user to solve the problems with complex geometry and physics precisely in a shorter run-time.

Equivalent dose calculation in simulation of lung cancer treatment and analysis of dose distribution profile

Currently, lung cancer is one of the most lethal types of cancer (IARC, 2012), the pathology being detected in advanced stage, when the tumor has considerable volume because the disease in most cases asymptomatic in the early stages (INCA, 2016). Dosimetry analysis of healthy organs under real conditions is not feasible. Therefore, computational simulations are used to aid in dose verification in organs of patients submitted to radiotherapy. The goal of this study was to calculate the equivalent dose, due to photons, in the surrounding of healthy organs of patients submitted to radiotherapy for lung cancer, through computational modeling. The simulation was performed using the MCNPX code (MNCPX, 2006), Rex and Regina phantoms (ICRP 110, 2009), radiotherapy room, Siemens Oncor Expression accelerator operating at 6 MV and treatment protocol adopted at the INCA (National Cancer Institute – Brazil). The results obtained, considering the dose due to photons for both phantoms indicate that organs located inside the thoracic cavity received higher dose, being the bronchi, heart and esophagus more affected, due to their anatomical positioning. Clinical data describe the development of bronchiolitis, esophagitis and cardiomyopathies with decreased cardiopulmonary function as one of the major effects of lung cancer treatment. In the Regina phantom, the second largest dose was in the region of the breasts with 615.73 mSv/Gy, while in the Rex the dose was 514.06 mSv/Gy, event related to the difference of anatomical structure of the organ. A qualitative analysis was performed between the dose deposition profile of the treatment planning system and the simulated treatment through the tmesh command and a similar profile of dose distribution was verified throughout the patient's body.