Radiation Therapy Room Research Articles

Features of the organization of space-planning solutions for nuclear medicine facilities

The purpose of this article is to determine the typology of the main functional zones for nuclear medicine facilities (NMF) and the formation of principles that affect the architecture of these typological zones. The methodology of this study is an analysis of scientific works, a generalization of practical experience in the architectural design and construction of the NMF.The result of the study is the definition of the main typological zones of the NMF, the identification of the principles that affect the formation of the architecture of the NMF in relation to each zone. The study is aimed at the formation of the space of the typological zones of the NMF, taking into account the maximum provision of comfort. Keywords: architecture of nuclear medicine facilities (NMF), typological zones of the NMF, principles of the NMF architecture, medical institution, adaptive space, radiation therapy rooms, radiopharmaceuticals production facilities, positron emission computed tomography (PET centers) research rooms, clean rooms.

A Report on Health Resource Use in Internal Radiation Therapy Using 177Lu-DOTA-TATE

Internal radiation therapy using lutetium-177(177Lu)-DOTA-TATE injection will be applied in actual clinical practice soon. However, the NHI medical technical fee for the use of 177Lu-DOTA-TATE injection has not yet been set. The Japanese Society of Nuclear Medicine surveyed health resource use in internal radiation therapy using 177Lu via questionnaires sent to medical institutions that have used 177Lu-DOTA-TATE injection. Results showed that the necessary cost per patient is 1,912,404 JPY, based on the Draft Proposal for Medical Examination Value (Ver. 7.2) of the Japanese Health Insurance Federation for Surgery. 177Lu-DOTA-TATE injection is supposed to be administered 4 times to each patient at 8-week intervals, and the fee per treatment was calculated to be 478,101 JPY. The appropriate NHI medical technical fee is thus considered to be 47,810 points per patient per treatment, which can be claimed 4 times per patient. In addition, it costs 649,030 JPY per patient to take special measures to make the hospital room similar to the radiation therapy room. The cost other than the basic hospitalization fee per day was calculated to be 81,129 JPY. The appropriate additional points for NHI basic hospitalization fee is thus considered to be 8,113 points per patient per day.

Effect of the Space Dose Rate due to Change of X-ray Irradiation Energy and MU Value in Radiation Therapy Room

Effect of the Space Dose Rate due to Change of X-ray Irradiation Energy and MU Value in Radiation Therapy Room

New Radiation-Hardened Design of a CMOS Instrumentation Amplifier and its Tolerant Characteristic Analysis

A radiation-hardened instrumentation amplifier (IA) that allows precise measurement in radiation environments, including nuclear power plants, space environments, and radiation therapy rooms, was designed and manufactured, and its characteristics were verified. Most electronic systems are currently designed using silicon-based complementary metal-oxide semiconductor (CMOS) integrated circuits (ICs) to achieve a highly integrated low-power design. However, fixed charges induced in silicon by ionization radiation cause various negative effects, resulting in, for example, the generation of leakage current in circuits, performance degradation, and malfunction. Given that such problems in radiation environments may directly lead to a loss of life or environmental contamination, it is critical to implement radiation-hardened CMOS IC technology. In this study, an IA used to amplify fine signals of the sensors was designed and fabricated in the 0.18 μm CMOS bulk process. The IA contained sub-circuits that ensured the stable voltage supply needed to implement system-on-chip (SoC) solutions. It was also equipped with special radiation-hardening technology by applying an I-gate n-MOSFET that blocks the radiation-induced leakage currents. Its ICs were verified to provide the intended performance following a total cumulative dose of up to 25 kGy(Si), ensuring its safety in radiation environments.

Treatment of medical radioactive liquid waste using Forward Osmosis (FO) membrane process

The use of forward osmosis (FO) for concentrating radioactive liquid waste from radiation therapy rooms in hospitals was systematically investigated in this study. The removal of natural and radioactive iodine using FO was first investigated with varying pHs and draw solutions (DSs) to identify the optimal conditions for FO concentration. Results showed that FO had a successful rejection rate for both natural and radioactive iodine (125I) of up to 99.3%. This high rejection rate was achieved at a high pH, mainly due to electric repulsion between iodine and membrane. Higher iodine removal by FO was also attained with a DS that exhibits a reverse salt flux (RSF) adequate to hinder iodine transport. Following this, actual radioactive medical liquid waste was collected and concentrated using FO under these optimal conditions. The radionuclides in the medical waste (131I) were removed effectively, but the water recovery rate was limited due to severe membrane fouling. To enhance the recovery rate, hydraulic washing was applied, but this had only limited success due to combined organic-inorganic fouling of the FO membrane. Finally, the effect of FO concentration on the reduction of septic tank volume was simulated as a function of recovery rate. To our knowledge, this study is the first attempt to explore the potential of FO technology for treating radioactive waste, and thus could be expanded to the dewatering of the radioactive liquid wastes from a variety of sources, such as nuclear power plants.

고 에너지 방사선에 기인된 방사선치료실 내 평균 오존 농도의 변화

This study was to evaluate the change in characteristics of concentration of ozone after exposure to high energy radiation in linac room. Background ozone concentration of linac room was measured and compared to ozone concentration around linac room. Background ozone concentration of linac room was mean 17.4±7.9 ppb. It was 50% of the ozone concentration(36.8±22.3 ppb) around linac room(p<0.05). The concentration of ozone after exposure to high energy radiation in linac room was elevated to double of background ozone level, intensity after exposure. with exposure time concentration of ozone increased proportionally. It showed maximum level at 130~180seconds and slowed a tendency to saturate. It required more than 10 minutes for ozone concentration in linac room to drop to ozone concentration around linac room. The concentration of ozone after exposure to high energy radiation is high enough to cause specific physical symptoms, such as acute dyspnea or chest pain due to dry cough. Exposure to high concentration of ozone in sealed linac room can aggravate pulmonary disease, so special attention is needed. Keyword : High energy radiation, Radiation therapy room, Indoor ozone concentration, Ambient air ozone concentration.

Dose reduction of scattered photons from concrete walls lined with lead: Implications for improvement in design of megavoltage radiation therapy facility mazes.

This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms. Experiments and Monte Carlo simulations were utilized to establish the possibility of using high-Z materials to cover the concrete walls of the maze in order to reduce the dose of the scatteredphotons at the maze entrance. The dose of the backscatteredphotons from a concrete wall was measured for various scattering angles. The dose was also calculated by the FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV. It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co-60 emissions and 70% for Cs-137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscatteredphotons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%. This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose.

TU‐A‐116‐08: A Methodology to Estimate Radiation Dose Reported On a Personal Radiation Monitor

Purpose: The purpose of this study was to estimate the expected reading on a personal radiation monitor (PRM) in a fluoroscopy procedure and to determine what information can be deduced from PRM reports. Our institution received a PRM report indicating a deep dose equivalent (DDE) exceeding our ALARA III level (1250 mrem) during a monitoring period. The employee (a radiation therapist) reported she underwent a 2 hour upper GI fluoroscopy examination and her PRM was in her purse 1 meter away during the procedure. Methods: Typical, minimum, and maximum dose area products (DAP) and x‐ray field sizes (FS) for upper GI examination were estimated based on a literature review. The ratio of DAP and FS gave an estimate of the entrance air kerma (EAK). The air kerma (K) at the location of the PRM was calculated by multiplying the EAK by the side‐scatter fraction at 1 meter. K at the PRM was corrected to 1 cm tissue depth to estimate DDE. Results: The DDE based on the scenario reported was estimated to be 12 mrem. Minimum and maximum readings were estimated as 3 and 26 mrem, respectively. If the reported DDE was due to the upper GI examination only, the EAK would be approximately 30 Gy. The PRM report also noted that imaging results were inconclusive. Shallow dose equivalent (SDE) was 5% less than DDE. Conclusions: The scenario reported by the employee is highly unlikely to have resulted in the DDE observed on the PRM. Reported beam quality from the PRM report and the relative ratio of shallow to deep dose suggest a higher energy beam (such as scatter in a radiation therapy room) to be the more likely cause.

Place de la radiothérapie externe dans les cancers de la thyroïde

Anaplastic thyroid cancers represent 1–2% of all thyroid tumours and are of very poor prognosis even with multimodality treatment including external beam radiation therapy. Conversely, differentiated thyroid carcinomas (at least 80% of thyroid cancers) hamper good prognosis with surgery with or without radioiodine and there is hardly any room for external beam radiation therapy. Insular and medullar carcinomas have intermediary prognosis and are rarely irradiated. We aimed to update recommendations for external beam irradiation in these different clinical situations and put in light the benefits of new irradiations techniques. A search of the French and English literature was performed using the following keywords: thyroid carcinoma, anaplastic, chemoradiation, radiation therapy, surgery, histology and prognostic. Non-mutilating surgery (often limited to debulking) followed by systematic external beam radiation therapy is the standard of care in anaplastic thyroid cancers (hyperfractionated-accelerated radiation therapy with low-dose weekly doxorubicin with or without cisplatin if possible). Given anaplastic thyroid cancers’ median survival of 10 months or less, neoadjuvant and adjuvant chemotherapy may also be discussed. Ten-year survival rates for patients with papillary, follicular and Hürthle-cell carcinomas are 93%, 85%, and 76%, respectively. Massive primary incompletely resected iodine-negative disease indicates external beam radiation therapy. Older age (45 or 60-year-old), poor-prognosis histological variants (including tall cell cancers) and insular cancers are increasingly reported as criteria for external beam radiation therapy. Massive extracapsular incompletely resected nodal medullary disease suggests external beam radiation therapy. Radiation therapy morbidity has been an important limitation. However, intensity modulated radiation therapy (IMRT) offers clear dosimetric advantages on tumour coverage and organ sparing, reducing late toxicities to less than 5%. The role of radiation therapy is evolving for anaplastic thyroid cancers using multimodal strategies and new chemotherapy molecules, and for differentiated cancers using minor criteria, such as histological variants, with IMRT becoming a standard of care.

TH-E-BRA-01: A Line-Source Method for Aligning Onboard-Robotic-Pinhole and Other SPECT-Pinhole Systems

Purpose: To achieve on‐board molecular imaging in the radiation therapy room, we are developing a robotic multi‐pinhole SPECT system. Alignment of the SPECT system to LINAC/CBCT coordinates is essential for target localization and image reconstruction. Pinhole alignment methods typically use point sources, which can be challenging to make and to localize. We propose a method that utilizes line sources and as few as one pinhole projection. This method is generally applicable to SPECT pinhole imaging.Methods: Line source positions are taken as known by CBCT or some other transmission imaging procedure. A model is developed relating line source positions and their pinhole‐SPECT projections to pinhole‐SPECT alignment parameters. Based on this model and a radon‐transform detection of projected lines, alignment parameters (three detector rotations, three detector translations, and in some cases three pinhole translations) are estimated. To evaluate the method, line‐source projections are computer‐simulated, with blur and noise included, for three and five lines, and for several pinhole‐SPECT rotations/translations. Alignment parameters are obtained and compared to true values. Results: For six parameters (3 translations, 3 rotations), errors were 0.3±0.6mm, 0.3±0.4mm, 1.1±2.2mm, 0.2±0.1deg, 0.3±0.6deg, 0.5±0.5deg using three line sources and 0.2±0.3mm, 0.5±1.2mm, 0.9±1.6mm, 0.1±0.2deg, 0.4±0.7deg, 0.2±0.4deg using five line sources. For nine parameters and five line sources, errors were 6.2±10.5mm, 8.4±16.7mm, 29.2±44.0mm, 1.9±2.8deg, 0.7±0.9deg, 0.7±1.6deg, 3.7±4.5mm, 4.8±3.3mm, 16.7±25.1mm. Replacing the line‐source projection positions determined by the radon transform with true values, these nine parameters were estimated with no error using five line sources. Conclusions: Estimation of alignment parameters can be achieved using one pinhole projection of line‐sources. Alignment errors are largely associated with limited accuracy of the radon transform in determining positions of line‐source projections. For robotic multi‐pinhole SPECT, this method shows promise to estimate relative and absolute alignment of each pinhole within the multi‐pinhole system. This work is supported by NIH grant R21‐CA156390‐01A1.

A new analytical formula for neutron capture gamma dose calculations in double-bend mazes in radiation therapy

BackgroundPhotoneutrons are produced in radiation therapy with high energy photons. Also, capture gamma rays are the byproduct of neutrons interactions with wall material of radiotherapy rooms. AimIn the current study an analytical formula was proposed for capture gamma dose calculations in double bend mazes in radiation therapy rooms. Materials and methodsA total of 40 different layouts with double-bend mazes and a 18MeV photon beam of Varian 2100 Clinac were simulated using MCNPX Monte Carlo (MC) code. Neutron capture gamma ray dose equivalent was calculated by the MC method along the maze and at the maze entrance door of all the simulated rooms. Then, all MC resulted data were fitted to an empirical formula for capture gamma dose calculations. Wu–McGinley analytical formula for capture gamma dose equivalent at the maze entrance door in single-bend mazes was also used for comparison purposes. ResultsFor capture gamma dose equivalents at the maze entrance door, the difference of 2–11% was seen between MC and the derived equation, while the difference of 36–87% was found between MC and the Wu–McGinley methods. ConclusionOur results showed that the derived formula results were consistent with the MC results for all of 40 different geometries. However, as a new formula, further evaluations are required to validate its use in practical situations. Finally, its application is recommend for capture gamma dose calculations in double-bend mazes to improve shielding calculations.

Sensitization of the analytical methods for photoneutron calculations to the wall concrete composition in radiation therapy

The effect of wall material on photoneutron production in radiation therapy rooms was studied using Monte Carlo (MC) simulations. An analytical formula was proposed to take into account the concrete composition in photoneutron dose calculations. Using the MCNPX MC code, the 18 MV photon beam of the Varian Clinac 2100 and a typical treatment room with concrete compositions according to report No. 144 of National Council of Radiation Protection (NCRP) were simulated. Number of room produced photoneutrons per Gray of X-ray at the isocenter was determined for different types of concrete and named as “Q W ”. This new factor was inserted in the used formula for photoneutron fluence calculations at the inner entrance of maze. The photoneutron fluence was calculated using new proposed formula at the inner entrance of maze for all studied concretes. The difference between conventional and proposed equations varied from 11% to 46% for studied concretes. It was found that room produced photoneutrons could be significant for high density concretes. Additionally, applying the new proposed formula can consider the effect of wall material composition on the photoneutron production in high energy radiation therapy rooms. Further studies to confirm the accuracy of newly developed method is recommended. ► A radiation therapy room with a linac was simulated in the current study. ► Photoneutron production from different commercial concrete was studied. ► The photoneutron production varied from 11% to 46% dependent on concrete density and elemental composition. ► Photoneutron production was higher for high density concretes.

Gantry orientation effect on the neutron and capture gamma ray dose equivalent at the maze entrance door in radiation therapy

In the present study, the effect of gantry orientation on the photoneutron and capture gamma dose calculations for maze entrance door was evaluated. A typical radiation therapy room made of ordinary concrete was simulated using MCNPX Monte Carlo code. Gantry rotation was simulated at eight different angles around the isocenter. Both neutron and capture gamma dose vary considerably with gantry angle. The ratios of the maximum to the minimum values for neutron and capture gamma dose equivalents were 1.9 and 1.4, respectively. On the other hand, comparison of the Monte Carlo calculated mean value over all orientations with Monte Carlo calculated neutron and gamma dose showed that the Wu-McGinley method differed by 5% and 2%, respectively. However, for more conservative shielding calculations, factors of 1.6 and 1.3 should be applied to the calculated neutron and capture gamma doses at downward irradiation. Finally, it can be concluded that the gantry angle influences neutron and capture gamma dose at the maze entrance door and it should be taken into account in shielding considerations.

Photoneutron production and backscattering in high density concretes used for radiation therapy shielding

In the current study, the effect of high density concretes on photoneutron productions in radiation therapy was studied using Monte Carlo simulations. The photon and neutron spectra of an 18 MeV photon beam of the Varian linac head were used for all simulations. Ordinary and five high density concretes made of high density elements were simulated. The studied concretes consisted of Magnetite, Datolite–Galena, Magnetite–Steel, Limonite–Steel, and Serpentine. Our results showed that photoneutron production in these concretes strongly depends on their composition. It appears that the application of high density elements with higher probability for photoneutron production, such as Fe and Pb, increases the photoneutron production in concrete walls of radiation therapy bunkers. Further studies on the effect of concrete composition on photoneutrons in radiation therapy room are recommended.

Photoneutron and capture gamma dose calculations for a radiotherapy room made of high density concrete

Neutron and capture gamma ray dose equivalent along the maze and entrance door of a radiation therapy room made of high density concrete was calculated using analytical and Monte Carlo methods. The room geometry and the 18 MV photon beam of a Varian 2100C/D linac were simulated using MCNPX MC code. Four analytical methods including Kersey, French, McCall, and Wu-McGinley methods were used in the current study. Average difference of 13-30% was seen between analytical and MC methods along the maze for photoneutron calculations. The difference between Wu-McGinley and MC methods was about 17% for capture gamma ray calculations. It was concluded that the analytical methods overestimate both neutron and capture gamma ray dose equivalents compared to MC. Moreover, it was shown that the analytical methods can be used as conservative estimators for neutron and capture gamma calculations.

Poster - Thurs Eve-16: Just-in-time tomography (JiTT).

Soft-tissue target motion is one of the main concerns in high-precision radiation therapy. Cone beam computed tomography (CBCT) has been developed recently to image soft-tissue targets in the treatment room for image-guided radiation therapy. However, due to its relatively long image acquisition time the CBCT approach cannot provide images of the target at the instant of the treatment and thus is not adequate for imaging targets with intrafraction motion. In this work, a new concept for image-guided radiation therapy- just-in-time tomography (JiTT) - is introduced. Differing from CBCT, JiTT takes much less time to generate the needed tomographical, beam's-eye-view images of the treatment target at the right moment to guide the radiation therapy treatment. A system to achieve JiTT is proposed and its feasibility is investigated. Research supported by Siemens.

4D laser camera for accurate patient positioning, collision avoidance, image fusion and adaptive approaches during diagnostic and therapeutic procedures

A four-dimensional (4D) laser camera (LC) has been developed for accurate patient imaging in diagnostic and therapeutic radiology. A complementary metal-oxide semiconductor camera images the intersection of a scanned fan shaped laser beam with the surface of the patient and allows real time recording of movements in a three-dimensional (3D) or four-dimensional (4D) format (3D +time). The LC system was first designed as an accurate patient setup tool during diagnostic and therapeutic applications but was found to be of much wider applicability as a general 4D photon "tag" for the surface of the patient in different clinical procedures. It is presently used as a 3D or 4D optical benchmark or tag for accurate delineation of the patient surface as demonstrated for patient auto setup, breathing and heart motion detection. Furthermore, its future potential applications in gating, adaptive therapy, 3D or 4D image fusion between most imaging modalities and image processing are discussed. It is shown that the LC system has a geometrical resolution of about 0, 1 mm and that the rigid body repositioning accuracy is about 0, 5 mm below 20 mm displacements, 1 mm below 40 mm and better than 2 mm at 70 mm. This indicates a slight need for repeated repositioning when the initial error is larger than about 50 mm. The positioning accuracy with standard patient setup procedures for prostate cancer at Karolinska was found to be about 5-6 mm when independently measured using the LC system. The system was found valuable for positron emission tomography-computed tomography (PET-CT) in vivo tumor and dose delivery imaging where it potentially may allow effective correction for breathing artifacts in 4D PET-CT and image fusion with lymph node atlases for accurate target volume definition in oncology. With a LC system in all imaging and radiation therapy rooms, auto setup during repeated diagnostic and therapeutic procedures may save around 5 min per session, increase accuracy and allow efficient image fusion between all imaging modalities employed.

MO‐B‐BRA‐01: Practical Examples, Including IMRT, TBI, SRS

NCRP Report No. 151(December 2005), titled “Structural Shielding Design and Evaluation for Megavoltage X‐ and Gamma‐Ray Radiotherapy Facilities”, presents updated methods and data for radiation therapy room shielding design. These calculation methods are applied in examples representing the more common shielding design situations. A radiation therapy vault with a maze barrier and intended for use with IMRT and TBI procedures is the principal example. Detailed calculations of the barriers and door shielding structures are presented. Procedures for evaluating compliance with the NRC licensing constraint on dose equivalent in‐any‐one‐hour are presented. An example of a high‐energy room where photoneutron production is of concern is presented with focus on assessing the dose equivalent at the entrance and the maze door design.Objectives: Learn by worked examples (1) how to apply the methods and data presented in NCRP 151 for designing high energy therapy vault barriers; (2) how to determine prospectively if the barrier design is adequate to satisfy the public areas “2 mrem in‐any‐one‐hour” constraint when it is applicable.

TENTH VALUE LAYERS FOR 60Co GAMMA RAYS AND FOR 4, 6, 10, 15, AND 18 MV X RAYS IN CONCRETE FOR BEAMS OF CONE ANGLES BETWEEN 0° AND 14° CALCULATED BY MONTE CARLO SIMULATION

The calculation of shielding barrier thicknesses for radiation therapy facilities according to the NCRP formalism is based on the use of broad beams (that is, the maximum possible field sizes). However, in practice, treatment fields used in radiation therapy are, on average, less than half the maximum size. Indeed, many contemporary treatment techniques call for reduced field sizes to reduce co-morbidity and the risk of second cancers. Therefore, published tenth value layers (TVLs) for shielding materials do not apply to these very small fields. There is, hence, a need to determine the TVLs for various beam modalities as a function of field size. The attenuation of (60)Co gamma rays and photons of 4, 6, 10, 15, and 18 MV bremsstrahlung x ray beams by concrete has been studied using the Monte Carlo technique (MCNP version 4C2) for beams of half-opening angles of 0 degrees , 3 degrees , 6 degrees , 9 degrees , 12 degrees , and 14 degrees . The distance between the x-ray source and the distal surface of the shielding wall was fixed at 600 cm, a distance that is typical for modern radiation therapy rooms. The maximum concrete thickness varied between 76.5 cm and 151.5 cm for (60)Co and 18 MV x rays, respectively. Detectors were placed at 630 cm, 700 cm, and 800 cm from the source. TVLs have been determined down to the third TVL. Energy spectra for 4, 6, 10, 15, and 18 MV x rays for 10 x 10 cm(2) and 40 x 40 cm(2) field sizes were used to generate depth dose curves in water that were compared with experimentally measured values.

WE‐B‐224A‐01: Shielding III: Practical Examples, Including IMRT, TBI, SRS

The recently published NCRP Report No. 151, “Structural Shielding Design and Evaluation for Megavoltage X‐ and Gamma‐Ray Radiotherapy Facilities”, presents updated methods and data for radiation therapy room shielding design. These calculational methods are applied in examples representing the more common shielding design situations. A radiation therapy vault with a maze barrier and intended for use with IMRT and TBI procedures is the principal example. Detailed calculations of the barriers and door shielding structures are presented. Procedures for evaluating compliance with the NRC licensing constraint on dose equivalent in‐anyone‐hour are presented. An example of a high‐energy room where photoneutron production is of concern is presented with focus on assessing the dose equivalent at the entrance and the maze door design.