Evaluation of an in-use chest CT protocol in lung cancer screening - A single institutional study.

Background: Lung cancer is the most common cause of cancer-related death worldwide and therefore there has been a growing demand for low-dose computed tomography (LDCT) protocols. Purpose: To investigate and evaluate the dose and image quality of patients undergoing lung cancer screening (LCS) using LDCT in Norway. Materials and Methods: Retrospective dosimetry data, volumetric CT dose index (CTDIvol) and dose-length product (DLP), from 70 average-size and 70 large-size patients who underwent LDCT scan for LCS were included in the survey. Effective dose and size-specific dose were calculated for each examination and were compared with the American Association of Physicists in Medicine (AAPM) requirement. For a quantitative image quality analysis, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were determined for different regions in the chest with two iterative reconstruction techniques, iDose and Iterative Model Reconstruction. Differences in dose and image quality between average-size and large-size patients were evaluated by Independent sample t test, and Wilcoxon signed rank test within the same patient group. Results: The independent sample t test revealed significant differences (p < .05) in dose values between average-size and large-size patients. Mean CTDIvol and DLP for average-size patients were 2.8 mGy and 115 mGy.cm, respectively, with appropriate increment for the large-size patients. Image quality (image noise, SNR, and CNR) did not significantly differ between patient groups when images were reconstructed with a model based iterative reconstruction algorithm. Conclusion: The screening protocol assessed in this study resulted in CTDIvol values that were compliant with AAPM recommendation. No significant differences in objective image quality were found between patient groups.

A Practical Method for Slice Spacing Measurement Using the American Association of Physicists in Medicine Computed Tomography Performance Phantom.

Background: The slice spacing has a crucial role in the accuracy of computed tomography (CT) images in sagittal and coronal planes. However, there is no practical method for measuring the accuracy of the slice spacing. Purpose: This study proposes a novel method to automatically measure the slice spacing using the American Association of Physicists in Medicine (AAPM) CT performance phantom. Methods: The AAPM CT performance phantom module 610-04 was used to measure slice spacing. The process of slice spacing measurement involves a pair of axial images of the module containing ramp aluminum objects located at adjacent slice positions. The middle aluminum plate of each image was automatically segmented. Next, the two segmented images were combined to produce one image with two stair objects. The centroid coordinates of two stair objects were automatically determined. Subsequently, the distance between these two centroids was measured to directly indicate the slice spacing. For comparison, the slice spacing was calculated by accessing the slice position attributes from the DICOM header of both images. The proposed method was tested on phantom images with variations in slice spacing and field of view (FOV). Results: The results showed that the automatic measurement of slice spacing was quite accurate for all variations of slice spacing and FOV, with average differences of 9.0% and 9.3%, respectively. Conclusion: A new automated method for measuring the slice spacing using the AAPM CT phantom was successfully demonstrated and tested for variations of slice spacing and FOV. Slice spacing measurement may be considered an additional parameter to be checked in addition to other established parameters.

Experiences of UK clinical scientists (Physical Sciences modality) with their regulator, the Health and Care Professions Council: results of a 2022 survey.

BACKGROUND: In healthcare, regulation of professions is an important tool to protect the public. With increasing regulation however, professions find themselves under increasing scrutiny. Recently there has also been considerable concern with regulator performance, with high profile reports pointing to cases of inefficiency and bias. Whilst reports have often focused on large staff groups, such as doctors, in the literature there is a dearth of data on the experiences of smaller professional groups such Clinical Scientists with their regulator, the Health and Care Professions Council. This article reports the findings of a survey from Clinical Scientists (Physical Sciences modality) about their experiences with their regulator, and their perception of the quality and safety of that regulation. METHODS: Between July-October 2022, a survey was conducted via the Medical Physics and Engineering mail-base, open to all medical physicists & engineers. Questions covered typical topics of registration, communication, audit and fitness to practice. The questionnaire consisted of open and closed questions. Likert scoring, and thematic analysis were used to assess the quantitative and qualitative data. RESULTS: Of 146 responses recorded, analysis was based on 143 respondents. Overall survey sentiment was significantly more negative than positive, in terms of regulator performance (negative responses 159; positive 106; significant at p < 0.001). Continuous Professional Development audit was rated median 4; other topics were rated as neutral (fitness to practice, policies & procedures); and some as poor (value). CONCLUSIONS: The Clinical Scientist (Physical Sciences) professional registrants rated the performance of their regulator more negatively than other reported assessments (by the Professional Standards Authority). Survey respondents suggested a variety of performance aspects, such as communication and fitness to practice, would benefit from improvement. Indications from this small dataset, suggest a larger survey of HCPC registrants would be useful.

Demographics of the members of the special interest group for early career medical physicists: A statistical analysis of survey results.

INTRODUCTION: The Early Career Medical Physicists Special Interest Group (SIG_FREC) that operates within EFOMP aims to represent individuals with less than 10 years of experience working as medical physics professionals. The purpose of this survey was to better understand the specific needs and expectations of early-career medical physicists across Europe. The aim of this study was to allow these early-career professionals to voice their ideas within EFOMP and provide insights into their challenges and opportunities while also providing them with the possibility of making suggestions for the growth of the SIG. Doing this, the members can be better equipped to be future leaders of the Medical Physics profession in their own country and in Europe. METHODS: The Steering Committee of SIG_FREC developed a questionnaire and distributed it to its members. RESULTS: Out of the total number of members of the SIG_FREC at the time of the questionnaire (97 members), 42 of them responded to the survey yielding a response rate of 43%. These provided valuable insights based on their experiences about medical physics in their country. CONCLUSION: The responses to the questionnaire provided a snapshot of the opinion of early-career medical physicists, representing a wide geographical distribution across Europe. The feedback from SIG_FREC members highlighted potential future operations within EFOMP.

Global status of medical physics human resource - The IOMP survey report.

PURPOSE: Realizing the need for periodic surveys about global medical physics human resource, the International Organization for Medical Physics (IOMP) performed a third survey following the previous two (2015 and 2018). The objective was to collect information about the current numbers of medical physicists (MPs) in individual countries, about their MP training, and accreditation pathways. METHODS: The survey was designed using Google Forms. Forms were distributed to national MP associations around the world. The data was collected during May-Nov 2022. MS Excel and SPSS software were used to perform descriptive statistics. RESULTS: 64 valid responses were received covering all continents. The largest numbers of MPs are in high income countries of Europe, Australia and North America, while the lowest numbers of MPs are seen in middle and low-income countries of Asia, Latin America and Africa. Among the respondents, 73% reported MP shortages in their countries. 69% reported the existence of an official MP training program which comprises university courses and in-service training. Furthermore, 85% of the respondents indicated the availability of MP university courses, primarily at the Master's degree level. Participation in research was between 10 and 30% of allocated work time for 42% and below 10% for 33% respondents. CONCLUSIONS: There are new findings on number of MPs per million population in different countries, with some expressing adequacy in the total number of MPs, but the data breakdown indicates a shortage in diagnostic X-ray physicists. Future surveys should also investigate in more detail data on outsourcing, and involvement in research.

Status of cancer treatment by radiotherapy and requirement of radiation oncology medical physicists in Asia Oceania federation of organizations for medical physics region.

Objective: Cancer is a major health problem worldwide including Asian-Pacific region. The region hosts over 4.5 billion people, over 60% of the world population and very divergent socioeconomically. The major cancers in the region in male include lung, stomach, liver, colorectal and esophagus and in female breast, lung, cervix, colorectal, and stomach. Over 60% of cancer patients need radiotherapy alone or in combination with surgery and/or chemotherapy, and therefore, radiotherapy is the main and essential modality of cancer treatment. Radiation oncology medical physicists play a pivotal role in efficient implementation of radiotherapy. This study was aimed to assess the status of cancer treatment by radiotherapy and the requirement of radiation oncology medical physicists in the region. Materials and Methods: To access the status and requirement of radiotherapy machines, availability of radiation oncology physicists in the region of Asia Oceania Federation of Organizations for Medical Physics (AFOMP), we have carried out a survey by sending questioners to AFOMP National Medical Physics Organizations (NMO). We received response from 21 countries, 100% response, regarding availability of teletherapy units, number of medical physicists working in radiotherapy and related information. Using GLOBOCAN cancer incidence data and considering 62.5% of cancer patients need radiotherapy treatment and up to 500 cancer patients can be treated in a year on one teletherapy machine, the gap between the available and required teletherapy machine to treat all the cancer patients requiring radiotherapy is estimated. Further, we estimated the gap between radiotherapy medical physicists available and required as per International Atomic Energy Agency and European Society for Therapeutic Radiology and Oncology guidelines. Results: It was observed that availability of teletherapy machines in AFOMP region is 0.21-14.0 teletherapy machine/million population and radiotherapy medical physicist are 0.82-2.43/teletherapy unit.

A survey on radiation protection awareness at various hospitals in Karachi, Pakistan.

Purpose: To assess the awareness level of radiation protection among the radiation workers (i.e. medical radiation technologists, medical physicists, and medical radiological professionals) at the selected radiology, nuclear medicine, and radiotherapy facilities in Karachi, Pakistan. Material and methods: This survey was carried out in Karachi which has the largest number of hospitals, including radiology, nuclear medicine, and radiotherapy facilities in all Pakistan. In this double-blind survey, a questionnaire was designed and distributed to one hundred and sixty five (165) medical radiation workers at their respective workplaces. These radiation workers included the medical radiation technologists, medical physicists, and medical radiological practitioners. These radiation workers had varying experiences, training records, education, and fields of specialization. Out of these total 165 respondents, 84 belonged to the radiology facilities, 20 to nuclear medicine facilities, and 61 to radiotherapy facilities. The educational level was classified as less than 16 years, and equal to or greater than 16 years. Similarly, the training was classified as "attended" or "never attended" and the experience as less than five years, between 5 and 10 years, and greater than ten years. The data was processed through SPSS (v.20) against a significance level (P ≤ 0.05). Results: The statistical analysis of the survey indicates that the radiation workers in radiology, nuclear medicine, and radiotherapy facilities in Karachi have limited awareness of radiation protection issues. The overall outcome of the survey also concluded that the awareness regarding radiation effects, radiation warning signs, and annual dose limit is optimum. However, the response to the questions related to patient protection remained unsatisfactory. Conclusion: This study showed that most of the radiation workers who participated in the survey lacked appropriate awareness of radiation protection measures. The radiation workers did show a better understanding of basic radiation protection parameters, such as the annual dose limit and radiation effects. However, the radiation workers needed an overall improvement in radiation protection awareness, particularly, related to patient protection. This awareness and knowledge should be improved through systematic and periodic trainings.

Palladium-103 plaque brachytherapy for retinoblastoma: Long term follow up.

Purpose: Radiation has been used in the treatment of retinoblastoma. Herein, we present the novel use of palladium-103 plaque brachytherapy as primary treatment. Observation: An 8-year-old asymptomatic girl presented was found to have a solitary peripheral retinoblastoma in her right eye. She was treated with primary palladium-103 plaque brachytherapy (47.4 Gray over 5 consecutive days). A secondary, vitreous hemorrhage noted 46 months after irradiation was successfully controlled by laser tumor-demarcation. With 19-years follow up, there has been no clinical scleropathy, or local tumor recurrence. The eye yields 20/20 vision and there has been no systemic metastasis. Conclusion and importance: Palladium-103 plaque brachytherapy successfully controlled retinoblastoma, while preserving the globe, vision, and life.

Brachytherapy workflow for locally advanced cervical cancer: A survey of Canadian Medical Physicists.

PURPOSE: To report on brachytherapy (BT) workflows for image-based treatments of locally advanced cervical cancer (CC) in Canada. METHODS: Medical Physicists in every Canadian cancer center were contacted and those with a CC-BT program were emailed a 44-item electronic questionnaire surveying workflow patterns including: fractionation schedules, prescription, equipment, imaging, and treatment delivery. RESULTS: Of 47 centers contacted, all 34 who performed CC-BT participated in the survey. Brachytherapy boost, following external beam treatments, was delivered using high-dose-rate (HDR); one center also used pulsed-dose-rate. Intracavitary and/or interstitial treatments were done in 47% centers for 25-80% of their patients. All centers used image-based planning: CT (32%), CT planned with MRI for contouring (47%), MRI (18%), or cone beam CT (3%). For those performing volume-based planning (74%), the contours commonly included Clinical Target Volume (CTV)-High Risk (HR), CTV-Intermediate Risk, rectum, sigmoid, and bladder. The most common HDR dose-fractionation schedule was 7 [4.6 - 10] Gy in 4 [3 - 6] fractions with radiobiological dose prescriptions performed in 62% centers. Medical physics contribution was significant during most activities along the BT treatment pathway in all centers, especially in planning (88%), second checks (68%), and during treatment delivery (88%). CONCLUSIONS: Compared to previous surveys, there is an increasing trend in the use of image-based volumetric planning, interstitial procedures, and radiobiological dose prescription. Cervical cancer brachytherapy in Canada is becoming more streamlined with the use of international practice guidelines. Involvement of medical physicists is vital to all stages of CC-BT, including program implementation, routine quality control, dosimetry, and treatment delivery.

[Utility of Point Dose Verification Using Measured Ionization Amount Ratio of Reference Irradiation to Volumetric Modulated Arc Therapy].

In the point dose verification of intensity-modulated radiation therapy (IMRT), we compared the commonly used method of measuring absolute dose (absolute method) with the measurement method by the American Association of Physicists in Medicine Task Group 119, which describes the point dose verification for IMRT using the ratio of reference irradiation and measured ionization. The target was 66 plans for head and neck cancer, 46 plans for lung cancer with 6 MV X-ray, and 31 plans for prostate cancer with 10 MV X-ray. They were treated with volumetric-modulated arc therapy (VMAT). Each plan was evaluated by the absolute method and the TG119 method using 3D-array. The average and 2SD of the verification results for head and neck cancer, lung cancer, and prostate cancer were 0.129±2.185%, 0.963±2.125%, and 0.259±2.019% by the absolute method, and 0.952±2.039%, 1.704±2.080%, and 0.524±1.274% by the TG119 method. The ratio between the average of the TG119 method and the absolute method corresponded to the error of reference irradiation dose. Considering that the measurement method is simple, the TG119 method enables more stable point dose verification of VMAT.

Dosimetric validation of Acuros® XB algorithm for RapidArc™ treatment technique: A post software upgrade analysis.

AIM: To validate the Acuros® XB (AXB) algorithm in Eclipse treatment planning system (TPS) for RapidArc™ (RA) technique following the software upgrades. MATERIALS AND METHODS: A Clinac-iX (2300CD) linear accelerator and Eclipse TPS (Varian Medical System, Inc., Palo Alto, USA) was used for commissioning of AXB algorithm using a 6 megavolts photon beam. Percentage depth dose (PDD) and profiles for field size 2 cm × 2 cm, 4 cm × 4 cm, 6 cm × 6 cm, 10 cm × 10 cm, 20 cm × 20 cm, 30 cm × 30 cm to 40 cm × 40 cm were taken. AXB calculated PDDs and profiles were evaluated against the measured and analytical anisotropic algorithm (AAA)-calculated PDDs and profiles. Test sites recommended by American Association of Physicists in Medicine task group (AAPM TG)-119 recommendation were used for RA planning and delivery verification using AXB algorithm.Dosimetric analysis of AXB calculated data showed that difference between calculated and measured data for PDD curves were maximum <1% beyond the depth of dose maximum and computed profiles in central region matches with maximum <1% for all considered field sizes. Ion-chamber measurements showed that the average confidence limit (CLs) was 0.034 and 0.020 in high-gradient and 0.047 and 0.042 in low-gradient regions, respectively, for AAA and AXB calculated RA plans. Portal measurements show the average CLs were 2.48 and 2.58 for AAA and AXB-calculated RA plans, with gamma passing criteria of 3%/3 mm. CONCLUSIONS: AXB shows excellent agreement with measurements and AAA calculated data. The CLs were consistent with the baseline values published by TG-119. AXB algorithm has the potential to perform photon dose calculation with comparable fast calculation speed without negotiating the accuracy. AAPM TG-119 was successfully implemented to access the proper configuration of AXB algorithm following the TPS upgrade.

Validation of American Association of Physicists in Medicine TG 43 Dosimetry Data in Commercial Treatment Planning System.

AIMS: This study aimed to validate the dosimetric data of low-energy photon-emitting low-dose rate (LE-LDR) brachytherapy seed sources in commercial treatment planning system (TPS). MATERIALS AND METHODS: The LE-LDR seed sources dosimetric data were published in the American Association of Physicists in Medicine (AAPM) Task Group reports TG-43 (1995), TG-43U1 (2004), TG-43U1S1 (2007), and TG-43U1S2. The Bhabha Atomic Research centre (BARC) 125I Ocu-Prosta seed dosimetry data are also available in the literature. The commercially available TPSs are using both two-dimensional (cylindrically symmetric line-source) and one-dimensional (1D) (point source) dose-calculation formalisms. TPS used in this study uses only 1D dose-calculation formalism for permanent implant dosimetry. The point-dose calculation, dose summation, isodose representation, and dose-volume histogram quality assurance tests were performed in this study. The point-source dose-calculation tests were performed for all the available sources in the literature. The others tests were performed for the I-125 BARC Ocu-Prosta seeds. The TPS-calculated doses were validated using manual calculation. RESULTS AND DISCUSSION: In point-source calculation test, the TPS-calculated point-dose values are within ±2% agreement with manually calculated dose for all the seeds studied. The agreement between the TPS and manually calculated dose is 0.5% for the dose summation test. The isodose line pass through the grid points at an equal distance was verified visually on the computer screen for seed used clinically. In dose-volume histogram test, the TPS-determined volume was compared with the real volume. CONCLUSION: Misinterpretation of the TPS test and/or misunderstanding of the TG-43 dose-calculation formalism may cause large errors. It is very important to validate the TPS using literature provided dosimetric data. The dosimetric data of BARC 125I Ocu-Prosta Seed are validated with other AAPM TG-43-recommended seeds. The dose calculation of Best® NOMOS permanent implant TPS is accurate for all permanent implant seeds studied.

The scientific publications of AIFM members in 2015-2019: A survey of the FutuRuS working group.

PURPOSE: Within the Italian Association of Medical Physics and Health Physics (AIFM) working group "FutuRuS" we carried out a survey regarding the number of the peer-reviewed articles by AIFM members. METHODS: We surveyed papers published in the years 2015-2019. Data extracted from Scopus included information regarding authors, title, journal, impact factor (IF), leading or standard authorship by AIFM members, keywords, type of collaboration (monocentric/multicentric/international), area of interest [radiation oncology (RO), radiology (RAD), nuclear medicine (NM), radioprotection (RP) and professional issue (PI)] and topics. RESULTS: We found 1210 papers published in peer-reviewed journals: 48%, 22%, 16%, 6%, 2 and 6% in RO, RAD, NM, RP, PI and other topics, respectively. Forty-seven percent of the papers involved monocentric teams, 31% multicentric and 22% international collaborations. Leading authorship of AIFM members was in 56% of papers, with a corresponding IF equal to 52% of the total IF (3342, IFmean = 2.8, IFmax = 35.4). The most represented journal was Physica Medica, with 15% of papers, while a relevant fraction of IF (54%) appeared in clinically oriented journals. The number of papers increased significantly between 2015 and 2016 and remained almost constant in 2017-2019. CONCLUSIONS: This survey led to the first quantitative assessment of the number and theme distribution of peer-reviewed scientific articles contributed by AIFM members. It constitutes a ground basis to support future AIFM strategies and promote working groups on scientific activity of medical physicists, and to build the basis for rational comparison with other countries, first of all within Europe.

Status of medical physics education and training in AFOMP region.

Medical physicists are health professionals recognized by the International Labour Organization (ILO) and hence medical physicists working in a clinical environment should have the required competency and undergo a structured training program and residency under an experienced medical physicist in a recognized institution. Furthermore, medical physics is a rapidly growing area needing a high degree of knowledge and professional competency due to the rise in complexity of treatment procedures, increasing access to medical technology, and the requirement of coordination between the disciplines of medicine, physics and biomedical engineering. The unprecedented surge in medical physics competency in the last 2-3 decades is due to the implementation of specialized physics intensive procedures such as particle therapy, image-guided & intra-operative radiotherapy, advanced imaging and nuclear medicine techniques. In this scenario to handle this new technology era the quantity of qualified medical physicists needs to be in consonance with the competency needed. There is a special requirement for education and training of medical physicists which led to the opening of numerous educational programs around the world. The Asia-Oceania Federation of Organizations for Medical Physics (AFOMP) was founded in 2000 and today 19 countries national medical physicist associations (NMPO) are member of AFOMP. The AFOMP region is populated by over 4.5 billion people and socioeconomically is very diverse with GDP per capita as high as around US $60,000 [Australia] to as low as around US $750 [Nepal]. We conducted a survey by sending questionnaires to AFOMP NMPOs to assess the status of medical physics education and training in the region. We have received responses from 20 countries in the AFOMP region to the questionnaire. It was observed that 16 [80%] countries from AFOMP have well organized master program in medical physics, however only 8 [50%] programs were accredited and in only 9 [45%] countries are medical physicists registered as health professionals.

Domain classification and analysis of national institutes of health-funded medical physics research.

PURPOSE: The American Association of Physicists in Medicine (AAPM) previously developed a research database consisting of the National Institutes of Health (NIH) grants that were awarded to its members. The purpose of this report is to classify these NIH grants into various medical physics subdisciplines and analyze the scope of AAPM member research. METHODS: For this report, an algorithm classified grant topics into medical physics research subdisciplines (grants from 2002 to 2019 were analyzed). This algorithm utilized a search for common words and phrases within grant titles, keywords, abstracts, and activity codes to perform the classification. AAPM member grants were compared with non-AAPM member grants in various relevant subcategories to assess what percentage of these grants was held by AAPM members. RESULTS: The percentage of AAPM member grants that included words relating to both imaging and therapy (image-guided therapy grants) increased from 13% (27/207) in 2002 to 27% (79/293) in 2019. The percentage of AAPM member grants utilizing words relating to artificial intelligence increased from 8% in 2002 to 20% in 2019. From 2002 to 2019, AAPM member grants referenced cancer more than all other diseases combined. The majority of AAPM member grants included words relating to clinical research (81% of grants in 2002 and 99% in 2019). When comparing AAPM member with non-AAPM member grants it was found that in 2019 AAPM members held a substantial fraction of all NIH grants that referenced stereotactic radiation therapies (41%), radionuclide therapies (10%), brachytherapies (35%), intensity-modulated radiation therapies (45%), and external beam particle therapies (55%). From 2002 to 2019, the percentage of AAPM membership holding NIH grants decreased for males (3.2% down to 2.3%) and increased for females (0.8% up to 1.3%) CONCLUSIONS: The majority of grants awarded to AAPM members focus on clinical research, which underlies the translational aspect of medical physics and suggests medical physicists are uniquely positioned to help translate new technologies such as artificial intelligence into the clinic. Since 2002, NIH grants awarded to AAPM members have increasingly referenced some form of image-guided therapy, suggesting opportunities for continued innovation of imaging technologies. A substantial fraction of all radiotherapy-related research grants were awarded to AAPM members, emphasizing the important role physicists have in developing radiotherapy-related treatments.

University physicists and the origins of the National Physical Laboratory, 1830-1900.

Traditionally, historians have taken it for granted that Britain's National Physical Laboratory (NPL) was created as the result of demands from a "professional" body of university-based physicists for a state-funded scientific institution. Yet paying detailed attention to the history of the NPL's originating institution, Kew Observatory, shows that the story is not so clear-cut. Starting in the 1850s, Kew Observatory was partly a center for testing meteorological instruments and other scientific equipment in return for fees. Long after the 1850s, the observatory was run by self-funded devotees of science. Paid university physicists only assumed a dominant role on its governing committee in the last two decades of the nineteenth century, by which time instrument-testing was already the observatory's main role. This paper argues that the rise of the university physicists - together with the desire of some of these physicists for a national institution that tested electrical standards - can only partially explain the origins of the NPL, and that Kew was in some ways a national physical laboratory before there were many physics teaching posts in British universities. This paper is a case study that illustrates a need to reassess the importance of university physicists in shaping British science at the end of the nineteenth century.

Present status of Medical Physics practice in Mexico: An occupational analysis.

PURPOSE: To present an overview of the status of Medical Physics practice in Mexico, promote the legal recognition of Medical Physics high-end training, and provide information that will potentially improve the Mexican healthcare system. METHODS: For the purpose of this research, the concept of "Medical Physics Professional/s" (MPP) is introduced to refer to any person/s executing the role of a clinical medical physicist (cMP) in whole or in part independent of academic profile, training or experience. A database of MPP in Mexico was built from official sources and personal communication with peers. Database records included the following fields: employer/s, specialty, academic profile, and annual income (when available). RESULTS: 133 centers in Mexico employ MPP, 49% of which are public institutions. 360 positions involving cMP roles were identified at the National Healthcare System (occupied by 283 MPP), 77% of which corresponded to radiation therapy. Public healthcare services hold 65% of the reported positions. Only 40% of MPP hold a graduate degree in Medical Physics, 46% of whom were located in the most densely populated region of Mexico. Of all MPP, 32% were women. CONCLUSIONS: This work allowed to clearly identify the current challenges of Medical Physics practice in Mexico, such as: insufficiency and uneven geographical distribution of qualified manpower, gender imparity, multishifting and wage gap. The products derived from this work could be used to guide the efforts to improve the Mexican healthcare system.

Development of Volumetric Independent Dose Calculation System for Verification of the Treatment Plan in Image-Guided Adaptive Brachytherapy.

Purpose: This study aimed to develop a volumetric independent dose calculation (vIDC) system for verification of the treatment plan in image-guided adaptive brachytherapy (IGABT) and to evaluate the feasibility of the vIDC in clinical practice with simulated cases. Methods: The vIDC is based on the formalism of TG-43. Four simulated cases of cervical cancer were selected to retrospectively evaluate the dose distributions in IGABT. Some reference point doses, such as points A and B and rectal points, were calculated by vIDC using absolute coordinate. The 3D dose volume was also calculated to acquire dose-volume histograms (DVHs) with grid resolutions of 1.0 × 1.0 (G1.0), 2.5 × 2.5 (G2.5), and 0.5 × 0.5 mm2 (G0.5). Dosimetric parameters such as D90% and D2cc doses covering 90% of the high-risk critical target volume (HR-CTV) and 2 cc of the organs at risk (OARs) were obtained from DVHs. D90% also converted to equivalent dose in 2-Gy fractions (EQD2) to produce the same radiobiological effect as external beam radiotherapy. In addition, D90% was obtained in two types with or without the applicator volume to confirm the effect of the applicator itself. Validation of the vIDC was also performed using gamma evaluation by comparison with Monte Carlo simulation. Results: The average percentage difference of point doses was <2.28%. The DVHs for the HR-CTV and OARs showed no significant differences between the vIDC and the treatment planning system (TPS). Without considering the applicator volume, the D90% of the HR-CTV calculated by the vIDC decreases with a decreasing calculated dose-grid size (32.4, 5.65, and -2.20 cGy in G2.5, G1.0, and G0.5, respectively). The overall D90% is higher when considering the applicator volume. The converted D90% by EQD2 ranged from -1.29 to 1.00%. The D2cc of the OARs showed that the averaged dose deviation is <10 cGy regardless of the dose-grid size. Based on gamma analysis, the passing rate was 98.81% for 3%/3-mm criteria. Conclusion: The vIDC was developed as an independent dose verification system for verification of the treatment plan in IGABT. We confirmed that the vIDC is suitable for second-check dose validation of the TPS under various conditions.

Validation of the RapidArc Delivery System Using a Volumetric Phantom as Per Task Group Report 119 of the American Association of Physicists in Medicine.

AIM: This study validated the RapidArc (RA) delivery using a volumetric ArcCHECK phantom as per the guidelines proposed in Task Group Report 119 from the American Association of Physicists in Medicine Task group 119 (AAPM TG 119). This study also investigated the impact of the Acuros XB (AXB) algorithm in comparison to analytical anisotropic algorithm (AAA) on the RA dose calculations in the homogeneous medium of the ArcCHECK phantom. MATERIALS AND METHODS: A volumetric ArcCHECK phantom along with AAPM TG 119 tests was used to evaluate the RA plans and verify the dose delivery for photon beam of 6 MV energy. RESULTS: The RA planning results were comparable and satisfied the planning criteria stated in the TG 119 report for all test cases. The average percentage gamma passing rates for the AAA-calculated plans were 98.5 (standard deviation [SD]: 0.6), 98.5 (SD: 1.3), and 98.1 (SD: 2.0) and for the AXB-calculated plans were 95.1 (SD: 1.8), 96.1 (SD: 1.3), and 94.0 (SD: 0.9) for the Clinac-iX (6 MV) and TrueBeam (TB)-STx (6 MV_filtered beam [FB] and 6 MV_flattening filter-free beam [FFFB]), respectively. For ion chamber measurements, the average percentage dose differences for the AAA-calculated plans were 1.5 (SD: 2.5), 2.7 (SD: 1.4), and 1.4(SD: 2.7) and for AXB-calculated plans were 2.3 (SD: 1.6), 3.2 (SD: 1.5), and 2.3 (SD: 2.0) for Clinac-iX (6 MV) and TB-STx (6 MV_FB and 6 MV_FFFB), respectively. CONCLUSION: Thus, the ArcCHECK can successfully be utilized for the validation of the RA delivery. The AXB has potential to perform dose calculations comparable to those of the AAA for RA plans in the homogeneous medium of the ArcCHECK phantom.