Conformal Radiotherapy Research Articles

MDB-53. SALVAGE CRANIOSPINAL IRRADIATION FOR RELAPSED WNT-PATHWAY MEDULLOBLASTOMA PATIENTS TREATED WITH UPFRONT FOCAL CONFORMAL RADIOTHERAPY AND CHEMOTHERAPY AT INITIAL DIAGNOSIS: LONG-TERM AND MATURE OUTCOMES FROM A PROSPECTIVE DE-INTENSIFICATION STUDY

Abstract BACKGROUND Excellent long-term outcomes (5-year overall survival >90%) in WNT-pathway medulloblastoma (MB) patients have prompted systematic attempts at de-intensification of therapy to mitigate treatment-related toxicities. Mature outcomes of a prospective study (FOR-WNT) treating low-risk WNT-MB children with focal conformal radiotherapy (RT) and adjuvant systemic chemotherapy omitting upfront craniospinal irradiation (CSI) are being reported herein. METHODS Seven children with rigorously-defined low-risk WNT-MB were treated with post-operative focal conformal RT to the index tumor-bed (54Gy/30 fractions) followed by 6-cycles of adjuvant systemic chemotherapy after written informed consent/assent. Survival outcomes were computed using Kaplan-Meier method and reported as point estimate with 95% confidence intervals (CI). The trial was terminated prematurely due to unacceptably high risk of neuraxial failures. RESULTS One child succumbed to chemotherapy-related toxicity while 3 of 7 children were detected with leptomeningeal relapse on surveillance neuro-imaging within 2-years of index diagnosis. Full-dose salvage CSI (35Gy/21 fractions) at relapse followed by further chemotherapy led to excellent clinico-radiological response in all 3 children; however, one child developed further local recurrence and leptomeningeal metastases and succumbed to recurrent/progressive disease despite further aggressive salvage therapy. Five of 7 children including the other two treated with salvage CSI and systemic chemotherapy are alive and continue to remain in remission on long-term follow-up. At a median follow up of 61 months, the 5-year Kaplan-Meier estimates of event-free survival, relapse-free survival, and overall survival were 42.9% (95%CI: 18.2-100%), 50.0% (95%CI: 22.5-100%), and 71.4% (44.7-100%) respectively. CONCLUSIONS Omission of upfront CSI in low-risk WNT-MB is associated with unacceptably high-risk of neuraxial failure. Although full-dose salvage CSI achieves excellent response, remissions are not durable resulting in sub-optimal long-term overall survival. Judicious de-escalation with upfront low-dose CSI (18Gy) is currently being tested in a successor study (FOR-WNT 2).

Short course irradiation in rectal cancer: Dosimetry study comparing 3D conformal radiotherapy versus intensity-modulated radiotherapy versus volumetric modulated arc therapy

The standard radiotherapy planning technique for locally advanced rectal cancer (LARC) was 3D Conformal Radiotherapy (3DCRT). Modern radiation delivery techniques, including Intensity-Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) techniques, have been developed in recent years in terms of dose delivery to the target while minimizing the dose to the organ at risk (OAR). The objective of this study was to identify the most suitable treatment plan technique from the available options of 3DCRT, IMRT and VMAT for LARC using short course radiotherapy (SCRT). Therefore, twenty-five adult patients with LARC in the last five-year period (2017–2021) were involved in this study. For each patient, three radiotherapy treatment plans were generated for dosimetric comparison of short course irradiation (25 Gy/5 fractions, which is the new standard of care) using Varian Eclipse software to generate 3DCRT in comparison with IMRT and VMAT plans. The conformity index (CI), the homogeneity index (HI), and the organs at risk (OAR), including bladder, small bowel, and femoral heads, were compared between the three plans. The results revealed that VMAT and IMRT plans had a higher level of conformity for the planning target volume (PTV) with 0.996 and 0.994, respectively, compared to the 3DCRT planning of 0.947 (both p < 0.005). The PTV dose distribution was less homogeneous with 3DCRT than with VMAT or IMRT plans. VMAT offered superior homogeneity to IMRT and 3DCRT plans with 1.055, 1.066, and 1.089, respectively (p < 0.005). The findings showed that VMAT is superior to IMRT and 3DCRT in almost all parameters, including dose distribution conformity and homogeneity of the target volume, as well as providing better OAR sparing in LARC patients.

Fetal dose assessment in a pregnant patient with brain tumor: A comparative study of proton PBS and 3DCRT/VMAT radiation therapy techniques.

The treatment of brain tumors in pregnant patients poses challenges, as the out-of-field dose exposure to the fetus can potentially be harmful. A pregnant patient with prior radiation treatment was presented with a brain tumor at our clinic. This work reports on our pre-treatment study that compared fetal dose exposure between intensity-modulated proton therapy (IMPT) using pencil beam scanning (PBS) and conventional photon 3D conformal radiation therapy (3DCRT) and volumetric-modulated arc therapy (VMAT), and the subsequent pregnant patient's radiation treatment. Pre-treatment measurements of clinical plans, 3DCRT, VMAT, and IMPT, were conducted on a phantom. Measurements were performed using a device capable of neutron detections, closely following AAPM guidelines, TG158. For photon measurements, fetus shielding was utilized. On patient treatment days, which was determined to be proton treatment, shielding was used only during daily imaging for patient setup. Additionally, an in vivo measurement was conducted on the patient. Measurements showed that IMPT delivered the lowest fetal dose, considering both photon and neutron out-of-field doses to the fetus, even when shielding was implemented for photon measurements. Additionally, the proton plans demonstrated superior treatment for the mother, a reirradiation case. The patient was treated with proton therapy, and the baby was subsequently delivered at full term with no complications. This case study supports previous clinical findings and advocates for the expanded use of proton therapy in this patient population.

The current state and future perspectives of radiotherapy for cervical cancer.

Radiotherapy is an effective treatment method for cervical cancer and is typically administered as external beam radiotherapy followed by intracavitary brachytherapy. In Japan, center shielding is used in external beam radiotherapy to shorten treatment time and reduce the doses delivered to the rectum or bladder. However, it has several challenges, such as uncertainties in calculating the cumulative dose. Recently, external beam radiotherapy has been increasingly performed with intensity-modulated radiotherapy, which reduces doses to the rectum or bladder without center shielding. In highly conformal radiotherapy, uncertainties in treatment delivery, such as inter-fractional anatomical structure movements, affect treatment outcomes; therefore, image-guided radiotherapy is essential for appropriate and safe performance. Regarding intracavitary brachytherapy, the use of magnetic resonance imaging-based image-guided adaptive brachytherapy is becoming increasingly widespread because it allows dose escalation to the tumor and accurately evaluates the dose delivered to the surrounding normal organs. According to current evidence, a minimal dose of D90% of the high-risk clinical target volume is significantly relevant to local control. Further improvements in target coverage have been achieved with combined interstitial and intracavity brachytherapy for massive tumors with extensive parametrical involvement. Introducing artificial intelligence will enable faster and more accurate generation of brachytherapy plans. Charged-particle therapies have biological and dosimetric advantages, and current evidence has proven their effectiveness and safety in cervical cancer treatment. Recently, radiotherapy-related technologies have advanced dramatically. This review provides an overview of technological innovations and future perspectives in radiotherapy for cervical cancer.

Radiation Therapy in Non-Melanoma Skin Cancers: An Italian Survey on Behalf of the Italian Association of Radiotherapy and Clinical Oncology

AimsThe National Palliative Care and Interventional Radiotherapy Study Groups of the Italian Association of Radiotherapy and Clinical Oncology (AIRO) carried out a survey whose aim was to obtain a "snapshot" of the real-world practice of nonmelanoma skin cancer (NMSC) treatments in Italy. Materials and methodsThe survey was conducted on SurveyMonkey's online interface and was sent via e-mail to our society Radiation Oncologists. ResultsFifty-eight Italian radiation oncologists (ROs), representing 54 centers, answered the survey. Thirteen percent of the ROs declared they treat fewer than 10 NMSC lesions annually, 36% treat between 11 and 20, and 51% treat more than 20 lesions annually. Interventional radiotherapy (IRT) was offered by 25% of the ROs, and every case was reportedly discussed by a multidisciplinary team (71%). Electrons (74%), volumetric modulated arc therapy (V-MAT) (57%), three-dimensional conformal radiotherapy (3D-CRT) (43%), and IRT (26%) were the main treatment options. With external beam radiotherapy (EBRT), 46 and 53 different RT schedules were treated for curative and palliative intent, respectively; whereas for IRT, there were 21 and 7 for curative and palliative intent, respectively. The most popular EBRT curative options were 50–70.95/22–35 fractions (fx) and 50–70 Gy/16-20fx and for EBRT palliative settings, 30Gy/10fx, and 20–35Gy/5fx. For IRT, the most popular curative options were 32–50Gy/8-10fx and 30–54Gy/3-5fx, whereas 30Gy/6fz was the palliative option. Less than 10 re-RT cases were reported in one year in 42.5%, 11–20 cases in 42.5%, and >20 cases annually in 15%. Electrons (61%), VMAT (49%), and BRT (25%) were the most widely used approaches: 20–40Gy in 10fx and 20–25Gy in 5fx were the recommended fractionations. ConclusionThe survey shows a variegated reality. A national registry with more detailed data could help in undercover its causes.

Feasibility of determining external beam radiotherapy dose using LuSy dosimeter.

Radiation dose measurement is an essential part of radiotherapy to verify the correct delivery of doses to patients and ensure patient safety. Recent advancements in radiotherapy technology have highlighted the need for fast and precise dosimeters. Technologies like FLASH radiotherapy and magnetic-resonance linear accelerators (MR-LINAC) demand dosimeters that can meet their unique requirements. One promising solution is the plastic scintillator-based dosimeter with high spatial resolution and real-time dose output. This study explores the feasibility of using the LuSy dosimeter, an in-house developed plastic scintillator dosimeter for dose verification across various radiotherapy techniques, including conformal radiotherapy (CRT), intensity-modulated radiation therapy (IMRT), volumetric-modulated arc therapy (VMAT), and stereotactic radiosurgery (SRS). A new dosimetry system, comprising a new plastic scintillator as the sensing material, was developed and characterized for radiotherapy beams. Treatment plans were created for conformal radiotherapy, IMRT, VMAT, and SRS and delivered to a phantom. LuSy dosimeter was used to measure the delivered dose for each plan on the surface of the phantom and inside the target volumes. Then, LuSy measurements were compared against an ionization chamber, MOSFET dosimeter, radiochromic films, and dose calculated using the treatment planning system (TPS). For CRT, surface dose measurement by LuSy dosimeter showed a deviation of -5.5% and -5.4% for breast and abdomen treatment from the TPS, respectively. When measuring inside the target volume for IMRT, VMAT, and SRS, the LuSy dosimeter produced a mean deviation of -3.0% from the TPS. Surface dose measurement resulted in higher TPS discrepancies where the deviations for IMRT, VMAT, and SRS were -2.0%, -19.5%, and 16.1%, respectively. The LuSy dosimeter was feasible for measuring radiotherapy doses for various treatment techniques. Treatment delivery verification enables early error detection, allowing for safe treatment delivery for radiotherapy patients.

Radiotherapy resources in the Philippines: A 2022 update

BackgroundCancer is the third leading cause of death in the Philippines. Radiotherapy (RT) is integral to the treatment and palliation of cancer. Therefore, RT resources across the country must be surveyed and optimized. MethodsOnline surveys were sent to the heads of all 50 RT facilities in the Philippines. The survey included items regarding the facility itself, personnel, and available services. FindingsThe survey had a 98% response rate. 76% of RT facilities in the Philippines are privately owned; 12 are government/public institutions and 8 are academic centers. Over a third are in the National Capital Region; three regions are without a single RT facility. For a population of >110 million, the Philippines has 53 linear accelerators, 125 radiation oncologists, 56 residents, 114 medical physicists, 113 radiation oncology nurses, and 343 radiation therapists. Nine radiation oncology residency programs are active. All facilities are capable of 3D conformal radiotherapy, and 96% are capable of intensity modulated radiotherapy. <30% offer stereotactic radiotherapy, and <50% offer HDR brachytherapy. ConclusionWhile there has been significant expansion of RT resources over the years, RT remains inaccessible for many in the Philippines. Urgent investment in training and retaining RT personnel is needed as well. Policy summary: With its current cancer burden, the Philippines needs at least 170 linear accelerators, 300 radiation oncologists, and 150 medical physicists. Public/government cancer centers must be built, with priority given to regions without RT facilities. HDR brachytherapy and stereotactic radiotherapy services must also be expanded. A national RT task force must be created to ensure the quality, availability, and accessibility of RT in the Philippines. Further work exploring payment schemes that improve access to RT and mitigate financial toxicity is needed, as well as integration of radiation oncology providers and health policy experts into national health system decision making.

Feasibility and Toxicity of Hypofractionated Radiation Therapy in Patients Undergoing Post Mastectomy Radiation Therapy

Introduction: Post mastectomy radiation (PMRT) plays major role in breast cancer treatment. Hypofractionated radiation is a relatively newer modality. Hypofractionation is more commonly used after breast conservation surgery. Landmark trials that studied hypofractionation had fewer PMRT subjects. Here we report our study on feasibility and toxicity profile of hypofractionated PMRT. Aim: To describe the clinical and toxicity profile of patients undergoing hypofractionated 3D conformal radiation therapy in breast cancer patients. Materials &amp; Methods: This study included patients who are eligible for post mastectomy radiation therapy above 18 years planned for adjuvant PMRT (40.05Gy in 15 fractions delivered over 3 weeks in 3D conformal radiation) to the chest wall and supraclavicular nodes between April 2021 to October 2022., active lung infection, patient preference for conventional fractionation. Dosimetric parameters to target &amp; organs at risk were analyzed. Toxicities including hematologic, dermatitis, pharyngitis &amp; other were monitored. Results: Of 71 patients, 70 patients were female and 1 is male. Majority (46%) of patients belonged to 46-55 years age group. Age ranged from 34 to 85 years. Mean age is 52 years. Clinical Stage IIIA was the most common stage with 29.5% patients followed by Stage IIB with 25.3% patients. Majority received adjuvant chemotherapy (52%). Mean treatment time is 21 days. All patients completed treatment without any major complications. Follow up ranged from 17 months to 27 months. Out of 71 patients, 1 patient expired on follow up after 4 months of radiation therapy due to non cancer related cause (Chronic pancreatitis). On follow up, 3 patients had distant metastasis alone (lung, bone metastasis, brain metastases) and 1 patient had both local disease and distant metastasis. 3 patients who progressed had stage IIIC disease &amp; 1 had stage IIIB disease. The V90 to the Planned Target volume (PTV) ranged from 90.4% to 99% to right sided disease, 90.3% to 96.5% to left sided disease. Heart V17Gy ranged from 1.27% to 12.5% &amp; heart V35Gy was 0.16% to 7.2%. Dermatitis was the most common adverse effect in this study. 31 patients (43.6%) developed fatigue during treatment. They continued their daily activities without any limitations. 35 patients (49.2%) had throat pain, of which 2 patients had it in 1st week, 21 patients had it in 2nd week and 12 patients had it in 3rd week. They were treated with non opioid analgesics. Shoulder pain was observed in 10 patients (14%) during treatment. Blood parameters were monitored weekly during treatment. No changes were observed. Conclusion: Hypofractionated post mastectomy radiation therapy is well tolerated in our study group. None of them developed any major acute reactions during and post treatment in the follow up period. Patients completed their treatment without any breaks during treatment. Respiratory motion management especially left sided disease patients should be used for achieving dose constraints.

The Value of PET/CT in Particle Therapy Planning of Various Tumors with SSTR2 Receptor Expression: Comparative Interobserver Study.

The overexpression of somatostatin receptor type 2 (SSTR2) is a property of various tumor types. Hybrid imaging utilizing [68Ga]1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra-acetic acid (DOTA) may improve the differentiation between tumor and healthy tissue. We conducted an experimental study on 47 anonymized patient cases including 30 meningiomas, 12 PitNET and 5 SBPGL. Four independent observers were instructed to contour the macroscopic tumor volume on planning MRI and then reassess their volumes with the additional information from DOTA-PET/CT. The conformity between observers and reference volumes was assessed. In total, 46 cases (97.9%) were DOTA-avid and included in the final analysis. In eight cases, PET/CT additional tumor volume was identified that was not detected by MRI; these PET/CT findings were potentially critical for the treatment plan in four cases. For meningiomas, the interobserver and observer to reference volume conformity indices were higher with PET/CT. For PitNET, the volumes had higher conformity between observers with MRI. With regard to SBGDL, no significant trend towards conformity with the addition of PET/CT information was observed. DOTA PET/CT supports accurate tumor recognition in meningioma and PitNET and is recommended in SSTR2-expressing tumors planned for treatment with highly conformal radiation.

A Prospective Study on the Use of Deep Inspiration Breath-Hold Technique in External Beam Radiotherapy for Breast Cancer

Background Breast cancer is the most common cancer and the leading cause of death in women. The deep inspiration breath-hold (DIBH) technique helps reduce the dose received by the heart and lungs in breast cancers during adjuvant radiotherapy (RT). We present the dosimetry of heart and lungs with DIBH technique, reproducibility, and ease of execution. Materials and Methods This is a prospective study among breast cancer patients planned for adjuvant RT following either breast conservation or mastectomy. Patients received adjuvant RT to a dose of 42.5 Gy/16 Fr to the chest wall/whole breast followed by a boost of 10 Gy/5 Fr for breast conservation surgery patients with either three-dimensional conformal RT or volumetric modulated arc therapy technique. The dosimetric parameters such as lung mean dose, heart mean dose, and V25 Gy were compared between DIBH and free-breathing (FB) scans. Data were analyzed using SPSS software, and p-value &lt;0.05 was considered statistically significant. Results The study was conducted from September 2018 to August 2020, and 32 patients were included. The compliance to the DIBH technique was good. The dose received by ipsilateral lung V20 (17 vs. 25%) and mean dose (9 vs. 12 Gy) were significantly lower in DIBH compared with FB (p &lt; 0.001). The V5 (31 vs. 15%), V25 (9 vs. 2%), and mean dose (7 vs. 3.3 Gy) to the heart were much higher in FB compared with DIBH (p &lt; 0.001). Conclusion DIBH-based RT treatment delivery for breast cancer patients requiring adjuvant RT showed good compliance and offers a significant reduction in radiation dose to the heart and lung.

Hybrid Treatment Planning for Chest Wall Irradiation Utilizing Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT): A Systematic Review.

Novel hybrid approaches for chest wall irradiation show promising outcomes regarding target coverage and sparing organs at risk (OARs). In this systematic review, we compared hybrid volumetric modulated arc therapy (H-VMAT) or hybrid intensity-modulated radiotherapy (H-IMRT) techniques with non-hybrid techniques, such as three-dimensional conformal radiation therapy (3DCRT), field-in-field (FIF), intensity-modulated arc therapy (IMRT), and volumetric modulated arc therapy (VMAT), for breast cancer patients with mastectomy. Our focus was the plan quality and dose distribution to the OARs. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, we performed a systematic review and quality appraisal of primary studies evaluating hybrid therapy to the chest wall and the OARs. An extensive online search of PubMed and Scopus databases was conducted using appropriate keywords. The dose to the OARs (lung, heart, and contralateral breast), planning target volume (PTV), homogeneity index (HI), and conformity index (CI) were extracted. The data were then tabulated and compared for the outcomes between modalities among the studies.Nine studies that met the search criteria were selected to evaluate the PTV coverage and dosimetric results of hybrid and non-hybrid techniques. In terms of 95% PTV coverage, among nine reviewed studies, the largest difference between the two techniques was between VMAT (47.6 Gy) and H-VMAT (48.4 Gy); for the conformity index, the largest difference was noted between 3DCRT (0.58) and H-VMAT (0.79). In both cases, differences were statistically significant (P < 0.005). Two studies showed dose homogeneity improvement within the treatment target in H-VMAT (0.15 and 0.07) compared with 3DCRT (0.41 and 0.12), with a P value of <0.001. Two studies did not report on the homogeneity index, and three others observed no statistical difference. Regarding OARs, in the comparison of H-VMAT and VMAT, the largest significant change was in the volume receiving 5 Gy (V5Gy) of the ipsilateral lung and the V10Gy of the contralateral lung. For the ipsilateral lung, V5Gy was 90.7% with VMAT versus 51.45% with H-VMAT. For the contralateral lung, V10Gy was 54.9% with VMAT versus 50.5% with H-VMAT. In six studies, the mean dose of the contralateral breast was lower in hybrid techniques than in single modalities: VMAT (4.2%, 6.0%, 1.9%, 7.1%, 4.57%) versus H-VMAT (1.4%, 3.4%, 1.8%, 3.5%, 2.34%)and IMRT (9.1%) versus H-IMRT (4.69%). Although most studies did not report on monitor units and treatment time, those that included them showed that hybrids had lower monitor units and shorter treatment times.Hybridtechniques in radiotherapy, such as combining two modalities, can indeed facilitate lower doses to OARsfor patients with a high risk of toxicities. Prospective clinical studies are needed to determine the outcomes of breast cancer treated with hybrid techniques.

Abstract PO5-22-03: Influence of the surgical clip concerning the dose and volume of irradiated surrounding tissues including lung and heart in the planning of radiotherapy boost with conservative breast surgery with and without oncoplasty

Abstract Introduction: Patients with the highest risk of breast cancer undergoing conservative surgery receive an additional boost dose of radiotherapy in the tumor bed during treatment planning, which is known to bring benefits in local control. Objectives: To evaluate the influence of the surgical clip concerning the volume of surrounding tissues irradiated during radiotherapy, in patients submitted to conservative breast surgery with and without oncoplasty. Materials/Methods. The analyzed variables were defined as: the volume of the boost (V100 Boost) and breast tissue (V100 Breast) that received 100% of the prescribed dose during the radiotherapy planning and the volume of the heart (V40 Heart) and lung (V40 Lung) that received 40% of the prescribed dose during the boost phase in patients undergoing treatment with breast conservation. The variables were compared about the insertion or not of the surgical clip and the influence of oncoplastic surgery on the volume of irradiated tissues of the breast, boost, heart and lung during radiotherapy planning. Student's t-test (95%CI; p&amp;lt; 0.05) was used to compare mean volumes as a function of the presence or not of surgical clips and oncoplastic surgery. Results: Retrospective study included 183 women with breast cancer who underwent treatment with conservative breast surgery and radiotherapy of the whole breast, followed by sequential boost, between January 2011 and January 2021. Boost, breast, heart, and lung volumes were evaluated during planning for conformational radiotherapy. The results showed a significant difference between the average boost volumes when the patient was clipped. The average boost volume that received 100% of the prescribed dose was V100 Boost=244.22cm³ (SD±158) in the absence of the clip. In the presence of 1 or 2 clips, this average was V100 Boost= 94.87cm³ (SD±37) and with 3 or more clips it was V100 Boost= 96.99cm³ (SD±39) (p&amp;lt; 0.001). There was also a significant difference in mean breast volumes that received 100% of the prescribed dose. In the absence of the clip, the V100 Breast=373.16 cm³ (SD±222) and when 1 or 2 clips were present, the V100 Breast=235.28 cm³ (SD±125) (p=0.01). The analyzes of the mean volumes of the heart (V40 Heart) and lung (V40 Lung) that received 40% of the prescribed boost dose were not statistically significant, regardless of the presence and number of clips. For the oncoplasty group, there was no statistical difference between the means of boost, breast, heart and lung volumes. Conclusion: The presence of the surgical clip reduced the volume of the boost and the breast that received 100% of the dose in the radiotherapy planning. The volume of the boost (V100 Boost), which received 100% of the dose prescribed during radiotherapy planning, was smaller in patients with a surgical clip, as was the volume of irradiated breast tissue (V100 Breast) in clipped patients. The volume of irradiated tissue in the heart (V40 Heart) and lung (V40 Lung) that received 40% of the prescribed dose during the boost phase in radiotherapy planning did not suffer statistical differences in insertion or not of the surgical clip. Oncoplastic surgery and the presence of surgical clips did not influence the volumes of irradiated boost, breast, heart and lung tissues during the radiotherapy planning of patients undergoing conservative surgical treatment of the breast. Table: Means of boost, breast, heart and lung irradiated volumes according to the presence or absence of clips and oncoplastic surgery Table. Means of boost, breast, heart and lung irradiated volumes according to the presence or absence of clips and oncoplasty surgery Variable (cm3) Clip p valor Oncoplasty p valor With Without With Without Means Means Means Means V100% Boost 94 244 &amp;lt; 0,001 102 118 0,906 V100% Breast 235 373 0,01 271 272 0,816 V40% Heart 1,10 4,52 0,33 1,96 1,39 0,903 V40% Lung 56,66 56,10 0,93 51,63 52,53 0,796 Citation Format: Nilceana Freitas, Priscila Watanabe, Jean Paiva, Carolina Bezerril, Marcelo Valentim, Thais Gontijo, Flavia Araujo, Ruffo Freitas-Junior. Influence of the surgical clip concerning the dose and volume of irradiated surrounding tissues including lung and heart in the planning of radiotherapy boost with conservative breast surgery with and without oncoplasty [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-22-03.

Treatment Related Acute Toxicities Between Treatment with 3D-CRT and IMRT in Localised Prostate Cancer.

To compare the acute toxicities of two radiation treatment techniques, intensity modulated radiation therapy (IMRT), and 3-dimensional conformal radiation therapy (3D-CRT) in localised prostate adenocarcinoma. Descriptive study. Place and Duration of the Study:Department of Oncology, Dr. Ziauddin Hospital, Karachi, Pakistan, from July 2016 to June 2022. Patients with localised prostate adenocarcinoma who underwent treatment using two different advanced radiotherapy techniques i.e., IMRT and 3D-CRT were recruited during the study period. They were followed up for six months for acute gastrointestinal (GI) and genitourinary (GU) adverse events (acute toxicities) related to both treatment modalities according to Modified radiation therapy oncology group (RTOG) criteria. The acute toxicities were assessed at the 2nd, 4th, and 6th week during treatment and at the 3rd and 6th month after treatment. There were 78 patients, with 39 patients in each group. The mean age was 68 ± 10 years in the 3D-CRT and 68 ± 07 years in the IMRT group. Patients in the IMRT group exhibited markedly lower treatment-related acute GI and GU effects at the end of 4th and 6th weeks for anorectal pain (p = 0.04) and (p = 0.01) and burning micturition (p = 0.003) and (p = 0.01), respectively. Furthermore, at 3 months anorectal pain (p = 0.02), loose stools (p = 0.005), and burning micturition (p = 0.01) were present and at 6 months anorectal pain was (p = 0.01) still present. Radiation therapy modalities 3D-CRT and IMRT both showed acceptable toxicity profile in the management of localised prostate cancer, while IMRT group exhibited significantly lower treatment-related acute GI and GU effects. 3D-CRT (3-Dimensional Conformal Radiation Therapy), IMRT (Intensity-Modulated Radiation Therapy), Radiation toxicity.

TEAM participation in the irradiation of IROC phantoms for cooperative group clinical trials

The participation of radiation oncology team members in the irradiation of Imaging and Radiation Oncology Core (IROC) phantom for cooperative group clinical trials is essential to comply with the latest quality management philosophy. Medical dosimetrists are expected to develop treatment plans for the irradiation of IROC phantoms. For advanced treatment techniques, such as three-dimensional conformal radiation therapy (3DCRT), intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT), the irradiation of the IROC phantoms serves as quality audit. If successful, the irradiation processes demonstrate that the institution has the knowledge of the protocol, and has the appropriate equipment to comply with the protocol requirements. This article describes three IROC phantoms used for credentialing external beam photon beam therapy, delivered using conventional medical linear accelerators, to the medical dosimetry community. Guidance and strategies for the development of treatment plans are discussed. Our institutional irradiation of the three IROC phantoms, delivered using the Truebeam medical linear accelerator, resulted in consistent dose accuracy to within ±1%. The participation of the team members may reduce the overall published failing rate stated to be about one-third of all participating institutions.

RADIATION PHYSICS IN CANCER TREATMENT- A STUDY OF RADIOTHERAPY TECHNIQUES

Radiation therapy plays a pivotal role in cancer treatment, utilizing advanced technologies to target and destroy cancer cells while minimizing damage to healthy tissues. This paper provides an in-depth analysis of radiotherapy techniques, including 3D Conformal Radiotherapy, Intensity-Modulated Radiotherapy (IMRT), and Proton Therapy, highlighting their mechanisms, applications, and effectiveness. The paper explores radiobiological effects, emphasizing the impact of radiation on cellular structures and tumour control, as well as challenges such as tumour heterogeneity, radio resistance, and normal tissue toxicity. With the integration of emerging technologies like artificial intelligence, the future of radiotherapy holds potential for personalized treatment plans and enhanced outcomes. Through a comprehensive discussion on current challenges and future directions, this study underscores the need for further innovation to overcome the limitations of current treatments and improve accessibility. The use of numerical data and tables reinforces key concepts, offering quantitative insights into radiotherapy's performance and its implications for cancer care. Ultimately, this paper contributes to the understanding of radiation physics in cancer treatment and presents forward-looking strategies for improving radiotherapy efficacy.

Effect of neoadjuvant concurrent three-dimensional conformal chemoradiotherapy with conventional two-dimensional chemoradiotherapy in locally advanced rectal cancer

Background: Rectal carcinoma is a prevalent clinical condition, and treatment hinges on factors like tumor specifics, staging, grading, and histopathological characteristics. While surgery remains the primary treatment, neoadjuvant chemoradiotherapy, particularly using 3D-CRT, has proven effective in reducing local recurrence rates for locally advanced cases. Alternatively, 2D-RT is considered for neoadjuvant treatment. This study aimed to compare the impact of neoadjuvant concurrent three-dimensional conformal chemoradiotherapy with conventional two-dimensional chemoradiotherapy in the context of locally advanced rectal cancer. Methods: In this multicentre quasi-experimental study, 60 patients with biopsy-proven adenocarcinoma and clinically confirmed locally advanced rectal cancer, were divided into Group A (receiving oral capecitabine with three-dimensional conformal radiotherapy) and Group B (receiving the same capecitabine dose with 50 Gy two-dimensional radiotherapy). After surgery within 6-12 weeks, outcomes were analysed. Results: After neoadjuvant chemoradiotherapy, clinical complete response rates were 16.7% in Group A and 10.0% in Group B, with a higher pathological complete response in Group A (10.0% vs. 3.3%). Tumor downsizing occurred in 83.3% of Group A and 73.3% of Group B, and sphincter-sparing surgery was achieved in 73.3% of Group A and 56.7% of Group B. Grade 2 toxicities included anemia (10.0% vs. 13.3%), leucopenia (13.3% vs. 20.0%), diarrhoea (10.0% vs. 16.7%), proctitis (13.3% vs. 40.0%), and urinary toxicity (10.0% vs. 20.0%). Grade-1 toxicities were nausea (20.0% vs. 40.0%), vomiting (20.0% vs. 36.7%), mucositis (56.7% vs. 60.0%), hand-foot syndrome (33.3% vs. 40.0%), and urinary toxicity (43.3% vs. 56.67%), with significant proctitis in Group A (p=0.012). Other toxicities showed non-significant p-values (&gt;0.05). Conclusions: Tumour response was not statistically significant between the patients of concurrent 3D-CRT and 2D-RT Arms. But the patients of 3D-CRT arm showed better response arithmetically. Also, there was an observable significant reduction of toxicities (lower gastrointestinal) in the 3D-CRT arm.

Characterisation of Portuguese radiotherapy departments: Organisation, occupational exposure values and diagnostic reference levels for breast and prostate computed tomography planning

IntroductionPortugal currently hosts 24 active radiotherapy departments, 8 public and 16 privates, presenting potential radiation exposure risks to multidisciplinary teams. Patients in these treatments also face ionising radiation during treatment planning and verification. MethodsAuthorisation and ethical approval were secured for a national online survey, disseminated to radiotherapy departments across Portugal. The survey encompassed three sections: equipment, staff, and radiographer role characterisation; occupational exposure values for one month; and exposure parameters, including computed tomography (CT) dose values [CT dose index (CTDIvol) and dose length product (DLP)] for breast and prostate cancer CT planning. Local Diagnostic Reference Levels (DRLs) derived were based on the 75th percentile of median dose values. ResultsThe study garnered a 50% response rate from public institutions, 12,5% from private and 25% from all active radiotherapy institutions in Portugal. All departments employ Three-Dimensional Conformal Radiation Therapy (3D–CRT) and incorporate Intensity Modulated Radiation Therapy (IMRT) and/or Volumetric Modulated Arc Therapy (VMAT) irradiation techniques. Additionally, half of the departments also perform Brachytherapy (BT). Radiographers demonstrated an occupational dose of zero mSv. CT planning dose values were 13 mGy and 512 mGy cm for breast CT and 16 mGy and 689 mGy cm for prostate CT, pertaining to CTDIvol and DLP, respectively. ConclusionMost aspects of national radiotherapy characterisation align with the established literature. Occupational exposure values exhibited consistency across radiotherapy modalities. An approach to national DRLs was formulated for breast and prostate CT planning, yielding values congruent with recent European studies. Implications for practiceThis study offers vital insights for analysing occupational contexts and risk prevention, serving as the initial characterisation of the national radiotherapy landscape. It also pioneers the calculation of DRLs for CT planning in radiotherapy to optimise procedures.

Current practices of craniospinal irradiation techniques in Turkey: a comprehensive dosimetric analysis

ObjectiveThis study evaluates various craniospinal irradiation (CSI) techniques used in Turkish centers to understand their advantages, disadvantages and overall effectiveness, with a focus on enhancing dose distribution.MethodsAnonymized CT scans of adult and pediatric patients, alongside target volumes and organ-at-risk (OAR) structures, were shared with 25 local radiotherapy centers. They were tasked to develop optimal treatment plans delivering 36 Gy in 20 fractions with 95% PTV coverage, while minimizing OAR exposure. The same CT data was sent to a US proton therapy center for comparison. Various planning systems and treatment techniques (3D conformal RT, IMRT, VMAT, tomotherapy) were utilized. Elekta Proknow software was used to analyze parameters, assess dose distributions, mean doses, conformity index (CI), and homogeneity index (HI) for both target volumes and OARs. Comparisons were made against proton therapy.ResultsAll techniques consistently achieved excellent PTV coverage (V95 > 98%) for both adult and pediatric patients. Tomotherapy closely approached ideal Dmean doses for all PTVs, while 3D-CRT had higher Dmean for PTV_brain. Tomotherapy excelled in CI and HI for PTVs. IMRT resulted in lower pediatric heart, kidney, parotid, and eye doses, while 3D-CRT achieved the lowest adult lung doses. Tomotherapy approached proton therapy doses for adult kidneys and thyroid, while IMRT excelled for adult heart, kidney, parotid, esophagus, and eyes.ConclusionModern radiotherapy techniques offer improved target coverage and OAR protection. However, 3D techniques are continued to be used for CSI. Notably, proton therapy stands out as the most efficient approach, closely followed by Tomotherapy in terms of achieving superior target coverage and OAR protection.

Impact of Radiation on Dysphagia-Related Structures: A Dosimetric and Clinical Comparative Analysis of Three-Dimensional Conformal Radiotherapy (3D-CRT) and Intensity-Modulated Radiation Therapy (IMRT) Techniques in Patients With Head and Neck Cancer.

Introduction Head and neck squamous cell carcinoma (HNSCC)is a significant health concern in India, with around one million new cases annually. The prevalence of HNSCC is notably high in Asia, especially in India, due to habitslike tobacco chewing, betel nut usage, and alcohol consumption. Treatment typically involves a combination of surgery, radiation, chemotherapy, and biological therapy, aiming for tumor control while preserving function and quality of life. However, survivors often face long-term side effectslike difficulty swallowing, leading to complicationssuch as aspiration pneumonia. Intensity-modulated radiotherapy (IMRT) has shown promise in improving outcomes by sparing critical swallowing structures. Efforts to minimize radiation-related dysphagia are crucial for enhancing patients' quality of life post-treatment. Our study focuses on examining dosimetric parameters associated with dysphagia aspiration, alongside evaluating dysphagia grades in both treatment groups using the RTOGscale. Material and methods Patients with histologically confirmed non-metastatic head and neck carcinomas were included in our study in November 2018-April 2020. A total of 56 patients were taken into our study with 28 in each arm. They underwent radical radiotherapy (RT) with a total dose of 66-70 Gy, with or without concurrent chemotherapy, meeting specific inclusion criteria and excluding those receiving reirradiation or with distant metastasis. Patients were divided into two groups: Group I received three-dimensional conformal radiotherapy (3D-CRT), and Group II received IMRT. Treatment planning involved immobilization, CT imaging, delineation of target volumes and organs at risk, and contouring of swallowing structures. Dose-volume histogram parameters (mean dose, maximum dose, V30, V70, V80, D50, and D80) were used to assess mean dose to swallowing structures outside the planning target volume (PTV), with a mean dose constraint of 50 Gy. Dysphagia was evaluated using the RTOGcriteria at baseline, during treatment, and six months post-treatment. Statistical analysis was performed using SPSS, with significance set at p < 0.05. Results In our study, the mean age at presentation differed slightly between the IMRT and 3D-CRT arms: 58 years versus 55 years, respectively. A higher proportion of patients in both arms experienced symptoms for three to six months, with 53.6% in 3D-CRT and 42.9% in IMRT. Stage distribution varied, with IV being most common in 3D-CRT and stage II in IMRT. Approximately 56% of patients in both groups had a history of smoking. Significant differences were observed in spinal cord dose between 3DCRT and IMRT techniques (p < 0.001). Similarly, a significant difference was found in the mean dose received by dysphagia aspiration-related structures (DARSs) between the 3D-CRT and IMRT arms (p = 0.04). Patients in the IMRT arm exhibited superior dysphagia grades compared to those in the 3D-CRT arm, with statistical significance observed in the third month (p = 0.008) and sixth month (p = 0.048). Conclusion Our study found a notable decrease in the mean DARS dose and reduced dysphagia severity at three and six months in the IMRT group compared to the 3D-CRT group. However, due to the diverse study population, establishing a definitive correlation between the DARS dose and dysphagia severity was challenging. Future large-scale studies are needed to validate these findings for improved preservation of DARS structures.

Artificial neural network-assisted prediction of radiobiological indices in head and neck cancer.

We proposed an artificial neural network model to predict radiobiological parameters for the head and neck squamous cell carcinoma patients treated with radiation therapy. The model uses the tumor specification, demographics, and radiation dose distribution to predict the tumor control probability and the normal tissue complications probability. These indices are crucial for the assessment and clinical management of cancer patients during treatment planning. Two publicly available datasets of 31 and 215 head and neck squamous cell carcinoma patients treated with conformal radiation therapy were selected. The demographics, tumor specifications, and radiation therapy treatment parameters were extracted from the datasets used as inputs for the training of perceptron. Radiobiological indices are calculated by open-source software using dosevolume histograms from radiation therapy treatment plans. Those indices were used as output in the training of a single-layer neural network. The distribution of data used for training, validation, and testing purposes was 70, 15, and 15%, respectively. The best performance of the neural network was noted at epoch number 32 with the mean squared error of 0.0465. The accuracy of the prediction of radiobiological indices by the artificial neural network in training, validation, and test phases were determined to be 0.89, 0.87, and 0.82, respectively. We also found that the percentage volume of parotid inside the planning target volume is the significant parameter for the prediction of normal tissue complications probability. We believe that the model has significant potential to predict radiobiological indices and help clinicians in treatment plan evaluation and treatment management of head and neck squamous cell carcinoma patients.