Changing Susceptibility of Staphylococci in Patients with Implant-Based Breast Reconstructions: A Single-Center Experience.

Background and Objectives: Infections and capsular contractures remain unresolved issues in implant-based breast reconstruction. Capsular contractures are thought to be caused by the endogenous flora of the nipple duct. However, little is known about the antibiotic susceptibility of the microorganisms involved. This study aimed to evaluate the composition of endogenous breast flora and its antimicrobial susceptibility in patients with breast cancer. This study will aid in selecting a prophylactic antibiotic regimen for breast reconstruction surgery. Materials and Methods: We obtained bacteriologic swabs from the nipple intraoperatively in patients who underwent implant-based breast reconstruction following nipple-sparing mastectomy between January 2019 and August 2021. Antibiotic susceptibility tests were performed according to the isolated bacteriology. Statistical analysis was performed based on several patient variables to identify which factors influence the antibiotic resistance rate of endogenous flora. Results: A total of 125 of 220 patients had positive results, of which 106 had positive culture results for coagulase-negative Staphylococcus species (CoNS). Among these 106 patients, 50 (47%) were found to have methicillin-resistant staphylococci, and 56 (53%) were found to have methicillin-susceptible staphylococci. The methicillin resistance rate in the neoadjuvant chemotherapy group (56.3%) was significantly higher (OR, 2.3; p = 0.039) than that in the non-neoadjuvant chemotherapy group (35.5%). Conclusions: Based on the results, demonstrating high and rising incidence of methicillin-resistant staphylococci of nipple endogenous flora in patients with breast cancer compared to the past, it is necessary to consider the selection of prophylactic antibiotics to reduce infections and capsular contracture after implant-based breast reconstruction.

Safe and Effective Method to Transfer Pedicle Vessels in Free Flap Reconstruction.

Free tissue transfer is a useful method to cover soft tissue defects following trauma or tumor excision. At the time of transfer of the pedicle, its status is not investigated. Therefore, kinking of the pedicle can occur, and pedicle injuries can result from surgical instruments. The authors would like to introduce a simple, safe, and effective method to overcome these problems using a Penrose drain. The present method can help reconstructive microsurgeons with the transfer of pedicle vessels through a tunnel without torsion or injury.

CT-Based Morphological Analysis of Isolated Inferior and Medial Blow-out Orbital Fractures in Korean Adults.

PURPOSE: To evaluate morphologic differences in isolated inferior medial orbital wall fractures (OWF) based on computed tomography scans. METHODS: This was a retrospective observational case study of 22 patients with an isolated inferior OWF and 32 patients with an isolated medial fracture between January 2008 and August 2010. We analyzed patient demographics and bony radiologic characteristics on CT scans, including the length and height of the lamina papyracea, the number of ethmoid air cell septa, the length of the anterior and posterior border of the orbital floor, the thickness of the orbital floor maxillary bone, and the axial length of the eyeball. RESULTS: There were no significant differences in sex, laterality, or concomitant intraocular injury between the two groups. The anteroposterior length (p = 0.391), the number of ethmoid septa (p = 0.869), and the thickness of the orbital floor (p = 0.419) did not differ significantly. The anterior (p < 0.001) or posterior (p = 0.014) height of the lamina papyracea, the lamina papyracea area (p < 0.001), and the lamina papyracea area/ethmoid air cell septa (p = 0.024) were significantly higher in the medial OWF group, while the anterior (p = 0.026) or posterior (p < 0.001) border length of the orbital floor and the axial length (p = 0.047) and volume (p = 0.034) of the eyeball were longer and smaller, respectively, in the inferior OWF group. CONCLUSIONS: Patients with a longer anterior or posterior border of the orbital floor, a shorter axial length, and a smaller eyeball volume are more likely to incur an isolated inferior OWF than an isolated medial OWF.

Consideration of bone regeneration effect of stem cells: comparison between adipose-derived stem cells and demineralized bone matrix.

BACKGROUND: Currently, many studies have sought to address the regeneration of extensive bone defects using stem cells. Here, the authors injected adipose-derived stem cells and demineralized bone matrix (DBM) into areas of bone defect in rabbits and compared their effect on bone regeneration to study the clinical usefulness of stem cells. METHODS: This study used 20 male New Zealand white rabbits. Four craniectomies were made in 20 male New Zealand white rabbits' calvaria, and 4 different groups of experimental conditions were applied to each of the 4 cranial defects. To the first group, 0.2 mL of DBX, a commercially available clinical preparation ofDBM, was applied with fibrin glue. To the second group, 0.2 mL of adipose-derived stem cells, with confirmed bone differentiation ability, was applied with fibrin glue. To the third group, 0.1 mL of DBX, 0.1 mL of adipose-derived stem cells, and fibrin glue were applied. The fourth group of defects acted as the control and was left unaltered. After 6 weeks, regenerated bone from each defect site in each rabbit was collected and measured for volume change. Bone regeneration was assessed with three-dimensional skull bone computed tomography and histological analysis. RESULTS: Osteoblasts were confirmed in all defect groups after 6 weeks. Overall, bone regeneration was weakest in the control group, whereas other groups of defects showed distinct bone regeneration. In particular, group 3, to which adipose-derived stem cells and DBM were applied, demonstrated the most active regeneration. CONCLUSIONS: Both adipose-derived stem cells and DBM demonstrated regeneration effect on cranial defects in rabbits, but it is difficult to conclude which was better, because in each case the amount of regenerated bone was within the margin of error. However, as the most active bone regeneration was observed when both adipose-derived stem cells and DBM were applied together, this combination could be helpful in the correction of extensive bone defects.

Clinical outcome of autologous bone marrow aspirates concentrate (BMAC) injection in degenerative arthritis of the knee.

PURPOSE: As a treatment method of degenerative arthritis of knee, this study evaluated the clinical efficacy of the intra-articular injection of autologous bone marrow aspirates concentrate (BMAC) with adipose tissue. MATERIALS AND METHODS: Between April 2011 and May 2012, 41 patients (75 knees) who were diagnosed as a degenerative knee arthritis and underwent the BMAC injection with adipose tissue were included in this study. Mean age was 60.7 years old (ranged 53-80). Kellgren-Lawrence grade was used for assessing radiologic degree of osteoarthritis; there were each 12, 24, 33, and 6 cases of grade I, II, III, and IV. At preoperative and postoperative 3, 6, and 12 months, pain score using visual analogue scale (VAS) and functional scales were used for evaluation. RESULTS: After the procedure, mean VAS score was decreased from 7.0 preoperatively to 4.1, 3.5, and 3.3 postoperatively 3, 6, and 12 months. And functional scores were also improved; International Knee Documentation Committee score (from 37.7 preoperatively to 59.3, 66.3, 69.3 postoperatively), SF-36 health score (from 31.5 to 43.5, 45.6, 47.7), knee and osteoarthritis outcome score (from 43.1 to 64.9, 68.5, 70.6), Lysholm Knee Questionnaire (from 37.3 to 65.4, 68.6, 71.0) were all increased after the procedure. When classified according to K-L grade, the improvement of VAS score in grade IV group was 8.2 preoperatively to 5.5, 5.3, and 5.7 postoperatively, which was significantly poorer than those of grade I-III groups. In the knee functional scales, similar pattern was checked. CONCLUSIONS: BMAC injection significantly improved both knee pain and functions in the patients with degenerative arthritis of knee. Also, the injection would be more effective in early to moderate phases.

What Is the Minimum Number of Sutures for Microvascular Anastomosis during Replantation?

As vessel diameter decreases, reperfusion after anastomosis becomes more difficult. When a blood vessel is sutured, its inner diameter becomes narrower owing to the thickness of the suture material and the number of sutures. To minimize this, we attempted replantation using a 2-point suture technique. We reviewed cases of arterial anastomosis in vessels with a diameter of less than 0.3 mm during replantation performed over a four-year period. In all cases, close observation was followed by absolute bed rest. If reperfusion was not achieved, a tie-over dressing was applied, and hyperbaric oxygen therapy was administered in the form of a composite graft. Of the 21 replantation cases, 19 were considered successful. Furthermore, the 2-point suture technique was performed in 12 cases, of which 11 survived. When three or four sutures were performed in nine patients, eight of these cases survived. Composite graft conversion was found in three cases in which the 2-point suture technique was used, and two of these cases survived. The survival rate was high in cases where 2-point sutures were used, and there were few cases of conversion to a composite graft. Reducing the number of sutures aids in optimizing reperfusion.

Is the retroauricular region a suitable donor site for full-thickness skin grafting in the era of mask wearing?

BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, the everyday use of face masks massively increased to prevent the spread of infection. Many people complain of ear pain and erosion when wearing a mask for extended periods of time. If prolonged mask usage is uncomfortable for ordinary people, a question arises-how much more inconvenient must mask wearing be for patients with a full-thickness skin graft (FTSG) donor site in the retroauricular region? Herein, we evaluated complications related to face mask use in 27 patients with a retroauricular FTSG donor site, with the goal of clarifying whether the retroauricular region is still an appropriate FTSG donor site in the context of the COVID-19 pandemic. METHODS: Complications in 27 patients treated by FTSGs harvested from the retroauricular region from 2019 to 2021 were investigated. A questionnaire comparing the normal and the operated sides was administered. Pain, itching, soreness, deformity, and symmetry were further investigated. RESULTS: Pain and itching were the only observed complications. The operated side was slightly more painful than the normal side in four patients (14.8%), and four patients (14.8%) reported itching on the operated side. However, all patients who experienced complications stated that the pain or itching did not interfere with mask wearing. Most symptomatic patients were older than 60 years of age (23.8%, p=0.185) and wore masks for longer periods of time (28.5%, p=0.326). CONCLUSION: Few retroauricular donor site-related complications occurred, and none of these complications caused inconvenience in daily life. Therefore, in the COVID-19 pandemic, the use of the retroauricular region as an FTSG donor site remains appropriate.

Correlation between Collagen Type I/III Ratio and Scar Formation in Patients Undergoing Immediate Reconstruction with the Round Block Technique after Breast-Conserving Surgery.

The aim of this study was to investigate the relationship between the collagen type I/III ratio and scarring in patients who underwent immediate reconstruction with the round block technique (RBT) after breast conservation surgery. Seventy-eight patients were included, and demographic and clinical characteristics were recorded. The collagen type I/III ratio was measured using immunofluorescence staining and digital imaging, and scarring was assessed using the Vancouver Scar Scale (VSS). The mean VSS scores were 1.92 ± 2.01 and 1.79 ± 1.89, as assessed by two independent plastic surgeons, with good reliability of the scores. A significant positive correlation was found between VSS and the collagen type I/III ratio (r = 0.552, p < 0.01), and a significant negative correlation was found between VSS and the collagen type III content (r = -0.326, p < 0.05). Multiple linear regression analysis showed that the collagen type I/III ratio had a significant positive effect on VSS (ß = 0.415, p = 0.028), whereas the collagen type I and collagen type III content had no significant effect on VSS. These findings suggest that the collagen type I/III ratio is associated with scar development in patients undergoing RBT after breast conservation surgery. Further research is needed to develop a patient-specific scar prediction model based on genetic factors affecting the collagen type I/III ratio.

Effects of a Topical Angiotensin-Converting Enzyme Inhibitor and a Selective COX-2 Inhibitor on the Prevention of Hypertrophic Scarring in the Skin of a Rabbit Ear.

UNLABELLED:  Angiotensin-converting enzyme (ACE) inhibitors have been reported to inhibit fibrogenesis, and cyclooxygenase-2 (COX-2) inhibitors, to reduce scarring by reducing the initial inflammation. The authors reasoned that the topical application of these 2 agents may have a complementary effect on scar reduction. METHODS: Captopril (ACE inhibitor), celecoxib (COX-2 inhibitor), or a combination of captopril and celecoxib were topically applied to a skin wound in a rabbit ear, and investigated for the effects on scar formation. RESULTS: The level of scar elevation decreased in the captopril group and the level of infiltration of inflammatory cells decreased in the celecoxib group. In the group where a combination of the 2 drugs was used, the level of scar elevation decreased the most, and collagen deposition and organization returned to normal most rapidly. Celecoxib was found to inhibit the initial inflammation in the ear wound of the rabbit, and captopril inhibited scar elevation. CONCLUSION: Clinical application of these drugs will require further studies with regard to adverse events and their absorptivity as topical agents. However, these findings suggest that the combined topical administration of an ACE inhibitor and COX-2 inhibitor to a skin wound could be an effective treatment for the prevention of hypertrophic scarring. .

Silicon Wafer CMP Slurry Using a Hydrolysis Reaction Accelerator with an Amine Functional Group Remarkably Enhances Polishing Rate.

Recently, as an alternative solution for overcoming the scaling-down limitations of logic devices with design length of less than 3 nm and enhancing DRAM operation performance, 3D heterogeneous packaging technology has been intensively researched, essentially requiring Si wafer polishing at a very high Si polishing rate (500 nm/min) by accelerating the degree of the hydrolysis reaction (i.e., Si-O-H) on the polished Si wafer surface during CMP. Unlike conventional hydrolysis reaction accelerators (i.e., sodium hydroxide and potassium hydroxide), a novel hydrolysis reaction accelerator with amine functional groups (i.e., 552.8 nm/min for ethylenediamine) surprisingly presented an Si wafer polishing rate >3 times higher than that of conventional hydrolysis reaction accelerators (177.1 nm/min for sodium hydroxide). This remarkable enhancement of the Si wafer polishing rate for ethylenediamine was principally the result of (i) the increased hydrolysis reaction, (ii) the enhanced degree of adsorption of the CMP slurry on the polished Si wafer surface during CMP, and (iii) the decreased electrostatic repulsive force between colloidal silica abrasives and the Si wafer surface. A higher ethylenediamine concentration in the Si wafer CMP slurry led to a higher extent of hydrolysis reaction and degree of adsorption for the slurry and a lower electrostatic repulsive force; thus, a higher ethylenediamine concentration resulted in a higher Si wafer polishing rate. With the aim of achieving further improvements to the Si wafer polishing rates using Si wafer CMP slurry including ethylenediamine, the Si wafer polishing rate increased remarkably and root-squarely with the increasing ethylenediamine concentration.

Surface Transformation of Spin-on-Carbon Film via Forming Carbon Iron Complex for Remarkably Enhanced Polishing Rate.

To scale down semiconductor devices to a size less than the design rule of 10 nm, lithography using a carbon polymer hard-mask was applied, e.g., spin-on-carbon (SOC) film. Spin coating of the SOC film produces a high surface topography induced by pattern density, requiring chemical-mechanical planarization (CMP) for removing such high surface topography. To achieve a relatively high polishing rate of the SOC film surface, the CMP principally requires a carbon-carbon (C-C) bond breakage on the SOC film surface. A new design of CMP slurry evidently accomplished C-C bond breakage via transformation from a hard surface with strong C-C covalent bonds into a soft surface with a metal carbon complex (i.e., C=Fe=C bonds) during CMP, resulting in a remarkable increase in the rate of the SOC film surface transformation with an increase in ferric catalyst concentration. However, this surface transformation on the SOC film surface resulted in a noticeable increase in the absorption degree (i.e., hydrophilicity) of the SOC film CMP slurry on the polished SOC film surface during CMP. The polishing rate of the SOC film surface decreased notably with increasing ferric catalyst concentration. Therefore, the maximum polishing rate of the SOC film surface (i.e., 272.3 nm/min) could be achieved with a specific ferric catalyst concentration (0.05 wt%), which was around seven times higher than the me-chanical-only CMP.

"Tear-Drop Appearance" Wrap: A Novel Implant Coverage Method for Creating Natural Contour in Prepectoral Prosthetic-Based Breast Reconstruction.

Various implant wrapping methods with acellular dermal matrix (ADM) have been introduced, but most focus on random trimming and suturing aimed to maximize implant coverage. Here we present our clinical experience using a "tear-drop appearance" wrapping method to achieve natural contours through upper pole volume replacement. We retrospectively reviewed the data of 56 consecutive cases of prepectoral prosthetic-based breast reconstruction (PPBR) using this wrapping method following nipple-sparing mastectomy between March 2020 and June 2021. The "tear-drop appearance" wrapping design creates an anatomical tear-drop-shaped pocket to encourage lower pole fullness and create a natural contour through upper pole volume replacement by ADM. Patients' baseline characteristics, operative data, and complications were analyzed. Aesthetic outcomes were measured using the BREAST-Q and Aesthetic Item Scale (AIS). A successful reconstruction was achieved without major complications and using a single ADM sheet. Four types and three sizes of ADMs were used. The mean resected breast tissue weight was 274.3 g, while the mean implant volume was 230.0 cc. The average BREAST-Q and AIS scores were 4.6 ± 0.8 and 4.5 ± 0.7, respectively. Owing to its simplicity, reproducibility, and effectivity, this method is an excellent implant coverage option that achieves a natural contour in PPBR.

Correlation between acellular dermal matrix (ADM) volume and breast implant size selection among patients undergoing prepectoral direct-to-implant (DTI) breast reconstruction using complete ADM.

BACKGROUND: In prepectoral direct-to-implant breast reconstruction using the acellular dermal matrix (ADM)-assisted technique, breast volume asymmetry can occur. We hypothesized that ADM size influences implant size selection in prepectoral breast reconstruction with implant coverage using an ADM. We investigated factors influencing implant size selection and provide guidelines for surgeons. METHODS: A retrospective chart review was performed to identify all patients who underwent prepectoral direct-to-implant breast reconstruction between January 2017 and October 2020. We assessed patient characteristics, preoperative expected implant volume, ADM size, volume of implant used in surgery, and symmetry scale of aesthetic item scale (AIS) 6 months after surgery. We compared the symmetry score of AIS between a group in which the preoperative expected silicone implant size (ES) was used and a group in which a silicone implant of a smaller size than planned (SS) was used. RESULTS: Patient characteristics, including age, body mass index (BMI), and excised breast volume, were similar between the groups (P > .05). ADM size had a significant effect on implant size selection (odds ratio = 1.760, P < .01). The symmetry score of AIS was higher in the SS group. CONCLUSIONS: ADM size must be considered when selecting implant size in prepectoral direct-to-implant breast reconstruction using the ADM-assisted technique.

Review of 107 Oncoplastic Surgeries Using an Acellular Dermal Matrix with the Round Block Technique.

The round block technique (RBT) is an oncoplastic surgery method that uses volume displacement techniques after partial mastectomy. However, cosmetic problems occur after tissue rearrangement in patients with small breasts or those in whom a large amount of breast tissue is excised. Therefore, we used an acellular dermal matrix (ADM) when the volume was insufficient after tissue rearrangement. Patients who underwent breast reconstruction using the ADM with the RBT after breast-conserving surgery (BCS) were included. The ADM graft was performed in two layers. First, it was placed on the glandular flap, and the patient was then seated to ascertain the degree of deformity. If the volume was insufficient, a graft was also performed under the skin flap. Overall, 107 oncoplastic surgeries were performed. Tumors were most commonly located in the upper outer quadrant of the breast, and the mean resected breast tissue was 27.1 g. Seroma was the most common complication, but it improved with several aspirations. There were no major complications or cosmetic problems requiring reoperation. Therefore, if the ADM was used for defects that could not be reconstructed with the RBT alone, safe and cosmetically good results could be obtained.

Polymer link breakage of polyimide-film-surface using hydrolysis reaction accelerator for enhancing chemical-mechanical-planarization polishing-rate.

In this study, the chemical decomposition of a polyimide-film (i.e., a PI-film)-surface into a soft-film-surface containing negatively charged pyromellitic dianhydride (PMDA) and neutral 4,4'-oxydianiline (ODA) was successfully performed. The chemical decomposition was conducted by designing the slurry containing 350 nm colloidal silica abrasive and small molecules with amine functional groups (i.e., ethylenediamine: EDA) for chemical-mechanical planarization (CMP). This chemical decomposition was performed through two types of hydrolysis reactions, that is, a hydrolysis reaction between OH- ions or R-NH3+ (i.e., EDA with a positively charged amine groups) and oxygen atoms covalently bonded with pyromellitimide on the PI-film-surface. In particular, the degree of slurry adsorption of the PI-film-surface was determined by the EDA concentration in the slurry because of the presence of R-NH3+, that is, a higher EDA concentration resulted in a higher degree of slurry adsorption. In addition, during CMP, the chemical decomposition degree of the PI-film-surface was principally determined by the EDA concentration; that is, the degree of chemical composition was increased noticeably and linearly with the EDA concentration. Thus, the polishing-rate of the PI-film-surface increased notably with the EDA concentration in the CMP slurry.

Evaluation of Radiation Resistance of Polystyrene Using Molecular Dynamics Simulation.

The scission rates of polystyrene and fluorinated polystyrene irradiated in an irradiation facility with Co-60 γ-rays were determined using molecular dynamics simulation and gel permeation chromatography (GPC) molecular weight distributions. The prediction was based on the assumption that γ-ray energy is transferred to the initial velocity of the primary knock-on atom. We employed a molecular dynamics simulation procedure to compute the changes in bond length between the connections for selected values of the absorbed dose and compared the calculated values with measurements made on the irradiated samples. The samples were exposed to four different absorbed doses of 25, 50, 75, and 100 kGy. The scission process and scission ratio were simulated with LAMMPS with ReaxFF potential for each bond, and we compared the simulation results with the experimental data especially measuring average molecular weight to evaluate the effect of fluorination on radiation enhancement.

Expression of the human cancer/testis antigen NY-SAR-35 is activated by CpG island hypomethylation.

The novel cancer/testis antigen gene, NY-SAR-35, is expressed exclusively in normal testis and in various histological types of tumor. However, the NY-SAR-35 gene expression is observed to be aberrant in several cancer cell lines and tissues. The analysis of methylation status of the NY-SAR-35 gene promoter in various cancer cell lines showed that its expression was related to methylation of the promoter region. Treatment of human cancer cell lines with the demethylating agent 5-aza-2'-deoxycytidine activated the expression of the NY-SAR-35 gene. In addition, transfection experiments on various fragments of the CpG-rich gene promoter indicate that in vitro methylation of the NY-SAR-35 gene promoter results in the loss of promoter activity. The expression of NY-SAR-35 is therefore activated by hypomethylation of the CpG island in the gene promoter.

A new approach to the treatment of nasal bone fracture: radiologic classification of nasal bone fractures and its clinical application.

PURPOSE: A radiologic examination is required in the treatment of nasal bone fracture to determine the fracture condition. Thus, there is an increasing need for radiologic classification of nasal bone fractures that can be applied to clinical practice. MATERIALS AND METHODS: Computed tomography was performed in 125 patients with nasal bone fractures to determine which axial view best showed the entire nasal view. The obtained axial view was then used as a reference for classification. The length from the top to the base of the nasal bone was divided into upper, middle, and lower levels, after which the fracture location was determined. If the fracture spanned the boundaries of these levels, it was classified as the total level. Subsequently, the fracture was subclassified based on the fracture direction and pattern and the concurrent fracture. RESULTS: Radiologic examination of patients with nasal bone fracture showed that nasal bone fracture was frequently found at the total, middle, upper, and lower levels, in that order. Nasal bone fractures at the upper level showed lower frequencies of complication and reoperation than the fractures at the other levels, whereas nasal bone fractures at the total level showed the highest frequencies of complication and reoperation. CONCLUSION: Radiologic classification can be useful for preoperative and postoperative evaluations of nasal bone fractures and can be helpful in understanding such fractures because it can efficiently predict the prognosis of a fracture.

Reconstruction of a small defect of the lower vermilion adjacent to white roll using a modified O-Z flap.

Reconstruction of lip defects is important because the lips play an important role in maintaining aesthetic facial balance, facial expressions, and speech. There are various methods of lip reconstruction such as primary repair, skin grafting, and utilization of local and free flaps. It is important to select a proper reconstruction method according to the size and location of lip defect. Failure to select an appropriate method may result in distortion, color mismatch, sensory loss, and aesthetic imbalance. Herein we present a case of successful aesthetic reconstruction of the lower vermilion. We removed a venous malformation, which was limited to the lower vermilion and adjacent to the white roll, and repaired the defect using the modified O-Z flap.

Preliminary Study on the Simulation of a Radiation Damage Analysis of Biodegradable Polymers.

In this study, biodegradable poly(L-lactide-co-ε-caprolactone) (PLCL) and poly(L-co-d,l lactide) (PLDLA) were evaluated using Geant4 (G4EmStandardPhysics_option4) for damage simulation, in order to predict the safety of these biodegradable polymers against gamma ray sterilization. In the PLCL damage model, both chain scission and crosslinking reactions appear to occur at a radiation dose in the range 0-200 kGy, but the chain cleavage reaction is expected to be relatively dominant at high irradiation doses above 500 kGy. On the other hand, the PLDLA damage model predicted that the chain cleavage reaction would prevail at the total irradiation dose (25-500 kGy). To verify the simulation results, the physicochemical changes in the irradiated PLCL and PLDLA films were characterized by GPC (gel permeation chromatography), ATR-FTIR (attenuated total reflection Fourier transform infrared), and DSC (difference scanning calorimetry) analyses. The Geant4 simulation curve for the radiation-induced damage to the molecular weight was consistent with the experimentally obtained results. These results imply that the pre-simulation study can be useful for predicting the optimal irradiation dose and ensuring material safety, particularly for implanted biodegradable materials in radiation processing.