Technical guide to DICOM UID generation

				
					import * as crypto from "crypto";

/**
 * DICOM hierarchy levels
 */
export enum DicomLevel {
  STUDY = 1,
  SERIES = 2,
  INSTANCE = 3
}

export interface GeneratorConfig {
  root?: string;
  deviceId?: string;
  softwareVersion?: string;
}

export class DicomUidGenerator {
  private readonly root: string;
  private readonly deviceId: string;
  private readonly swVersion: string;
  private lastTimestamp: string = "";
  private counter: number = 0;

  constructor(config: GeneratorConfig = {}) {
    this.root = config.root || "2.25";
    this.deviceId = (config.deviceId || "1").replace(/\D/g, "");
    this.swVersion = (config.softwareVersion || "1").replace(/\D/g, "");
  }

  /**
   * Method 2.25: Generation via UUID
   */
  public generateFromRandom(): string {
    const buffer = crypto.randomBytes(16);
    const decimalValue = BigInt("0x" + buffer.toString("hex"));
    return this.finalize(`2.25.${decimalValue.toString()}`);
  }

  /**
   * Structured Method: For those who own a registered Root
   */
  public generateStructured(level: DicomLevel): string {
    if (this.root === "2.25") {
      throw new Error("ISO/ANSI Root required for structured generation.");
    }

    const timestamp = this.getDicomTimestamp();
    if (timestamp === this.lastTimestamp) {
      this.counter++;
    } else {
      this.lastTimestamp = timestamp;
      this.counter = 0;
    }

    const components = [
      this.root,
      this.deviceId,
      this.swVersion,
      level,
      timestamp,
      this.counter
    ];
    return this.finalize(components.join("."));
  }

  private getDicomTimestamp(): string {
    const now = new Date();
    return [
      now.getFullYear(),
      (now.getMonth() + 1).toString().padStart(2, "0"),
      now.getDate().toString().padStart(2, "0"),
      now.getHours().toString().padStart(2, "0"),
      now.getMinutes().toString().padStart(2, "0"),
      now.getSeconds().toString().padStart(2, "0"),
      now.getMilliseconds().toString().padStart(3, "0")
    ].join("");
  }

  private finalize(uid: string): string {
    const sanitized = uid
      .split(".")
      .map(part =>
        part.length > 1 && part.startsWith("0") ? part.replace(/^0+/, "") : part
      )
      .join(".");

    if (sanitized.length > 64) {
      throw new Error(`UID Overflow (${sanitized.length} characters).`);
    }

    const dicomRegex = /^(0|[1-9][0-9]*)(\.(0|[1-9][0-9]*))*$/;
    if (!dicomRegex.test(sanitized)) {
      throw new Error("Invalid DICOM syntax.");
    }

    return sanitized;
  }
}